The existing methods of measuring combined toxicity of heavy metal mixtures in environment do not fully consider three major factors (i.e., number of heavy metal species, aquatic biota, all investigated sites as an entity). Herein, a new method named joint probabilistic risk (JPR) method is proposed for evaluating the combined toxicity of heavy metal mixtures to aquatic biota. In this new method, the above three factors are fully taken into account. In order to evaluate the feasibility of the new method, the Pearl River Estuary (PRE) is selected as a case study. Concentrations of heavy metals (Cd, Pb, Cr, Ni, Cu, and Zn) in surface sediments of PRE are investigated and toxic equivalent factors (TEFs) of these heavy metals are calculated. Based on TEFs, sedimental concentrations of heavy metals of PRE are converted to Cd toxic equivalent concentration (Cd_eq), while the Cd toxicity data (Cd_to) are extracted from the literature. The probability density curves for Cd_eq and Cd_to are constructed and the overlap area is quantified as 0.2497. This indicates that the surface sediments of PRE have a 24.97% probability of toxic effect towards aquatic biota. Finally, this new method is validated by two indirect methods of mERMq and mPELq.

现有的测量环境中重金属混合物综合毒性的方法并未完全考虑三个主要因素（即，重金属物种的数量，水生生物群落，所有被调查地点均作为一个整体）。在此，提出了一种称为联合概率风险（JPR）方法的新方法，用于评估重金属混合物对水生生物的综合毒性。在这种新方法中，充分考虑了以上三个因素。为了评估新方法的可行性，选择了珠江口（PRE）作为案例研究。研究了PRE表面沉积物中重金属（Cd，Pb，Cr，Ni，Cu和Zn）的浓度，并计算了这些重金属的毒性当量因子（TEFs）。基于TEF，_式中的Cd毒性数据（Cd_至）是从文献中提取的。构造Cd _eq和Cd _to的概率密度曲线，并将重叠区域量化为0.2497。这表明PRE的表面沉积物对水生生物具有24.97％的毒性作用可能性。最后，该新方法通过mERMq和mPELq的两种间接方法进行了验证。