Mercury speciation in preserved historical sludge: Potential risk from sludge contained within reclaimed land of Minamata Bay, Japan.
Mercury speciation in preserved historical sludge: Potential risk from sludge contained within reclaimed land of Minamata Bay, Japan.
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DOI：
10.1016/j.envres.2019.108668
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发表时间：
2019
影响因子：
8.3
通讯作者：
M. Sakamoto;T. Itai;K. Marumoto;Masumi Marumoto;Hitoshi Kodamatani;T. Tomiyasu;H. Nagasaka;K. Mori;Alexandre J. Poulain;J. Domingo;M. Horvat;A. Matsuyama
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作者：
M. Sakamoto;T. Itai;K. Marumoto;Masumi Marumoto;Hitoshi Kodamatani;T. Tomiyasu;H. Nagasaka;K. Mori;Alexandre J. Poulain;J. Domingo;M. Horvat;A. Matsuyama
20世纪50年代后半期，日本一家化工厂将大量甲基汞（MeHg）直接排放到水俣湾，导致鱼类和贝类受到污染。最后，爆发了一场被称为水俣病的甲基汞中毒。从1977年到1988年，熊本县政府将总汞（THg，干基）超过25 μg/g的沉积物疏浚并转移到废水出口附近海湾的严格隔离区域，然后将该区域填埋。我们进行了保存的水俣湾污泥样品（从海湾内部收集的修复项目终止之前，n=4）和最近的水俣湾沉积物（收集海湾疏浚区以外，n=5）的汞形态分析，以评估潜在的风险的污泥/沉积物泄漏的填海土地的水俣湾。中位THg（干基）浓度为241 μg/g的保存污泥，6.1 μg/g的最近的水俣湾沉积物，和0.18 μg/g的一个单一的控制样本;中位甲基汞浓度（甲基汞在THg中的百分比）分别为108纳克/克（0.031%），3.7纳克/克（0.12%），和0.71纳克/克（0.41%）。在所有样品中，甲基汞%随THg浓度的增加呈指数下降。从每个样品到海水中的THg的可提取性被证明是远远低于甲基汞。提取的甲基汞为0.86%的保存污泥，4.57%的最近的水俣湾沉积物，和7.89%的控制。基于透射电子显微镜结合能量色散X射线能谱（TEM-EDX）和X射线吸收精细结构（XAFS）分析，发现在含有最高THg浓度的保存污泥中汞的主要化学形式是稳定的β-硫化汞（HgS）。
In the latter half of the 1950s, a large amount of methylmercury (MeHg) was discharged directly into Minamata Bay, Japan by a chemical factory, resulting in the contamination of the fish and shellfish. Ultimately, an outbreak of MeHg intoxication, called Minamata disease, occurred. From 1977 to 1988, the Kumamoto Prefectural Government dredged and transferred sediments exceeding 25 μg/g of total mercury (THg, dry basis) into a strictly segregated area of the bay near the wastewater outlet, then this area was landfilled. We conducted analyses of the mercury speciation in preserved Minamata Bay sludge samples (collected from inside of the bay prior to the termination of the remediation project; n=4) and recent Minamata Bay sediments (collected outside the dredging area of the bay; n=5) to evaluate the potential risk of the sludge/sediment leakage from the reclaimed land to the Minamata Bay. Median THg (dry basis) concentrations were 241 μg/g for the preserved sludge, 6.1 μg/g for the recent Minamata Bay sediments, and 0.18 μg/g for a single control sample; median MeHg concentrations (percentage of MeHg in THg) were 108 ng/g (0.031%), 3.7 ng/g (0.12%), and 0.71 ng/g (0.41%), respectively. In all the samples, the MeHg% decreased exponentially with increasing THg concentration. The extractability of THg from each sample into seawater was shown to be much lower than that of MeHg. The extracted MeHg was 0.86% for the preserved sludge, 4.57% for the recent Minamata Bay sediments, and 7.89% for the control. The predominant chemical form of mercury in the preserved sludge containing the highest THg concentration was found to be stable β-mercury sulfide (HgS) based on transmission electron microscopy linked with energy-dispersive X-ray spectroscopy (TEM-EDX) and X-ray absorption fine structure (XAFS) analyses.