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Review

Isotopes in Archeology: Perspectives on Post-Mortem Alteration and Climate Change

by
Antonio Simonetti
1,* and
Michele R. Buzon
2
1
Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46656, USA
2
Department of Anthropology, Purdue University, West Lafayette, IN 47907, USA
*
Author to whom correspondence should be addressed.
Geosciences 2025, 15(8), 307; https://doi.org/10.3390/geosciences15080307
Submission received: 16 May 2025 / Revised: 25 July 2025 / Accepted: 4 August 2025 / Published: 7 August 2025

Abstract

Isotopic investigations focused on determining the mobility and provenance of ancient human civilizations and sourcing of archeological artifacts continue to gain prominence in archeology. Most studies focus on the premise that the geographic variation in isotope systems of interest (e.g., Sr, Pb, Nd, O) in the natural environment is recorded in both human hard tissues of local individuals and raw materials sourced for artifacts within the same region. The introduction of multi-collection–inductively coupled plasma mass spectrometry (MC-ICP-MS) and laser ablation systems are techniques that consume smaller sample sizes compared to previous mass spectrometric approaches due to their higher ionization efficiency and increased sensitivity. This development has facilitated the isotopic measurement of trace elements present at low abundances (e.g., Pb, Nd, <1-to-low ppm range) particularly in human tooth enamel. Accurate interpretation of any isotope ratio measurement for the proveniencing of such low-abundance samples requires the adequate evaluation of post-mortem diagenetic alteration. A synopsis of practices currently in use for identifying post-mortem alteration in human archeological samples is discussed here. Post-mortem shifts in radiogenic isotope signatures resulting from secondary alteration are distinct from those potentially related to the impact of climate change on the bioavailable budgets for these elements. This topic is of interest to the archeological community and discussed here in the context of Holocene-aged samples from burial sites within the Nile River Valley System, and preferred dust source areas from the neighboring Sahara Desert.

1. Introduction

Over the past decades, the field of archeology has benefited immensely from the chemical and isotopic investigation of biogenic samples such as tooth enamel and bone, which are lifetime recorders of elements (e.g., Sr) that have entered an individual through environmental exposure. Differing rates of the latter depend on several factors such as geography, diet, disease, and social status, which ultimately result in variable concentrations of incorporated trace elements within bone and tooth. Previous chemical and isotopic investigations of archeological samples of interest have been shown, therefore, to be effective in deciphering customs and cultural practices of ancient populations, human residential mobility, and source provenance. For regions of the globe where the isotopic nature of the geologic background has been characterized well, and is sufficiently variable, it is possible to significantly clarify interactions between distinct, ancient societies.
The first isotopic investigations of tooth and bone were primarily restricted to Sr, and there are a significant number of previous isotopic studies documenting the successful application of this technique for anthropological purposes, including the pioneering work to identify immigrants in ancient Maya communities [1,2,3], the North American Southwest and Mexico [4,5,6,7,8], Central Europe [9,10,11,12,13,14,15], Bolivia and Peru [16,17], South Africa [18,19], Roman period mobility in Britain and Europe (e.g., [15,20,21] and the migrations of the Wari, Inca, and Tiwanaku in South America (e.g., [22,23,24,25,26]). The reader is referred to the Supplementary Materials for a more detailed overview of the principles and pertinent background information in relation to describing the mobility and bioavailability of trace elements, namely Sr, Pb, and Nd, in the natural environment, and the application of their corresponding radiogenic isotope systematics in human tooth enamel for the purpose of proveniencing.
The early archeological studies reporting Pb isotope ratios focused on samples characterized by relatively high contents of Pb (10 s to 100 s of ppm) since ratio measurements were carried out predominantly using less sensitive mass spectrometric techniques, such as thermal ionization mass spectrometry (TIMS). For example, Pb isotope ratio examination of archeological artifacts, such as earthenware and pottery covered with Pb-bearing glaze and ceramics were reported [27,28,29]. With the advent of more recent and sensitive techniques, such as multi-collection–inductively coupled mass spectrometry (MC-ICP-MS), which requires less sample size/total analyte for processing and analysis, samples containing lower abundances of Pb were investigated for use as a provenance tool. For example, studies investigating native Cu used in the production of tools such as knives and awls within Indigenous inhabitants of North America [30,31].
Numerous previous human epidemiological studies show that Pb contents in hard tissues such as tooth and bone generally represent a longer-term indicator of several years—e.g., [32,33]. In general, the presence of Pb in human tooth enamel typically reflects a complex interplay between natural and industrial (anthropogenic) sources. In the absence of direct anthropogenic point sources (e.g., Pb paint, leaded gasoline), it is believed that local soil and dust are the main sources of Pb in modern humans [34,35,36,37]. Pb abundance in teeth is roughly an order of magnitude lower (i.e., ~1 to 10 s of ppm; [32,33,38,39,40]) compared to that of Sr. Higher Pb abundances in teeth may be the result of exposure to increased levels of this heavy metal in the environment from either natural or anthropogenic origin. The processing and use of Pb-bearing ore minerals, such as galena (PbS) release heavy metal emissions that can overprint the Pb isotope ratios of the natural environment. This industrial Pb will be characterized by a distinct isotope signature, typically less radiogenic when compared with that of local geology—e.g., [41]. Previous investigations of the Pb isotope composition of atmospheric aerosols and their environmental sample proxies, such as precipitation, snowpack, and lichens indicate that these are region specific worldwide since these are dependent on the source of Pb ores used for anthropogenic activities—e.g., [42,43,44]. Therefore, accurate assessment of the historical Pb usage (for Pb-bearing artifacts, glaze), local geology, and modern industrial activity within a given region of interest must take place to define the Pb isotopic signature of the local environment.
More recent archeological provenance studies have focused on the use of other radiogenic isotope systems, such as Nd [45,46]. As with Sr and Pb, neodymium that originates from the local geology and subsequently transferred to vegetation and water, enters the human body substitutes for Ca in human tooth enamel [47]. Moreover, the biological and physical activities involved in this entire process do not produce any mass dependent fractionation of the Nd isotope ratios [48,49]. Hence, 143Nd/144Nd ratios of unaltered human tooth enamel should reflect those of an individual’s diet and consequently record the isotope signal of the local bioavailable Nd. However, due to the low concentrations of Nd in human hard tissues (<1 ppm; [45]), the biological and physiological functions regulating the distribution and incorporation of Nd in the human body are not fully documented and understood. Neodymium may be considered toxic in large quantities for the human body [47], and it has no specific physiological function in humans [47]. Previous studies indicate that individuals with occupations that involve frequent exposure to REE-bearing dust are characterized by elevated Nd abundances in lung tissues (>50 ppb), urine (>4 ppb) and hair (>160 ppb), which suggests that Nd may enter and be stored within the human body by inhalation or through dermal contact [50,51].
Non-traditional heavy stable isotope systems have also been applied in recent archeological investigations ([52] and references therein). However, this review will not present a thorough examination of the latter since a relatively recent paper [52] reports a detailed summary of the methodologies and synopsis of results. Of note, it was concluded that none of the non-traditional isotopic systems utilized thus far prove very useful for proveniencing since the isotopic ratios reported for archeological samples investigated define either limited ranges in values and/or exhibit significant overlap with their corresponding geological sources [52]. The same can be stated for the recent archeological study reporting 87Sr/86Sr ratios and δ88/86 values for human samples (tooth enamel, bone, cranial fragments) from archeological sites in northern Chile [53]. While the conventional 87Sr86Sr ratios exhibit significant variation, δ88/86 values, which are mass dependent, display much overlap between archeological sites that span hundreds of kilometers in northern Chile [53].
The overall objectives of this review paper are to discuss two topics of importance for archeological investigations into proveniencing based on the chemical and isotopic investigation of samples of human hard tissues, such as tooth enamel. The first topic focuses on the current practices for evaluating post-mortem alteration in human tooth enamel, while the second theme discusses the issue of climate change and its role in possibly altering the radiogenic isotope record (namely Sr) of bioavailable signatures during the past ~7000 years within the Nile River Valley System (NRVS; Figure 1).
Naturally, the two topics are related since prior to the interpretation of any radiogenic isotope result for an archeological sample, it must be determined that the isotope signature represents the original ratio from pristine material. The latter is then used to accurately establish whether individuals are local or immigrants when compared to the isotopic baseline, or signature of the local burial environment based on results from time-equivalent faunal samples. The availability of a significant amount of chemical and isotope data for various types of samples (human and faunal tooth enamel, present-day botanicals) from different time periods, and their proximity to Earth’s largest source of atmospheric mineral dust, the Sahara Desert, renders the NRVS an ideal location for investigating the possible impact of climate change [54,56]. Any investigation that attempts to link recent changes in climatic conditions and its impact on the bioavailable signals of Sr, Nd, and Pb for samples within an archeological site or region of interest requires the following elements (as outlined in [54,56]): 1—Record of the 87Sr/86Sr signals of archeological samples with well constrained time of death; 2—An established temporal evolution of the bioavailable isotope record by comparing the 87Sr/86Sr ratios for archeological samples to their present-day counterparts; and 3—The latter may be assessed by examining the radiogenic isotope signatures of modern-day botanical samples. Moreover, the simultaneous investigation of multiple isotope systems provides an opportunity to better evaluate the possible impact of aeolian/wind-borne contribution during the Holocene within the NRVS.

2. Samples and Methods

The Supplementary Materials contain additional details both in relation to other types of archeological samples investigated in addition to human tooth enamel, and the analytical procedures employed in proveniencing studies.

2.1. Tooth Enamel Preparation and Chemical Procedures

The degree of tooth preservation may be graded using the Enamel Preservation Classification, a scale that ranges from 0 (modern enamel) to 6 for archeological samples in extremely poor state with incomplete mineralization [57]; typically, preservation of archeological samples for elemental and/or isotopic investigation should rate at a minimum as either good (=3) or satisfactory (=4). The latter corresponds to crowns that are essentially fully intact (i.e., not too fragmented), some superficial soil concretions, or evidence of plant abrasion, and possible separation from the underlaying dentine. However, despite the presence of mineralized features, the enamel of the selected samples is generally hard, glossy, and milky-white with only some minor areas of discoloration. Typically, enamel samples are mechanically cleaned and abraded prior to sample digestion and chemical processing to minimize post-mortem contamination.
Detailed laboratory procedures for the preparation and digestion of samples of tooth enamel, faunal, and botanicals have been described in previous studies—e.g., [54,56]. Overall, all analytical protocols employ the use of low blank, ultrapure acids and water and processing in ultraclean (class 1000 or lower) laboratories. Subsequent sample digestion using concentrated nitric and/or hydrofluoric acid with Savillex© Teflon clean beakers and hot plate, samples are processed through ion chromatography columns for the separation of elements of interest (Sr, Nd, Pb) employing well established ion exchange separation procedures. Separated and purified sample aliquots containing the elements of interest are then dried down and dissolved again in 2% HNO3 prior to solution mode MC-ICP-MS analysis.

2.2. Multi-Collection Mass Spectrometry

It is not the intent here to provide a detailed review of the main components for the different types of mass spectrometric instruments that are available to obtain accurate and precise isotope ratios for archeological samples since numerous such assessments have been reported previously—e.g., [58,59]; detailed information is also contained within the Supplementary Materials. Suffice to state that the instrument of choice for isotope analysis is a magnetic sector, multi-collector mass spectrometer, which provides the main advantage (over single collector instruments) of acquisition of multiple ion signals simultaneously. The latter negates any negative effects (less precise and possibly less accurate isotope ratio measurements) caused during acquisition of unstable ion signals using a peak-jumping protocol for single collector instruments. The two principal types of multi-collector (MC), magnetic sector mass spectrometers (MS) currently available are thermal ionization-MS (TIMS) and inductively coupled plasma-MS (MC-ICP-MS), with the main difference pertaining to the method used to introduce the samples into the respective instruments prior to ionization.

3. Post-Mortem Alteration—Methods of Evaluation

Post-mortem alteration of human tooth enamel is believed to be limited due to its dense structure and low amounts of both pore space and organic content (~2%). Thus, tooth enamel will most likely preserve the original isotopic signal of bioavailable Sr and may be employed for mobility and migration studies—e.g., [60]. If post-mortem diagenetic alteration is suspected or has occurred, then it must be assessed correctly prior to isotope analysis since combined post-burial chemical, physical, and biological processes may perturb the original bioavailable Sr, Nd, and Pb isotopic signatures—e.g., [61]. Voids, vacancies, and recrystallization of the hydroxyapatite lattice of tooth enamel may result in the production of secondary minerals, such as brushite (CaHPO4⋅2H2O) or carbonate (CaCO3) and the addition of diagenetic Sr, which will change the original (in vivo) radiogenic isotope signatures [62,63,64,65,66]. For example, Sr and Pb present within groundwater at the burial site may become incorporated within tooth enamel subsequent burial, if the site is prone to periodic flooding, and change the original Pb isotopic signatures, respectively—e.g., [56]. Diagenetic processes that involve groundwater may be accompanied by strong dissolution/recrystallization effects and microbial bioerosion. In arid regions, such as the Nile River Valley System (NRVS; Figure 1), the formation rate of secondary phases is higher relative to that of bacterial corrosion [67,68].
When dealing with a suite of samples, open system behavior such as post-mortem alteration, may be assessed by investigating the presence of linear correlations (mixing lines) between multiple components with characteristic concentrations of the element in question and its corresponding distinct isotope ratios [69]. For example, binary mixing between two endmembers in a plot of 1/(Sr,Pb,Nd) contents vs. their corresponding radiogenic isotope ratios will produce a linear correlation; a closed system will in contrast define a horizontal line on the same plot. Previous studies focused on human tooth enamel for proveniencing have assessed the degree of alteration based on the relative proportions of Sr present in tooth dentine vs. enamel [60]; moreover, samples with either elevated (>250 μg g−1 or ppm) or depleted (<100 μg g−1 or ppm) abundances should be considered doubtful [68]. Dentine is more disposed to post-mortem alteration due to its higher porosity, organic content (~30%), and smaller crystallites [70].
Previous investigations have also employed the Ca/P mass fraction ratio to detect post-mortem alteration of human and animal enamel with those samples that record ratios above the theoretical value of biogenic hydroxyapatite (2.16; [71]), and elevated abundances of various types of trace elements (e.g., V, Fe, Mn, rare earth elements (REEs), Y, Hf, Th, and U [63,72,73,74,75,76,77]. A recent investigation reported the quantity of crustal-derived elements (e.g., Rb) with limited substitution for Ca in biogenic samples at high spatial resolution, such as 85Rb ion signal during laser ablation-MC-ICP-MS analysis of egg shells [78]. The level of Rb enrichment being directly proportional to the degree of alteration subsequent burial.
The accurate evaluation of post-mortem diagenesis may be problematic and has employed different methods; several have been stated above. It is generally accepted that tooth enamel is relatively resistant to diagenetic alteration due to its compact structure and minor organic content (~2%). Therefore, most samples of tooth enamel will preserve their original biogenic radiogenic isotope values, and represent reliable sample material for investigation of the mobility and migration patterns of ancient populations [79,80,81,82,83,84]. In contrast, given that human dentine is more susceptible to diagenesis, its use in relation to archeological migration studies is somewhat controversial [70,80,85,86]. Several approaches for evaluating post-mortem alteration are presented and discussed below; it is recommended that at least one of these be adopted for a subset of samples (at the minimum), especially when beginning a new investigation of a burial site.

