Effects of three remediation agents on methylmercury bioaccumulation in rice grain

In this study, field experiments were conducted to study the effects of three low-cost remediation agents（selenium fertilizer, wheat straw-compost, and chitin）on rice grain methylmercury（MeHg) levels. Additionally, possible mechanisms that lead to a reduction of MeHg in rice tissues were explored. The results showed that selenium（Se）fertilizer and wheat straw-compost amendments significantly de⁃ creased the concentration of MeHg in rice tissues, both grain and straw, by 35% and 52%, respectively. MeHg levels in soil decreased by 55%~69% under Se fertilizer amendment during the rice growth period（days 10~80）, and decreased by 45%~64% under wheat straw-com⁃ post amendment from days 40 to 100. In addition, wheat straw-compost amendment significantly reduced the phytoavailability of MeHg in soil during the rice growth period. However, chitin did not significantly affect MeHg concentration in soil and rice tissues. These results dem⁃ onstrate that the reduction of MeHg levels in rice tissues could be attributed to decrease MeHg levels and MeHg phytoavailability in paddy soils that result from the use of Se fertilizer or wheat straw-compost amendment. This study provides a scientific reference for reducing Me⁃ Hg risks in rice paddy fields and suggests that application of Se and/or wheat straw-compost should be considered as a method to remediate MeHg-contaminated paddy soils.