Mercury dataset over the Third Pole

Kang, Shichang; Huang, Jie; Zhang, Qianggong; Guo, Junming; Yin, Xiufeng; Sun, Shiwei; Sun, Xuejun; Tripathee, Lekhendra; Abdullaev, Sabur; Tang, Wenjun; Zhang, Yi; Miao, Xiwen; Liao, Liujian; Che, Lusheng

doi:10.5194/essd-2025-551

Preprints

https://doi.org/10.5194/essd-2025-551

Preprints

13 Mar 2026

| 13 Mar 2026

Status: this preprint is currently under review for the journal ESSD.

Mercury dataset over the Third Pole

Shichang Kang, Jie Huang, Qianggong Zhang, Junming Guo, Xiufeng Yin, Shiwei Sun, Xuejun Sun, Lekhendra Tripathee, Sabur Abdullaev, Wenjun Tang, Yi Zhang, Xiwen Miao, Liujian Liao, and Lusheng Che

Abstract. The Tibetan Plateau and its surrounding regions, collectively known as the Third Pole, constitute one of Earth’s largest topographic and cryospheric features, playing a pivotal role in the cycling of trace elements at both regional and global scales. Mercury (Hg), a toxic heavy metal of global concern, has garnered increasing attention due to its detrimental effects on environmental and human health. Large-scale atmospheric circulation facilitates the long-range transport of atmospheric Hg pollutants, which can subsequently be deposited across the Third Pole. Over recent decades, the Atmospheric Pollution and Cryospheric Change (APCC) program has established and sustained an integrated monitoring network throughout this region to systematically examine the interactions between Hg biogeochemical cycling and cryospheric changes. This paper presents a comprehensive Hg dataset encompassing air (2 stations), aerosols (9 stations), precipitation (16 stations), glaciers (12 glaciers; including snowpit, surface snow, and cryoconite samples), soils (50 sites), surface waters (53 locations; including river, lake, and glacial meltwater), glacier ice cores (1 core), and lake sediment cores (8 cores) collected across the Third Pole. The data were acquired through both in situ (online) monitoring and laboratory analyses. High-resolution atmospheric Hg concentrations were measured using a Tekran 2537B analyzer at the Nam Co and Tanggula stations. Spatial and temporal distributions of Hg in aerosols, precipitation, glaciers, soils, and sediment cores revealed distinct patterns and trends across different sectors of the Third Pole, influenced significantly by emission sources, transport pathways, and environmental processes. Depositional chronologies derived from glacier ice and lake sediment cores reflect anthropogenic perturbations in the historical Hg record since the Industrial Revolution. Stable Hg isotope compositions from aerosols, soils, and lake sediments provide evidence for transboundary transport of Hg pollution and its northward incursion into the interior Tibetan Plateau from South Asia. This updated dataset is made publicly available to support interdisciplinary research linking the cryosphere, atmosphere, soils, and hydrology. The data are archived in standardized Excel format and accessible through the institutional repository of the State Key Laboratory of Cryospheric Science and Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou (Kang et al., 2024).

Received: 09 Sep 2025 – Discussion started: 13 Mar 2026

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.

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Shichang Kang, Jie Huang, Qianggong Zhang, Junming Guo, Xiufeng Yin, Shiwei Sun, Xuejun Sun, Lekhendra Tripathee, Sabur Abdullaev, Wenjun Tang, Yi Zhang, Xiwen Miao, Liujian Liao, and Lusheng Che

Status: open (until 16 May 2026)

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RC1:
'Comment on essd-2025-551', Anonymous Referee #1, 10 Apr 2026 reply
The authors have conducted long-term, high-altitude field observations across the Third Pole under extremely challenging conditions. The resulting comprehensive mercury dataset-covering air, aerosols, precipitation, glaciers, soils, waters, ice cores, and sediment cores-represents a remarkable logistical and scientific achievement. Given the outstanding observational efforts and the overall good quality of the data presented, the manuscript is promising. The clarity of the writing and the value of the dataset are commendable. I recommend acceptance after a moderate revision, as this dataset will serve as a valuable resource for the cryospheric and environmental geochemistry community.
Major concerns
As a data paper, the manuscript lacks critical QA/QC metadata, including detection limits, analytical precision, blank corrections, and reference material results for each measurement matrix (air, aerosols, precipitation, snow, soils, waters, ice cores, sediment cores, and Hg isotopes). A comprehensive QA/QC table should be provided to ensure data transparency and reusability.
The dataset spans a vast and heterogeneous region yet relies on only two air monitoring stations, one ice core, and limited spatial coverage for several media. The authors should add a concise statement in the data description acknowledging these spatial limitations, discuss how the existing data still support the main conclusions, and clarify which findings are regionally robust versus site‑specific. This is essential for proper use of the dataset by the community.
Specific concerns
[Lines 87-88 and 644-645] Here, the full name of APCC is written as "Cryospheric Changes," whereas later table and figure captions use "Cryospheric Change." I recommend making this consistent throughout the manuscript.