3.1. Box and Whisker (BW) Plot

In a previous study of human enamel samples from various burial sites within the NRVS (Tombos, Selib Bahri, Selib 1, Shendi, El-Kurru, Nuri, Old Dongola; n = 90 samples in total; (Figure 2; [54,56,87,88]), the distribution of major and trace elemental abundances was evaluated using BW plots to help identify distinct populations and/or visually identify outliers (i.e., values outside the 1.5 interquartile range-IQR). For comparison, the BW plots also include elemental concentrations for modern (n = 77) and archeological (n = 45) tooth samples [77], which stem from several countries for the modern suite (Europe, North America, Central America, South America, Caribbean, and Africa). Archeological samples originate from pre-historic and early historic Florida sites, the Philippines, and from an early historic site in Peru [89].
Figure 2 displays the mean values and range of abundances for elements (Fe, Mn, Zn, Sr, Nd, and U) deemed highly susceptible to post-mortem alteration for tooth enamel samples reported in previous studies, and those from burial sites within the NRVS that are characterized by varying degrees of alteration [54,56]. The elemental abundances of Mn, Nd, Sr, Zn, and U indicate overlapping/similar contents and ranges for all the tooth enamel samples except for Fe (Figure 2); the abundances of Fe are clearly higher and more scattered in the enamel samples from various NRVS burial sites [54,55,87] compared to modern-day enamel [77] and pristine archeological samples (e.g., Tombos, [88]). Moreover, the U concentrations in the high Sr isotope group enamel samples from El-Kurru (as defined by [56]; Figure 2F) are significantly elevated, which was attributed to post-mortem alteration of enamel by U-bearing groundwater that occurred during burial site flooding events [56]. Thus, based on the data as displayed in the BW plots, the only significant difference between altered and pristine enamel samples are the higher Fe contents in the former.

3.2. Iron Contents as Diagenetic Indicator

Iron is an important dietary trace element that is widespread in the environment, and poorly absorbed by the human body except for iron consumed within red meat [90]. Body iron homeostasis in healthy humans is regulated at the sites of absorption, utilization, and recycling [91], which results in constant abundances of Fe in tooth enamel since tooth formation [92]. Iron contents in modern tooth enamel are low and range from 10 to 104 ppm [77,93,94], and for modern surface enamel vary between 10 and 140 ppm [95,96,97]. In situ examination of surface enamel for archeological teeth using both PIXE (proton induced X-ray emission) and electron microprobe methods indicate Fe levels that are higher than modern counterparts, which was attributed to post-mortem alteration; however, Fe enrichment was restricted to the outer 100 microns of enamel [90]. Iron oxide precipitation in bioapatite subsequent burial has also been reported in other previous studies [98,99]. Post-mortem diagenesis may increase the concentrations of Sr, Zn and Fe in tooth enamel through their absorption from the surrounding environment [100]. The relative contents of trace elements within the pore fluid are important to modeling their inclusion into tooth enamel at individual burial sites, which is a function of the soil composition and local geology [87,100,101]. In addition, results from diffusion and adsorption modeling experiments indicate that a shorter time interval (<100 yr) is required for the leaching of Fe into tooth enamel compared to that for Zn, Sr and Pb (±300 yr), and is not dependent on either the pore fluid concentrations or the type of burial site [100]. Thus, the amount of time required for leaching is about an order of magnitude lower than the age of the samples [100]. Moreover, on the basis of evidence from fossilized teeth, it takes approximately 3000 years for leaching fronts to penetrate to a depth of ~300–400 μm [100]. Hence, this outer portion of tooth enamel should be removed to avoid perturbing the endogenous trace element and isotopic signatures. Thus, it is most likely that post-mortem alteration is restricted to the outer ~100 to 300 μm of tooth enamel, and consequently, a significant portion of the sample will nonetheless retain its endogenous chemical and isotopic signatures. However, the exact relationship/correlation between Fe contents and their corresponding isotopic (87Sr/86Sr) signatures for samples of tooth enamel has not been extensively investigated and is discussed below.

3.3. Maximum Threshold Concentration (MTC) Values

The level of Fe enrichment in archeological tooth enamel samples may also be evaluated by comparison to Fe concentrations in modern-day tooth enamel (i.e., in vivo). The sample elemental concentration (C) is divided by the maximum threshold concentrations (MTC) based on pristine samples equivalent to modern-day enamel, which then yields C/MTC values [77]. The MTC was determined by the addition of the maximum concentration of an element and its corresponding 2-sigma standard deviation based on 77 samples of modern (pristine) tooth enamel from sites worldwide. Thus, archeological enamel samples that record C/MTC values ≤ 1 should represent non-altered samples. Assessing the degree of post-mortem alteration based on C/MTC values is most likely not a 100% full proof approach, especially given these were determined using a single archeological population [77]. For a vast majority of tooth enamel samples from the NRVS, these yield C/MTC values ≤ 1 for most elements, and should therefore denote non-altered tooth enamel and similar to those for their modern-day teeth [87]; in contrast, C/MTC values for V, Fe, and Nd are greater than unity (Figure 3). Hence, samples of enamel characterized by C/MTC values > 1.0 for Fe and Nd possibly combined with anomalous εNd values, i.e., those that are distinct from either the main group of remaining enamel and/or faunal samples from the same region should be considered questionable (Figure 3; [87]).
Tooth enamel that is characterized by elevated Fe-C/MTC values (>1.0), however, does not necessarily imply that the corresponding Sr isotope ratios reflect those acquired after burial. For example, Figure 4 is a diagram that plots Fe-C/MTC values against their corresponding 87Sr/86Sr signatures for tooth enamel samples for various burial sites from the NRVS. Elevated Fe-C/MTC values (>1.0) that are positively correlated with 87Sr/86Sr ratios may most likely be attributed to post-mortem diagenetic alteration given the comparative results shown in Figure 2E. As stated earlier, positive correlations between variable 87Sr/86Sr ratios and their corresponding Sr abundances in human tooth enamel may be attributed to binary mixing of multiple sources of dietary Sr-, e.g., [102]. Tooth enamel samples from the regions of El-Kurru, Detti/Selib, Tombos, Selib Bahri, and Shendi all display vertical arrays in Figure 4, i.e., relatively constant Sr isotope ratios despite being characterized by varying and increasing Fe-C/MTC values. In contrast, tooth enamel samples from El-Kurru, Dongola, and Nuri all display the expected positive correlations between these same two parameters shown in Figure 4 [87]. Thus, these results once again indicate that despite the possible chemical evidences for the occurrence of post-mortem diagenetic alteration of tooth enamel, this does not necessarily preclude that the associated 87Sr/86Sr ratios no longer reflect their original bioavailable Sr isotope signatures.

3.4. Pb Isotope Ratios

Perhaps a more robust approach to evaluating post-mortem alteration involves combined use of both trace element abundances and Pb isotope ratios, such as recently demonstrated for tooth enamel from human remains at El-Kurru, Sudan [56]. Lead ingested into the human body originates predominantly from either natural (soil-derived) and/or anthropogenic (modern industrial activities) sources; overall, the latter is not considered a significant factor in the study of ancient human migration studies given that ancient industrial activity, if present, was not as extensive on a regional/global scale as today. Pb from natural sources (water, soil) at the Earth’s surface may be ingested in variable (generally low, ~0.5 to 0.7 ppm) abundances and characterized by variable isotope ratios that are recorded in teeth [83,101]. Pb concentrations in tooth enamel for prehistoric Native Americans was reported to range between 0.01 ppm and 0.3 ppm [103], whereas Pb abundances of 0.31 ppm characterize the enamel of pre-industrial remains from UK archeological sites [104]. Thus, exposure to solely natural (non-anthropogenic) Pb is associated with lower Pb abundances (sub ppm level) as recorded in human tooth enamel.
In a recent study, the Pb isotope ratios for enamel samples from El-Kurru plot along a mixing line involving radiogenic Pb derived from U-rich groundwater, which interacted with the burial remains during periodic flooding events ([56] Figure 5). However, as stated in an earlier section and by the results shown in Figure 4, the present-day, recorded Sr isotope ratio of tooth enamel will most likely be buffered against post-mortem alteration events since this is dependent on the mass balance of the Sr budget between the original concentration of Sr in the enamel versus that present in the agent of alteration, and the frequency and duration of the alteration event(s).

4. Possible Impact of Climate Change on the Budget of Bioavailable Sr?

4.1. Sources of Bioavailable Sr and Its Uptake by Humans

In relation to climate change processes changing the mass budget of bioavailable Sr in the NRVS region, the content of Sr in aeolian dust is rather low (~25 to 66 ppm) in Saharan dust due to high solubility and removal of Sr (and Ca) from the surface during weathering prior to sediments becoming airborne [105]. Hence, given these low Sr abundances associated with aeolian dust, it is very difficult to modify the Sr isotope composition and mass budget of the local bioavailable Sr. Additionally, the ingestion of fine clay (Si)-hosted Sr from aeolian dust into the human body requires for it to be exchanged and mixed with blood Sr (buffered by bone Sr), and fixed into tooth enamel and mixed with Sr contributions from other food stuff [106,107,108,109]. The latter will dilute the imprint of dust-derived Sr on the time-averaged Sr isotope signal being recorded into the body’s hard tissues. Strontium is also present in rock, soil, minerals, and seawater and is considered one of the essential trace elements (at low abundances of ~10.6 to 12.2 ppm) in the human body [110,111,112], and is incorporated predominantly in human bones (99%) with the remaining 0.7% is located within extracellular fluid [113]. Strontium uptake by humans is derived mainly from the consumption of food and water [114] (Figure S1).
The mean concentration of Sr in agricultural soils is ~240 ppm but may exceed 600 ppm in soils treated with phosphate fertilizer or limestone [115]. The emission of Sr into Earth’s atmosphere may be due to natural processes, such as entrainment of dust particles and their resuspension by wind action. Certain anthropogenic activities will also result in the release of Sr into the atmosphere, such as the processing and grinding of Sr-bearing compounds (e.g., production of cement), burning of coal, use of pyrotechnic devices, and application of phosphate fertilizers [116,117]. Worldwide distribution of Sr also occurs within the natural, aquatic realms of rivers, springs, lakes, and oceans with variable concentrations that is dependent on the local geology.
In the natural environment, plants take up Sr mainly from soil and water via their roots, although its exact nutritional function is not known [118,119]. The various factors that exert a control on the uptake of Sr into plants include: soil moisture, the presence of humus in the upper organic soil horizon, composition of the mineral soil, pH level, presence of other ions, plant and root taxonomy, morphology, physiology, and microorganisms and is discussed in detail in [112]. Plant uptake of Sr occurs mainly in clay and sandy soils characterized by a low organic content; however, the presence of Ca reduces the absorption of Sr by aboveground vegetation [120]. The average Sr concentration in plants is low and ranges between 1 and 169 ppm (average dry weight of 36 ppm; [121]), and compared to roots, leaves absorb very little Sr. The plant distributes its Sr mainly to the leaves and associated fruits, which then become a natural component of food [122]. In general, lower abundances of Sr are found in meat, poultry, potatoes, fruits, milk, and dairy products, whereas cereals, root vegetables, and seafood had higher Sr contents (e.g., 3.7, 3.6, 1.6, and 1.3 ppm for bread, fish, green vegetables, and cereals, respectively; [120]). The main mechanism for the ingestion of Sr by humans is via the consumption of food and water and subsequently processed by the gastrointestinal tract. The daily consumption of Sr is dependent on geographic localities, food types [123,124], and content of Sr in drinking water [125,126,127]. The average, daily intake of Sr worldwide is reported to be approximately 1.5 mg [128]. The human body deposits ~99% of the incorporated Sr in bone, connective tissue, and teeth, and tracks the distribution of calcium [113]. At first, calcium may be substituted by Sr on the bone surface and then exchanging rapidly with Ca in plasma or bone mass [119]. The preferred incorporation of strontium into both bone and tooth structures is attributable mainly to the interaction between Sr2+ and Ca2+ [114].
The Sr isotopic signature of human (diphyodont mammal) tooth enamel, record the 87Sr/86Sr ratios of bioavailable Sr ingested during different early life stages, and reflect those of geological materials found at Earth’s surface systems, such as soil and water that are sourced in large part by underlying bedrock; it can vary significantly at the local scale compared to that of soils, surface water, and organisms due to variation in weathering rates for different minerals, the local soil pH, animal behavior, or possible input from aeolian sources [82,129,130,131]. The sources of Sr and corresponding life histories in many archeological populations are typically poorly understood, and therefore, intra-population variability is not properly evaluated; this may impact the interpretations based on Sr results from tooth–bone or tooth–tooth for delineating local vs. non local samples within an archeological site [106]. One method for carefully evaluating intra- and/or inter-individual variability is by conducting feeding experiments with controlled diet/water Sr inputs and analyses of Sr contents and isotopic compositions—e.g., [106,132].
In recently conducted series of laboratory-controlled feed experiments [106], the Sr isotope compositions of bone and tooth enamel of rodents (Rattus norvegicus- omnivorous feeding rat, Cavia porcellus- herbivorous guinea pig) that were provided food and water with varying 87Sr/86Sr isotope ratios for a period of up to 54 days were investigated. In contrast to human tooth enamel, rodent incisors are ever growing, and therefore, constitute a means for the continuous recording of Sr being incorporated into hard tissue from diet and water sources. Given their scavenging nature and non-migratory behavior, rodent tooth enamel is frequently used as a proxy for determining the average Sr isotope composition of the local, faunal environment of an archeological site. Three different experimental setups were conducted and referred to as 1—Diet Switch, 2—Basic Diets, and 3—Dust Addition, which involved 3 groups of guinea pigs [106]. In relation to the scope of this paper, we will focus solely on the results obtained for the experiment (#3) involving the addition of loess and kaolinite to the guinea pigs’ diet to simulate contribution of atmospheric dust. In this experiment, 3 groups of guinea pigs (6 each) were fed a standard plant pelleted diet for a period of 23 to 29 days both with and without loess and kaolinite; the latter two components contained distinctively higher 87Sr/86Sr compositions (0.71034 and 0.71147, respectively; Figure 6) compared to the standard plant pelleted diet (87Sr/86Sr = 0.70944).
Figure 6 illustrates that the 87Sr/86Sr ratios of the three feeding groups mainly overlap in the apex (oldest) section of the guinea pigs’ incisors. For the middle section of the teeth, the Sr isotope ratios for the 3 groups exhibit more scatter and some overlap with those animals eating the kaolin-laced pellets recording slightly higher 87Sr/86Sr ratios compared to the other 2 groups (Figure 6). For the samples taken at the base (youngest), there is much overlap once again for the 3 groups. Of note, the 87Sr/86Sr ratios progressively decreased relative to the standard pelleted food and verged towards the Sr isotope composition of the drinking water (Figure 6), which suggests that a fraction of the radiogenic Sr from the loess and kaolin was not bioavailable to the rodents. The results clearly indicate that mixing is an important process taking place between the different Sr-bearing experimental components (water, food, and surrogates for atmospheric dust) [106]. However, one can also conclude that the process of incorporating and metabolizing silicate mineral dust components into animals is complex and not a direct cause-and-effect relationship. Additionally, based on their experiments and Sr isotope results, inter-individual variability is generally low and likely does not affect provenance studies; in contrast, intra-population variability was recorded to be <0.001 for 87Sr/86Sr ratios, and lower than previously reported for mammals [106]. In relation to the rodents’ incisors, these exhibited much higher variability such that a complete turnover of isotopic ratios was recorded after 54 days in rats’ incisors, whereas those for guinea pigs still retained inherent isotope signatures from the supplier food in the oldest part of the teeth [106]. Thus, these results must be taken into careful consideration for human provenance investigations that frequently use rodents’ teeth to establish the local bioavailable Sr isotope signature.

