the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 24 Feb 2025
Toxic Dust Emission from Drought-Exposed Lakebeds – A New Air Pollution Threat from Dried Lakes
Abstract. A large number of lakes worldwide are shrinking rapidly due to climate change and human activities. Pollutants accumulated in dried lakebed sediments may be released into the atmosphere as dust aerosols. However, whether lakebed dust carry sufficient toxic materials and exceeds threshold atmospheric concentrations to pose a significant health risk is currently unknown. Recently, Poyang Lake and Dongting Lake, largest lakes in East China, experienced record-breaking droughts with 99 % and 88 % areas exposed to the air. Here, we demonstrate, through field sampling, laboratory simulations, and model validation, that lakebed dust from these lakes could contribute maximum daily PM10 concentrations up to 637.5 μg/m³. Critically, for the first time, we show that the dust generated from lakebeds exceeded regional thresholds for short-term non-carcinogenic risk (HQ=4.13) and Cr carcinogenic risk (~2.10×10-6). These findings also suggest that lakebed dust could have a greater impact on human health as climate change leads to more extreme drought conditions in the future.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2025-596', Anonymous Referee #1, 18 Apr 2025
Overall, the paper is well written, it is clear, and the work is interesting. I think small changes are needed to improve the paper.
You need more discussion in the introduction section about the presence of heavy metals and PAHs in dust events in general, to show if the lake produces more, and how the emissions you found compare to these findings.
The map( Figure 1) should appear earlier to explain the sampling locations, as it was unclear to me until I got to the result part and saw that figure. Also, the usage of A, B, and C is weird. Can you give it a normal name?
Consider moving some of the figs from the supplement section to the main section, as some of them are important for the understanding of the paper.
You have several figs that seem too small, like Fig 2, or I couldn't see the numbers of some of the figures in the supplements, as Fig S5, the yellow color is not showing, and the size of the figures was very hard to examine, even when I used a magnification of 200
Specific comments
Line 68, Owen Lake is not the primary dust source in the US
Line 151 misplacement of () in citation
Lines 444-454: Is there any level of exposure for these metals that you could add to how, if the values were above these thresholds
Line 473 is missing a space between s15 and to present
Table S5 seems like a mistake, or unclear, most heavy metals do not have values.
Citation: https://doi.org/10.5194/egusphere-2025-596-RC1 - AC1: 'Reply on RC1', Xiaofei Wang, 27 Jun 2025
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RC2: 'Comment on egusphere-2025-596', Anonymous Referee #2, 23 Apr 2025
Review of "Toxic Dust Emission from Drought-Exposed Lakebeds – A New Air Pollution Threat from Dried Lakes" by Qianqian Gao, Guochao Chen, Xiaohui Lu, Jianmin Chen, Hongliang Zhang, and Xiaofei Wang
The aim of this article is to study dust emissions and transport during droughts affecting lakes in China that have become erodible. Sediments can store pollutants (polycyclic aromatic hydrocarbons (PAHs), metals) that can then have an impact on human health. The methodology consists of taking sediment samples and then using a laboratory aerosol generator (GAMEL) to study the size distribution and composition of the emitted flux. The second part uses the regional CMAQ model. The third part calculates the population's exposure to these aerosols. The article is original and deals with a subject that has not yet been studied to any great extent. The methodology is based on measurements both in situ and in a wind tunnel to reproduce an emission due to wind erosion.
Major comments:
Structure of the paper:
The supplement is very long and some parts could be included directly in the article: either in the text itself or as an appendix. The authors should sort out what is essential for understanding the work and what is extra (i.e. in the supplement). In this version, there are 4 figures in the article but 15 in the supplement. There could be 10 in the article, making it easier to understand the study as you read.
Model validation:
The CMAQ simulation appears to be not fully validated (only one site: Nanchang). Surface PM2.5 and PM10 measurements exist, as well as AOD and Angstrom exponent with the AERONET network to quantify whether the simulation is realistic or not. It is important to validate the concentration before concluding on exposure and impacts. And the "alignment" (l.556) may be quantified with correlation (defined in the Supplement) for example. And the limitations of the simulation are not only due to the meteorology or landuse but probably alos to the source and sinks scheme i.e the dust production model and the wet and dry depsition schemes used. Please informations and data about these points.
Minor comments:
Some sentences are difficult to understand, as in the abstract:
l.36 "Critically, for the first time, we show that..."
l.135 What are A1 and A2? It is unclear where it is cited. The Figure is here necessary and a list of the sampling sites should be more understandable. And the already existing Table S1 could be in the main text in section 2.1.
l.157: The Table is in the supplement but could be where it is cited. The caption could be enriched and provide much more details about the Table's content.
Figure S3: what are 2007.2 and 2007.7: month and year? please use a correct notation.
l.208: the domain is large and it is not sure that only three days of spin-up are enough. Can you explain this choice?
l.265: The choice to estimate 'inhalation exposure' may be correct. But why calculate it using PM10 when you have PM2.5 more able to deeply penetrate the lungs?
l.271: why daily maximum and not daily mean?
l.332: this part is partly a repeat of the 'methodology' section
l.348: Perhaps it should be interesting to have the population map superimposed to the locations of the sampling sites.
l.372: I don't undersatnd how it is possible to have PM2.5 > PM10 > soil in concentrations ng/g??
The fact to have PM2.5>PM10 is not possible. Please check and explain.
l.456 Figure 3: maximum daily concentrations are huge. It is the first vertical model level? Some concentrations are n ug/m3 others in ng/m3, could you explain?
Citation: https://doi.org/10.5194/egusphere-2025-596-RC2 - AC2: 'Reply on RC2', Xiaofei Wang, 27 Jun 2025
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