Total vs. Partial Acid Digestion Methods for Trace Element Analysis in Archaeological Sediments

Round 1

Reviewer 1 Report

The manuscript entitled "Total vs Partial acid digestion methods for trace elements analysis in archaeological sediments" investigates anthropic impact archaeological sites employing trace elements analysis. Two sample preparation methods are compared, partial and total digestion acid attack. Overall, I found the manuscript well-written, in terms of content, structure, and syntax.

The data from the measurements are presented succinctly - the tables and figures of the manuscript and the Supplementary Material are well-constructed and relevant, conveying the information clearly.

Given that the data in the specific topic are more and more published, I think that there is a novelty in the manuscript due to reaching a well-supported conclusion on the proposed methodology. Thus, I recommend that it merits publication after some MINOR changes. Please find some suggestions below:

-I encourage the authors to include a QA/QC paragraph, if data is available.

-Line 47: please change “for” to “per”

-Line 49: please change “debated” to “discussed”

-Line 84: please change “th” to “the”

-Line 145: please change “as can” to “as it can”

-Line 191-192: Please interpret this sentence in a more appealing and understanding way. “As regards REE fractionation, Gallello et al. (2021) [14] showed that levels interested by anthropic impact are characterised by depletion of Ce compared to other lanthanides”

-Figure 4: Please repeat the axis title “mg/kg” in the second row of boxplots 

SEE SOME MORE COMMENTS IN THE ATTACHED FILE

Comments for author File: Comments.pdf

Author Response

Reviewer #1

The manuscript entitled "Total vs Partial acid digestion methods for trace elements analysis in archaeological sediments" investigates anthropic impact archaeological sites employing trace elements analysis. Two sample preparation methods are compared, partial and total digestion acid attack. Overall, I found the manuscript well-written, in terms of content, structure, and syntax.

The data from the measurements are presented succinctly - the tables and figures of the manuscript and the Supplementary Material are well-constructed and relevant, conveying the information clearly.

Given that the data in the specific topic are more and more published, I think that there is a novelty in the manuscript due to reaching a well-supported conclusion on the proposed methodology. Thus, I recommend that it merits publication after some MINOR changes. Please find some suggestions below

We would like to thank the Reviewer for her/his positive comments.

-I encourage the authors to include a QA/QC paragraph, if data is available.

A statement has been added about QA/QC for ICP-MS analyses in “2.2 Analytical Methods” section.

“A certified reference material (NIM-GBW07408 Soil) was used for the control of the analytical results.”

QA/QC data are reported and commented in Gallello et al. (2021) as reported in the new version of the manuscript.

“More details on the analytical methods employed and quality control of the analytical results can be found in Gallello et al. [14].”

-Line 47: please change “for” to “per”

-Line 49: please change “debated” to “discussed”

-Line 84: please change “th” to “the”

-Line 145: please change “as can” to “as it can”

These words were changed as suggested by the Reviewer.

-Line 191-192: Please interpret this sentence in a more appealing and understanding way. “As regards REE fractionation, Gallello et al. (2021) [14] showed that levels interested by anthropic impact are characterised by depletion of Ce compared to other lanthanides”

The statement was slightly changed to clarify this issue:

“..Gallello et al. (2021) [14] showed that anthropic activity levels were characterised by lower Cen/Ce* anomaly related to the depletion of Ce compared to other lanthanides”.

-Figure 4: Please repeat the axis title “mg/kg” in the second row of boxplots 

Ratios are shown in the second row, which are dimensionless. This was now highlighted in the figure title.

SEE SOME MORE COMMENTS IN THE ATTACHED FILE

Please explain why ? (lines 127-128)

In “3.1. Trace elements” section the statement has been changed to: "PC1 vs PC2 samples/scores plot (Figure 2a) shows that the samples from the two digestion methods have similar scores, suggesting that, taking into account the overall set of samples, the difference are not significant for many elements."

It is possible that the differnce is not statisticaly important (lines 182-183)

In “3.2. Rare earth elements (REE)” section the statement was changed adding the observation of the Reviewer: "... while for disturbed earth the results are less clear and possibly the differences are not significant."

Obviously, since Sc and Y are REE. Is there any other particular relationship? (lines 187-188)

Although Sc and Y are related with lanthanides their geochemical behaviour can change or could be different so the relationship between those elements is not always evident.

Please use n as lower case (line 205)

This issue has been corrected.

