摘要
在淡水生物区系中,溶解有机碳(DOC)和pH是影响汞含量的两个主要因子。DOC与汞络合促使汞向水生生态系统的传输和积累。低pH环境宜于汞的甲基化及其在水生食物链中的生物淀积。汞在食肉鱼类体内的富集与DOC呈正相关,而与pH则呈负相关关系。在亚马孙河一条名为内格罗河的黑水支流上游,我们在食鱼人群中遇到了相似的模式。人类汞污染最严重的区域均位于DOC异常高及低pH值支流中。在考虑了其他亚马孙河支流的数据后,一个总体模式随之产生。头发中的汞含量与河水中的DOC呈正相关,而与pH值呈负相关关系。金矿挖掘对汞污染没有明显的影响。研究结果表明了河流化学在确定亚马孙流域汞污染模式中的重要性。
Dissolved organic carbon (DOC) and pH are key variables influencing mercury levels in freshwater biota. DOC complexes with mercury, facilitates its transport to and accumulation in aquatic ecosystems. Low pH favors the methylation and bioaccumulation of mercury in aquatic food chains. Mercury concentrations in predatory fish tend to be positively correlated with DOC and negatively correlated with pH. We encountered a similar pattern for fish-eating human populations in the upper Rio Negro, a black water tributary of the Amazon river. The highest levels of human contamination were encountered in affluents with exceptionally high DOC and low pH. When data from other Amazonian tributaries were included, a general pattern emerged. Hair mercury was positively correlated with river DOC and negatively correlated with pH. No clear effect of gold-mining activities was encountered. The results demonstrate the importance of river chemistry in determining the pattern of mercury contamination in the Amazon basin.
