Search Results (18)

Tree rings record environmental conditions and can serve as long-term biomonitors of urban pollution. This study evaluated the radial growth and chemical composition of Pinus greggii wood in three urban green areas of Mexico City: San Juan de Aragón Park (SJA), Sierra de Guadalupe State Park (GUAD), and Vivero Coyoacán National Park (COY). Tree ring chemical elements were analyzed at annual resolution for the period 2002 to 2022, and their relationships with atmospheric pollutant concentrations, including nitrogen oxides (NO_x), carbon monoxide (CO), ozone (O₃), and particulate matter (PM), of medium size or smaller than 10 µm, including the fractions PM_2.5 and PM₁₀, were assessed using a spatial scaling approach. Elemental concentrations were determined using X-ray fluorescence (XRF). Statistical analyses included analysis of variance (ANOVA), Theil–Sen trend estimation, and Pearson correlation with lag analysis (up to 3 years). The oldest trees were recorded in COY (52 years), while the youngest were recorded in GUAD (13 years). Distinct temporal patterns in elemental concentrations were detected among sites; for instance, peak concentrations of Fe (307 ppm), Cu (11 ppm), and Zn (51 ppm) occurred in GUAD in 2021, while Pb concentrations declined during 2019–2020 across all three sites. Significant correlations (p < 0.05) were identified between Cu, Fe, Zn, and Pb and the atmospheric pollutants (NO_x, PM_2.5, PM₁₀, O₃). Notably, O₃ showed significant positive correlations with Fe at SJA (up to r = 0.80) and GUAD (up to r = 0.46) with lags ranging from 0 to 3 years, suggesting delayed responses between atmospheric pollution and elemental deposition in tree rings. These findings highlight the sensitivity of P. greggii to urban atmospheric pollution and support its potential as a long-term biomonitoring tool, as well as its importance for informing policies aimed at improving air quality and promoting the sustainable management of urban green spaces. Full article

Dendrochemistry was applied to a small town, Taylorville, Illinois, which has a superfund site and apparently more cases of cancer than expected based on background rates. As an ecologic study, dendrochemistry is not intended to unequivocally associate particular elements to specific illnesses, but rather dendrochemistry serves more generally to characterize changes in element availability through time, which then might lead to follow-up epidemiological studies. In Taylorville, multiple elements measured in decadal chunks of tree rings of 12 trees showed no trend though time going back several decades. This non-result is important, demonstrating that element concentrations can remain constant across tree rings. By contrast, multiple other elements showed an uptick in concentration beginning by about 2000. Some of these elements are known to be harmful to human health, while others are not. More broadly, it could be of interest to consider increases through time in multiple metals as a combined burden in public health. Spatially, tree sampling for dendrochemistry is often not dense enough to isolate sources of element availability. Other techniques of environmental monitoring exist for elucidating spatial patterns of elements, and leaf surface chemistry is recommendable as a companion technique for dendrochemistry to discover spatial and temporal environmental patterns. Full article