4.2. Trace Element Bioavailability and Climate Change

The possible impact of the climate drying during the Holocene within the NRVS has drawn much attention recently within the archeological community. It has been argued that the increased contribution of aeolian material from the neighboring Sahara Desert during the Holocene has significantly impacted the isotope compositions of bioavailable Sr relative to the geological background—e.g., [133]. Consequently, this phenomenon hinders the proveniencing of human remains within the NRVS (Figure 1). For example, higher 87Sr/86Sr ratios at the burial site of Tombos have been attributed to the presence of non-locals during the Egyptian colonial period [134]. Alternatively, it was proposed that dust from the neighboring Sahara overprinted the Sr isotope anthropological record in the NRVS, in particular during the drying climate of the Holocene period [133]. This hypothesis was based on Sr and Nd isotope data for dated floodplain deposits in the Desert Nile, which indicate that the sediment load of the Nile has been dominated by input from the Ethiopian Highlands for much of the Holocene; however, aeolian sediments also had an impact on the valley floor sedimentation. It was postulated therefore that global climate change throughout the Holocene influenced Nile Valley drainage, and hence altered the temporal strontium isotope signatures and impacted the bioarchaeological approaches that assess population mobility using this method. Thus, aeolian wind-borne dust ingested by Egyptians and Nubians may have resulted in a progressive increase in their 87Sr/86Sr values [133].
The Nile River is an effective transport mechanism of lithogenic material over significant distances derived from bedrock that consists of distinctive isotope characteristics. Neighboring the eastern Saharan region, the bedrock and alluvium deposits that are present within and surrounding the NRVS include the volcanic Ethiopian Highlands, Precambrian basement rocks of the Arabian Nubian Shield (ANS) and Saharan Metacraton (SMC), and Phanerozoic sedimentary cover. Crystalline basement rocks (between ~1000 and ~600 million years old) are present within the ANS [135,136], whereas geological units from the SMC represent older cratonic crust that was deformed during the Neoproterozoic (between ~1000 and ~550 million years old, e.g., [137]). The SMC contains mainly felsic medium- to high-grade poly-metamorphic granitoids ([138,139,140] and references therein). Overall, the NRVS region’s varied geology results in a significant range of Sr and Nd isotope compositions, which are as follows: Ethiopian basalts: 0.7030 to 0.7043 and +7 to −1 ‰ [141]; ANS-SMC Precambrian basement: 0.7032 to 0.7089 and +8 to −4 ‰ [142]; Cenozoic marine deposits: 0.7090 to 0.7092 [143]. In the interest of brevity, the main interpretations based on the Sr, Nd, and Pb isotope compositions for various archeological samples from burial sites within the NRVS reported in [54] are summarized in the Supplementary Materials.

4.3. Geochemical and Isotopic Signatures of Preferential Dust Source Areas (PSAs)

Mineral dust plays an important role in Earth’s climate system and contributes to atmospheric aerosol loading thus impacting processes in both terrestrial and oceanic environments—e.g., [144]. Atmospheric dust not only affects the global radiation budget and hydrological cycle, but is also an airborne pollutant with possible harmful consequences on human respiratory and cardiovascular health [145,146]. Extensive geographic areas that are subjected to major atmospheric dust events may be recognized by remote sensing methods that include ultraviolet, infrared, and visible imagery—e.g., [147,148], along with dust source ‘hot spots’—e.g., [149] and established long-range atmospheric circulation patterns [150]. Moreover, aerosol optical depth (AOD) data from the Total Ozone Mapping Spectrometer (TOMS), together with output from atmospheric circulation models provide estimates of the contributions to the total global dust load of various dust producing zones—e.g., [148]. Globally, the northern dust belt (from North Africa through the Arabian Peninsula and into Central Asia) dictates atmospheric dust loading [144]. Additionally, paleoclimate records from the North Atlantic Ocean indicate that the Sahara Desert is the driving force of dust production today, and has also been rhythmically arid and an exporter of dust for a minimum the last 11 million years [151]. Recent advances in the identification of dust emission sources include using Meteosat Second Generation (MSG) and Spinning Enhanced Visible and Infrared Imager (SEVIRI) dust index images to identify dust emission sources every 15 min [152]. The latter technologies provide the means for deciphering dust emission and transport, and permit quantitative mapping of modern dust source activation frequency (DSAF) in North Africa, Western Asia, and the Arabian Peninsula (Figure 7; [152,153]). This multi-prong approach serves to improve knowledge of dust sources and provide a better understanding of the causes in the temporal variability in dust present in paleoclimate archives [154,155,156].
The fingerprinting of dust sources remains problematic since there is a lack of a well-developed source-to-sink understanding of dust circulation patterns, and attempts to use airborne particulate records to decipher past climatic conditions on continents at geological timescales—e.g., [154,159]—because of poorly constrained provenance. Hence, more in-depth knowledge of the mineralogical and chemical properties of dust source regions is required. However, this type of investigation presents logistical challenges given the expanse and working conditions in the field. Previous studies conducted in North Africa report results that are based on non-related sample collections, which may not be the most representative sample of the atmospheric mineral dust—e.g., ([160,161,162] and references therein). Recently, the three main source areas of airborne material within North Africa were established based on the weighted geochemical data for dust source activation frequency [163]. Overall, the geochemical data for unconsolidated sediments from major dust-producing areas are sparse and/or limited [144]. New Sr and Nd radiogenic isotope data were reported for unconsolidated sediments from dust-producing areas in West Asia and combined them with literature data [144]. Moreover, this latter study integrated dust activation data [152,153] to produce a composite dust source activation frequency map centered on the Arabian Peninsula and extending into Western Asia and North Africa (Figure 7B; [144]). Consequently, the estimated Sr and Nd isotope signatures of aeolian material emanating from distinct dust-producing areas were identified across this region based on weighted calculations using dust source activation frequency (DSAF) information ([144] approach adopted from [163]). This DSAF-weighted geochemical approach helped to delineate four main geographically extensive dust producing regions, which are: 1—the Eastern Sahara, 2—the central belt of the Arabian Peninsula, 3—Mesopotamia, and 4—the Sistan-Lut Desert area in Iran (Figure 7).
Within the Eastern Sahara region, the highest DSAFs are located within the Nubian Desert, central Sudan between latitudes 14° N and 22° N with the lowest values occurring in the summer (Figure 7B). The alluvial deposits within this region of the Nubian Desert are responsible for the most active sources of deflatable dust [164], which formed during the past intervals of higher net-precipitation during humid periods (e.g., mid-Holocene African Humid Period; [165]). Atmospheric dust from this region is transported in a northeasterly direction all year round by meso-to micro-scale winds, such as haboobs, which are dust events resulting when cold air outflows from deep convective clouds [144].
Strontium and neodymium isotope data indicate that preferential dust source areas (PSAs) from the Western and Central Sahara are distinct and more radiogenic in Sr and less radiogenic in Nd compared to those from the Eastern Sahara (Figure 8; [144]); the isotope signatures of PSAs for the latter are also distinct compared to those found in the Western Asia and the Arabian Peninsula regions since they are less radiogenic in Sr and more radiogenic in Nd (Figure 8). The marked difference in the radiogenic isotope characteristics between PSAs from Eastern Sahara and the remaining neighboring arid regions is attributed primarily to the overprinting by long-range fluvial transportation of sediments in the Eastern Sahara by the Nile River (Figure 8; [144]).

4.4. Influence of Climate Change?

All the evidences listed above do not support a major contribution of aeolian dust during the Holocene from the neighboring Saharan region towards the bioavailable Sr budget of the NRVS [54]. If the Sr isotope compositions for tooth enamel samples from within the NRVS that cover the past ~7000 years do indeed reflect an increased amount of aeolian dust from the neighboring Saharan desert, the radiogenic isotope ratios should tend to verge towards the compositions outlined for the three PSAs cited above [144]. For example, Figure 9 compares the radiogenic Sr and Nd isotope compositions for the PSAs to those for tooth enamel samples from the NRVS, and these data sets do not overlap. Figure 9 shows that most of the aeolian dust samples from the Eastern Sahara PSA are characterized by 87Sr/86Sr ratios < 0.7066 and are therefore much lower compared to those for NRVS enamel samples. Moreover, Figure 10 (modified from [54]) illustrates their Sr isotope and age data along with those previously reported for a variety of samples (enamel, faunal, and present-day sediments/soil) within the NRVS from previous studies. If aeolian dust from the major PSAs from northern Africa had impacted the budget of bioavailable Sr during the past ~7000 years, then the 87Sr/86Sr signatures of archeological samples from the NRVS should verge towards or overlap with the respective fields for Western/Central or Eastern PSAs, respectively (Figure 9). However, the 87Sr/86Sr ratios for tooth enamel samples from the NRVS region have remained relatively constant during the last ~7000 years (Figure 10), and for each group of samples of similar age, the Sr isotope signatures for tooth enamel overlap with those for their corresponding faunal samples. Also, the Sr isotope compositions for samples of present-day plants overlap with those for older enamel and faunal samples [54]. Again, this result does not support an increase in aeolian material originating from the neighboring Saharan desert in the mass budget of bioavailable Sr incorporated within tooth enamel and faunal samples from the NRVS during the past ~7000 years. Consequently, the results for human tooth enamel shown in Figure 9 define Sr isotope fields that are correlated to the geographic location of their corresponding burial sites, which reflect differences in the local geology and therefore provide important proveniencing information; detailed discussion of the anthropological implications of the data distribution shown in Figure 10 is beyond the scope of this review paper.

5. Summary

The post-mortem alteration of human tooth enamel may indeed reveal physical and chemical evidence indicative of post-burial perturbance. Here, we outlined several approaches that are used to evaluate the degree of post-mortem alteration in human tooth enamel based mainly on trace element abundance. For example, C/MTC values for highly mobile elements (V, Nd, and U) in the burial environment are usually characterized by values > 1.0 for non-modern-day samples of human tooth enamel, which in theory confirms the occurrence of diagenetic alteration. However, these indices are rarely correlated with variable Sr isotope ratios. In the case of iron, increased abundances due to post-mortem alteration are typically confined to the outer few 100s of microns, and thus these outer portions of altered tooth enamel may be mechanically removed prior to sample processing in the lab; however, this does not necessarily guarantee that the enamel sample will be completely alteration-free. In contrast to both the Pb and Nd that are present at low abundances (few ppm or lower) within tooth enamel, Sr concentrations are significantly higher (hundreds of ppm) such that in most of the investigations reported to date, the original, in vivo 87Sr/86Sr signatures are still preserved, rendering their Sr isotopic compositions as effective and reliable tools in proveniencing studies of ancient civilizations.
The comparison of the available Sr and Nd isotopic data for human tooth enamel samples, faunal, and present-day botanical samples spanning ~7000 years of recent history within the NRVS, as well as the radiogenic isotope compositions of aeolian materials from the major dusting-producing regions of the neighboring Saharan Desert, shows the impact of climate change in influencing the historical record can be considered negligible or non-detectable. This interpretation may be explained and attributed to one or a combination of the following features: 1—the assimilation of dust-borne Sr by the human body does not readily occur, especially if it is present in a less ingestible form (e.g., silicate-based rather than in aqueous form or carbonate-based); 2—the aeolian Sr is preferentially leached while airborne or removed from the soil subsequent to its deposition at the surface; 3—the radiogenic contribution from aeolian Saharan dust has yet to impact the bioavailable Sr within the NRVS since this process may take more than the thousands of years represented in the archeological record; 4—as shown in Figure 7B, Saharan dust is blown to the west by the prevailing easterlies (opposite direction to NRVS) during the boreal winter months, and this is dependent on the seasonal position of the Inter-Tropical Convergence Zone (ITCZ; [177] and references therein); and/or 5—it is simply a reflection of the mass budget that is controlled by the relatively high abundances of Sr (hundreds of ppm) in human tooth enamel compared to the much lower concentrations found in aeolian-derived Sr. This feature buffers the former against any climate change-related impacts to the local environment.
Consequently, the conclusions put forward by previous studies based on the Sr isotope compositions of human tooth enamel samples from Egyptian and Nubian sites within the NRVS are valid, and confirm that immigrant Egyptians were present during the Egyptian New Kingdom period (~1450–1050 B.C.) occupation of Nubia [134,166]. Particularly, enamel samples investigated from Tombos, believed to be at the boundary between ancient Nubia and Egypt during a period of rapid governmental change from Egyptian colony to independent Nubian Napatan state (ca. 1400–650 B.C.), provide important information regarding the sociopolitical activities and interactions during the New Kingdom and Napatan periods [166]. During the Early Napatan period leading to the time when Nubia ruled Egypt as the 25th Dynasty, 87Sr/86Sr values indicate that only locals were present at Tombos at this time of development since their isotope compositions are statistically distinct compared to those recorded for the New Kingdom.

Supplementary Materials

The following supporting information on the basic principles of Sr, Nd, and Pb isotope and trace element (Sr, Pb, and Nd) systematics in tooth enamel, samples and analytical methods, multi-collection mass spectrometry, Figure S1: Pathways for the incorporation of Sr into the human body from different sources within the natural environment, and summary of radiogenic isotope results from recent study [54] based on archaeological sites within the NVRS can be downloaded at: https://www.mdpi.com/article/10.3390/geosciences15080307/s1. References [178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197] are cited in the supplementary materials.

Author Contributions

A.S. and M.R.B. contributed to the preparation and writing of this manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

All data reported here are sourced from publicly available publications.

