Bouffard Ariane, Amyot Marc
Département de Sciences Biologiques, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Québec H3C3J7, Canada.
Chemosphere. 2009 Feb;74(8):1098-103. doi: 10.1016/j.chemosphere.2008.10.045. Epub 2008 Dec 16.
Mercury (Hg) redox changes in sediments are poorly studied and understood, even though they potentially control Hg availability for methylation and can alter sediment-water Hg exchange. Elemental Hg (Hg(0)) concentrations in sediments of two Canadian Shield lakes were assessed by thermodesorption. Hg(0) concentrations in sediments varied between 6.3 and 60.3 pg g(-1) (wet weight) which represented 7.4-28.4% of total mercury (HgT) concentration. Hg(0) concentrations were similar in both lakes. Hg(0) was rapidly adsorbed on sediments in controlled adsorption experiments and surface sediments sampled in summer had a stronger affinity for Hg(0) than deeper sediments and sediments sampled in fall. This adsorption was positively correlated to organic matter content and negatively related to particle grain size, pH and oxygen concentration in overlying water. This study demonstrates that Hg(0) is a prevalent species in sediments, but not in porewater, because of the high sorptive capacity of sediments towards Hg(0). Its potential availability towards Hg methylating bacteria remains to be determined.
尽管沉积物中的汞（Hg）氧化还原变化可能控制汞甲基化的有效性并能改变沉积物 - 水之间的汞交换，但目前对其研究和了解甚少。通过热脱附法评估了加拿大盾形区两个湖泊沉积物中的元素汞（Hg(0)）浓度。沉积物中Hg(0)浓度在6.3至60.3 pg g(-1)（湿重）之间变化，占总汞（HgT）浓度的7.4 - 28.4%。两个湖泊中的Hg(0)浓度相似。在控制吸附实验中，Hg(0)迅速吸附在沉积物上，夏季采集的表层沉积物对Hg(0)的亲和力强于深层沉积物以及秋季采集的沉积物。这种吸附与有机质含量呈正相关，与颗粒粒径、pH值以及上覆水中的氧浓度呈负相关。该研究表明，由于沉积物对Hg(0)具有高吸附能力，Hg(0)是沉积物中的普遍形态，但在孔隙水中并非如此。其对汞甲基化细菌的潜在有效性仍有待确定。
