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Contrasting mercury contamination scenarios and site susceptibilities confound fish mercury burdens in Suriname, South America
Citation:
Vreedzaam, A., P. Ouboter, A. Hindori-Mohangoo, R. Lepak, S. Rumschlag, S. Janssen, G. Landburg, A. Shankar, W. Zijlmans, M. Lichtveld, AND J. Wickliffe. Contrasting mercury contamination scenarios and site susceptibilities confound fish mercury burdens in Suriname, South America. ENVIRONMENTAL POLLUTION. Elsevier Science Ltd, New York, NY, 336:122447, (2023). https://doi.org/10.1016/j.envpol.2023.122447
Impact/Purpose:
Taken in part from the conclusions: In a national assessment of mercury burdens in fish, combined with mercury stable isotopes we found concerning fish mercury content which will be of interest to the “Minamata Convention on Mercury”. Since 2000, Suriname has been undergoing rapid socioeconomic change and correspondingly shifts in resource exploitation, including increased gold mining. Yet, we found that fish-mercury burdens went largely unchanged. Likely due to the complex trophic ecology existing in the tropics, size-based predictions of fish-mercury burdens were unreliable. Surprisingly, the degree of human exploitation in gold mining also failed to yield predictable differences in food web mercury burden. Using mercury isotopes measured in fish, we revealed this is because intact remote ecosystems are highly efficient at transferring mercury to the food web, often offsetting the increased Hg baselines introduced by gold mining activity. This further confounds our ability to predict fish-mercury burdens across the landscape and sets up a troubling scenario where non-mining communities who are reliant on local fish subsidies may be at heightened disadvantage for mercury contamination both when they are proximate to and far from mercury-use gold mining.
Description:
In Suriname, mercury (Hg) use has recently increased because of gold mining, which has put fish-reliant communities (e.g., Indigenous and Tribal) at risk of enhanced Hg exposure through the riverine fish these communities consume. To quantify how the magnitude of these risks change according to location and time, we measured total mercury (HgT) in fish at sites downstream and upstream of an artisanal and small-scale gold mining (ASGM) operation in 2004–2005 and in 2017–2018. We tested whether fish HgT burdens over dynamic ranges were increased. Surprisingly, our findings did not support broadly increased fish Hg burden over time or that proximity to ASGM was diagnostic to fish HgT-burden. Subsequently, we elected to test the HgT stable isotope ratios on a set of freshly collected 2020 fish to determine whether differences in Hg source and delivery pathways might cofound results. We found that remote unmined sites were more susceptible to gaseous elemental Hg deposition pathways, leading to enhanced risk of contamination, whereas ASGM proximate sites were not. These results highlight that elemental mercury releases from ASGM practices may have significant impact on fish-reliant communities that are far removed from ASGM point source contamination.
URLs/Downloads:
DOI: Contrasting mercury contamination scenarios and site susceptibilities confound fish mercury burdens in Suriname, South America
https://pubmed.ncbi.nlm.nih.gov/37648055/