Acknowledgments

We thank William White for the invitation to contribute to this Special Issue of Geosciences. The comments and feedback from three reviewers are greatly appreciated.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Hodell, D.A.; Quinn, R.L.; Brenner, M.; Kamenov, G. Spatial Variation of Strontium Isotopes (87Sr/86Sr) in the Maya Region: A Tool for Tracking Ancient Human Migration. J. Archaeol. Sci. 2004, 31, 585–601. [Google Scholar] [CrossRef]
  2. Wright, L.E. In Search of Yax Nunn Ayiin I: Revisiting the Tikal Project’s Burial 10. Anc. Mesoam. 2005, 16, 89–100. [Google Scholar] [CrossRef]
  3. Wright, L.E. Identifying Immigrants to Tikal, Guatemala: Defining Local Variability in Strontium Isotope Ratios of Human Tooth Enamel. J. Archaeol. Sci. 2005, 32, 555–566. [Google Scholar] [CrossRef]
  4. Ezzo, J.A.; Johnson, C.M.; Price, T.D. Analytical Perspectives on Prehistoric Migration: A Case Study from East-Central Arizona. J. Archaeol. Sci. 1997, 24, 447–466. [Google Scholar] [CrossRef]
  5. Ezzo, J.A.; Price, T.D. Migration, Regional Reorganization, and Spatial Group Composition at Grasshopper Pueblo, Arizona. J. Archaeol. Sci. 2002, 29, 499–520. [Google Scholar] [CrossRef]
  6. Price, T.D.; Johnson, C.M.; Ezzo, J.A.; Ericson, J.; Burton, J.H. Residential Mobility in the Prehistoric Southwest United States: A Preliminary Study Using Strontium Isotope Analysis. J. Archaeol. Sci. 1994, 21, 315–330. [Google Scholar] [CrossRef]
  7. Price, T.D.; Manzanilla, L.; Middleton, W.D. Immigration and the Ancient City of Teotihuacan in Mexico: A Study Using Strontium Isotope Ratios in Human Bone and Teeth. J. Archaeol. Sci. 2000, 27, 903–913. [Google Scholar] [CrossRef]
  8. Price, T.D.; Tiesler, V.; Burton, J.H. Early African Diaspora in Colonial Campeche, Mexico: Strontium Isotopic Evidence. Am. J. Phys. Anthropol. 2006, 130, 485–490. [Google Scholar] [CrossRef]
  9. Bentley, R.A.; Krause, R.; Price, T.D.; Kaufmann, B. Human Mobility at the Early Neolithic Settlement of Vaihingen, Germany: Evidence from Strontium Isotope Analysis. Archaeometry 2003, 45, 471–486. [Google Scholar] [CrossRef]
  10. Bentley, R.A.; Price, T.D.; Stephan, E. Determining the ‘Local’ 87Sr/86Sr Range for Archaeological Skeletons: A Case Study from Neolithic Europe. J. Archaeol. Sci. 2004, 31, 365–375. [Google Scholar] [CrossRef]
  11. Grupe, G.; Price, T.D.; Schröter, P.; Söllner, F.; Johnson, C.M.; Beard, B.L. Mobility of Bell Beaker People Revealed by Strontium Isotope Ratios of Tooth and Bone: A Study of Southern Bavarian Skeletal Remains. Appl. Geochem. 1997, 12, 517–525. [Google Scholar] [CrossRef]
  12. Price, T.D.; Grupe, G.; Schröter, P. Migration in the Bell Beaker Period of Central Europe. Antiquity 1998, 72, 405–411. [Google Scholar] [CrossRef]
  13. Price, T.D.; Bentley, R.A.; Lüning, J.; Gronenborn, D.; Wahl, J. Prehistoric Human Migration in the Linearbandkeramik of Central Europe. Antiquity 2001, 75, 593–603. [Google Scholar] [CrossRef]
  14. Price, T.D.; Knipper, C.; Grupe, G.; Smrcka, V. Strontium Isotopes and Prehistoric Human Migration: The Bell Beaker Period in Central Europe. Eur. J. Archaeol. 2004, 7, 9–40. [Google Scholar] [CrossRef]
  15. Schweissing, M.M.; Grupe, G. Stable Strontium Isotopes in Human Teeth and Bone: A Key to Migration Events of the Late Roman Period in Bavaria. J. Archaeol. Sci. 2003, 30, 1373–1383. [Google Scholar] [CrossRef]
  16. Knudson, K.J.; Price, T.D.; Buikstra, J.E.; Blom, D.E. The Use of Strontium Isotope Analysis to Investigate Tiwanaku Migration and Mortuary Ritual in Bolivia and Peru. Archaeometry 2004, 46, 5–18. [Google Scholar] [CrossRef]
  17. Knudson, K.J.; Tung, T.A.; Nystrom, K.C.; Price, T.D.; Fullagar, P.D. The Origin of the Juch’uypampa Cave Mummies: Strontium Isotope Analysis of Archaeological Human Remains from Bolivia. J. Archaeol. Sci. 2005, 32, 903–913. [Google Scholar] [CrossRef]
  18. Cox, G.; Sealy, J. Investigating Identity and Life Histories: Isotopic Analysis and Historical Documentation of Slave Skeletons Found on the Cape Town Foreshore, South Africa. Int. J. Hist. Archaeol. 1997, 1, 207–224. Available online: https://www.jstor.org/stable/20852885 (accessed on 7 May 2025). [CrossRef]
  19. Sillen, A.; Hall, G.; Armstrong, R. Strontium Calcium Ratios (Sr/Ca) and Strontium Isotopic Ratios (87Sr/86Sr) of Australopithecus Robustus and Homo Sp. from Swartkrans. J. Hum. Evol. 1995, 28, 277–285. [Google Scholar] [CrossRef]
  20. Evans, J.; Stoodley, N.; Chenery, C. A Strontium and Oxygen Isotope Assessment of a Possible Fourth Century Immigrant Population in a Hampshire Cemetery, Southern England. J. Archaeol. Sci. 2006, 33, 265–272. [Google Scholar] [CrossRef]
  21. Chenery, C.; Müldner, G.; Evans, J.; Eckardt, H.; Lewis, M. Strontium and Stable Isotope Evidence for Diet and Mobility in Roman Gloucester, UK. J. Archaeol. Sci. 2010, 37, 150–163. [Google Scholar] [CrossRef]
  22. Knudson, K.J. Tiwanaku Influence in the South Central Andes: Strontium Isotope Analysis and Middle Horizon Migration. Lat. Am. Antiq. 2008, 19, 3–23. [Google Scholar] [CrossRef]
  23. Andrushko, V.A.; Buzon, M.R.; Simonetti, A.; Creaser, R.A. Strontium Isotope Evidence for Prehistoric Migration at Chokepukio, Valley of Cuzco, Peru. Lat. Am. Antiq. 2009, 20, 57–75. [Google Scholar] [CrossRef]
  24. Slovak, N.M.; Paytan, A.; Wiegand, B.A. Reconstructing Middle Horizon Mobility Patterns on the Coast of Peru through Strontium Isotope Analysis. J. Archaeol. Sci. 2009, 36, 157–165. [Google Scholar] [CrossRef]
  25. Turner, B.L.; Kamenov, G.D.; Kingston, J.D.; Armelagos, G.J. Insights into Immigration and Social Class at Machu Picchu, Peru Based on Oxygen, Strontium, and Lead Isotopic Analysis. J. Archaeol. Sci. 2009, 36, 317–332. [Google Scholar] [CrossRef]
  26. Buzon, M.R.; Conlee, C.A.; Simonetti, A.; Bowen, G.J. The Consequences of Wari Contact in the Nasca Region during the Middle Horizon: Archaeological, Skeletal, and Isotopic Evidence. J. Archaeol. Sci. 2012, 39, 2627–2636. [Google Scholar] [CrossRef]
  27. Shortland, A.J. Application of Lead Isotope Analysis to a Wide Range of Late Bronze Age Egyptian Materials. Archaeometry 2006, 48, 657–669. [Google Scholar] [CrossRef]
  28. Iñañez, J.G.; Bellucci, J.J.; Rodríguez-Alegría, E.; Ash, R.; McDonough, W.; Speakman, R.J. Romita Pottery Revisited: A Reassessment of the Provenance of Ceramics from Colonial Mexico by LA-MC-ICP-MS. J. Archaeol. Sci. 2010, 37, 2698–2704. [Google Scholar] [CrossRef]
  29. Schurr, M.R.; Donohue, P.H.; Simonetti, A.; Dawson, E.L. Multi-Element and Lead Isotope Characterization of Early Nineteenth Century Pottery Sherds from Native American and Euro-American Sites. J. Archaeol. Sci. Rep. 2018, 20, 390–399. [Google Scholar] [CrossRef]
  30. Cooper, H.K.; Duke, M.J.M.; Simonetti, A.; Chen, G. Trace Element and Pb Isotope Provenance Analyses of Native Copper in Northwestern North America: Results of a Recent Pilot Study Using INAA, ICP-MS, and LA-MC-ICP-MS. J. Archaeol. Sci. 2008, 35, 1732–1747. [Google Scholar] [CrossRef]
  31. Cooper, H.K.; Simonetti, A. Lead Isotope Analysis of Geological Native Copper: Implications for Archaeological Provenance Research in the North American Arctic and Subarctic. Minerals 2021, 11, 667. [Google Scholar] [CrossRef]
  32. Gulson, B.L. Tooth Analyses of Sources and Intensity of Lead Exposure in Children. Environ. Health Perspect. 1996, 104, 306–312. [Google Scholar] [CrossRef]
  33. Johnston, J.E.; Franklin, M.; Roh, H.; Austin, C.; Arora, M. Lead and Arsenic in Shed Deciduous Teeth of Children Living Near a Lead-Acid Battery Smelter. Environ. Sci. Technol. 2019, 53, 6000–6006. [Google Scholar] [CrossRef]
  34. Kamenov, G.D. High-Precision Pb Isotopic Measurements of Teeth and Environmental Samples from Sofia (Bulgaria): Insights for Regional Lead Sources and Possible Pathways to the Human Body. Environ. Geol. 2008, 55, 669–680. [Google Scholar] [CrossRef]
  35. Laidlaw, M.A.S.; Mielke, H.W.; Filippelli, G.M.; Johnson, D.L.; Gonzales, C.R. Seasonality and Children’s Blood Lead Levels: Developing a Predictive Model Using Climatic Variables and Blood Lead Data from Indianapolis, Indiana, Syracuse, New York, and New Orleans, Louisiana (USA). Environ. Health Perspect. 2005, 113, 793–800. [Google Scholar] [CrossRef] [PubMed]
  36. Mielke, H.W.; Gonzales, C.R.; Powell, E.T.; Laidlaw, M.A.S.; Berry, K.J.; Mielke, P.W.; Egendorf, S.P. The Concurrent Decline of Soil Lead and Children’s Blood Lead in New Orleans. Proc. Natl. Acad. Sci. USA 2019, 116, 22058–22064. [Google Scholar] [CrossRef]
  37. Mielke, H.W.; Reagan, P.L. Soil Is an Important Pathway of Human Lead Exposure. Environ. Health Perspect. 1998, 106 (Suppl. S1), 217–229. [Google Scholar] [CrossRef]
  38. Purchase, N.G.; Fergusson, J.E. Lead in Teeth: The Influence of the Tooth Type and the Sample within a Tooth on Lead Levels. Sci. Total Environ. 1986, 52, 239–250. [Google Scholar] [CrossRef]
  39. Wychowanski, P.; Malkiewicz, K. Evaluation of Metal Ion Concentration in Hard Tissues of Teeth in Residents of Central Poland. BioMed Res. Int. 2017, 2017, 6419709. [Google Scholar] [CrossRef]
  40. Kamenov, G.D.; Krigbaum, J. Pb Isotopes and Human Mobility: Natural, Cultural, or Diagenetic Signal? In Isotopic Proveniencing and Mobility: The Current State of Research; Price, T.D., Ed.; Springer International Publishing: Cham, Switzerland, 2023; pp. 163–185. ISBN 978-3-031-25722-3. [Google Scholar]
  41. Gulson, B.L.; Mizon, K.J.; Law, A.J.; Korsch, M.J.; Davis, J.J.; Howarth, D. Source and Pathways of Lead in Humans from the Broken Hill Mining Community—An Alternative Use of Exploration Methods. Econ. Geol. 1994, 89, 889–908. [Google Scholar] [CrossRef]
  42. Simonetti, A.; Gariépy, C.; Carignan, J. Pb and Sr Isotopic Compositions of Snowpack from Québec, Canada: Inferences on the Sources and Deposition Budgets of Atmospheric Heavy Metals. Geochim. Cosmochim. Acta 2000, 64, 5–20. [Google Scholar] [CrossRef]
  43. Simonetti, A.; Gariépy, C.; Carignan, J. Tracing Sources of Atmospheric Pollution in Western Canada Using the Pb Isotopic Composition and Heavy Metal Abundances of Epiphytic Lichens. Atmos. Environ. 2003, 37, 2853–2865. [Google Scholar] [CrossRef]
  44. Simonetti, A.; Gariépy, C.; Banic, C.M.; Tanabe, R.; Wong, H.K. Pb Isotopic Investigation of Aircraft-Sampled Emissions from the Horne Smelter (Rouyn, Québec): Implications for Atmospheric Pollution in Northeastern North America. Geochim. Cosmochim. Acta 2004, 68, 3285–3294. [Google Scholar] [CrossRef]
  45. Plomp, E.; Von Holstein, I.C.C.; Koornneef, J.M.; Smeets, R.J.; Font, L.; Baart, J.A.; Forouzanfar, T.; Davies, G.R. TIMS Analysis of Neodymium Isotopes in Human Tooth Enamel Using 1013 Ω Amplifiers. J. Anal. At. Spectrom. 2017, 32, 2391–2400. [Google Scholar] [CrossRef]
  46. Plomp, E.; Von Holstein, I.C.C.; Koornneef, J.M.; Smeets, R.J.; Baart, J.A.; Forouzanfar, T.; Davies, G.R. Evaluation of Neodymium Isotope Analysis of Human Dental Enamel as a Provenance Indicator Using 1013 Ω Amplifiers (TIMS). Sci. Justice 2019, 59, 322–331. [Google Scholar] [CrossRef]
  47. Whipkey, C.E.; Capo, R.C.; Chadwick, O.A.; Stewart, B.W. The Importance of Sea Spray to the Cation Budget of a Coastal Hawaiian Soil: A Strontium Isotope Approach. Chem. Geol. 2000, 168, 37–48. [Google Scholar] [CrossRef]
  48. Bowen, G.J. Isoscapes: Spatial Pattern in Isotopic Biogeochemistry. Annu. Rev. Earth Planet. Sci. 2010, 38, 161–187. [Google Scholar] [CrossRef]
  49. Keller, A.T.; Regan, L.A.; Lundstrom, C.C.; Bower, N.W. Evaluation of the Efficacy of Spatiotemporal Pb Isoscapes for Provenancing of Human Remains. Forensic Sci. Int. 2016, 261, 83–92. [Google Scholar] [CrossRef] [PubMed]
  50. Boschetti, C.; Henderson, J.; Evans, J. Mosaic Tesserae from Italy and the Production of Mediterranean Coloured Glass (4th Century BCE–4th Century CE). Part II: Isotopic Provenance. J. Archaeol. Sci. Rep. 2017, 11, 647–657. [Google Scholar] [CrossRef]
  51. Brems, D.; Pauwels, J.; Blomme, A.; Scott, R.B.; Degryse, P. Geochemical Heterogeneity of Sand Deposits and Its Implications for the Provenance Determination of Roman Glass. STAR Sci. Technol. Archaeol. Res. 2015, 1, 115–124. [Google Scholar] [CrossRef]
  52. Stephens, J.A.; Ducea, M.N.; Killick, D.J.; Ruiz, J. Use of Non-Traditional Heavy Stable Isotopes in Archaeological Research. J. Archaeol. Sci. 2021, 127, 105334. [Google Scholar] [CrossRef]
  53. Knudson, K.J.; Torres, C.M.; Pestle, W. Isotopic Analyses in the Andes: From the Macro- to Micro-Scale. In Isotopic Proveniencing and Mobility: The Current State of Research; Price, T.D., Ed.; Springer International Publishing: Cham, Switzerland, 2023; pp. 29–66. ISBN 978-3-031-25722-3. [Google Scholar]