For dendrochemical research, it may be important to be aware of the effects of stem asymmetry and the intra-ring structure because these may introduce unwanted dispersion in the results. In dendrochemical studies, separate analysis of the elemental content of early- and latewood is rare. Also, explanations of how the elemental content may relate to stem asymmetry originating from conditions at the edges of contrasting environments are largely lacking in these studies. The purpose of the current study was to estimate the impact of the seasonal tree ring structure and stem asymmetry on the distribution of elements in tree stems. The study population was a plantation of Scots pine (Pinus sylvestris L.) at an afforestation experiment area, with the sample trees being at the edge of the stand, causing strong crown asymmetry. Six pine trees were cored through the thickness from the maximal crown side (max-side) to the minimal crown side (min-side), and the cores were subsequently scanned through an Itrax Multiscanner unit. The count rates of aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), calcium (Ca), iron (Fe), copper (Cu), zinc (Zn), and strontium (Sr) in the tree rings from 1990 to 2022 were analyzed. A group of elements (Al, Si, P, S, and Cl) tended to consistently concentrate on the min-side, both in early- and latewood, the difference being most significant for S and Cl. Regarding early- vs. latewood, Al, Si, P, S, Cl, Cu, and Zn always had lower concentration in earlywood than in latewood, while others (Ca, Fe, and Sr) had lower concentrations in latewood, the relations being consistently significant. Overall, the role of the min- or max-side of the stem in allocation of elements appears to have been weaker that the intra-ring structure (early- and latewood). Some elements such as Al, Si, P, S, Cl, and Ca (in latewood) were often more abundant on the min-side; other elements such as Fe and Sr (in latewood) were often more abundant on the max-side, but these relations were significant only on rare occasions. Intra-ring heterogeneity (in early- and latewood) appears to be more decisive than the asymmetry of the tree stem in regard to the distribution of elements in Scots pine xylem. Nevertheless, tree stems with high and obvious asymmetry should be more extensively explored because a possibility remains that extreme asymmetry does impact the allocation of elements. Full article

The release of mercury (Hg) from coal-fired power plants (CPPs) into local ecosystems poses substantial environmental and health hazards. This study was conducted in Chungcheong-nam-do, South Korea, a region featuring over half of the country’s coal power facilities, to estimate the impacts of CPPs on Hg distribution in forest ecosystems. By analyzing Hg concentrations in pine tree rings and soil at 21 locations around CPPs and comparing them to control sites and industrial zones, we present a nuanced understanding of the effects of CPPs on Hg concentration. The analysis of Hg concentrations in tree rings showed a significant decrease in Hg levels as the distance from the power plants increased, suggesting that CPPs primarily influence Hg distribution in trees within a 25 km radius. In contrast, soil Hg concentrations did not exhibit a clear trend. This may reflect the limitations of this study in accounting for the physicochemical properties of the soil at each sampling site. Nevertheless, the Potential Ecological Risk Index for soil Hg contamination indicated a higher risk rating within a 1 km radius of the CPPs compared to other locations. Hg concentrations in tree rings have shown a steady decline since the 1970s, suggesting the positive effects of air pollution regulations. This also highlights the value of tree core samples as effective tools for monitoring historical Hg pollution. Furthermore, the higher historical concentrations of Hg in tree rings imply that trees may have acted as sinks for atmospheric Hg in the past. Full article

This study explored whether consistent differences can be found between early-wood and late-wood in terms of elemental content of tree rings. The species to study was Pinus sylvestris L. growing within an even-aged stand planted during the early 1970s in eastern Siberia. The wood specimens were extracted from the north and south sides of trees and subsequently scanned through an X-ray fluorescent facility Itrax Multiscanner. A sequence of relatively wide tree-rings was chosen for the analysis. The scanning data on a number of elements (Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Sr, and Hg) were split into early-wood and late-wood data for each year of growth. The early- and late-wood data in the same ring were analyzed for basic statistics against each other as well as against available meteorological data. In the northern direction, the elements Al, Si, P, Cl, Cu, and Zn are always more abundant in the late-wood, while Ca, Fe, and Sr are always more abundant in the early-wood. What is important is how the differences for P, Ca, Fe, Cu, Zn, and Sr were always significant. The calcium content in the early-wood was the most consistently reflective regarding the meteorological data for the early summer (June). In some trees, the late-wood K content was well correlated with the Vysotskii–Ivanov climatic index. In the southern direction, Cu and Zn were always more abundant in the late-wood, while Sr was more abundant in the early-wood. The differences for all three elements were always significant. The cases of consistent relationships, though rare, help to develop a research program in the area of dendrochemistry. Full article

