New insights into species sensitivity, hazard and ecological risks of trace metals to algae in aquatic environments

As primary producers at the base of aquatic food chain, algae are particularly vulnerable to trace metals due to their direct interference with algal cell wall, photosynthetic pigments and photosynthesis. Through the construction of species sensitivity distributions, this study represented the first attempt to evaluate species sensitivity of various algal groups with different cell wall and pigments, and hazard and ecological risks of trace metals to algae in aquatic environments. The results of this study showed that diatoms were relatively sensitive to metals, while green algae were less sensitive. Organotin and mercury were generally the most toxic, whereas selenium and nickel were the least toxic. Freshwater algae were more sensitive to cadmium, copper and chromium, while their saltwater counterparts were more sensitive to lead. According to the hazard quotients derived from average metal environmental concentrations, 40% of cases posed high risks to algae in the Pearl River Estuary, which is one of the most severely polluted estuaries in China. This study has provided reliable information about hazard and risks of trace metals on various algal groups and facilitates future research to incorporate such information to further improve risk assessment and regulation of trace metals.