  54. Simonetti, A.; Buzon, M.; Simonetti, S.; Guilbault, K.; Kordofani, M.A.; Miller, N. Assessing the Impact of Holocene Climate Change on Bioavailable Strontium Within the Nile River Valley: Geochemical and Radiogenic Isotope Perspectives. Bioarchaeol. Int. 2023, 7, 3. [Google Scholar] [CrossRef]
  55. Padoan, M.; Garzanti, E.; Harlavan, Y.; Villa, I.M. Tracing Nile Sediment Sources by Sr and Nd Isotope Signatures (Uganda, Ethiopia, Sudan). Geochim. Cosmochim. Acta 2011, 75, 3627–3644. [Google Scholar] [CrossRef]
  56. Simonetti, A.; Buzon, M.R.; Corcoran, L.; Breidenstein, A.M.; Emberling, G. Trace Element and Pb and Sr Isotope Investigation of Tooth Enamel from Archaeological Remains at El-Kurru, Sudan: Evaluating the Role of Groundwater-Related Diagenetic Alteration. Appl. Geochem. 2021, 132, 105068. [Google Scholar] [CrossRef]
  57. Montgomery, J. Lead and Strontium Isotope Compositions of Human Dental Tissues as an Indicator of Ancient Exposure and Population Dynamics. Ph.D. Thesis, University of Bradford, Bradford, UK, 2002. [Google Scholar] [CrossRef]
  58. Price, T.D. An Introduction to Isotopic Proveniencing and Mobility. In Isotopic Proveniencing and Mobility: The Current State of Research; Price, T.D., Ed.; Interdisciplinary Contributions to Archaeology; Springer International Publishing: Cham, Switzerland, 2023; ISBN 978-3-031-25721-6. [Google Scholar]
  59. Longerich, H.P.; Diegor, W. Introduction to Mass Spectrometry. In Laser-Ablation-ICPMS in the Earth Sciences; Short Course Series; Mineralogical Association of Canada: Tornto, ON, Canada, 2008; Volume 29, pp. 1–19. ISBN 0-921294-29-8. [Google Scholar]
  60. Retzmann, A.; Budka, J.; Sattmann, H.; Irrgeher, J.; Prohaska, T. The New Kingdom Population on Sai Island: Application of Sr Isotopes to Investigate Cultural Entanglement in Ancient Nubia. Int. J. Egypt. Archaeol. Relat. Discip. 2019, 29, 355–380. [Google Scholar] [CrossRef]
  61. Wilson, L.; Pollard, A.M. Here Today, Gone Tomorrow? Integrated Experimentation and Geochemical Modeling in Studies of Archaeological Diagenetic Change. Acc. Chem. Res. 2002, 35, 644–651. [Google Scholar] [CrossRef]
  62. Nelson, B.K.; Deniro, M.J.; Schoeninger, M.J.; De Paolo, D.J.; Hare, P.E. Effects of Diagenesis on Strontium, Carbon, Nitrogen and Oxygen Concentration and Isotopic Composition of Bone. Geochim. Cosmochim. Acta 1986, 50, 1941–1949. [Google Scholar] [CrossRef]
  63. Kohn, M.J.; Schoeninger, M.J.; Barker, W.W. Altered States: Effects of Diagenesis on Fossil Tooth Chemistry. Geochim. Cosmochim. Acta 1999, 63, 2737–2747. [Google Scholar] [CrossRef]
  64. Nielsen-Marsh, C.M.; Hedges, R.E.M. Patterns of Diagenesis in Bone I: The Effects of Site Environments. J. Archaeol. Sci. 2000, 27, 1139–1150. [Google Scholar] [CrossRef]
  65. Prohaska, T.; Latkoczy, C.; Schultheis, G.; Teschler-Nicola, M.; Stingeder, G. Investigation of Sr Isotope Ratios in Prehistoric Human Bones and Teeth Using Laser Ablation ICP-MS and ICP-MS after Rb/Sr Separation. J. Anal. At. Spectrom. 2002, 17, 887–891. [Google Scholar] [CrossRef]
  66. Hoppe, K.A.; Koch, P.L.; Furutani, T.T. Assessing the Preservation of Biogenic Strontium in Fossil Bones and Tooth Enamel. Int. J. Osteoarchaeol. 2003, 13, 20–28. [Google Scholar] [CrossRef]
  67. Maurer, A.-F.; Galer, S.J.G.; Knipper, C.; Beierlein, L.; Nunn, E.V.; Peters, D.; Tütken, T.; Alt, K.W.; Schöne, B.R. Bioavailable 87Sr/86Sr in Different Environmental Samples—Effects of Anthropogenic Contamination and Implications for Isoscapes in Past Migration Studies. Sci. Total Environ. 2012, 433, 216–229. [Google Scholar] [CrossRef] [PubMed]
  68. Dudás, F.Ö.; LeBlanc, S.A.; Carter, S.W.; Bowring, S.A. Pb and Sr Concentrations and Isotopic Compositions in Prehistoric North American Teeth: A Methodological Study. Chem. Geol. 2016, 429, 21–32. [Google Scholar] [CrossRef]
  69. Faure, G.; Mensing, T.M. Isotopes: Principles and Applications, 3rd ed.; John Wiley and Sons, Inc.: Hoboken, NJ, USA, 2005. [Google Scholar]
  70. Driessens, F.C.M.; Verbeeck, R.M.H. (Eds.) Biominerals; CRC Press: Boca Raton, FL, USA, 1990; ISBN 978-0-8493-5280-5. [Google Scholar]
  71. Sillen, A. Biogenic and Diagenetic Sr/Ca in Plio-Pleistocene Fossils of the Omo Shungura Formation. Paleobiology 1986, 12, 311–323. [Google Scholar] [CrossRef]
  72. Kohn, M.J.; Moses, R.J. Trace Element Diffusivities in Bone Rule out Simple Diffusive Uptake during Fossilization but Explain in Vivo Uptake and Release. Proc. Natl. Acad. Sci. USA 2013, 110, 419–424. [Google Scholar] [CrossRef]
  73. Trueman, C.N.; Palmer, M.R.; Field, J.; Privat, K.; Ludgate, N.; Chavagnac, V.; Eberth, D.A.; Cifelli, R.; Rogers, R.R. Comparing Rates of Recrystallisation and the Potential for Preservation of Biomolecules from the Distribution of Trace Elements in Fossil Bones. Comptes Rendus Palevol 2008, 7, 145–158. [Google Scholar] [CrossRef]
  74. Koenig, A.E.; Rogers, R.R.; Trueman, C.N. Visualizing Fossilization Using Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry Maps of Trace Elements in Late Cretaceous Bones. Geology 2009, 37, 511–514. [Google Scholar] [CrossRef]
  75. Benson, A.; Kinsley, L.; Willmes, M.; Defleur, A.; Kokkonen, H.; Mussi, M.; Grün, R. Laser Ablation Depth Profiling of U-Series and Sr Isotopes in Human Fossils. J. Archaeol. Sci. 2013, 40, 2991–3000. [Google Scholar] [CrossRef]
  76. Willmes, M.; Kinsley, L.; Moncel, M.-H.; Armstrong, R.A.; Aubert, M.; Eggins, S.; Grün, R. Improvement of Laser Ablation in Situ Micro-Analysis to Identify Diagenetic Alteration and Measure Strontium Isotope Ratios in Fossil Human Teeth. J. Archaeol. Sci. 2016, 70, 102–116. [Google Scholar] [CrossRef]
  77. Kamenov, G.D.; Lofaro, E.M.; Goad, G.; Krigbaum, J. Trace Elements in Modern and Archaeological Human Teeth: Implications for Human Metal Exposure and Enamel Diagenetic Changes. J. Archaeol. Sci. 2018, 99, 27–34. [Google Scholar] [CrossRef]
  78. Bertacchi, A.; Zipkin, A.M.; Giblin, J.; Gordon, G.; Goepfert, T.; Asael, D.; Knudson, K.J. Trace Element Concentrations as Proxies for Diagenetic Alteration in the African Archaeofaunal Record: Implications for Isotope Analysis. J. Archaeol. Sci. Rep. 2024, 53, 104403. [Google Scholar] [CrossRef]
  79. Kyle, J.H. Effect of Post-Burial Contamination on the Concentrations of Major and Minor Elements in Human Bones and Teeth—The Implications for Palaeodietary Research. J. Archaeol. Sci. 1986, 13, 403–416. [Google Scholar] [CrossRef]
  80. Sponheimer, M.; Lee-Thorp, J.A. Alteration of Enamel Carbonate Environments during Fossilization. J. Archaeol. Sci. 1999, 26, 143–150. [Google Scholar] [CrossRef]
  81. Bentley, A.R. Strontium Isotopes from the Earth to the Archaeological Skeleton: A Review. J. Archaeol. Method Theory 2006, 13, 135–187. [Google Scholar] [CrossRef]
  82. Montgomery, J. Passports from the Past: Investigating Human Dispersals Using Strontium Isotope Analysis of Tooth Enamel. Ann. Hum. Biol. 2010, 37, 325–346. [Google Scholar] [CrossRef]
  83. Slovak, N.M.; Paytan, A. Applications of Sr Isotopes in Archaeology. In Handbook of Environmental Isotope Geochemistry; Baskaran, M., Ed.; Springer: Berlin/Heidelberg, Germany, 2012; Volume I, pp. 743–768. ISBN 978-3-642-10637-8. [Google Scholar]
  84. Szostek, K.; Mądrzyk, K.; Cienkosz-Stepańczak, B. Strontium Isotopes as an Indicator of Human Migration—Easy Questions, Difficult Answers. Anthropol. Rev. 2015, 78, 133–156. [Google Scholar] [CrossRef]
  85. Budd, P.; Montgomery, J.; Barreiro, B.; Thomas, R.G. Differential Diagenesis of Strontium in Archaeological Human Dental Tissues. Appl. Geochem. 2000, 15, 687–694. [Google Scholar] [CrossRef]
  86. Copeland, S.R.; Sponheimer, M.; Lee-Thorp, J.A.; le Roux, P.J.; de Ruiter, D.J.; Richards, M.P. Strontium Isotope Ratios in Fossil Teeth from South Africa: Assessing Laser Ablation MC-ICP-MS Analysis and the Extent of Diagenesis. J. Archaeol. Sci. 2010, 37, 1437–1446. [Google Scholar] [CrossRef]
  87. Simonetti, A.; Buzon, M.R.; Guilbault, K.A.; Simonetti, S.S. The Role of Post-Mortem Alteration in Tooth Enamel Revisited: A Combined Strontium Isotope and Geochemical Evaluation. J. Archaeol. Sci. Rep. 2024, 53, 104323. [Google Scholar] [CrossRef]
  88. Simonetti, A.; Buzon, M.R.; Creaser, R.A. In-situ Elemental ad Sr Isotope Investigation of Human Tooth Enamel by Laser Ablation-(MC)-ICP-MS: Successes and Pitfalls. Archaeometry 2008, 50, 371–385. [Google Scholar] [CrossRef]
  89. Lofaro, E.M. Ad Majorem Dei Gloriam: An Isotopic Investigation of Indigenous Lifeways in a Jesuit Church from Early Colonial Huamanga (Ayacucho) Peru. Ph.D. Thesis, University of Florida, Gainesville, FL, USA, 2016. [Google Scholar]
  90. Williams, A.-M.M.; Siegele, R. Iron Deposition in Modern and Archaeological Teeth. Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. At. 2014, 335, 19–23. [Google Scholar] [CrossRef]
  91. Wallace, R.D.; Bargeron, C.T.; Moorhead, D.J.; LaForest, J.H. IveGot1: Reporting and Tracking Invasive Species in Florida. Southeast. Nat. 2016, 15, 51–62. [Google Scholar] [CrossRef]
  92. Brown, C.J.; Chenery, S.R.N.; Smith, B.; Mason, C.; Tomkins, A.; Roberts, G.J.; Sserunjogi, L.; Tiberindwa, J.V. Environmental Influences on the Trace Element Content of Teeth—Implications for Disease and Nutritional Status. Arch. Oral Biol. 2004, 49, 705–717. [Google Scholar] [CrossRef] [PubMed]
  93. Anttila, A.; Anttila, A. Trace-Element Content in the Enamel Surface and in Whole Enamel of Deciduous Incisors by Proton-Induced X-Ray Emission of Children from Rural and Urban Finnish Areas. Arch. Oral Biol. 1987, 32, 713–717. [Google Scholar] [CrossRef]
  94. Arshed, W.; Akanle, O.A.; Spyrou, N.M. The Distribution of Fluorine and Other Elements in Teeth Using Proton Induced Reaction Analysis Techniques. J. Radioanal. Nucl. Chem. 1994, 179, 349–355. [Google Scholar] [CrossRef]
  95. Cutress, T.W. The Inorganic Composition and Solubility of Dental Enamel from Several Specified Population Groups. Arch. Oral Biol. 1972, 17, 93–109. [Google Scholar] [CrossRef]
  96. Preoteasa, E.A.; Preoteasa, E.; Kuczumow, A.; Gurban, D.; Harangus, L.; Grambole, D.; Herrmann, F. Broad-Beam PIXE and µ-PIXE Analysis of Normal and in Vitro Demineralized Dental Enamel. X-Ray Spectrom. 2008, 37, 517–535. [Google Scholar] [CrossRef]
  97. Rautray, T.R.; Das, S.; Rautray, A.C. In Situ Analysis of Human Teeth by External PIXE. Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. At. 2010, 268, 2371–2374. [Google Scholar] [CrossRef]
  98. Jacques, L.; Ogle, N.; Moussa, I.; Kalin, R.; Vignaud, P.; Brunet, M.; Bocherens, H. Implications of Diagenesis for the Isotopic Analysis of Upper Miocene Large Mammalian Herbivore Tooth Enamel from Chad. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2008, 266, 200–210. [Google Scholar] [CrossRef]
  99. Kuczumow, A.; Cukrowska, E.; Stachniuk, A.; Gawęda, R.; Mroczka, R.; Paszkowicz, W.; Skrzypiec, K.; Falkenberg, R.; Backwell, L. Investigation of Chemical Changes in Bone Material from South African Fossil Hominid Deposits. J. Archaeol. Sci. 2010, 37, 107–115. [Google Scholar] [CrossRef]
  100. de Winter, N.J.; Snoeck, C.; Schulting, R.; Fernández-Crespo, T.; Claeys, P. High-Resolution Trace Element Distributions and Models of Trace Element Diffusion in Enamel of Late Neolithic/Early Chalcolithic Human Molars from the Rioja Alavesa Region (North-Central Spain) Help to Separate Biogenic from Diagenetic Trends. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2019, 532, 109260. [Google Scholar] [CrossRef]
  101. Millard, A.; Montgomery, J.; Trickett, M.; Beaumont, J.; Evans, J.; Chenery, S. Childhood Lead Exposure in the British Isles during the Industrial Revolution. In Modern Environments and Human Health; John Wiley & Sons, Ltd.: New York, NY, USA, 2014; pp. 279–299. ISBN 978-1-118-50433-8. [Google Scholar]
  102. Montgomery, J.; Evans, J.A.; Cooper, R.E. Resolving Archaeological Populations with Sr-Isotope Mixing Models. Appl. Geochem. 2007, 22, 1502–1514. [Google Scholar] [CrossRef]
  103. Patterson, C.; Ericson, J.; Manea-Krichten, M.; Shirahata, H. Natural Skeletal Levels of Lead in Homo Sapiens Sapiens Uncontaminated by Technological Lead. Sci. Total Environ. 1991, 107, 205–236. [Google Scholar] [CrossRef] [PubMed]
  104. Budd, P.; Montgomery, J.; Evans, J.; Trickett, M. Human Lead Exposure in England from Approximately 5500 Bp to the 16th Century Ad. Sci. Total Environ. 2004, 318, 45–58. [Google Scholar] [CrossRef] [PubMed]
