基于权重敏感度分布研究太湖有机磷农药单一和复合风险

基于实验室能得到的有限毒性数据的物种敏感度分布法(species sensitivity distribution, SSD)很难充分代表特定区域生态系统的物种分布,需要采用考虑生物区系特征进行赋予权重的物种敏感度分布法(weighted species sensitivity distribution,WSSD)。基于太湖物种组成构建WSSD,使用最大累积率(maximum cumulative ratio, MCR)(含风险商法(hazard quotient, HQ))和概率风险评价法(probabilistic risk assessment, PRA)对太湖地区单一和混合有机磷农药的风险进行研究。结果表明,相对于传统SSD方法,加权SSD方法计算的风险商大,且5%生物受影响的概率更大。单一风险评价中,敌敌畏和乐果5%生物受影响的概率超过40%,需要优先控制;最大累积率表明,敌敌畏是复合风险的主要贡献者,单一风险评价中风险较小的马拉硫磷和对硫磷也对复合风险贡献较大,复合暴露风险评价是必要的,混合物的风险商>1,5%生物受复合暴露影响的概率高达90%,有机磷农药复合生态风险不容忽视。

Study on Risk of Organophosphate Pesticides Mixture in Tai Lake Based on Weight Species Sensitivity Distribution

Due to limited laboratorial toxicity data, the traditional species sensitivity distribution (SSD) without considering species composition may not sufficiently represent the species distribution of site-specific ecosystems. Based on the species composition of Tai Lake, the weighted species sensitivity distribution (WSSD) method is used to link the laboratorial toxicity data to actual environmental scene. The maximum cumulative ratio with hazard quotient and probabilistic risk assessment are further used to compare risk of single and mixture organophosphate pesticides in Tai Lake. The results show that the hazard quotient calculated by the WSSD is larger and 5% of the species are more likely to be affected comparing with the traditional SSD method. The probability that 5% of species will be affected is more than 40%, dichlorvos or dimethoate need to be controlled first. In the mixture exposure risk assessment, dichlorvos is the main contributor. Malathion and parathion which have lower risk in the single risk assessment also contribute greatly to the combined risk. Combined exposure risk assessment is necessary. The hazard quotient of the mixture is greater than 1. The probability that 5% of species will be affected is greater than 90% under the current conditions of 5 organophosphate pesticides. The ecological risk of organophosphate pesticides in Tai Lake cannot be ignored.