School of Environmental Sciences, Mahatma Gandhi University, Kottayam, Kerala, India.
Environ Geochem Health. 2012 Oct;34(5):575-86. doi: 10.1007/s10653-012-9457-z. Epub 2012 May 8.
Transformations among different mercury species associated with sediments can have a major effect on the metal's mobility and potential for methylation and hence bioaccumulation. In the present study, various fractions of mercury in the sediments of Vembanad wetland system analysed. Total mercury (THg) concentration in the surface sediment varied from 16.3 to 4,230 ng/g. The results of sequential extraction showed that the major portion of mercury in these sediments existed as elemental form followed by organo-chelated form. The least portion observed was the residual fraction (mercury of natural origin). Even though the percentage of mercury observed in the easily available fractions is relatively small, absolute values of these mobile Hg fractions are quite high due to the very high total mercury values. The fractionation of mercury in the sediment was controlled by the organic matter, sulphur complexes and concentration of THg. The results showed that the bioavailability of mercury is high as the amount of mercury found in the initial three fractions is high, which can also enhance the methylation potential of the Vembanad wetland sediments. The fractionation pattern of mercury also revealed the presence of anthropogenic mercury content in the Vembanad wetland sediments.
不同汞形态在沉积物中的转化会对金属的迁移性以及甲基化和生物累积的潜力产生重大影响。本研究分析了维布纳湿地系统沉积物中的各种汞形态。表层沉积物中的总汞（THg）浓度从 16.3 到 4,230ng/g 不等。连续提取的结果表明，这些沉积物中的大部分汞以元素形态存在，其次是有机络合形态。观察到的最少部分是残余形态（天然来源的汞）。尽管易获得的汞形态中汞的百分比相对较小，但由于总汞值非常高，这些可移动 Hg 形态的绝对值相当高。汞在沉积物中的分馏受有机质、硫络合物和 THg 浓度的控制。结果表明，由于前三个汞形态的含量较高，汞的生物可利用性较高，这也可以增强维布纳湿地沉积物的甲基化潜力。汞的分馏模式还揭示了维布纳湿地沉积物中存在人为汞含量。
