三种有机物料对稻田土壤汞甲基化及水稻汞积累的影响

施用有机物料是水稻生产过程中提高产量的一条重要途径，明确有机物料的施用对糙米Hg积累的影响，对于Hg污染稻田的安全利用具有重要的指导意义。本研究采用盆栽实验，设置等量（3%，w/w）的油菜秸秆、猪粪和水稻秸秆生物炭，对比分析3种有机物料的施用对水稻产量及其对Hg在稻田系统的迁移转化的影响。结果表明，3种有机物料的施用均显著提高了水稻产量，但对土壤Hg甲基化和糙米Hg的积累影响则并不一致。油菜秸秆、猪粪和水稻秸秆生物炭处理下水稻产量分别提高17.6%、33.0%和39.9%。与相同水平土壤Hg处理相比，施用猪粪提高了土壤Hg的生物有效性，促进了土壤MeHg的生成，提高了糙米THg的富集系数，使糙米THg和MeHg的含量分别提高了34.5%和30.3%；施用油菜秸秆降低了土壤Hg的生物有效性，抑制了土壤Hg甲基化过程和水稻对Hg的富集，糙米THg和MeHg的含量分别降低了34.6%和36.2%；施用水稻秸秆生物炭降低了土壤Hg生物有效性和糙米THg的富集系数，糙米THg和MeHg的含量分别降低了46.9%和48.4%。因此，在Hg污染稻田中应慎重施用猪粪，可选择施用水稻秸秆生物炭和油菜秸秆，达到提高产量和阻控糙米Hg积累的双重效果。

Effects of Three Kinds of Organic Materials on Mercury Methylation in Paddy Soil and Mercury Accumulation in Brown Rice

Application of organic materials is an important way to increase rice yield. It is of great guiding significance to clarify the effect of application of organic materials on Hg accumulation in brown rice for safe utilization of Hg contaminated rice fields. In this study, pot experiments were conducted to set rape straw, pig manure and rice straw biochar with the same amount (3%, w/w), compare the effects of application of different organic materials to rice yield and Hg migration and transformation in rice field system. The results showed that the application of 3 kinds of organic materials significantly increased rice yield, but the effect on Hg methylation in soil and Hg accumulation in brown rice was not consistent. Rice yield was increased by 17.6%, 33.0% and 39.9% under the treatments of rape straw, pig manure and rice straw biochar treatments, respectively. Comparing with the same level of soil Hg treatment, the application of pig manure increased the bioavailability of Hg in soil, promoted the MeHg production and the bioaccumulation factor of Hg in brown rice, and the concentration of THg and MeHg in brown rice was increased by 34.5% and 30.3%, respectively. However, the application of rape straw reduced the Hg bioavailability in soil, inhibited the methylation of Hg in soil and the bioaccumulation of Hg in brown rice, the concentration of THg and MeHg in brown rice decreased by 34.6% and 36.2%. The Hg bioavailability in soil and the bioaccumulation factor of THg in brown rice were decreased by applying rice straw biochar, and the THg and MeHg content in brown rice decreased by 46.9% and 48.4%, respectively. Therefore, application of rice straw biochar and rape straw is potential measure to achieve the dual effects of increasing yield and preventing Hg accumulation in brown rice in Hg contaminated paddy fields, while pig manure is not recommended.