我国稻田系统镉污染风险与阻控

Cadmium risk and mitigation in paddy systems in China

过去30年的工业化和环保措施不到位导致我国部分地区农田土壤Cd污染较为严重。南方部分地区稻米Cd含量超标严重,危害农产品安全和人体健康。农田Cd不断输入、土壤酸化以及种植Cd积累能力较强的籼稻品种是部分地区稻米Cd含量超标的主要原因。我国人群Cd平均摄入量在过去30年里增加了一倍。本文综述了人体Cd摄入量的安全阈值,鉴于食用大米是我国人群Cd摄入的主要来源,重点介绍稻田系统控制稻米Cd积累的主要生物地球化学过程以及水稻Cd吸收积累与转运的分子遗传机制,在此基础上还建议了稻米Cd积累阻控的农艺和育种措施。

Rapid industrialization in China coupled with a lack of stringent environmental protection in the past 30 years has resulted in serious and widespread soil Cd contamination in agricultural land.As a consequence,a large proportion of rice produced in some areas of South China currently exceeds the maximum permissible limit of Cd in China,threatening the food safety and human health.The elevated exceed.ance rates in South China are attributed to a combined consequence of serious soil Cd contamination,the cumulative acidification of soils due to excessive applications of nitrogen fertilizers,and cultivation of Indica cultivars in south region which tend to accumulate more Cd in the grain than Japonica.Dietary Cd intake of Chinese general populations has more than doubled over the past three decades with the consumption of rice being the dominant contributor.Here,we review the information available regarding Cd exposure levels and contributions to dietary Cd intake.Given that rice presents the dominant contributor,particular emphasis is placed on biogeochemical processes controlling Cd availability in paddy soils and the molecular mechanisms responsible for Cd accumulation in rice.A number of mitigating strategies in agronomy and breeding are also suggested for the movement towards low-Cd rice.