硒和生物炭联合施用降低稻米甲基汞累积的研究

汞矿区土壤汞污染是造成水稻及其他作物中汞累积的主要原因，尤其是稻米中甲基汞的累积已成为当地居民甲基汞暴露的重要途径之一。本文针对含汞废水排放所造成的稻田汞污染情形，分别进行了模拟实验和盆栽试验，探究无机硒、生物炭、硒和生物炭联合施用对降低稻米甲基汞累积的作用效果。结果表明，无论向土壤中添加无机硒，还是生物炭，抑或是两者的组合均能有效降低土壤中甲基汞含量，且随着硒添加量的增加，其相应处理组土壤甲基汞含量不断降低。盆栽试验表明稻米中甲基汞含量因硒或生物炭的添加降低62%～73%（硒处理）、88%（生物炭处理）和90%～91%（硒+生物炭处理），表明了硒和生物炭共同施用的作用效果要好于单独施用硒的作用效果。这种效果可能与生物炭降低了土壤中甲基汞的生物可利用性有关。总之，本研究为原位修复控制稻田汞污染风险提供了可能途径。

Effects of the Co-applications of Selenium and Biochar on Methylmercury Accumulation in Rice

Soil mercury (Hg) pollution in mining areas could lead to the accumulation of Hg in crops, especially of methylmercury (MeHg) in rice, which has become one of the most important pathways by which humans are exposed to MeHg in such areas. To mitigate Hg pollution in paddy soils resulting from Hg-containing wastewater discharge, we used microcosm and pot experiments to explore the effects of adding selenium (Se) and biochar, or a combination of both Se and biochar, on MeHg bioaccumulation in rice. The results show that either Se or bamboo-derived biochar treatments, or a co-application of the two, can effectively reduce the concentrations of MeHg in paddy soil. In addition, we found that soil MeHg concentrations decreased with increasing doses of Se. The pot experiments reveal that the accumulation of MeHg in rice grain decreased by 62%-73% (Se treatments), 88% (biochar treatments) and 90%-91% (Se+biochar treatments), indicating that the effect of co-application is more effective than applying Se alone. This may be mainly attributed to the reduction of the bioavailability of MeHg in soil under biochar treatment. It is concluded that multiple applications of Se and biochar could provide a practical solution to reducing the risk of Hg pollution in paddy soils.