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Diurnal trends in methylmercury concentration in a wetland adjacent to Great Salt Lake, Utah, USA

Chemical Geology
By: , , , , , and 
https://doi.org/10.1016/j.chemgeo.2011.02.005

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Abstract

A 24-h field experiment was conducted during July 2008 at a wetland on the eastern shore of Great Salt Lake (GSL) to assess the diurnal cycling of methylmercury (MeHg). Dissolved (< 0.45 μm) MeHg showed a strong diurnal variation with consistently decreasing concentrations during daylight periods and increasing concentrations during non-daylight periods. The proportion of MeHg relative to total Hg in the water column consistently decreased with increasing sunlight duration, indicative of photodegradation. During the field experiment, measured MeHg photodegradation rates ranged from 0.02 to 0.06 ng L− 1 h− 1. Convective overturn of the water column driven by nighttime cooling of the water surface was hypothesized as the likely mechanism to replace the MeHg in the water column lost via photodegradation processes. A hydrodynamic model of the wetland successfully simulated convective overturn of the water column during the field experiment. Study results indicate that daytime monitoring of selected wetlands surrounding GSL may significantly underestimate the MeHg content in the water column. Wetland managers should consider practices that maximize the photodegradation of MeHg during daylight periods.

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Publication type Article
Publication Subtype Journal Article
Title Diurnal trends in methylmercury concentration in a wetland adjacent to Great Salt Lake, Utah, USA
Series title Chemical Geology
DOI 10.1016/j.chemgeo.2011.02.005
Volume 283
Issue 1-2
Year Published 2011
Language English
Publisher Elsevier
Contributing office(s) Mercury Research Laboratory, Toxic Substances Hydrology Program
Description 9 p.
First page 78
Last page 86
Country United States
State Utah
Other Geospatial Great Salt Lake
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