Historic contamination alters mercury sources and cycling in temperate estuaries relative to uncontaminated sites

WATER RESEARCH

卷:190

Article

Seelen, Emily A.^1,5  Chen, Celia Y.²  Balcom, Prentiss H.^1,4  Buckman, Kate L.²  Taylor, Vivien F.³  Mason, Robert P.¹ 

[1] Univ Connecticut, Dept Marine Sci, 1084 Shennecossett Rd, Groton, CT 06340 USA

[2] Dartmouth Coll, Dept Biol Sci, Hanover, NH 03755 USA

[3] Dartmouth Coll, Dept Earth Sci, Hanover, NH 03755 USA

[4] Harvard John A Paulson Sch Engn & Appl Sci SEAS, 29 Oxford St, Cambridge, MA 02138 USA

[5] Univ Southern Calif Dornsife, Dept Earth Sci, 3651 Trousdale Pkwy, Los Angeles, CA 90089 USA

关键词: Mercury;    Methylmercury;    Coastal Systems;    Contamination;    Multi-Estuary Analysis;    Source Dynamics;   

DOI  :  10.1016/j.watres.2020.116684

来源: Elsevier

【 摘 要 】

Mercury (Hg) is a global and persistent pollutant which can be methylated to more toxic forms (methylmercury; MeHg) in natural systems. Both forms pose a health risk to humans and wildlife, and exposure often begins in aquatic environments. Therefore, quantifying aquatic concentrations and identifying source pathways is important for understanding biotic exposure. In this study, data from estuaries in the Northeast United States were combined to evaluate how point source contamination impacts the concentration and source dynamics of water column total and MeHg with an emphasis on sediment versus non-sediment sources. Partial least squares regression models were implemented to identify a set of variables most related to water column MeHg and total Hg (HgT) across the estuaries. The main findings suggest that contaminated sites have strong internal recycling of HgT that dominates over external inputs, and this leads to elevated concentrations of HgT and MeHg in the local water columns. However, HgT sources in uncontaminated estuarine systems have a strong connection to the local watershed with dissolved HgT linked to dissolved organic carbon, and particulate HgT linked to watershed land use and estuarine mixing. There was little correlative evidence that water column MeHg concentrations were linked to sediment in such systems, but unlike HgT, the concentrations were also not clearly linked to the watershed. Instead, in situ methylation of dissolved water column HgT appeared to dominate the MeHg source pathway. The results suggest that Hg point-source contaminated sites should be considered independently from non-contaminated sites in terms of management, and that land use plays an important indirect role in coastal MeHg dynamics. (c) 2020 Elsevier Ltd. All rights reserved.

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