[Lines 99-104, 536-564, and 577] The section arrangement here does not match the actual structure that appears later in the manuscript. The later text first has "5. Dataset limitations and applications," then "6. Data availability," followed by another "6. Conclusions." I recommend revising the section numbering consistently throughout the paper.

[Line 115] There is a minor typo here: a space is missing after the colon. I suggest revising it to “including: 2 stations ...”.

[Lines 115 and 140] There appears to be a consistency issue: Section 2.3 states 10 sites, whereas the abstract and earlier overview describe aerosol sampling at 9 stations. I recommend checking the station count for the aerosol dataset throughout the manuscript and unifying it across the abstract, methods, and results.

[Lines 115-116, 153-156, and 160-163] After reading this carefully, I think the statistical counting here should be rechecked: this sentence states 12 stations, but later Nepal is listed separately as having 5 stations, while the abstract states that precipitation was sampled at 16 stations. Additionally, the numbers of monsoon and westerlies stations given in this sentence do not fully correspond to "6 + 6." I recommend carrying out a dedicated cross-check using a complete summary table.

[Lines 162-163 and 613-628] The abbreviation for Gosainkunda is written as GSK here, but as PKR in Table 1. I recommend unifying the abbreviation; otherwise, readers may become confused when trying to identify the station later.

[Lines 150-151] The reference information here is clearly incomplete: "Huang et al., 4" appears to be a leftover year or numbering artifact. Please complete it.

[Lines 167-168 and 417-418] The overview states 12 glaciers, but the beginning of Section 4.4 later says, “Systematic snowpit surveys conducted at 9 glaciers.” If the latter refers only to a subset of glaciers where snowpits were collected, I recommend explicitly stating in the results section that this is a subset, to avoid giving readers the impression that the two statements are contradictory.

[Lines 195-197, 205-208, and 489-490] Here, the surface water section states 9 glacier-fed streams, but Section 4.6 later refers to 7 glacier runoffs. Please verify whether the correct number is 7 or 9, or clarify that the 7 represent a subset for which results are presented.

[Line 225] British spelling ("analyser") is used here, but American spelling ("analyzer") appears later on the same page. I recommend using one spelling system consistently throughout the manuscript.

[Lines 301-302] I suggest revising “certificated” to the more common and standard expression “certified reference materials.”

[Line 307] I have a minor question here: "FLPE bottles" is not a very common material description. Please check whether this should instead be one of the more common terms, such as HDPE, LDPE, or FEP. If FLPE is indeed correct, I suggest explaining it the first time it appears.

[Lines 121 and 359] typo, dataset I-13 should be I-1, please verify and correct it.

[Lines 115-116, 153-156, and 406-407] Again, the results section states 9 stations, whereas the earlier methods section states 12 stations and the abstract gives 16 stations. I recommend conducting another full consistency check of the precipitation station count.

[Lines 167-168 and 417-419] If this refers to a subset of the snowpit survey, I suggest stating it explicitly—for example, "9 of the 12 glaciers"—otherwise, it directly conflicts with the "12 glaciers" given in the methods section.

[Lines 168 and 419] I suggest using a consistent format here. Earlier in the manuscript, the form "APCC dataset I-4" is used more frequently. Although "APCC I-4" is understandable in this instance, it would be better to keep the format consistent throughout.

[Lines 565-566] From a grammatical perspective, I suggest revising this to either "All Hg datasets presented in this study ..." or "The complete Hg dataset ..." The current wording feels somewhat awkward.

[Line 603] There is also a very minor typo here: "by" and "the" are run together. I suggest revising it to "supported by the ...".

[Lines 613-628] When reading the table, I suspect the latitude and longitude may have been reversed. In the Kashgar row, “Latitude = 75.45, Longitude = 39.29” is obviously inconsistent with the known GPS positions, and the same issue seems to appear in the MF/TZ/RQ/TX rows below. I recommend checking all latitude and longitude entries systematically and also ensuring they are reported with three decimal places in this table.

[Lines 162-163 and 613-628] Here, the abbreviation for Gosainkunda is written as PKR, which is inconsistent with the GSK used in Section 2.4 of the main text. I suggest unifying the two.

[Lines 629-635] Here, "zhadang glacier glacier" contains a repeated word. I suggest deleting one of them to correct this small textual error.

[Lines 629-635] “Tanggulha” looks like a spelling typo. Please check whether it should be “Tanggula Mts.”.

[Lines 636-643 and 823-824] The correct spelling should be "Lingge Co". Please revise accordingly.

[Lines 87-88 and 644-645] In the caption of Figure 1, the full name of APCC is still given in the singular form "Change," which is inconsistent with the wording in Section 1 of the main text. Please unify the two.

[Line 646] I suggest revising "India monsoon" to the more common expression "Indian monsoon."

[Lines 636-643 and 823-824] The lake name here is still inconsistent with Table 3. I recommend carrying out a one-time, unified proofreading of all proper names in the figure captions, main text, and tables.

[Lines 1001-1002] This reference entry appears incomplete. Scientific Reports entries should normally include the full volume and article number, and the DOI on this page is also truncated. Please verify the original reference and correct it consistently.