Repetition (line 206)

Identified thanks.

Please be more clear. In the next sentence is written the opposite. (line 207)

The statement was changed to: “However, although the relationship among the different class of sediments were conserved, lower ratios values were obtained by total digestion than by partial one, at least for La_n/Yb_n and La_n/Sm_n.”

 

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, the authors compare different methods of measuring chemical composition of archaeological deposits using PXRF, partial digestion by weak-acid extraction (aqua regia), and complete digestion of sediment samples drawn from the site of Cueva de la Cocina. They find, unsurprisingly, that these methods produce different results, although being broadly comparable. Specifically, they argue that weak-acid extraction of sediments may actually be better for identifying chemical signatures associated with human activity as complete digestion adds in an additional purely geological signature from dissolved silicates and other soil constituents that may mask anthropogenic signatures (REE patterns in particular) in archaeological sediments. For other elemental markers, the two methods appear to produce broadly comparable results. Consequently, the authors suggest that it is not necessary to undertake more costly (and potentially more dangerous) complete dissolution work to isolate anthropogenic chemical social indicators. The paper is overall well done and easy to follow, however, there are a few issues that should be corrected and/or addressed before publication.

General suggestions:

Although PXRF measurements, Soil Organic Matter (SOI), and pH are provided, there is little discussion of the results in the paper. Organic matter is clearly implicated in discussing P content as well as Eu fractionation, but no discussion of how these elements relate to either SOI or pH is provided. The pXRF data provide major element content for certain minerals like Si, Ti, and Zr which predictably vary most between weak-acid extraction and total digestion, but no attempt is made to link these analyses together. Similarly, clay content could be broadly displayed using a combination of K and other elements and plotted against samples to show differences between natural and anthropogenic soils, as this difference is mentioned in the text. In short, I would better incorporate these data into the discussion.

Table 1-would be useful to include a site map indicating where each sample was collected from, and also to provide depth information. This would also provide a way of helping the reader to follow how different elements and SOI/pH are patterned at the site so we can understand more clearly why and how these things vary in different portions of the site.

Page 3, line 112-113: How were measurements standardized? Were log ratios used, or simple log10 transformation?

Author Response

Reviewer #2

In this paper, the authors compare different methods of measuring chemical composition of archaeological deposits using PXRF, partial digestion by weak-acid extraction (aqua regia), and complete digestion of sediment samples drawn from the site of Cueva de la Cocina. They find, unsurprisingly, that these methods produce different results, although being broadly comparable. Specifically, they argue that weak-acid extraction of sediments may actually be better for identifying chemical signatures associated with human activity as complete digestion adds in an additional purely geological signature from dissolved silicates and other soil constituents that may mask anthropogenic signatures (REE patterns in particular) in archaeological sediments. For other elemental markers, the two methods appear to produce broadly comparable results. Consequently, the authors suggest that it is not necessary to undertake more costly (and potentially more dangerous) complete dissolution work to isolate anthropogenic chemical social indicators. The paper is overall well done and easy to follow, however, there are a few issues that should be corrected and/or addressed before publication.

We are grateful to the Reviewer for  the positive comments.

Although PXRF measurements, Soil Organic Matter (SOI), and pH are provided, there is little discussion of the results in the paper. Organic matter is clearly implicated in discussing P content as well as Eu fractionation, but no discussion of how these elements relate to either SOI or pH is provided. The pXRF data provide major element content for certain minerals like Si, Ti, and Zr which predictably vary most between weak-acid extraction and total digestion, but no attempt is made to link these analyses together. Similarly, clay content could be broadly displayed using a combination of K and other elements and plotted against samples to show differences between natural and anthropogenic soils, as this difference is mentioned in the text. In short, I would better incorporate these data into the discussion.

We appreciate the Reviewer suggestions. pXRF data were obtained previous to the acid digestions on powdered samples. We cross-reference the different results obtained by the two digestion methods and the pXRF and SOM data analysis. The differences are linked to the presence of clay and other aluminosilicates (see section 3.1 last paragraph, 3.2 fourth paragraph), Ti- and Zr-bearing heavy minerals, phosphates and carbonates, whose presence is inferred by pXRF results, and organic matter (3.2 fourth paragraph). Concerning pH, no particular differences were observed among the different types of sediment.

