Organic material: The primary control on mercury methylation and ambient methyl mercury concentrations in estuarine sediments
Organic material: The primary control on mercury methylation and ambient methyl mercury concentrations in estuarine sediments
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DOI：
10.1021/es051785h
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发表时间：
2006-03-15
影响因子：
11.4
通讯作者：
Nilsson, M
中科院分区：
文献类型：
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作者：
Lambertsson, L;Nilsson, M
没有汞(汞)直接污染源的河口环境，其沉积物中甲基汞(甲基汞)的浓度可能与受污染的海洋环境的浓度一样高。在这项研究中，我们研究了影响净甲基化和沉积物甲基汞浓度的生物地球化学因素，该环境是一个未受污染的河口环境，排放到博斯年湾的Ore River河口(总汞g(-1)干沉积物为20-120，盐度为3-5‰)。我们分析了堆积型和剥蚀型海底表层沉积物中甲基汞浓度、汞甲基化、甲基汞去甲基化以及硫化物和氧气浓度的时空差异。所研究的底质之间的主要差异是沉积物中有机物质(OM)的比例，范围在0.8%到10.8%之间。不同地点和季节的孔隙水硫化物浓度剖面也有很大差异，从0到20亩M，最大值为100亩M。沉积物中甲基汞的浓度剖面(0-10 cm)大多在0.1-7 ng g(-1)干重(dw，as Hg)之间变化。甲基汞去甲基化的速率相对较低，并且随着季节、地点和深度的变化，这些速率的深度剖面相对恒定。相比之下，汞最大甲基化的速度和深度在不同的谷底都不同。结果表明，底泥中有机质的累积量是影响甲基汞净生产量的主要因素，而汞的总量对沉积物中甲基汞的含量影响很小或没有影响。
Estuarine environments that have no direct sources of mercury (Hg) pollution may have sediment concentrations of methylmercury (MeHg) as high as those of polluted marine environments. In this study we examined the biogeochemical factors affecting net methylation and sediment MeHg concentrations in an unpolluted estuarine environment, the Ore River estuary, which discharges into the Bothnian Bay (20-120 Ing total Hg g(-1) dry sediment, salinity 3-5 parts per thousand). We analyzed the spatial and temporal differences in surface sediment profiles of MeHg concentration, Hg methylation, MeHg demethylation, and concentrations of sulfide and oxygen between accumulation and erosion type bottoms. The main difference between the bottoms studied was in the proportion of organic material (OM) in the sediment, ranging between 0.8% and 10.8%. The pore water sulfide concentration profiles also differed considerably between sites and seasons, from 0 to 20,mu M, with 100 mu M as the extreme maximum. The sediment MeHg concentration profiles (0-10 cm) mostly varied between 0.1 and 7 ng g(-1) dry weight (dw, as Hg). The MeHg demethylation rates were relatively low and the depth profiles of the rates were relatively constant over season, site, and depth. In contrast, both rates and depths of maximum Hg methylation differed between the bottoms. The results indicate that the amount of OM accumulated at the bottoms was the main factor affecting net MeHg production, while the total amount of Hg had little or no influence on the amount of MeHg in the sediment.