Methylmercury stable isotopes: New insights on assessing aquatic food web bioaccumulation in legacy impacted regions

ACS ES&T Water
By: , and 

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Abstract

Through stable isotope measurements of total mercury (HgT), identification of crucial processes and transformations affecting different sources of mercury (Hg) has become possible. However, attempting to use HgT stable isotopes to track bioaccumulation of Hg sources among different food web compartments can be challenging, if not impossible, when tissues have varying methylmercury (MeHg) contents. We measured HgT and MeHg stable isotope ratios within the lower Fox River to examine how these values differed across the food web and if isotope values in biota were influenced by legacy contamination. We showed that seston, invertebrates, and fish had a large range of δ202HgT (−0.74 to 0.15 ‰, n = 11) due to varying MeHg contents in tissues but a commonly conserved MeHg isotope value (δ202MeHgave = 0.01 ± 0.12 ‰, 1 standard deviation, n = 11). We also examined some mathematical approaches to estimate the MeHg isotope values, which were mostly comparable to measured MeHg isotope values in the Fox River, with some exceptions. In this study, we observed that the MeHg isotope values can elucidate links between different food web compartments and provide insight on aquatic Hg cycling that can be masked by the sole use of HgT isotopes in contaminated sites.

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Publication type Article
Publication Subtype Journal Article
Title Methylmercury stable isotopes: New insights on assessing aquatic food web bioaccumulation in legacy impacted regions
Series title ACS ES&T Water
DOI 10.1021/acsestwater.1c00285
Volume 2
Issue 5
Year Published 2022
Language English
Publisher American Chemical Society
Contributing office(s) Upper Midwest Water Science Center
Description 9 p.
First page 701
Last page 709
Country United States
State Wisconsin
Other Geospatial lower Fox River
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