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Title: X-ray fluorescence mapping of mercury on suspended mineral particles and diatoms in a contaminated freshwater system

Mercury (Hg) bioavailability and geochemical cycling is affected by its partitioning between the aqueous and particulate phases. We applied a synchrotron-based X-ray fluorescence (XRF) microprobe to visualize and quantify directly the spatial localization of Hg and its correlations with other elements of interest on suspended particles from a Hg-contaminated freshwater system. Up to 175 μg g−1 Hg is found on suspended particles, but less than 0.01% is in the form of methylmercury. Mercury is heterogeneously distributed among phytoplankton (e.g., diatoms) and mineral particles that are rich in iron oxides and natural organic matter (NOM). The diatom-bound Hg is mostly found on outer surfaces of the cells, suggesting passive sorption of Hg on diatoms. Our results indicate that localized sorption of Hg onto suspended particles, including diatoms and NOM-coated oxide minerals, may play an important role in affecting the partitioning, reactivity, and biogeochemical cycling of Hg in natural aquatic environments.
Authors:
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Publication Date:
OSTI Identifier:
1198214
Grant/Contract Number:
AC02-06CH11357
Type:
Published Article
Journal Name:
Biogeosciences (Online)
Additional Journal Information:
Journal Name: Biogeosciences (Online); Journal Volume: 11; Journal Issue: 18; Journal ID: ISSN 1726-4189
Publisher:
European Geosciences Union
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
Germany
Language:
English