三种修复剂对稻米甲基汞富集的影响研究

Effects of three remediation agents on methylmercury bioaccumulation in rice grain

为降低稻田汞(Hg)污染风险,减少稻米中甲基汞(MeHg)的富集,开展了汞污染修复的田间试验,研究3种低成本修复剂(硒肥、秸秆堆肥和甲壳素)施用降低稻米MeHg累积的效果及其可能的作用机理。结果表明:硒肥和秸秆堆肥均显著降低稻米中MeHg的浓度,分别降低35%和52%。同时,在水稻生长前中期(10～80 d),硒肥显著降低土壤MeHg浓度55%～69%;在40～100 d,秸秆堆肥显著降低土壤MeHg浓度45%～64%。此外,秸秆堆肥施用显著降低土壤中MeHg的植物可利用性。甲壳素对土壤MeHg浓度及水稻中MeHg的累积没有显著影响。研究表明,硒肥与秸秆堆肥施用能够显著降低土壤中MeHg浓度,进而导致稻米中MeHg浓度显著降低,表明硒肥与秸秆堆肥应用于稻田土壤汞污染修复具有现实可行性。

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 ofMeHg in rice tissues were explored. The results showed that selenium(Se)fertilizer and wheat straw-compost amendments significantly decreased 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-compost amendment from days 40 to 100. In addition, wheat straw-compost amendment significantly reduced the phytoavailability of MeHg insoil during the rice growth period. However, chitin did not significantly affect MeHg concentration in soil and rice tissues. These results demonstrate that the reduction of MeHg levels in rice tissues could be attributed to decrease MeHg levels and MeHg phytoavailability in paddysoils that result from the use of Se fertilizer or wheat straw-compost amendment. This study provides a scientific reference for reducing MeHg 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.