Chemical Ecological Risk Assessment for Aquatic Life Under Climate Change: A Review from Occurrence, Bioaccumulation, and Toxicity Perspective

Abstract

The contamination of the natural environment by chemical substances resulting from human activities represents a significant global environmental concern. The aquatic environment is the final destination of most of these chemicals, and aquatic organisms living in it could inevitably be exposed to chemicals, which would introduce certain ecological risks. The occurrence and bioaccumulation of chemicals can be altered by climate change-driven temperature and other environmental factors (precipitation, wind, extreme weather), which in turn affects the risk assessment of chemicals. However, current ecological risk assessment frameworks do not fully consider the effect of temperature. This review presents a synthesis of the current knowledge regarding the influence of climate change-driven environmental factors (mainly temperature) on the occurrence, bioaccumulation, and toxicity of chemicals, and finally proposes an integrated ecological risk assessment framework. We first synthesized observed evidence of chemical occurrence change in the atmosphere and aquatic systems. In general, knowledge gaps remain regarding the quantitative effects of environmental factors (temperature, precipitation, extreme weather) on the occurrence of chemicals in aquatic ecosystems. Temperature affects the bioavailability and toxicokinetics of chemicals, which ultimately affect the accumulation. As temperatures rise, the accumulation by organisms can be strengthened, weakened, or even unchanged. Interestingly, there are cases shown that temperature can reduce toxicity while most of the existing studies have reported that temperature increases the toxicity of chemicals. Temperature can change the toxicity of chemicals by increasing the internal exposure dose of chemicals, promoting oxidative stress, interfering with the metabolic rate of chemicals, and affecting the biological growth rate. Given that the risks of chemicals are greatly affected by climate change, it is essential to consider the impacts of climate change in future chemical risk assessments.