Table 1-would be useful to include a site map indicating where each sample was collected from, and also to provide depth information. This would also provide a way of helping the reader to follow how different elements and SOI/pH are patterned at the site so we can understand more clearly why and how these things vary in different portions of the site.

Thanks for the observation, the map of the site and pictures with columns and samples location have been added in the supplementary online materials (SM1).

Page 3, line 112-113: How were measurements standardized? Were log ratios used, or simple log10 transformation?

The variables were z-scored. This fact is now clarified in the text:

“Z-score standardisation was performed prior to the PCA.” (2.3 section)

Reviewer 3 Report

The manuscript entitled Total vs Partial acid digestion methods for trace elements analysis in archaeological sediments investigates two methods of sample digestion for ICP-MS analysis. The results are based on samples from Cueva de la Cocina. The authors recommend using partial digestion as preferable method for archaeological sediments due to being less time consuming and more safe for the analyst as well as giving a more distinct difference between natural and archaeological levels.

General comments

Firstly, since the aim of this research is to recommend different digestion method for sediments, for archaeological purposes, it would require comparing more than one location, and of different lithology.

Secondly, I don’t see significant improvements from the last paper by authors that included this discussion, on somewhat lower number of samples (if I understand correctly, 9 new samples have been included in this MS, and all are categorized as disturbed, for which results of the two methods mostly overlap) but from the same location and reaching the same conclusion. If this topic wanted to be extended - it should have included additional samples from other locations.

If this topic wants to be discussed in detail, lithology and detail mineralogical analyses must be included.

Additionally, the sampling part is not described in a way that it can be easily understood and raises numerous questions: what is the size of the area were sampling was performed? How were the sediments sampled? What is a column – where is the bottom, at what depth? If the samples (20g) are distant from each other 10-15 cm, that seems as a too small distance for taking geochemically different samples or at least where one would expect differences. What is a natural sample? How do the authors know it is “natural”, e.g. undisturbed? Where was it sampled? What are disturbed samples? Why are they even included in the MS if the aim was to see the distinction between natural and anthropogenic signals? The authors compare 25 disturbed samples, 2 natural and 12 archaeological, the ratio of these samples should at least be similar. What is disturbed earth and how is it different from the disturbed samples?

Pictures of the sampling area should be included.

Sediment classes in sedimentology refer to a different categorization, so this category should be renamed.

 

Author Response

Reviewer #3

The manuscript entitled Total vs Partial acid digestion methods for trace elements analysis in archaeological sediments investigates two methods of sample digestion for ICP-MS analysis. The results are based on samples from Cueva de la Cocina. The authors recommend using partial digestion as preferable method for archaeological sediments due to being less time consuming and more safe for the analyst as well as giving a more distinct difference between natural and archaeological levels.

Thanks to the Reviewer for her/his comments.

Firstly, since the aim of this research is to recommend different digestion method for sediments, for archaeological purposes, it would require comparing more than one location, and of different lithology.

Thanks  for your suggestion, our work at the moment is limited to Cueva de la Cocina and is possibly extendable to similar environment, this is clearly stated in the conclusions of the paper (see in particular the first and the last paragraphs). However the development of the digestion method should be evaluated taking into account the sedimentological and geological characteristics of each site. Also depending on the aims of the research a proper and reliable ad hoc sampling strategy (e.g.: looking at open-air or cave sites) and analytical approach should be developed.

Secondly, I don’t see significant improvements from the last paper by authors that included this discussion, on somewhat lower number of samples (if I understand correctly, 9 new samples have been included in this MS, and all are categorized as disturbed, for which results of the two methods mostly overlap) but from the same location and reaching the same conclusion. If this topic wanted to be extended - it should have included additional samples from other locations.

The aim and the development of this new paper is significantly different to that of Gallello et al. (2021). In that case only aqua regia results were discussed in order to observe which parameters mark the archaeological levels of Cueva de la Cocina, with a particular focus on REE as anthropic markers. In this case we explored in depth the difference between two sediment digestion methods to understand which one would have been the best to carry out this kind of study. Although the obtained conclusions cannot be extended to all the archaeological environments, we strongly believe that the results of this study are a useful contribution to a relevant topic of the archaeological and geochemical research. In fact few studies report and discuss comparative data between archaeological sediments digestion methods. This work contribute to enhance the optimization of the sediment digestion methods for archaeological stratigraphy issues.   

If this topic wants to be discussed in detail, lithology and detail mineralogical analyses must be included.

