Deriving an Ecological Risk Assessment Criterion Concentration for Populations with Seasonal Variation Reconsidering and improving the algorithm

摘要

Population-level ecological risk assessment (PLERA) for chemicals has been advocated for broader application in chemicals' risk management. The persistence capability, indicated by the finite growth rate ( λ) of certain population is scientifically soundly founded and is an appropriate risk assessment endpoint. In accordance, the concentration by which a population vitality is so stressed that its λ value is reduced to be one, can serve as a criterion concentration, denoted as C λ=1.Nonetheless, seasonal variation is desirably taken into account when deriving C λ=1 for better ecological relevance. This paper revisited the algorithm for C λ=1 derivation and proposed an improved algorithm for faster calculation. Specifically, in the algorithm, the age-structured projection matrix (namely Leslie matrix) was collapsed into a much smaller stage-structured projection matrix. The new algorithm was compared to the normal algorithm with a case study of nonylphenol on Japanese medaka (Oryzias latipes), and the simulation results suggest that the new algorithm can save computation time by around three quarters with a small underestimation of the variance and slight bias. The proposed algorithm is considered useful for a fast or screening stage of PLERA.