Simulation of the chemical fate and bioavailability of liquid elemental mercury drops from gold mining in amazonian freshwater systems
Simulation of the chemical fate and bioavailability of liquid elemental mercury drops from gold mining in amazonian freshwater systems
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DOI：
10.1021/es070268r
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发表时间：
2007-11-01
影响因子：
11.4
通讯作者：
Boudou, Alain
中科院分区：
文献类型：
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作者：
Dominique, Yannick;Muresan, Bogdan;Boudou, Alain
用于金汞齐的元素汞（Hg-o）是南美洲手工采金工人采用的主要工艺，导致大量排放到淡水生态系统中。通过为期28天的实验方法为基础。在室内微观环境中，我们模拟了Hg-o液滴在有或没有沉积物的情况下的化学命运和生物利用度，这些沉积物来自一个典型的森林小溪，不受金矿开采活动的影响。我们的研究结果清楚地表明，汞在水柱中以溶解的气态Hgo和氧化（Hg(II)）形式进行了显著的转移，并受到沉积物存在的显著影响。28天后，无沉积物单元水柱中Hg总浓度（HgT）提高了25倍（108 17 vs 4 +/- 0.4 nM）。溶解部分的甲基汞（MeHg）测定结果显示，只有在沉积物存在的情况下，7天和14天后才有显著增加。以斑马鱼（Danio rerio）为汞生物利用度指标。早在暴露7天后，四个器官的HgT测定就显示出显著的积累水平，从无沉积物单元收集的鱼有明显的差异。只有当沉积物存在时，四个器官中才观察到显著的甲基汞增加。用于估计硫酸盐还原细菌群落的基因组工具显示，汞对其在不同隔间（水、沉积物、生物膜、鱼肠）中的多样性和分布有影响。
Elemental mercury (Hg-o) for gold amalgamation is the main process applied by artisanal gold miners in South America, leading to important discharges into freshwater ecosystems. Through a 28-day experimental approach based. on indoor microcosms, we simulated the chemical fate and bioavailability of Hg-o droplets in the presence or absence of sediment collected from a typical forest creek that is unaffected by gold mining activities. Our results clearly showed significant mercury transfers in the water column in both the dissolved gaseous Hgo and oxidized (Hg(II)) forms, with a marked effect of the presence of sediment. After 28 days, Hg total (HgT) concentration in the water column was 25 times higher in sediment-free units (108 17 vs 4 +/- 0.4 nM). Methylmercury (MeHg) determinations in the dissolved fraction showed a significant increase only in the presence of sediment after 7 and 14 days. Zebrafish (Danio rerio) were used as indicators for mercury bioavailability. The HgT determinations in four organs revealed significant accumulation levels as early as 7 days exposure, with marked differences in favor of fish collected from the sediment-free units. Significant MeHg increases were observed in the four organs only when sediment was present. Genomic tools applied to estimate sulfate-reducing bacteria communities showed mercury impacts on their diversity and distribution in the different compartments (water, sediment, biofilm, fish gut).