Total and methylmercury concentrations in ground and surface waters in natural and restored freshwater wetlands in north
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Total and methylmercury concentrations in ground and surface waters in natural and restored freshwater wetlands in northern New York Ting Wang
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Charles T. Driscoll1 Kyotaek Hwang1 David Chandler1 Mario Montesdeoca1 ●
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Accepted: 18 December 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Nearly half of freshwater wetlands have been lost due to human disturbance. In response, wetlands are being restored to retain their ecosystem services. A potentially adverse consequence of wetland function is the production of methylmercury (MeHg). We measured concentrations of mercury (Hg) species and ancillary parameters in groundwaters and surface waters from four natural and 16 restored wetlands in northern New York State, USA to investigate differences in concentrations of Hg species among wetlands. We found no obvious differences in concentrations of total mercury (THg) and methylmercury in pond waters between natural and restored wetlands. High values of %methylmercury were evident in both ground (38.8 ± 27.6%) and surface waters (43.4 ± 25.6%) suggesting these wetland complexes are highly efficient in converting ionic Hg to methylmercury, regardless if restored or natural. High methylation efficiency may be due to observed drying and rewetting cycles. Hg in pond waters is likely derived from direct atmospheric deposition or by mobilization from near-wetland shallow sediments, in addition to groundwater inflows. Water flow of groundwaters from the associated watershed into pond waters resulted in increases in concentrations of THg and methylmercury. Dissolved organic matter likely plays an important role in the supply of Hg to pond waters. Relationships between methylmercury and %methylmercury with sulfate and nitrate in groundwaters may suggest some chemical limitation on Hg methylation at higher concentrations of these anions. Because of the similarity in Hg dynamics for natural and restored wetlands, the most effective strategy to mitigate methylmercury production would be to decrease atmospheric Hg deposition. Keywords Restored and natural wetlands Total mercury Methylmercury St. Lawrence drainage Dissolved organic carbon Sulfate-reducing bacteria ●
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Introduction Wetlands are generally areas with standing water for a considerable period. They have special soil conditions and organisms due to their persistent hydrologic condition of soil saturation, and represent important linkages between upland terrestrial and aquatic ecosystems (Mitsch and
Supplementary information The online version of this article (https:// doi.org/10.1007/s10646-019-02155-6) contains supplementary material, which is available to authorized users. * Ting Wang [email protected] 1
Department of Civil and Environmental Engineering, Syracuse University, 151 Link Hall, Syracuse, NY 13244, USA
Gosselink 2007). Notably, wetlands typically experience wet-dry cycles which facilitate alternating redox conditions (Driscoll et al. 1998; Strickman and Mitchell 2017). Althou
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