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To properly understand the uptakes of Se in the rice plant(Oryza sativa L)in mercury mining areas,29 whole rice plant samples were collected from both artisanal Hg mining area(still operating)and abandoned Hg mining area(ceased),in Wanshan,Guizhou of China,during the rice harvest season.Specifically,based on the observed control of Se uptake by mining history and Hg concentration we have proposed mechanistic insight into the process of Se uptake by paddy rice.Se content in soil varies across these two areas,but is much higher than the global soil Se background level(200ng g-1).Despite this elevated Se concentration in soil,the Se concentration in rice grain is low and may lead to Se deficiency in the human population.This deficiency is more apparent in the artisanal mining areas where the average rice Se was just 51 ng g-1,compared to the Se concentration in rice produced in seleniferous areas such as Enshi(2730 ng g-1).The difference between Wanshan and Enshi is the practice of Hg mining,which has never been conducted at Enshi.Study has demonstrated that Se may play an important role in limiting the absorption and bioaccumulation of Hg in the aerial tissues of rice plants.Deposited Hg were more available than other kind of Hg in the soil,which usually coherence with the TGM in the ambient air.It indeed existed a negative correlation(R2=0.242,P=0.074)between Se in grain and TGM in the artisanal mining area,though the relation was not significant.However,neither positive nor negative correlation was found in abandoned mining areas.Because the TGM in this area were not as high as in artisanal area.On the other hand,the characteristics of different chemical Se forms in soil based on the pH and redox conditions.It estimated that perhaps 50%of Se in some soil may be held in organic compound,and selenomethionine is 2 to 4 times more bioavailable to plants than inorganic selenite.The newly deposited Hg in the soil is more readily transformed to MeHg and accumulated in rice plant.The channel or transporter to carry the MeHg or the SeMet are limited,once the plant choose to transport the MeHg,there is not enough carrier for the SeMet.That is the reason the rice Se in artisanal mining area is low,but soil Se in this area still high.