The main geological features of the area and the cave were reported in in the introduction:

“From the geological point of view, Cueva de la Cocina is a cavity excavated by karstic phenomena in Late Cretaceous limestone levels, filled by the sediments carried along La Ventana ravine, produced by the weathering of the surrounding environment, dominated by the Cretaceous sedimentary sequence characterised mainly by carbonate rocks (limestones and marlstones), and by sandstone and clayish/sandy sediments [27].” (Introduction section third paragraph).

Concerning the mineralogical features, we think that the overall composition of the sediments can be inferred by major elements and SOM concentrations, and pH.

Additionally, the sampling part is not described in a way that it can be easily understood and raises numerous questions: what is the size of the area were sampling was performed? How were the sediments sampled? What is a column – where is the bottom, at what depth?

Dimensions of the area and the other parameters requested are reported in the supplementary online materials (SM1). As regards, sampling method, some statements have been added to the paragraph about the materials: “The surface of the sampled cross-sections were scraped with a trowel to remove the most exposed surface, then, about 20 g of sediments were collected with a laboratory spoon from different points along five columns (a, b, c, d, e, f) from the bottom of the cross-section (e.g.: from S4a1) and going up following an ideal vertical line (e.g.: up to S4a8). Each sample of the column is distant about 10-15 cm from the previous one”.

If the samples (20g) are distant from each other 10-15 cm, that seems as a too small distance for taking geochemically different samples or at least where one would expect differences.

Differences are not necessarily expected from a sample to the others, it depends on the conditions of pedogenesis, which can be marked by environmental conditions or different anthropic activities. For example, in the area S4 of Cueva de la Cocina, the difference between sediments characterised by anthropic activities (S4c3-8) and natural ones (S4c1-2) is well-marked in spite of the short distance along the same column.

What is a natural sample? How do the authors know it is “natural”, e.g. undisturbed? Where was it sampled? What are disturbed samples?

Types of sediment and classification criteria were clarified adding some details: “According to the remains found during the excavation, the study of the area revealed the presence of natural (no signs of anthropic activities) and archaeological strata (presence of remains of anthropic activities), as well as of disturbed levels linked to recent works (mixed remains including contemporary ones).” (“2.1. The sediments” second paragraph).

Why are they even included in the MS if the aim was to see the distinction between natural and anthropogenic signals? The authors compare 25 disturbed samples, 2 natural and 12 archaeological, the ratio of these samples should at least be similar.

The aims of Gallello et al. 2021 were to observe chemical differences among sediments present in the cave, including archaeological levels characterised by different anthropic activities, focussing in particular on REE data and cross-referencing with archaeological data. Anyway, the sample strategy was developed and adopted based on the site condition and the area of the excavated strata to obtain meaningful and reliable results.

What is disturbed earth and how is it different from the disturbed samples?

Disturbed earth and disturbed sample are the same thing, we have changed the statement to avoid misunderstandings.

Pictures of the sampling area should be included.

The pictures of the sampling area and the position of the samples were added in the supplementary online materials (SM1).

Sediment classes in sedimentology refer to a different categorization, so this category should be renamed.

The word class was changed to type in the manuscript, in the Table 1, and Figures 3 and 4.

Round 2

Reviewer 3 Report

While I understand the need for this kind of study in the field of archaeology, and welcome this kind of investigation, in my opinion, the MS has serious weaknesses. Firstly, the authors should have included analysis of the mineralogical composition, especially since they rely on it throughout the MS.

The authors state that: “Concerning the mineralogical features, we think that the overall composition of the sediments can be inferred by major elements and SOM concentrations, and pH.”

This is not correct. Especially having in mind the aim of the MS, mineralogical analysis of the sediment samples must be included.

The results on SOM and pH, on the other hand, seem to not be relevant since they are not included in the discussion.

In reply to my comments the authors state “ However the development of the digestion method should be evaluated taking into account the sedimentological and geological characteristics of each site.” However, the authors did not include these parameters in the discussion. And without this data, similar investigations cannot compare their research or choose a suitable method of digestion on another location, based on these results. Having in mind that the authors discuss this topic so it can be translated to similar settings, and used in similar purposes, then as much details on the sedimentological characteristics, lithology and mineralogical composition should be provided, since these are the main factors determining the multi-element composition of sediments. 