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Citation: https://doi.org/10.5194/essd-2025-551-RC1
RC2: 'Comment on essd-2025-551', Anonymous Referee #2, 14 Apr 2026 reply

The comment was uploaded in the form of a supplement: https://essd.copernicus.org/preprints/essd-2025-551/essd-2025-551-RC2-supplement.pdf
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Citation: https://doi.org/10.5194/essd-2025-551-RC2
RC3: 'Comment on essd-2025-551', Anonymous Referee #3, 15 Apr 2026 reply

This manuscript presents a comprehensive mercury dataset comprising air, aerosols, precipitation, glaciers, soils, surface waters, glacier ice cores, and lake sediment cores collected across the Third Pole. The authors have made a commendable effort to establish the integrated monitoring network through the Atmospheric Pollution and Cryospheric Change (APCC) program, thereby making it accessible to collect samples from harsh environments across the Tibetan Plateau and its surrounding regions. The data are publicly available. I believe this dataset will be of high interest to the Earth system science community, particularly for improving predictions of mercury cycling in cryosphere environments and evaluating its impact under rapid climate warming and cryosphere ablation on the Third Pole. My comments are as follows:
1. Section 2. Observation site descriptions and section 3. Field sampling and measurement methods share a similar structure for introducing various environmental matrices. Is it possible to combine these two sections?

2. Observation site descriptions: 1) L152: format error for Huang et al., 4.

3. Field sampling and measurement methods: 1) Vegetation is a useful environmental compartment to explore mercury cycling between the atmosphere and terrestrial ecosystem. Why didn’t the authors collect vegetation samples? 2) L237: HgP is not defined. 3) L305: If the same analytical procedures were applied as for aerosol and cryoconite samples, these analytical details should be presented above when you describe the aerosol and cryoconite samples. 4) L317: What is MOS-grade? 5) L336-338: The authors did not specify which samples were processed for isotope analysis. For aerosol samples, aqua regia digestion cannot eliminate the influence of interfering elements remaining in samples, which may cause the lower recovery of samples and have an impact on the accuracy of mercury isotope analysis. The authors need to point out this limitation.

4. Data descriptions. 1) There are no mercury isotope data from other matrices, why? 2) L352: Do you mean yearly TGM rather than monthly TGM? 3) L410: There is no MeHg in Fig. 3b. 3) L440: here and elsewhere, is the difference significant? 4) L457-463: The expression of “n” is not consistent. 5) L531-536: There is no description of lake sediment core δ202Hg values. Based on Δ199Hg, I think it cannot illustrate the rising anthropogenic Hg emissions originating from South Asia, especially for the Tanglha Lake sediment, mercury photochemical reactions can also lead to the positive Δ199Hg value. Anthropogenic Hg emission signal may be modified by the atmospheric redox before deposition into the lake sediment. The last sentence, “The dataset offers empirical constraints on Hg distribution, with an emphasis on observational evidence rather than source attribution”, looks strange in the current context. 6) There is no further discussion about the mercury isotope data of aerosols and soils. (7) I think many of the Hg isotope data from the third pole, including air and vegetation, are not included.

5. Dataset limitations and applications: The discussion about potential applications is very broad and vague. Please try to be more specific.

Figures: Fig. 4 is not referred to in the main text. Fig. 7 only shows the sampling location. Is it possible to add THg concentrations like other figures? Fig. 9 only shows the lakes from the northern slopes. Why not show the data from the southern slopes?

Tables: The information in tables doesn’t match well with the main text. The authors need to carefully check all the details.

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Citation: https://doi.org/10.5194/essd-2025-551-RC3

Shichang Kang, Jie Huang, Qianggong Zhang, Junming Guo, Xiufeng Yin, Shiwei Sun, Xuejun Sun, Lekhendra Tripathee, Sabur Abdullaev, Wenjun Tang, Yi Zhang, Xiwen Miao, Liujian Liao, and Lusheng Che

Data sets

Hg dataset over the Third Pole Shichang Kang, Jie Huang, Qianggong Zhang, Junming Guo, Xiufeng Yin, Shiwei Sun, and Xuejun Sun https://www.doi.org/10.12072/ncdc.qzkk.db6654.2024

Shichang Kang, Jie Huang, Qianggong Zhang, Junming Guo, Xiufeng Yin, Shiwei Sun, Xuejun Sun, Lekhendra Tripathee, Sabur Abdullaev, Wenjun Tang, Yi Zhang, Xiwen Miao, Liujian Liao, and Lusheng Che

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Short summary

The Third Pole is a critical region for studying global mercury (Hg) cycling due to its extensive cryosphere. This comprehensive dataset-spanning air, aerosols, precipitation, glaciers, soils, surface waters, ice cores, and sediments-was collected through the Atmospheric Pollution and Cryospheric Change program. It reveals spatial and temporal Hg patterns influenced by emissions, transport, and deposition processes. The data support interdisciplinary research on multi-sphere interactions.


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