  105. Abouchami, W.; Näthe, K.; Kumar, A.; Galer, S.J.G.; Jochum, K.P.; Williams, E.; Horbe, A.M.C.; Rosa, J.W.C.; Balsam, W.; Adams, D.; et al. Geochemical and Isotopic Characterization of the Bodélé Depression Dust Source and Implications for Transatlantic Dust Transport to the Amazon Basin. Earth Planet. Sci. Lett. 2013, 380, 112–123. [Google Scholar] [CrossRef]
  106. Weber, M.; Tacail, T.; Lugli, F.; Clauss, M.; Weber, K.; Leichliter, J.; Winkler, D.E.; Mertz-Kraus, R.; Tütken, T. Strontium Uptake and Intra-Population 87Sr/86Sr Variability of Bones and Teeth—Controlled Feeding Experiments With Rodents (Rattus Norvegicus, Cavia Porcellus). Front. Ecol. Evol. 2020, 8, 569940. [Google Scholar] [CrossRef]
  107. Sillen, A.; Hall, G.; Richardson, S.; Armstrong, R. 87Sr/86Sr Ratios in Modern and Fossil Food-Webs of the Sterkfontein Valley: Implications for Early Hominid Habitat Preference. Geochim. Cosmochim. Acta 1998, 62, 2463–2473. [Google Scholar] [CrossRef]
  108. Price, T.D.; Burton, J.H.; Bentley, R.A. The Characterization of Biologically Available Strontium Isotope Ratios for the Study of Prehistoric Migration. Archaeometry 2002, 44, 117–135. [Google Scholar] [CrossRef]
  109. Frei, K.M.; Frei, R. The Geographic Distribution of Strontium Isotopes in Danish Surface Waters—A Base for Provenance Studies in Archaeology, Hydrology and Agriculture. Appl. Geochem. 2011, 26, 326–340. [Google Scholar] [CrossRef]
  110. Varo, P.; Saari, E.; Paaso, A.; Koivistoinen, P. Strontium in Finnish Foods. Int. J. Vitam. Nutr. Res. 1982, 52, 342–350. [Google Scholar]
  111. Piette, M.; Desmet, B.; Dams, R. Determination of Strontium in Human Whole Blood by ICP-AES. Sci. Total Environ. 1994, 141, 269–273. [Google Scholar] [CrossRef]
  112. Wang, S.; Sun, J.; Gu, L.; Wang, Y.; Du, C.; Wang, H.; Ma, Y.; Wang, L. Association of Urinary Strontium with Cardiovascular Disease Among the US Adults: A Cross-Sectional Analysis of the National Health and Nutrition Examination Survey. Biol. Trace Elem. Res. 2023, 201, 3583–3591. [Google Scholar] [CrossRef]
  113. Cai, Z.; Li, Y.; Song, W.; He, Y.; Li, H.; Liu, X. Anti-Inflammatory and Prochondrogenic In Situ-Formed Injectable Hydrogel Crosslinked by Strontium-Doped Bioglass for Cartilage Regeneration. ACS Appl. Mater. Interfaces 2021, 13, 59772–59786. [Google Scholar] [CrossRef] [PubMed]
  114. Marie, P.J.; Ammann, P.; Boivin, G.; Rey, C. Mechanisms of Action and Therapeutic Potential of Strontium in Bone. Calcif. Tissue Int. 2001, 69, 121–129. [Google Scholar] [CrossRef] [PubMed]
  115. Bohn, H.L.; McNeal, B.L.; O’Connor, G.A. Soil Chemistry; John Wiley & Sons: New York, NY, USA, 1979; ISBN 978-0-471-04082-8. [Google Scholar]
  116. Feng, J.; Yu, H.; Su, X.; Liu, S.; Li, Y.; Pan, Y.; Sun, J.-H. Chemical Composition and Source Apportionment of PM2.5 during Chinese Spring Festival at Xinxiang, a Heavily Polluted City in North China: Fireworks and Health Risks. Atmos. Res. 2016, 182, 176–188. [Google Scholar] [CrossRef]
  117. Pathak, P.; Srivastava, R.R.; Ojasvi. Assessment of Legislation and Practices for the Sustainable Management of Waste Electrical and Electronic Equipment in India. Renew. Sustain. Energy Rev. 2017, 78, 220–232. [Google Scholar] [CrossRef]
  118. Hara, T.; Furuta, T.; Sonoda, Y.; Iwai, I. Growth Response of Cabbage Plants to Beryllium and Strontium under Water Culture Conditions. Soil Sci. Plant Nutr. 1977, 23, 373–380. [Google Scholar] [CrossRef]
  119. Reynolds, A.C.; Quade, J.; Betancourt, J.L. Strontium Isotopes and Nutrient Sourcing in a Semi-Arid Woodland. Geoderma 2012, 189–190, 574–584. [Google Scholar] [CrossRef]
  120. Ru, X.; Yang, L.; Shen, G.; Wang, K.; Xu, Z.; Bian, W.; Zhu, W.; Guo, Y. Microelement Strontium and Human Health: Comprehensive Analysis of the Role in Inflammation and Non-Communicable Diseases (NCDs). Front. Chem. 2024, 12, 1367395. [Google Scholar] [CrossRef]
  121. Russell, R.S.; Squire, H.M. The Absorption and Distribution of Strontium in Plants: I. Preliminary Studies in Water Culture. J. Exp. Bot. 1958, 9, 262–276. [Google Scholar] [CrossRef]
  122. Qi, L.; Qin, X.; Li, F.-M.; Siddique, K.H.M.; Brandl, H.; Xu, J.; Li, X. Uptake and Distribution of Stable Strontium in 26 Cultivars of Three Crop Species: Oats, Wheat, and Barley for Their Potential Use in Phytoremediation. Int. J. Phytoremediation 2015, 17, 264–271. [Google Scholar] [CrossRef]
  123. Lv, J.; Wang, W.; Krafft, T.; Li, Y.; Zhang, F.; Yuan, F. Effects of Several Environmental Factors on Longevity and Health of the Human Population of Zhongxiang, Hubei, China. Biol. Trace Elem. Res. 2011, 143, 702–716. [Google Scholar] [CrossRef]
  124. Liu, Y.; Yuan, Y.; Luo, K. Regional Distribution of Longevity Population and Elements in Drinking Water in Jiangjin District, Chongqing City, China. Biol. Trace Elem. Res. 2018, 184, 287–299. [Google Scholar] [CrossRef] [PubMed]
  125. Curzon, M.E.J.; Spector, P.C.; Iker, H.P. An Association between Strontium in Drinking Water Supplies and Low Caries Prevalence in Man. Arch. Oral Biol. 1978, 23, 317–321. [Google Scholar] [CrossRef] [PubMed]
  126. Fraga, C.G. Relevance, Essentiality and Toxicity of Trace Elements in Human Health. Mol. Aspects Med. 2005, 26, 235–244. [Google Scholar] [CrossRef] [PubMed]
  127. Li, X.; Liu, Z.; Yao, Y.; Liu, Y.; Guo, D.; Ju, W.; Wu, G.; Li, Z.; Gao, X. Comparison of the Mineral Elements in Drinking Water between Mengshan Longevity District and Jinan City. Trace Elem. Electrolytes 2016, 33, 116–119. [Google Scholar] [CrossRef]
  128. Pors Nielsen, S. The Biological Role of Strontium. Bone 2004, 35, 583–588. [Google Scholar] [CrossRef]
  129. Stewart, B.W.; Capo, R.C.; Chadwick, O.A. Quantitative Strontium Isotope Models for Weathering, Pedogenesis and Biogeochemical Cycling. Geoderma 1998, 82, 173–195. [Google Scholar] [CrossRef]
  130. Chadwick, O.A.; Derry, L.A.; Vitousek, P.M.; Huebert, B.J.; Hedin, L.O. Changing Sources of Nutrients during Four Million Years of Ecosystem Development. Nature 1999, 397, 491–497. [Google Scholar] [CrossRef]
  131. Capo, R.C.; Stewart, B.W.; Chadwick, O.A. Strontium Isotopes as Tracers of Ecosystem Processes: Theory and Methods. Geoderma 1998, 82, 197–225. [Google Scholar] [CrossRef]
  132. Lewis, J.; Pike, A.W.G.; Coath, C.D.; Evershed, R.P. Strontium Concentration, Radiogenic (87Sr/86Sr) and Stable (δ88Sr) Strontium Isotope Systematics in a Controlled Feeding Study. STAR Sci. Tech. Archaeol. Res. 2017, 3, 45–57. [Google Scholar] [CrossRef]
  133. Woodward, J.; Macklin, M.; Fielding, L.; Millar, I.; Spencer, N.; Welsby, D.; Williams, M. Shifting Sediment Sources in the World’s Longest River: A Strontium Isotope Record for the Holocene Nile. Quat. Sci. Revi. 2015, 130, 124–140. [Google Scholar] [CrossRef]
  134. Buzon, M.R.; Simonetti, A.; Creaser, R.A. Migration in the Nile Valley during the New Kingdom Period: A Preliminary Strontium Isotope Study. J. Archaeol. Sci. 2007, 34, 1391–1401. [Google Scholar] [CrossRef]
  135. Abdel Rahman, E.M. Geochemical and geotectonic controls of the metallogenic evolution of selected ophiolite complexes from the Sudan. In Berliner Geowissenschaftliche Abhandlungen; Reihe A, Geologie und Paläontologie; Selbstverlag Fachbereich Geowissenschaften FU Berlin: Berlin, Germany, 1993; Volume 145, p. 187. [Google Scholar] [CrossRef]
  136. Abdelsalam, M.G.; Stern, R.J.; Copeland, P.; Elfaki, E.M.; Elhur, B.; Ibrahim, F.M. The Neoproterozoic Keraf Suture in NE Sudan: Sinistral Transpression along the Eastern Margin of West Gondwana. J. Geol. 1998, 106, 133–148. [Google Scholar] [CrossRef]
  137. Küster, D.; Liégeois, J.-P., Sr. Nd Isotopes and Geochemistry of the Bayuda Desert High-Grade Metamorphic Basement (Sudan): An Early Pan-African Oceanic Convergent Margin, Not the Edge of the East Saharan Ghost Craton? Precambrian Res. 2001, 109, 1–23. [Google Scholar] [CrossRef]
  138. Barth, H.; Meinhold, D.K. Mineral prospecting in the Bayuda Desert. In Investigation of Mineral Potential; Technical Report Sudanese-German Exploration Project; Bundesanstalt für Geowissenschaften und Rohstoffe: Hannover, Germany, 1979; Part 1, Volume A. [Google Scholar]
  139. Küster, D.; Liégeois, J.-P.; Matukov, D.; Sergeev, S.; Lucassen, F. Zircon Geochronology and Sr, Nd, Pb Isotope Geochemistry of Granitoids from Bayuda Desert and Sabaloka (Sudan): Evidence for a Bayudian Event (920–900Ma) Preceding the Pan-African Orogenic Cycle (860–590Ma) at the Eastern Boundary of the Saharan Metacraton. Precambrian Res. 2008, 164, 16–39. [Google Scholar] [CrossRef]
  140. Evuk, D.; Franz, G.; Frei, D.; Lucassen, F. The Neoproterozoic Evolution of the Central-Eastern Bayuda Desert (Sudan). Precambrian Res. 2014, 240, 108–125. [Google Scholar] [CrossRef]
  141. Pik, R.; Deniel, C.; Coulon, C.; Yirgu, G.; Marty, B. Isotopic and Trace Element Signatures of Ethiopian Flood Basalts: Evidence for Plume–Lithosphere Interactions. Geochim. Cosmochim. Acta 1999, 63, 2263–2279. [Google Scholar] [CrossRef]
  142. Evuk, D.; Lucassen, F.; Franz, G. Lead Isotope Evolution across the Neoproterozoic Boundary between Craton and Juvenile Crust, Bayuda Desert, Sudan. J. Afr. Earth Sci. 2017, 135, 72–81. [Google Scholar] [CrossRef]
  143. Reinhardt, E.G.; Jean Stanley, D.; Timothy Patterson, R. Strontium Isotopic-Paleontological Method as a High-Resolution Paleosalinity Tool for Lagoonal Environments. Geology 1998, 26, 1003–1006. [Google Scholar] [CrossRef]
  144. Kunkelova, T.; Crocker, A.J.; Jewell, A.M.; Breeze, P.S.; Drake, N.A.; Cooper, M.J.; Milton, J.A.; Hennen, M.; Shahgedanova, M.; Petraglia, M.; et al. Dust Sources in Westernmost Asia Have a Different Geochemical Fingerprint to Those in the Sahara. Quat. Sci. Rev. 2022, 294, 107717. [Google Scholar] [CrossRef]
  145. Khaniabadi, Y.O.; Daryanoosh, S.M.; Amrane, A.; Polosa, R.; Hopke, P.K.; Goudarzi, G.; Mohammadi, M.J.; Sicard, P.; Armin, H. Impact of Middle Eastern Dust Storms on Human Health. Atmos. Polluction Res. 2017, 8, 606–613. [Google Scholar] [CrossRef]
  146. Tam, W.W.; Wong, T.W.; Wong, A.H.; Hui, D.S. Effect of Dust Storm Events on Daily Emergency Admissions for Respiratory Diseases. Respirology 2012, 17, 143–148. [Google Scholar] [CrossRef] [PubMed]
  147. Prospero, J.M.; Ginoux, P.; Torres, O.; Nicholson, S.E.; Gill, T.E. Environmental Characterization of Global Sources of Atmospheric Soil Dust Identified with the Nimbus 7 Total Ozone Mapping Spectrometer (Toms) Absorbing Aerosol Product. Rev. Geophys. 2002, 40, 1002. [Google Scholar] [CrossRef]
  148. Ginoux, P.; Prospero, J.M.; Torres, O.; Chin, M. Long-Term Simulation of Global Dust Distribution with the GOCART Model: Correlation with North Atlantic Oscillation. Environ. Model. Softw. 2004, 19, 113–128. [Google Scholar] [CrossRef]
  149. Washington, R.; Todd, M.; Middleton, N.J.; Goudie, A.S. Dust-Storm Source Areas Determined by the Total Ozone Monitoring Spectrometer and Surface Observations. Ann. Assoc. Am. Geogr. 2003, 93, 297–313. [Google Scholar] [CrossRef]
  150. Kaufman, Y.J.; Koren, I.; Remer, L.A.; Rosenfeld, D.; Rudich, Y. The Effect of Smoke, Dust, and Pollution Aerosol on Shallow Cloud Development over the Atlantic Ocean. Proc. Natl. Acad. Sci. USA 2005, 102, 11207–11212. [Google Scholar] [CrossRef]
  151. Crocker, A.J.; Naafs, B.D.A.; Westerhold, T.; James, R.H.; Cooper, M.J.; Röhl, U.; Pancost, R.D.; Xuan, C.; Osborne, C.P.; Beerling, D.J.; et al. Astronomically Controlled Aridity in the Sahara since at Least 11 Million Years Ago. Nat. Geosci. 2022, 15, 671–676. [Google Scholar] [CrossRef]
  152. Schepanski, K.; Tegen, I.; Macke, A. Comparison of Satellite Based Observations of Saharan Dust Source Areas. Remote Sens. Environ. 2012, 123, 90–97. [Google Scholar] [CrossRef]
  153. Hennen, M. Characterisation of Mineral Dust Emission in the Middle East Using Remote Sensing Techniques; University of Reading: Reading, UK, 2017. [Google Scholar]
  154. Clemens, S.C.; Murray, D.W.; Prell, W.L. Nonstationary Phase of the Plio-Pleistocene Asian Monsoon. Science 1996, 274, 943–948. [Google Scholar] [CrossRef]
  155. Kutuzov, S.; Legrand, M.; Preunkert, S.; Ginot, P.; Mikhalenko, V.; Shukurov, K.; Poliukhov, A.; Toropov, P. The Elbrus (Caucasus, Russia) Ice Core Record—Part 2: History of Desert Dust Deposition. Atmos. Chem. Phys. 2019, 19, 14133–14148. [Google Scholar] [CrossRef]
  156. Vaks, A.; Woodhead, J.; Bar-Matthews, M.; Ayalon, A.; Cliff, R.A.; Zilberman, T.; Matthews, A.; Frumkin, A. Pliocene–Pleistocene Climate of the Northern Margin of Saharan–Arabian Desert Recorded in Speleothems from the Negev Desert, Israel. Earth Planet. Sci. Lett. 2013, 368, 88–100. [Google Scholar] [CrossRef]