A major issue of the MS is the fact that majority of the data in the submitted MS was published in the previous paper by the authors (Gallello, G.; Ramacciotti, M.; García-Puchol, O.; Chenery, S.; Cortell-Nicolau, A.; Cervera, Mar.L.; Diez-Castillo, A.; Pastor, A.; McClure, S.B. Analysis of Stratigraphical Sequences at Cocina Cave (Spain) Using Rare Earth Elements Geochemistry. Boreas 397, 2021, 50, 1190–1208, doi:10.1111/bor.12530). Of the total of 39 samples discussed here, the results of XRF and ICP-MS analysis (total and partial digestion), SOM and pH of 30 samples (samples S4a8-1, S4b8-1, S4c8-1, S4d6-1) were already published in the previous paper. These results are used here again, and the indication that these are already published results (along with citation) should be stated everywhere, in tables in particular, as well as in the text (it is mentioned only in the methodology section). It should be clearly stated in the entire MS that the discussion presented here relies on the previously published data, combined with new results.

In my opinion, however, the 9 new samples (disturbed) didn’t improve the discussion of the MS. Having this in mind, the need for additional analysis that could have contributed to the MS (mineralogical and sedimentological analysis) is even greater.

Below are additional comments:

If the samples (20g) are distant from each other 10-15 cm, that seems as a too small distance for taking geochemically different samples or at least where one would expect differences.

Differences are not necessarily expected from a sample to the others, it depends on the conditions of pedogenesis, which can be marked by environmental conditions or different anthropic activities. For example, in the area S4 of Cueva de la Cocina, the difference between sediments characterised by anthropic activities (S4c3-8) and natural ones (S4c1-2) is well-marked in spite of the short distance along the same column.

- Pedogenesis is related to the genesis of soil. Soils and sediments must not be mistaken. However, I understand that in this specific case, the explanation on distance is valid.

What is disturbed earth and how is it different from the disturbed samples?

Disturbed earth and disturbed sample are the same thing, we have changed the statement to avoid misunderstandings.

In the revised MS again are “disturbed samples” and “disturbed earth samples”.

Author Response

While I understand the need for this kind of study in the field of archaeology, and welcome this kind of investigation, in my opinion, the MS has serious weaknesses. Firstly, the authors should have included analysis of the mineralogical composition, especially since they rely on it throughout the MS.

The authors state that: “Concerning the mineralogical features, we think that the overall composition of the sediments can be inferred by major elements and SOM concentrations, and pH.”

This is not correct. Especially having in mind the aim of the MS, mineralogical analysis of the sediment samples must be included. The results on SOM and pH, on the other hand, seem to not be relevant since they are not included in the discussion. In reply to my comments the authors state “However the development of the digestion method should be evaluated taking into account the sedimentological and geological characteristics of each site.” However, the authors did not include these parameters in the discussion. And without this data, similar investigations cannot compare their research or choose a suitable method of digestion on another location, based on these results. Having in mind that the authors discuss this topic so it can be translated to similar settings, and used in similar purposes, then as much details on the sedimentological characteristics, lithology and mineralogical composition should be provided, since these are the main factors determining the multi-element composition of sediments.

• We thanks the Reviewer_3 for her/his comments giving the opportunity to further clarify some issues.

Since the many years researchers have carried out studies at the Cueva de la Cocina. During the 70s and 80s Fortea was studying sedimentological and mineralogical features of this cave sediments (Fumanal 1979; 1986) Fumanal, M.P. Estudio sedimentológico de la Cueva de la Cocina. Dos Aguas (Valencia). Cuad. Geografía Univ. Valencia 1979, 24, 79–98; Fumanal, M.P. Sedimentología y clima en el País Valenciano: las cuevas habitadas en el Cuaternario reciente. Servicio de Prehistoria Prehistórica, Serie de Trabajos Varios 1986, 83.

