State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Laboratory of Metallomics and Nanometallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; College of Resources and Environment, Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China.
State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Laboratory of Metallomics and Nanometallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
Chemosphere. 2017 Sep;182:293-300. doi: 10.1016/j.chemosphere.2017.04.129. Epub 2017 Apr 26.
Sulfur (S) is an essential element for plant growth and its biogeochemical cycling is strongly linked to the species of heavy metals in soil. In this work, the effects of S (sulfate and elemental sulfur) treatment on the accumulation, distribution and chemical forms of Hg in rice growing in Hg contaminated soil were investigated. It was found that S could promote the formation of iron plaque on the root surface and decrease total mercury (T-Hg) and methylmercury (MeHg) accumulation in rice grains, straw, and roots. Hg in the root was dominated in the form of RS-Hg-SR. Sulfate treatment increased the percentage of RS-Hg-SR to T-Hg in the rice root and changed the Hg species in soil. The dominant Hg species (70%) in soil was organic substance bound fractions. Sulfur treatment decreased Hg motility in the rhizosphere soils by promoting the conversion of RS-Hg-SR to HgS. This study is significant since it suggests that low dose sulfur treatment in Hg-containing water irrigated soil can decrease both T-Hg and MeHg accumulation in rice via inactivating Hg in the soil and promoting the formation of iron plaque in rice root, which may reduce health risk for people consuming those crops.
硫（S）是植物生长的必需元素，其生物地球化学循环与土壤中重金属的种类密切相关。在这项工作中，研究了 S（硫酸盐和单质硫）处理对 Hg 污染土壤中生长的水稻中 Hg 积累、分布和化学形态的影响。结果发现，S 可以促进根表面铁斑的形成，降低大米籽粒、秸秆和根部的总汞（T-Hg）和甲基汞（MeHg）积累。根中的 Hg 主要以 RS-Hg-SR 的形式存在。硫酸盐处理增加了水稻根部 RS-Hg-SR 占 T-Hg 的比例，并改变了土壤中的 Hg 形态。土壤中主要的 Hg 形态（70%）为有机物质结合态。硫处理通过促进 RS-Hg-SR 向 HgS 的转化，降低了根际土壤中 Hg 的迁移性。这项研究意义重大，因为它表明在含 Hg 水灌溉土壤中进行低剂量硫处理可以通过使土壤中的 Hg 失活和促进水稻根中铁斑的形成来降低水稻中 T-Hg 和 MeHg 的积累，从而降低食用这些作物的人群的健康风险。
