基于pH分段土壤中镉对水稻毒性的生态风险阈值（HCx）研究

土壤镉(Cd)污染对水稻的生态风险受关注已久，然而现行的土壤环境质量标准已难以对不同土壤类型水稻Cd污染进行有效控制。本项目拟通过剂量-效应关系Log-logistic分布模型的应用、物种敏感度分布（SSD）的构建以及土壤中Cd预测无效应浓度（PNEC）的测定等最新环境风险评价方法，研究基于不同pH分段土壤中Cd的水稻毒性生态风险阈值（HCx，x=5,10）。主要内容包括1）不同品种水稻对土壤中Cd吸收、转运的剂量-效应关系；2）基于籽粒Cd含量的不同水稻对土壤中Cd毒性反应的敏感度分布特征；3）水稻Cd的吸收与主要土壤性质（pH,OC,CEC）间的量化关系与归趋化模型；4）不同水稻Cd毒性有效数据的归一化处理及数据库构建；5）预测无效应浓度（PNEC）测定及基于不同pH分段土壤中Cd水稻毒性的生态风险阈值及其验证。研究结果将为我国水稻Cd污染的防治及土壤环境质量标准的修订提供科学依据

Considerable efforts had been made on the study of cadmium (Cd) uptake and accumulation by rice varieties and its' ecological risk to human's health in the past decades, however, so far the practice of Cd pollution protection to rice has been becoming very difficult according to the protocol of current environmental quality standard for soils in China. This project will focus on the study of ecological toxicity threshold (i.e. the hazardous concentration of Cd for x% (x=5, 10) of the rice varieties) of Cd to rice varieties with different pH scales in soils using the current log-logistic distribution models for dose-response calculation, species sensitivity distributions (SSD) curves and predicted no effect concentration (PNEC) of Cd in soils etc. The main contents of the project will include 1) the dose-response of Cd toxicity to rice varieties in different soils; 2) the charcateristics of species sensitivity distributions of rice varieties to Cd toxicity stress in soils; 3) the quantification of Cd accumulation by rice species and its' couple relationship with the basic soil properties such as the pH valves, organic matter (OC) and cation exchange capacity (CEC) etc; 4) the normalization of effected concentration (ECx) of Cd toxicity to rice varieties with different soil properties and database foundation of Cd toxicity to rice varieties in soils and 5) the determination of predicted no effect concentration (PNEC) of Cd toxicity to rice varieties, the determination of ecological toxicity threshold of Cd for x% (x=5, 10) of the rice species with different pH scales in soils and its validation under field conditions. The results will help to protect Cd pollution of rice greatly and provide vital database for the revision of the current environmental quality standard for soils in China.