In Fortea works a meaningful sampling strategy was designed and the most representative areas of Cocina were analysed. The mineralogical results showed that the main sediments compounds were carbonates (50%) and silt and clays (between 20 and 35 %). Our obtained results are clearly in line with those already obtained by Fortea as shown by the mayor elements profile of the studied samples. Therefore the sedimentological and mineralogical information of the studied site was already obtained by previous works. Must be highlighted that ICP-MS analyses have been carried out to observe trace elements differences between the studied strata that with other methods such as mineralogy or sedimentology were not observed. Therefore based on this the Reviewer_3 cited sentences “Concerning the mineralogical features, we think that the overall composition of the sediments can be inferred by major elements and SOM concentrations, and pH.” and “However the development of the digestion method should be evaluated taking into account the sedimentological and geological characteristics of each site.”,   in the revised version of our MS, can be assumed as correct and coherent with the previous studies. However following the Reviewer_3 comments to better clarify the aforementioned issues the third paragraph of the Introduction section have been modified and improved as follows:

“A detailed study of the geological and sedimentological characteristics of Cueva de la Cocina and their links with its surroundings was previously carried out by Fumanal [27,28]. From the geological point of view, Cueva de la Cocina is a cavity excavated in Late Cretaceous limestone levels by the combination of chemical lixiviation and fluvial mechanical erosion, filled by the sediments carried along La Ventana ravine. Sediment parent materials can be identified from the Early to Late Cretaceous levels outcropping in the area which include carbonate rocks (limestones and marlstones), as well as sandstones and sandy/clayish sediments. The studied area is part of the first Holocene sedimentary sequence. The analyses carried out by Fumanal [27, 28], highlighted the alkalinity of the environment, pointing out the presence of an decalcified and archaeo-logically sterile layer of reddish clay below the human occupation levels, which are in-stead rich in organic matter and carbonates (about 50% of the fraction) while silt and clay range between 20 and 35% , due to both anthropic activities and environmental condition changes.”

A major issue of the MS is the fact that majority of the data in the submitted MS was published in the previous paper by the authors (Gallello, G.; Ramacciotti, M.; GarcíaPuchol, O.; Chenery, S.; Cortell-Nicolau, A.; Cervera, Mar.L.; Diez-Castillo, A.; Pastor, A.; McClure, S.B. Analysis of Stratigraphical Sequences at Cocina Cave (Spain) Using Rare Earth Elements Geochemistry. Boreas 397, 2021, 50, 1190–1208, doi:10.1111/bor.12530). Of the total of 39 samples discussed here, the results of XRF and ICP-MS analysis (total and partial digestion), SOM and pH of 30 samples (samples S4a8-1, S4b8-1, S4c8-1, S4d6-1) were already published in the previous paper.

These results are used here again, and the indication that these are already published results (along with citation) should be stated everywhere, in tables in particular, as well as in the text (it is mentioned only in the methodology section). It should be clearly stated in the entire MS that the discussion presented here relies on the previously published data, combined with new results. In my opinion, however, the 9 new samples (disturbed) didn’t improve the discussion of the MS. Having this in mind, the need for additional analysis that could have contributed to the MS (mineralogical and sedimentological analysis) is even greater.

• We are grateful to the Reviewer_3 for her/his suggestions. Should be explained that samples S4a8-1, S4b8-1, S4c8-1, S4d6-1 total digestion results were just shown as raw data in the supplementary material of Gallello et al 2021. Therefore should be highlighted that the total digestion data were not statistically processed and ratio calculated neither published in the paper, those data are totally original and not discussed at all in the previous work being the aims clearly different. Here for the first time we show that is extremely important to develop a proper acid digestion method adjusted to the archaeological scope to be achieved.

Although, on our opinion the mention in methodology section should be enough, following the Reviewer_ 3 suggestions, in the supplementary materials file new version the sentence “Samples S4a8-1, S4b8-1, S4c8-1 and S4d6-1 data from Gallello et al. (2021).”  were added in the corresponding tables note.

 

 Below are additional comments:

If the samples (20g) are distant from each other 10-15 cm, that seems as a too small distance for taking geochemically different samples or at least where one would expect differences.

Differences are not necessarily expected from a sample to the others, it depends on the conditions of pedogenesis, which can be marked by environmental conditions or different anthropic activities. For example, in the area S4 of Cueva de la Cocina, the difference between sediments characterised by anthropic activities (S4c3-8) and natural ones (S4c1-2) is well-marked in spite of the short distance along the same column.

- Pedogenesis is related to the genesis of soil. Soils and sediments must not be mistaken. However, I understand that in this specific case, the explanation on distance is valid.

- Ok Thanks for clarifying this aspect.

 

What is disturbed earth and how is it different from the disturbed samples?

Disturbed earth and disturbed sample are the same thing, we have changed the statement to avoid misunderstandings.

In the revised MS again are “disturbed samples” and “disturbed earth samples”

• In the new version of the manuscript this was normalized.
  •  

Author Response File: Author Response.pdf