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Impact of Dissolved Organic Matter on Porewater Hg and MeHg Concentrations in St. Louis River Estuary Sediments
ACS Earth and Space Chemistry ( IF 2.9 ) Pub Date : 2020-07-24 , DOI: 10.1021/acsearthspacechem.0c00134
Marissa L. Kneer 1 , Amber White 1, 2 , Kristofer R. Rolfhus 3 , Jeffrey D. Jeremiason 4 , Nathan W. Johnson 2, 5 , Matthew Ginder-Vogel 1
Affiliation  

Inorganic mercury in sediments is a potential source of bioaccumulative methylmercury in the aquatic food web; however, in many cases, total mercury concentrations in the sediment alone cannot predict methylmercury production and distribution. Fish that primarily feed in the St. Louis River Estuary, a Great Lakes coastal wetland, have higher concentrations of methylmercury in their tissues than fish that primarily feed upriver or in Lake Superior; however, the exact sources of mercury to methylating microorganisms and methylmercury to fish remain unknown. Solid-phase mercury pools, sediment and porewater chemistry, and sediment–porewater partitioning are assessed here to obtain a more detailed understanding of the role of sediments in methylmercury production. We show that in sediments where concentrations of reduced sulfur groups in dissolved organic matter in the porewater approach or exceed aqueous inorganic sulfide, there are higher concentrations of total mercury in the porewater. Reduced sulfur groups in dissolved organic matter raise the fraction of total mercury in the porewater where it may be more accessible for methylation and uptake to the food web. In the St. Louis River Estuary, conditions which facilitate greater partitioning of total mercury to the porewater correspond to sediments with lower sediment total mercury concentrations, highlighting that absolute total mercury concentration in the sediment alone cannot accurately assess the potential for mercury mobility and bioaccumulation. This study elucidates factors, mainly the presence of reduced sulfur groups in dissolved organic matter in the porewater, which facilitate the partitioning of total mercury to the porewater.

中文翻译:

溶解性有机物对圣路易斯河河口沉积物中孔隙水Hg和MeHg浓度的影响

沉积物中的无机汞是水生食物网中生物蓄积性甲基汞的潜在来源。但是,在许多情况下,仅沉积物中的总汞浓度无法预测甲基汞的生产和分布。与主要摄食上游或苏必利尔湖的鱼类相比,主要摄食在大湖沿岸湿地圣路易斯河口的鱼类的组织中甲基汞的浓度更高。然而,甲基化微生物和鱼类甲基汞的确切来源仍然未知。本文对固相汞池,沉积物和孔隙水的化学性质以及沉积物-孔隙水的分配进行了评估,以更详细地了解沉积物在甲基汞生产中的作用。我们表明,在孔隙水中溶解的有机物中还原硫基团的浓度接近或超过无机硫化物水溶液的沉积物中,孔隙水中的总汞浓度较高。溶解的有机物中的硫含量降低,增加了孔隙水中总汞的比例,在该处汞更易于甲基化并被食物网吸收。在圣路易斯河河口,促进总汞向孔隙水分配的条件对应于沉积物中总汞浓度较低的沉积物,这突出表明,仅沉积物中的绝对总汞浓度无法准确评估汞迁移和生物富集的潜力。这项研究阐明了因素,
更新日期:2020-08-20
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