Dendrochemistry, the study of elements found within tree rings, has been used to understand environmental changes from both natural and anthropogenic sources. When used appropriately, dendrochemistry can provide a greater understanding of the elemental changes in the environment. However, environmental and species-specific processes have been shown to impact results, and research from the field has been scrutinized due to the need for a greater understanding that role-specific processes such as translocation play. This systematic literature review examines dendrochemistry’s history, highlights how the field has changed, and hypothesizes where it might be headed. From this review, we recommend the following measures: (1) promoting the use of new experimental techniques and methods with faster data acquisition time to allow for a greater number of samples to be processed and included in studies to increase statistical significance; (2) that more studies focus on the two- and three-dimensional space that trees grow in and consider the complex physiological processes occurring in that space and over time and (3) more lab-based studies to reduce the variables that cannot be controlled when sampling in situ. Understanding the challenges and opportunities from the past, present, and future research of dendrochemistry is crucial to the advancement of the field. Full article

Multiproxy reconstructions of fire regimes in forest ecosystems can provide a clearer understanding of past fire activity and circumvent some limitations of single proxy reconstructions. While inferring fire history from scars in trees is the most precise method to reconstruct temporal fire patterns, this method is limited in Araucaria araucana forests by rot after fire injuries, successive fires that destroy the evidence and the prohibition of sample extraction from living Araucaria trees. In this context, dendrochemical studies in Araucaria trees and charcoal analysis from sediment cores can complement and extend the time perspective of the fire history in the relictual Araucaria-Nothofagus forests of the coastal range. We used dendrochemical, fire scar and charcoal records from the Nahuelbuta Coastal Range (37.8° S; 73° W) spanning the last 1000 years to reconstruct the fire history. The results indicate that periods with higher fire activity occurred between 1400 and 1650 AD. Long-term changes in the fire regime are related to increased climate variability over the last 1000 years, and especially with the arrival of settlers to the area after 1860 CE. The most severe fire events in the Nothofagus and Araucaria forests occurred when suitable fire-prone conditions were superimposed with high human densities. Full article

Trees may represent useful long-term monitors of historical trends of atmospheric pollution due to the trace elements stored along the tree rings caused by modifications in the environment during a tree’s life. Chestnut (Castanea sativa Mill.) tree trunk sections were used to document the yearly evolution of atmospheric Hg in the world-class mining district of Monte Amiata (MAMD; Central Italy) and were exploited until 1982. An additional source of Hg emissions in the area have been the active geothermal power plants. A marked decrease (from >200 µg/kg to <100 µg/kg) in Hg contents in heartwood tree rings is recorded, likely because of mine closure; the average contents (tens of µg/kg) in recent years remain higher than in a reference area ~150 km away from the district (average 4.6 µg/kg). Chestnut barks, recording present-day Hg pollution, systematically show higher Hg concentrations than sapwood (up to 394 µg/kg in the mining area). This study shows that tree rings may be a good record of the atmospheric Hg changes in areas affected by mining activity and geothermal plants and can be used as a low-cost biomonitoring method for impact minimization and optimal resource and land management. Full article

In this study, the focus was on evaluating the effects of the initial treatment of wood ash and sewage sludge on hybrid alder clones’ aboveground biomass and elemental content. To measure the element concentrations in the tree rings, laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) was utilized, which is a valuable tool for dendrochemistry research, albeit with some challenges in accurate quantification. One important aspect of the study was the development and comparison of different “in-house” matrix-matched standards for the precise quantification of element concentrations in tree rings. It was found that the commercially available reference materials, IAEA 413 (algae) and IAEA 392 (algae), were the best choices due to their homogeneity. The study also revealed that the use of sewage sludge and wood ash as soil improvers significantly benefited the increase in hybrid alder biomass. However, no significant increase in element content was found in the obtained wood mass, and for some elements, there was a decrease in concentration. Full article

