1527 / 2019-08-14 16:24:25

Accumulation of Mercury promotes Selenium Uptake and Translocation in the Soil–Rice System

3、环境科学 > 专题10：汞的环境地球化学

Hg uptake by rice can be inhibited by Se in soil, which has been widely reported and demonstrated in recent years. However, in both field and pot studies, the role of total gaseous Hg in Hg-Se interactions and the effect of Hg-Se interactions on Se uptake in the soil-rice system have been rarely investigated and thus are poorly understood. Here, we investigated rice plants grown in a Hg mining area, which contains gradients of mercury concentrations in the soil and air. We found that the Se concentrations in ground tissues in artisanal mining sites were significantly higher than those in non-artisanal mining sites, and the Hg in soil showed a positive correlation with BAFs of Se in rice tissues, which is a paradox in that the mobility of Se in soil should be inhibited by Hg-Se formation in soil. The Hg in rice ground tissues, especially in leaves, primarily originates from air. In the present study, the Hg concentrations and BAFs of Hg in rice ground tissues were significantly positively associated with BAFs of Se, revealing that high Hg accumulation in rice ground tissues induces high Se translocation from soil to rice tissues. The Se in leaves is converted to reduced species and bound with Hg2+ due to its higher binding ability than that of S. Thus, we propose that Hg-Se interactions may occur in rice ground tissues, especially in leaves, to relieve Hg toxicity caused by high Hg uptake from the air.