自中科院地化所冯新斌课题组发现我国西南汞矿区食用稻米是农村居民甲基汞暴露的主要途径以来，水稻富集甲基汞机理研究成为汞生物地球化学过程的重要内容。冯新斌课题组针对水稻富集甲基汞机理这一科研问题，进行了一系列深入的研究，发现稻田土壤是水稻体内甲基汞的主要来源，水稻对甲基汞的富集是一个吸收-运移-富集的动态变化过程。因此，准确评估稻田土壤中甲基汞的生物可利用性成为人体水稻食用风险评估的重要内容。
近期，冯新斌课题组首次采用国际新兴技术——薄膜扩散技术（The diffusive gradient in thin films technique，DGT）原理，自制DGT采样装置，并在水稻整个生长生殖期对稻田土壤中甲基汞的含量变化进行动态监测。研究发现，DGT技术测定的土壤-孔隙水界面甲基汞通量与水稻（Oryza sativa L.）根系吸收土壤甲基汞通量呈显著正相关（R=0.853，p<0.01），且DGT对土壤甲基汞的富集量与水稻果实对甲基汞的富集量呈显著正相关（R=0.768，p<0.05）。这一发现证明DGT技术可用于有效评估汞污染土壤种植水稻可能存在的生态毒性风险。
以上成果以“Prediction of Methyl Mercury Uptake by Rice Plants (Oryza sativa L.) Using the Diffusive Gradient in Thin Films Technique”为题发表在最新一期国际期刊Environmental Science & Technology（2012，46卷，20期，11013-11020）上。(生物谷Bioon.com)
DOI: 10.1021/es302187t
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Prediction of Methyl Mercury Uptake by Rice Plants (Oryza sativa L.) Using the Diffusive Gradient in Thin Films Technique
Jinling Liu †‡, Xinbin Feng *†, Guangle Qiu †,Christopher W. N. Anderson §, and Heng Yao †
Rice consumption is the primary pathway for methyl mercury (MeHg) exposure at inland mercury (Hg) mining areas of SW China. Mechanistic information on MeHg accumulation in rice is, however, limited. The process of MeHg exchange between paddy soil and rice plants predominantly occurs in pore water. The detection of bioavailable MeHg in pore water is therefore important to predict MeHg uptake by rice plants (Oryza sativa L.). This study investigated MeHg dynamics and spatial MeHg trends in pore water during the rice growing season using the diffusive gradient in thin films (DGT) technique and tested the ability of DGT to predict MeHg uptake by rice. The MeHg uptake flux from soil to rice plants via roots was significantly correlated with the DGT-measured MeHg flux (R = 0.853, p < 0.01). Our study implies that DGT can predict the bioavailability of MeHg in rice paddy soil and that the DGT method can provide quantitative description of the rate of uptake of this bioavailable MeHg. The DGT technique is demonstrated as a useful indicator of the likely ecotoxicological risk that might be apparent where paddy rice is grown in MeHg contaminated soil.