In dendrochemical studies, an analysis of wooden cores extracted from tree stems is a widely spread research method. A methodological problem is related to the method: whether a single core per tree can be representative of all the stems. The study aimed to estimate how the elemental contents are variable in the tree rings and whether the contents correlate among different cores. The cores were extracted from stems of Pinus sylvestris L., four cores per tree, according to the cardinal directions (east, west, north, south). The elemental contents (Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, and Sr) were estimated through the X-ray fluorescent analysis facility Itrax Multiscanner (COX Analytical Systems). The agreement between the temporal series of different cores was estimated through Spearman’s correlation coefficients. It has been found that the temporal intra-tree series for almost all the studied elements do not correlate with each other. The exclusions are Ca and K which show strong consistent correlations. The source for the correlations is, however, the long-term trends from the pith to the bark. The detrending of the Ca and K series reveals some high-frequency correlations which are not consistent among the trees. At least for Scots pine, a single core is unlikely to be a reliable representative of the whole stem in the respect of elemental content. A few research directions to overcome the uncertainty has been discussed. Full article

Rapid industrialization has led to a dramatic increase in air pollution. In China, the factors driving the abundance and composition of smog, particularly fine particulate matter, remain poorly understood, and short-term air pollution data are available from few air quality monitoring networks. Using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), chemical elements (Mg, Al, Si, S, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Tl, Pb, Bi) were analyzed in Quercus mongolica Fisch. ex Ledeb. tree rings from Harbin, China, in latewood at 5-year resolution over the period 1965–2020. The temporal trend of some elements was influenced by physiological factors, by environmental factors such as pollution, or influenced by both. Mg, K, Zn, Cu, Ni, Pb, As, Sr and Tl showed changes in pollution levels over time. The signal of K, Zn, Ni, Cu and Pb in trees from Harbin statistically did not differ from those at the control site after the 2000s. Our analysis confirmed the success of the undertaken emission reduction measures, which lead to an improvement in China’s urban air quality after 2010. However, As increased from 2000 to 2020 in Harbin which is consistent with rising As concentrations in China. Our study proved that dendrochemistry is a reliable tool to monitor the long-term history of pollution and to contribute to extending instrumental records of pollution back in time. Full article

This research documents spatial and temporal patterns of effluent uptake by riparian trees through development of a new and innovative application for dendrochronology, specifically dendrochemistry. The rare-earth element (REE) gadolinium (Gd) is a known micro-pollutant in its anthropogenic form and enters streams from wastewater treatment plants. Anthropogenic Gd was first used in select medical procedures in 1988 and has since been used as a contrast agent for medical imaging. It is naturally flushed from the body following procedures and is subsequently discharged via treatment plants into waterways. Riparian trees that utilize effluent-dominated surface water take up Gd, which then remains in annual growth rings. The year 1988 serves as presence/absence date stamp for Gd in tree rings, thereby making Gd an ideal marker for this dendrochronological study. Results from this study along the Upper Santa Cruz River in southeastern Arizona show levels of Gd in effluent-dominated surface flows to be elevated above the threshold that distinguishes an anthropogenic anomaly from natural Gd_SN abundance in freshwater, thereby confirming that anthropogenic Gd is present. Gd was found in the growth rings of cottonwood trees (Populus fremontii var. arizonica (Sarg.) Jeps.) that are growing in the floodway adjacent to the effluent-dominated portion of the stream. The presence of Gd in cottonwood annual rings confirms that the trees are utilizing effluent over the course of the growing season. Furthermore, temporal patterns of Gd concentrations in trees directly adjacent to the stream may be reflective of high-frequency changes in surface water quality. Information on the impacts of effluent quality on the chemical composition of tree rings can be a useful monitoring tool to evaluate the spatial and temporal patterns of effluent use in riparian trees and to identify high-frequency changes in surface water quality. Full article

