Which commonly monitored chemical contaminant in the Bohai region and the Yangtze and Pearl Rivers of China poses the greatest threat to aquatic wildlife?

The present study assessed the relative risk of 29 chemical contaminants to aquatic wildlife in the Bohai region and the Yangtze and Pearl Rivers of China. River monitoring data from 2010 to 2015 for metals, pesticides, plasticizers, surfactants, polyaromatic hydrocarbons, flame retardants, and ammonia were collected. For each chemical, ecotoxicity data were compiled for Chinese-relevant aquatic species. The chemicals were ranked by relative risk either by comparing the ratios of the median river concentration divided by the median ecotoxicity concentration or by the percentage of river measurements which exceeded the lower 10th percentile ecotoxicity value. To provide context, these results were compared with the same analysis for rivers in the United Kingdom. From this collection of chemicals in Chinese rivers, the highest risks appear to be from Cu, closely followed by Zn, Fe, and Ni together with linear alkyl benzene sulfonate, nonylphenol, and NH3 . This risk, particularly from the metals, can be several times higher than that experienced in UK rivers when using the same analysis. Ammonia median concentrations were notably higher in the Pearl and Yangtze than in UK rivers. The results suggest that China should focus on controlling metal contamination to protect its aquatic wildlife. Environ Toxicol Chem 2018;37:1115-1121. © 2017 SETAC.