  157. Inness, A.; Ades, M.; Agustí-Panareda, A.; Barré, J.; Benedictow, A.; Blechschmidt, A.-M.; Dominguez, J.J.; Engelen, R.; Eskes, H.; Flemming, J.; et al. The CAMS Reanalysis of Atmospheric Composition. Atmos. Chem. Phys. 2019, 19, 3515–3556. [Google Scholar] [CrossRef]
  158. Breeze, P.S.; Drake, N.A.; Groucutt, H.S.; Parton, A.; Jennings, R.P.; White, T.S.; Clark-Balzan, L.; Shipton, C.; Scerri, E.M.L.; Stimpson, C.M.; et al. Remote Sensing and GIS Techniques for Reconstructing Arabian Palaeohydrology and Identifying Archaeological Sites. Quat. Int. 2015, 382, 98–119. [Google Scholar] [CrossRef]
  159. deMenocal, P.B. African Climate Change and Faunal Evolution during the Pliocene–Pleistocene. Earth Planet. Sci. Lett. 2004, 220, 3–24. [Google Scholar] [CrossRef]
  160. Palchan, D.; Stein, M.; Almogi-Labin, A.; Erel, Y.; Goldstein, S.L. Dust Transport and Synoptic Conditions over the Sahara–Arabia Deserts during the MIS6/5 and 2/1 Transitions from Grain-Size, Chemical and Isotopic Properties of Red Sea Cores. Earth Planet. Sci. Lett. 2013, 382, 125–139. [Google Scholar] [CrossRef]
  161. Scheuvens, D.; Schütz, L.; Kandler, K.; Ebert, M.; Weinbruch, S. Bulk Composition of Northern African Dust and Its Source Sediments—A Compilation. Earth Sci. Rev. 2013, 116, 170–194. [Google Scholar] [CrossRef]
  162. Skonieczny, C.; Bory, A.; Bout-Roumazeilles, V.; Abouchami, W.; Galer, S.J.G.; Crosta, X.; Diallo, A.; Ndiaye, T.A. Three-Year Time Series of Mineral Dust Deposits on the West African Margin: Sedimentological and Geochemical Signatures and Implications for Interpretation of Marine Paleo-Dust Records. Earth Planet. Sci. Lett. 2013, 364, 145–156. [Google Scholar] [CrossRef]
  163. Jewell, A.M.; Drake, N.; Crocker, A.J.; Bakker, N.L.; Kunkelova, T.; Bristow, C.S.; Cooper, M.J.; Milton, J.A.; Breeze, P.S.; Wilson, P.A. Three North African Dust Source Areas and Their Geochemical Fingerprint. Earth Planet. Sci. Lett. 2021, 554, 116645. [Google Scholar] [CrossRef]
  164. Bakker, N.L.; Drake, N.A.; Bristow, C.S. Evaluating the Relative Importance of Northern African Mineral Dust Sources Using Remote Sensing. Atmos. Chem. Phys. 2019, 19, 10525–10535. [Google Scholar] [CrossRef]
  165. Tierney, J.E.; Lewis, S.C.; Cook, B.I.; LeGrande, A.N.; Schmidt, G.A. Model, Proxy and Isotopic Perspectives on the East African Humid Period. Earth Planet. Sci. Lett. 2011, 307, 103–112. [Google Scholar] [CrossRef]
  166. Buzon, M.R.; Simonetti, A. Strontium Isotope (87 Sr/86 Sr) Variability in the Nile Valley: Identifying Residential Mobility during Ancient Egyptian and Nubian Sociopolitical Changes in the New Kingdom and Napatan Periods. Am. J. Phys. Anthropol. 2013, 151, 1–9. [Google Scholar] [CrossRef]
  167. Dominy, N.J.; Ikram, S.; Moritz, G.L.; Wheatley, P.V.; Christensen, J.N.; Chipman, J.W.; Koch, P.L. Mummified Baboons Reveal the Far Reach of Early Egyptian Mariners. eLife 2020, 9, e60860. [Google Scholar] [CrossRef] [PubMed]
  168. Gregoricka, L.A.; Baker, B.J. Residential mobility, pastoralism, and community in ancient Kush. In Proceedings of the Meeting of the American Association of Physical Anthropologists, Baltimore, MD, USA, 7–28 April 2021. [Google Scholar]
  169. Herrick, H. Applying Sr Geoprovenance to anthropogenic charcoal: In theory & practice. In Proceedings of the Frontiers in Archaeological Science, Burnaby, BC, Canada, 27–29 August 2018; Simon Fraser University: Burnaby, BC, Canada, 2018. [Google Scholar]
  170. Kozieradzka-Ogunmakin, I. Chapter 7 Isotope Analysis and Radiocarbon Dating of Human Remains from El-Zuma; Brill: Leiden, The Netherlands, 2021. [Google Scholar]
  171. Maritan, L.; Gravagna, E.; Cavazzini, G.; Zerboni, A.; Mazzoli, C.; Grifa, C.; Mercurio, M.; Mohamed, A.A.; Usai, D.; Salvatori, S. Nile River Clayey Materials in Sudan: Chemical and Isotope Analysis as Reference Data for Ancient Pottery Provenance Studies. Quat. Int. 2023, 657, 50–66. [Google Scholar] [CrossRef]
  172. Osypinska, M.; Osypinski, P.; Belka, Z.; Chlodnicki, M.; Wiktorowicz, P.; Ryndziewicz, R.; Kubiak, M. Wild and Domestic Cattle in the Ancient Nile Valley: Marks of Ecological Change. J. Field Archaeol. 2021, 46, 429–447. [Google Scholar] [CrossRef]
  173. Schrader, S.A.; Buzon, M.R.; Corcoran, L.; Simonetti, A. Intraregional 87Sr/86Sr Variation in Nubia: New Insights from the Third Cataract. J. Archaeol. Sci. Rep. 2019, 24, 373–379. [Google Scholar] [CrossRef]
  174. Stantis, C.; Kharobi, A.; Maaranen, N.; Nowell, G.M.; Bietak, M.; Prell, S.; Schutkowski, H. Who Were the Hyksos? Challenging Traditional Narratives Using Strontium Isotope (87Sr/86Sr) Analysis of Human Remains from Ancient Egypt. PLoS ONE 2020, 15, e0235414. [Google Scholar] [CrossRef]
  175. Stantis, C.; Kharobi, A.; Maaranen, N.; Macpherson, C.; Bietak, M.; Prell, S.; Schutkowski, H. Multi-Isotopic Study of Diet and Mobility in the Northeastern Nile Delta. Archaeol. Anthropol. Sci. 2021, 13, 105. [Google Scholar] [CrossRef]
  176. Touzeau, A.; Blichert-Toft, J.; Amiot, R.; Fourel, F.; Martineau, F.; Cockitt, J.; Hall, K.; Flandrois, J.-P.; Lécuyer, C. Egyptian Mummies Record Increasing Aridity in the Nile Valley from 5500 to 1500yr before Present. Earth Planet. Sci. Lett. 2013, 375, 92–100. [Google Scholar] [CrossRef]
  177. Guinoiseau, D.; Singh, S.P.; Galer, S.J.G.; Abouchami, W.; Bhattacharyya, R.; Kandler, K.; Bristow, C.; Andreae, M.O. Characterization of Saharan and Sahelian Dust Sources Based on Geochemical and Radiogenic Isotope Signatures. Quat. Sci. Rev. 2022, 293, 107729. [Google Scholar] [CrossRef]
  178. Rudnick, R.L.; Fountain, D.M. Nature and Composition of the Continental Crust: A Lower Crustal Perspective. Rev. Geophys. 1995, 33, 267–309. [Google Scholar] [CrossRef]
  179. Faure, G. Principles of Isotope Geology, 2nd ed.; John Wiley and Sons: New York, NY, USA, 1986. [Google Scholar]
  180. Ericson, J.E. Strontium Isotope Characterization in the Study of Prehistoric Human Ecology. J. Hum. Evol. 1985, 14, 503–514. [Google Scholar] [CrossRef]
  181. Gallo, F.; Silvestri, A.; Degryse, P.; Ganio, M.; Longinelli, A.; Molin, G. Roman and Late-Roman Glass from North-Eastern Italy: The Isotopic Perspective to Provenance Its Raw Materials. J. Archaeol. Sci. 2015, 62, 55–65. [Google Scholar] [CrossRef]
  182. Jung, S.J.A.; Davies, G.R.; Ganssen, G.M.; Kroon, D. Stepwise Holocene Aridification in NE Africa Deduced from Dust-Borne Radiogenic Isotope Records. Earth Planet. Sci. Lett. 2004, 221, 27–37. [Google Scholar] [CrossRef]
  183. Tütken, T.; Vennemann, T.W.; Pfretzschner, H.-U. Nd and Sr Isotope Compositions in Modern and Fossil Bones—Proxies for Vertebrate Provenance and Taphonomy. Geochim. Cosmochim. Acta 2011, 75, 5951–5970. [Google Scholar] [CrossRef]
  184. Brill, R.H.; Wampler, J.M. Isotope Studies of Ancient Lead. Am. J. Archaeol. 1967, 71, 63–77. [Google Scholar] [CrossRef]
  185. Sangster, D.F.; Outridge, P.M.; Davis, W.J. Stable Lead Isotope Characteristics of Lead Ore Deposits of Environmental Significance. Environ. Rev. 2000, 8, 115–147. [Google Scholar] [CrossRef]
  186. Mirnejad, H.; Simonetti, A.; Molasalehi, F. Pb Isotopic Compositions of Some Zn–Pb Deposits and Occurrences from Urumieh–Dokhtar and Sanandaj–Sirjan Zones in Iran. Ore Geol. Rev. 2011, 39, 181–187. [Google Scholar] [CrossRef]
  187. Mirnejad, H.; Simonetti, A.; Molasalehi, F. Origin and Formational History of Some Pb-Zn Deposits from Alborz and Central Iran: Pb Isotope Constraints. Int. Geol. Rev. 2015, 57, 463–471. [Google Scholar] [CrossRef]
  188. Samuelsen, J.R.; Potra, A. Biologically Available Pb: A Method for Ancient Human Sourcing Using Pb Isotopes from Prehistoric Animal Tooth Enamel. J. Archaeol. Sci. 2020, 115, 105079. [Google Scholar] [CrossRef]
  189. Cutress, T.W.; Curzon, M.E.J. Trace Elements and Dental Disease. In Postgraduate Dental Handbook Series; J. Wright/PSG Inc.: Littleton, MA, USA, 1983; Volume 9, ISBN 978-0-7236-7035-3. [Google Scholar]
  190. Hinz, E.A.; Kohn, M.J. The Effect of Tissue Structure and Soil Chemistry on Trace Element Uptake in Fossils. Geochim. Cosmochim. Acta 2010, 74, 3213–3231. [Google Scholar] [CrossRef]
  191. Steele, D.G.; Bramblett, C.A. The Anatomy and Biology of the Human Skeleton; Texas A&M University: College Station, TX, USA, 1988. [Google Scholar]
  192. Arends, J.; Ten Cate, J.M. Tooth Enamel Remineralization. J. Cryst. Growth 1981, 53, 135–147. [Google Scholar] [CrossRef]
  193. Kennedy, M.J.; Chadwick, O.A.; Vitousek, P.M.; Derry, L.A.; Hendricks, D.M. Changing Sources of Base Cations during Ecosystem Development, Hawaiian Islands. Geology 1998, 26, 1015. [Google Scholar] [CrossRef]
  194. Vitousek, P.M.; Kennedy, M.J.; Derry, L.A.; Chadwick, O.A. Weathering versus Atmospheric Sources of Strontium in Ecosystems on Young Volcanic Soils. Oecologia 1999, 121, 255–259. [Google Scholar] [CrossRef] [PubMed]
  195. Canadell, J.; Jackson, R.B.; Ehleringer, J.B.; Mooney, H.A.; Sala, O.E.; Schulze, E.-D. Maximum Rooting Depth of Vegetation Types at the Global Scale. Oecologia 1996, 108, 583–595. [Google Scholar] [CrossRef] [PubMed]
  196. Horstwood, M.S.A.; Evans, J.A.; Montgomery, J. Determination of Sr Isotopes in Calcium Phosphates Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry and Their Application to Archaeological Tooth Enamel. Geochim. Cosmochim. Acta 2008, 72, 5659–5674. [Google Scholar] [CrossRef]
  197. Nowell, G.M.; Horstwood, M.S.A. Comments on Richards et al., Journal of Archaeological Science 35, 2008 “Strontium Isotope Evidence of Neanderthal Mobility at the Site of Lakonis, Greece Using Laser-Ablation PIMMS”. J. Archaeol. Sci. 2009, 36, 1334–1341. [Google Scholar] [CrossRef]
Figure 1. (A) A satellite image of the Sahara by NASA WorldWind with red box indicating the location of the NRVS shown in the bottom map. (B) Modified Google Earth map illustrating the locations of the NRVS archeological sites within the NRVS cited here [54]. The letter abbreviations correspond to the following burial sites: A = Askut; AB = Abri; AF = Abu Fatima; AFD = Afad; AK = Al-Khiday; AW = Amara West; D = Dongola sites (El-Detti, Selib Bahri, Selib 1); E-K = El-Kurru; G = Gournah; H = Hannek; KZ = Khozan; N = Nuri; Q = Qurneh; S = Shellal; SH = Shendi/Meroe; SI = Sai Island; SQ = Saqqara; T = Tombos; TED = Tell el-Dab’a; W-H = Wadi Halfa. Inset (top right): Regional geological sketch map modified from [55]. Green shaded areas = Precambrian basement rocks of the Saharan Metacraton (SMC) and Arabian Nubian Shield (ANS), orange shaded areas = Mesozoic and Tertiary sedimentary deposits (mainly sandstone), brick pattern = Paleogene limestone deposits, and areas in white represent regions covered in unconsolidated alluvium deposits. Locations of Cataracts numbers 2 to 6 are also illustrated.
Figure 1. (A) A satellite image of the Sahara by NASA WorldWind with red box indicating the location of the NRVS shown in the bottom map. (B) Modified Google Earth map illustrating the locations of the NRVS archeological sites within the NRVS cited here [54]. The letter abbreviations correspond to the following burial sites: A = Askut; AB = Abri; AF = Abu Fatima; AFD = Afad; AK = Al-Khiday; AW = Amara West; D = Dongola sites (El-Detti, Selib Bahri, Selib 1); E-K = El-Kurru; G = Gournah; H = Hannek; KZ = Khozan; N = Nuri; Q = Qurneh; S = Shellal; SH = Shendi/Meroe; SI = Sai Island; SQ = Saqqara; T = Tombos; TED = Tell el-Dab’a; W-H = Wadi Halfa. Inset (top right): Regional geological sketch map modified from [55]. Green shaded areas = Precambrian basement rocks of the Saharan Metacraton (SMC) and Arabian Nubian Shield (ANS), orange shaded areas = Mesozoic and Tertiary sedimentary deposits (mainly sandstone), brick pattern = Paleogene limestone deposits, and areas in white represent regions covered in unconsolidated alluvium deposits. Locations of Cataracts numbers 2 to 6 are also illustrated.
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Figure 2. Box and Whisker (BW) diagrams that illustrate concentrations (ppm) for various trace elements (A) Mn; (B) Zn; (C) Sr; (D) Nd; (E) Fe; and (F) U for samples of tooth enamel from various sources (described in text). Solid dots and X’s represent abundances for individual samples and mean values for each group, respectively. Data for modern-day and pristine archeological samples are from [77]; pristine samples from Tombos [88]; NRVS are from [54]; altered samples from Nuri and Old Dongola [87]; El-Kurru (high Sr isotope group) from [56].
