自中科院地化所馮新斌課題組發(fā)現(xiàn)我國西南汞礦區(qū)食用稻米是農(nóng)村居民甲基汞暴露的主要途徑以來,，水稻富集甲基汞機理研究成為汞生物地球化學(xué)過程的重要內(nèi)容。馮新斌課題組針對水稻富集甲基汞機理這一科研問題,，進行了一系列深入的研究,，發(fā)現(xiàn)稻田土壤是水稻體內(nèi)甲基汞的主要來源，水稻對甲基汞的富集是一個吸收-運移-富集的動態(tài)變化過程,。因此,，準確評估稻田土壤中甲基汞的生物可利用性成為人體水稻食用風(fēng)險評估的重要內(nèi)容。
近期,，馮新斌課題組首次采用國際新興技術(shù)——薄膜擴散技術(shù)（The diffusive gradient in thin films technique,，DGT）原理，自制DGT采樣裝置,，并在水稻整個生長生殖期對稻田土壤中甲基汞的含量變化進行動態(tài)監(jiān)測,。研究發(fā)現(xiàn),，DGT技術(shù)測定的土壤-孔隙水界面甲基汞通量與水稻（Oryza sativa L.）根系吸收土壤甲基汞通量呈顯著正相關(guān)（R=0.853,，p<0.01），且DGT對土壤甲基汞的富集量與水稻果實對甲基汞的富集量呈顯著正相關(guān)（R=0.768,，p<0.05）,。這一發(fā)現(xiàn)證明DGT技術(shù)可用于有效評估汞污染土壤種植水稻可能存在的生態(tài)毒性風(fēng)險。
以上成果以“Prediction of Methyl Mercury Uptake by Rice Plants (Oryza sativa L.) Using the Diffusive Gradient in Thin Films Technique”為題發(fā)表在最新一期國際期刊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.
