A hybrid statistical model for ecological risk integral assessment of PAHs in sediments

Abstract

For integral ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs), the interdependence is always ignored by assuming concentration additivity (CA) and independent action (IA). This paper proposed a hybrid assessment model, named hierarchical Archimedean copula integral assessment (HACIA), to treat inherent relations and assess the multi-dimensional holistic ecological risks of exposure concentrations of 16 PAHs. The HACIA model couples with hierarchical Archimedean copulas (HACs) and ecological evaluation criteria, sediment quality guidelines (SQGs), which depends on copulas to construe the connotations of correlations among exposure concentrations of PAHs. The two case studies, the exposure concentrations of 16 PAHs from Taihu Lake in China and the Bay of Bengal coast in Bangladesh, respectively, are used to verify the adaptability and feasibility of HACIA model and evaluate their comprehensive environmental risk. In addition, a theoretical and empirical comparison with three frequently-used methods was provided objectively, which focused on presuppositions, principles, evaluations and consequences. The results indicated that the HACIA model has good feasibility and applicability to evaluate the synthetic ecological risk according to PAHs exposure concentrations, remedies for the situation that the interdependence among other methods is neglected, and can produce more deliberate classification of hazards theoretically and better demonstrations of assessment results than the other three. Although the more accurate risk assessments rely on detecting quantity of samples, the integral ecological risk assessment based on the proposed HACIA model is reliable and robust because of its reasonable structure.