基于健康风险的改进CCME WQI模型及其应用

Improved CCME WQI Model Based on Health Risk Theory and Its Application

重金属对人体的健康危害具有协同性,即使各指标的实测值均在目标阈值以内,累积健康风险也可能超出容许限值。传统的CCME WQI模型难以处理这类具有协同性的水质评价问题,常导致评价结果过于乐观。因此,基于健康风险理论,对传统的CCME WQI进行改进,并将其应用于我国南方某市的饮用水水源地水质评价。结果显示,该市各测站的砷与六价铬的单项浓度均满足地表水Ⅲ类要求,但累积健康风险均超出了容许限值1×10-4/a;传统的CCME WQI模型综合水质指数计算结果为Q=84.7,水质等级为"良好";改进的CCME WQI综合水质指数计算结果Q*=62.9,水质等级为"较差",表明通过引入累积健康风险项,改进的CCME WQI能准确地反映水环境中的重金属污染物对人体的协同影响,从而更全面地量化水环境的污染状况,评价结果更为科学。

The harm of heavy metals to human health is synergistic.Even if the measured values of all indexes are within the target threshold,the cumulative health risk may exceed the permissible value.It is difficult to deal with such collaborative water quality evaluation problems with the traditional CCME WQI model,which often leads to overly optimistic results.Therefore,our study improved the traditional CCME WQI model based on the health risk theory and applied to the water quality evaluation of drinking water source in a city in south China.The results show that the monomial concentrations of arsenic and hexavalent chromium meet the requirements of classⅢ surface water at each test station,but the cumulative health risks exceeded the allowable limit of 1×10-4/a.The comprehensive water quality index calculation result by the traditional CCME WQI model is 84.7,and the water quality grade is "good";while the improved comprehensive water quality index of CCME WQI is 62.9,which is rated as "poor".By introducing cumulative health risks,the improved CCME WQI model can accurately reflect the synergistic effect of heavy metal pollutants on human body in water environment,so as to quantify the pollution status of water environment more comprehensively and make the evaluation result more scientific.