Figure 2. Box and Whisker (BW) diagrams that illustrate concentrations (ppm) for various trace elements (A) Mn; (B) Zn; (C) Sr; (D) Nd; (E) Fe; and (F) U for samples of tooth enamel from various sources (described in text). Solid dots and X’s represent abundances for individual samples and mean values for each group, respectively. Data for modern-day and pristine archeological samples are from [77]; pristine samples from Tombos [88]; NRVS are from [54]; altered samples from Nuri and Old Dongola [87]; El-Kurru (high Sr isotope group) from [56].
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Figure 3. Diagram is a log plot that displays the average concentration (C) of trace elements for tooth enamel from various burial sites within the NRVS divided by the Mean Threshold Concentration (MTC) values for each element [77]. Shaded field represents the range of trace element abundances (average values plus 1σ standard deviation) for typical, non-altered fossilized tooth enamel [77]. Diagram modified from [87].
Figure 3. Diagram is a log plot that displays the average concentration (C) of trace elements for tooth enamel from various burial sites within the NRVS divided by the Mean Threshold Concentration (MTC) values for each element [77]. Shaded field represents the range of trace element abundances (average values plus 1σ standard deviation) for typical, non-altered fossilized tooth enamel [77]. Diagram modified from [87].
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Figure 4. Plot displays the Sr isotope compositions and associated C/MTC-Fe values for human enamel samples from various archeological sites within the NRVS [54]. Despite being characterized by C/MTC-Fe values that are variable and >1.0, which may be interpreted as indicative of post-mortem alteration, the 87Sr/86Sr ratios for tooth enamel samples from Detti/Selib, Shendi, Tombos, Selib Bahri, and El-Kurru (low group) are, respectively, constant (i.e., define vertical arrays). In contrast, enamel samples from Nuri, Old Dongola, and El-Kurru (high group) do correlate with their corresponding Sr isotope ratios. These results imply that the presence of C/MTC values > 1.0 for human tooth enamel does not necessarily preclude that these will be associated with perturbed 87Sr/86Sr ratio consistent with alteration.
Figure 4. Plot displays the Sr isotope compositions and associated C/MTC-Fe values for human enamel samples from various archeological sites within the NRVS [54]. Despite being characterized by C/MTC-Fe values that are variable and >1.0, which may be interpreted as indicative of post-mortem alteration, the 87Sr/86Sr ratios for tooth enamel samples from Detti/Selib, Shendi, Tombos, Selib Bahri, and El-Kurru (low group) are, respectively, constant (i.e., define vertical arrays). In contrast, enamel samples from Nuri, Old Dongola, and El-Kurru (high group) do correlate with their corresponding Sr isotope ratios. These results imply that the presence of C/MTC values > 1.0 for human tooth enamel does not necessarily preclude that these will be associated with perturbed 87Sr/86Sr ratio consistent with alteration.
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Figure 5. 207Pb/204Pb vs. 206Pb/204Pb plot that shows the Pb isotope ratios for present-day botanical (veg.= vegetation), faunal (sheep, goat, hare, pig), and enamel samples from archeological sites located with the NRVS (Figure 1). These are compared to those for dust samples (solid red circles) from the Bodélé Depression, Sahara Desert [105]. The dashed line with arrow identifies the groundwater-controlled, post-mortem alteration (Pb mixing) trend based on enamel and present-day botanical samples from El-Kurru [56]. The 2σ level uncertainties associated with the isotope ratios are within the size of the symbol (diagram modified from [56]).
Figure 5. 207Pb/204Pb vs. 206Pb/204Pb plot that shows the Pb isotope ratios for present-day botanical (veg.= vegetation), faunal (sheep, goat, hare, pig), and enamel samples from archeological sites located with the NRVS (Figure 1). These are compared to those for dust samples (solid red circles) from the Bodélé Depression, Sahara Desert [105]. The dashed line with arrow identifies the groundwater-controlled, post-mortem alteration (Pb mixing) trend based on enamel and present-day botanical samples from El-Kurru [56]. The 2σ level uncertainties associated with the isotope ratios are within the size of the symbol (diagram modified from [56]).
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Figure 6. Diagram illustrates the Sr isotope results for incisors from guinea pigs fed 3 different diets, standard pellet, and standard pellet with the addition of either loess or kaolin for a period up to 29 days to investigate the addition of atmospheric dust within the food supply (modified from [106]). Apex of tooth represents the oldest segment and base is the youngest. Orange arrow on the left indicates the Sr isotope composition of Zurich tap water (87Sr/86Sr = 0.7091) used in the lab experiments, whereas red and blue arrows show the 87Sr/86Sr ratios of loess- and kaolin-enriched diets, respectively. Horizontal (black) dashed line delineates the Sr isotope composition of the standard pellet diet (0.70944). See text for detailed discussion.
Figure 6. Diagram illustrates the Sr isotope results for incisors from guinea pigs fed 3 different diets, standard pellet, and standard pellet with the addition of either loess or kaolin for a period up to 29 days to investigate the addition of atmospheric dust within the food supply (modified from [106]). Apex of tooth represents the oldest segment and base is the youngest. Orange arrow on the left indicates the Sr isotope composition of Zurich tap water (87Sr/86Sr = 0.7091) used in the lab experiments, whereas red and blue arrows show the 87Sr/86Sr ratios of loess- and kaolin-enriched diets, respectively. Horizontal (black) dashed line delineates the Sr isotope composition of the standard pellet diet (0.70944). See text for detailed discussion.
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Figure 7. Diagrams indicate general wind patterns for Dust Aerosol Optical Depth map at 550 nm from 2020 using Copernicus Atmosphere Monitoring Service (CAMS) global Atmospheric Composition Reanalysis 4 (EAC4) for boreal (A) summer (July) and (B) winter (January; [157]). Higher aerosol abundances are represented by darker shading. Arrows show wind direction at 850 hPa, and the position of the intertropical convergence zone (ITCZ) is shown by the dashed line, and is based on monthly composites from National Oceanic and Atmospheric Administration (NOAA) data accessed from the IRI Climate Data Library. (C) Map of yearly dust source activation frequency (DSAF) for the Eastern Sahara from March 2006 and February 2010 [152,153] superimposed with major river channels (blue) [158]. Higher DSAF % values are represented by darker shades (figure modified from [144]). For ease of reference, the red boxes in all three figures represent the NRVS study area outlined in Figure 1.
Figure 7. Diagrams indicate general wind patterns for Dust Aerosol Optical Depth map at 550 nm from 2020 using Copernicus Atmosphere Monitoring Service (CAMS) global Atmospheric Composition Reanalysis 4 (EAC4) for boreal (A) summer (July) and (B) winter (January; [157]). Higher aerosol abundances are represented by darker shading. Arrows show wind direction at 850 hPa, and the position of the intertropical convergence zone (ITCZ) is shown by the dashed line, and is based on monthly composites from National Oceanic and Atmospheric Administration (NOAA) data accessed from the IRI Climate Data Library. (C) Map of yearly dust source activation frequency (DSAF) for the Eastern Sahara from March 2006 and February 2010 [152,153] superimposed with major river channels (blue) [158]. Higher DSAF % values are represented by darker shades (figure modified from [144]). For ease of reference, the red boxes in all three figures represent the NRVS study area outlined in Figure 1.
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Figure 8. Map shows the weighted means of 87Sr/86Sr and εNd values (and corresponding ± 1σ standard deviation) for unconsolidated surface sediments in preferential source areas (PSAs) of dust generation: Eastern Sahara (purple, [163]), central belt of the Arabian Peninsula (red), Southern Levant (orange) and Mesopotamia (green). Dust map for Eastern Sahara [152], the Arabian Peninsula and SW Asia [153] indicates DSAF (%) of >5% (dark colors) and 1–5% (pale colors). Yellow box outlines NRVS region shown in Figure 1. Diagram modified from [144].
Figure 8. Map shows the weighted means of 87Sr/86Sr and εNd values (and corresponding ± 1σ standard deviation) for unconsolidated surface sediments in preferential source areas (PSAs) of dust generation: Eastern Sahara (purple, [163]), central belt of the Arabian Peninsula (red), Southern Levant (orange) and Mesopotamia (green). Dust map for Eastern Sahara [152], the Arabian Peninsula and SW Asia [153] indicates DSAF (%) of >5% (dark colors) and 1–5% (pale colors). Yellow box outlines NRVS region shown in Figure 1. Diagram modified from [144].
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Figure 9. (A) Plot illustrates εNd values (‰) versus 87Sr/86Sr ratios for human tooth enamel samples (open symbols and Xs) from archeological sites within the NRVS [54] are compared to those for sediments (soil, paleolake, paleoriver, river, and lake; solid green circles) retrieved from the three main PSAs of North Africa (Western, Central, and Eastern Sahara; [163]). The latter represent present-day Nd and Sr isotope compositions of surficial deposits (sediments) and water in this region, which reflect input from atmospheric deposition. The orange box outline represents the section shown at enlarged scale in bottom diagram (B), which indicates minimal overlap between the Nd-Sr isotope fields defined by the NRVS human enamel samples and sediments from the Eastern Sahara PSA [163].
Figure 9. (A) Plot illustrates εNd values (‰) versus 87Sr/86Sr ratios for human tooth enamel samples (open symbols and Xs) from archeological sites within the NRVS [54] are compared to those for sediments (soil, paleolake, paleoriver, river, and lake; solid green circles) retrieved from the three main PSAs of North Africa (Western, Central, and Eastern Sahara; [163]). The latter represent present-day Nd and Sr isotope compositions of surficial deposits (sediments) and water in this region, which reflect input from atmospheric deposition. The orange box outline represents the section shown at enlarged scale in bottom diagram (B), which indicates minimal overlap between the Nd-Sr isotope fields defined by the NRVS human enamel samples and sediments from the Eastern Sahara PSA [163].
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Figure 10. Diagram shows the Time (years before present) versus 87Sr/86Sr ratios for NRVS samples (dated tooth enamel and faunal) compiled from literature data [61,144,166,167,168,169,170,171,172,173,174,175,176] and modified from [54]. The age adopted for a suite of samples from an individual burial site is represented as the middle of the age range reported for the period. The ranges of Sr isotope compositions for the three main PSAs in northern Africa are from [163].
Figure 10. Diagram shows the Time (years before present) versus 87Sr/86Sr ratios for NRVS samples (dated tooth enamel and faunal) compiled from literature data [61,144,166,167,168,169,170,171,172,173,174,175,176] and modified from [54]. The age adopted for a suite of samples from an individual burial site is represented as the middle of the age range reported for the period. The ranges of Sr isotope compositions for the three main PSAs in northern Africa are from [163].
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Simonetti, A.; Buzon, M.R. Isotopes in Archeology: Perspectives on Post-Mortem Alteration and Climate Change. Geosciences 2025, 15, 307. https://doi.org/10.3390/geosciences15080307

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Simonetti A, Buzon MR. Isotopes in Archeology: Perspectives on Post-Mortem Alteration and Climate Change. Geosciences. 2025; 15(8):307. https://doi.org/10.3390/geosciences15080307

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Simonetti, Antonio, and Michele R. Buzon. 2025. "Isotopes in Archeology: Perspectives on Post-Mortem Alteration and Climate Change" Geosciences 15, no. 8: 307. https://doi.org/10.3390/geosciences15080307

APA Style

Simonetti, A., & Buzon, M. R. (2025). Isotopes in Archeology: Perspectives on Post-Mortem Alteration and Climate Change. Geosciences, 15(8), 307. https://doi.org/10.3390/geosciences15080307

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