Dendrochemistry, the measurement of element concentrations in tree rings for the purpose of assessing temporal changes in chemical environments, was used to study an area in south-central North Carolina, USA, that has experienced higher than expected incidences of a couple human illnesses. A principal objective of applying dendrochemistry around an area with public health problems is to assess the environmental chemistry through time to see if the environmental abundance of any elements has changed recently, which then might inform further research into the possible linkage between those elements and the reported illnesses. Loblolly pine is common in the study area and, therefore, was chosen for sampling. Using acid digestion ICP-MS, decadal chunks of rings were measured for the concentration of multiple elements. Most of the elements measured do not show any particular changes in concentration throughout the time period covered by the trees, but four elements (molybdenum, chromium, iron, and, possibly, vanadium) show concentrations in the most recent decade (the 2010s) that were higher than for previous decades. Because this study was ecologic in design, it is not possible to associate these elements with the illnesses that are being reported for the area based on this study alone, but further environmental monitoring might be merited to confirm the temporal pattern found here. Full article

The application of dendrochronology for understanding climatic variations has been of great interest to climatologists, ecologists, geographers, archeologists, among other sciences, particularly in recent decades when more dendrochronological studies have been developed. We analyzed and identified the current state and recent advances in dendroclimatology in Latin America for the period 1990 to 2020. We carried out reviews in ScienceDirect, Web of Science, and Scopus databases with the keywords “dendrochronology”, “dendroclimatology”, “dendrochronology and climatic variability”, “dendroclimatology and climatic variability”, “dendrochronology and trend”, and “dendroclimatology and trend” for each Latin American country. Results show that dendroclimatological research in the last 11 years has increased and has been mainly developed in temperate climate zones (83%) and tropical or subtropical areas (17%), where conifer species have been the most used with over 59% of the studies. However, broadleaf species for dendrochronological studies have also increased in the last decade. Dendroclimatological research in Latin America has provided important advances in the study of climatic variability by defining the response functions of tree-rings to climate and developing climatic reconstructions. Our research identified areas where it is necessary to increase dendroclimatic studies (e.g., dry and tropical forests), in addition to applying new techniques such as isotope analysis, blue intensity, dendrochemistry, among other tree-ring applications. Full article

This research investigates the long-term environmental impact and historical temporal pollution patterns caused by a former copper mine in Iwiny (south-western Poland) using a dendrochemical approach. An additional aspect of this research was considering the possibility of using the inductively coupled plasma-optical emission spectrometry (ICP-OES) measurement technique as a cheaper alternative to inductively coupled plasma mass spectrometry (ICP-MS) in dendrochemical analyses conducted in copper mining areas. In the study area, a tailings storage facility (TSF) dam failure (1967) took place and the alkaline flotation waste containing high concentration of Cu and Pb are stored. Tree cores from pedunculate oak (Quercus robur L.) were analysed for the content of 11 trace elements (TEs) (Cd, Mn, Ni, Zn, Cr, Co, Pb, Cu, Fe, Al, Ag) using the ICP-OES technique, while tree rings’ widths (TRWs) were also measured. Samples that were most significant in the context of the research goals were verified with the ICP-MS method. The results revealed the strong long-term impact of the copper industry as reflected in a substantial increase in the mean contents of: (1) Mn, Ni, Zn, Cr, Pb, Cu and Fe in industrial vs. control trees, (2) TRWs for control vs. industrial trees. However, the observed patterns of TEs and TRWs did not correspond to the known timing of pollution inputs (mining activity, tailings spill). Peak levels were observed for Zn and Fe after the mine was closed. The lack of new sources of pollution and the temporal relationship strongly suggests that the tree rings recorded the chemical signal of the TSF reclamation (the use of fertilizers and agrotechnical interventions). Patterns of 7 elements were detected in most of the samples by ICP-OES (Co and Cd were not detected, Al and Ag were partly detected), while ICP-MS detected all of the elements. Significant differences were obtained for Ag, Cd, and Co. Despite challenges with the application of dendrochemistry in research on old mining areas (e.g., lack of old trees), it has proved to be a useful tool for investigating the aggregate environmental impact. Full article