Experimental dosing of wetlands with coagulants removes mercury from surface water and decreases mercury bioaccumulation in fish

Environmental Science & Technology
By: , and 

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Abstract

Mercury pollution is widespread globally, and strategies for managing mercury contamination in aquatic environments are necessary. We tested whether coagulation with metal-based salts could remove mercury from wetland surface waters and decrease mercury bioaccumulation in fish. In a complete randomized block design, we constructed nine experimental wetlands in California’s Sacramento–San Joaquin Delta, stocked them with mosquitofish (Gambusia affinis), and then continuously applied agricultural drainage water that was either untreated (control), or treated with polyaluminum chloride or ferric sulfate coagulants. Total mercury and methylmercury concentrations in surface waters were decreased by 62% and 63% in polyaluminum chloride treated wetlands and 50% and 76% in ferric sulfate treated wetlands compared to control wetlands. Specifically, following coagulation, mercury was transferred from the filtered fraction of water into the particulate fraction of water which then settled within the wetland. Mosquitofish mercury concentrations were decreased by 35% in ferric sulfate treated wetlands compared to control wetlands. There was no reduction in mosquitofish mercury concentrations within the polyaluminum chloride treated wetlands, which may have been caused by production of bioavailable methylmercury within those wetlands. Coagulation may be an effective management strategy for reducing mercury contamination within wetlands, but further studies should explore potential effects on wetland ecosystems.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Experimental dosing of wetlands with coagulants removes mercury from surface water and decreases mercury bioaccumulation in fish
Series title Environmental Science & Technology
DOI 10.1021/acs.est.5b00655
Volume 49
Issue 10
Year Published 2015
Language English
Publisher American Chemical Society
Contributing office(s) California Water Science Center, Western Ecological Research Center, Toxic Substances Hydrology Program
Description 8 p.
First page 6304
Last page 6311
Country United States
State California
Other Geospatial Sacramento-San Joaquin Delta
Online Only (Y/N) N
Additional Online Files (Y/N) N