基于物种敏感性分布(Burr-Ⅲ)模型预测Cd对水稻毒害的生态风险阈值HC_5

Ecological Hazard Concentration(HC_5) of Cadmium(Cd) to Rice Cultivars Under Hydroponic Culture as Determined with Species Sensitivity Distribution Model(Burr-Ⅲ)

Burr-Ⅲ型分布是一种灵活的分布函数模型，对有害物质产生毒性的物种敏感性数据有很好的拟合效果。本研究采用水培实验研究了我国常见的17种不同水稻对Cd毒性的剂量-效应关系，结合Burr—Ⅲ物种敏感性分布模型对不同水稻Cd毒性的物种敏感性分布频次和基于保护95％水稻品种的Cd毒性阈值HC5进行了预测。结果表明：水培条件下，随着Cd处理浓度（0．30 - 6．0mg·L^-1）的增加，水稻对Cd富集系数（SCV）明显下降，而转运系数（TF）呈现出增加的趋势，总体而言，杂交品种水稻对Cd的转运系数高于常规品种水稻。不同水稻对Cd胁迫的半抑制浓度阈值（EC50）变化范围为0．552—24．01mg·L^-1，不同水稻品种EC50相差1．18-43．49倍，10％抑制浓度（EC10）变化范围为0．033～1．624mg·L^-1，不同水稻品种EC50相差1．758-49．21倍。不同水稻对Cd的毒性呈现出明显的敏感性差异特征，Bur-Ⅲ分布模型预测结果表明，基于保护95％的水稻品种，Cd的10％抑制浓度值（HC5^10%）为0．045mg·L^-1，50％抑制浓度值（HC550％）为0．594mg·L^-1。研究结果为我国水稻Cd污染防治及土壤Cd质量标准的修订提供了依据。

Burr type Ⅲ distribution is a continuous distribution model and could best describe species sensitivity distributions （SSD） of chemical pollutants to organisms. A hydroponic culture experiment was conducted to investigate dose-responses of cadmium （Cd） to 17 different rice cultivars. Bur-Ⅲ was employed to determine ecological hazard concentrations（HC5： protection of 95% rice species ） of Cd to rice cuhivars. With increasing Cd levels（0.30 mg·L-l to 6.0 mg·L-1 ）, biologic concentration factors （BCFs） of Cd to rice species generally decreased, while transfer factors（TFs） of Cd increased. Higher TFs of Cd were found in hybrid rice than in traditional rice cuhivars. Effective concentration （EC50） of Cd at 50% inhibition of rice responses ranged from 0.552-24.01 mg·L^-1 in solution, and ECho from 0.033-1.624mg·L^-1. The Burr- Ⅲ model predicted that HC5^10% of Cd at 10% inhibition was 0.045mg·L^-1 and HC5^50% was 0.594mg·L^-1. These results provide useful information for ecological risk assessment of Cd to rice.