Determination of tungsten’s toxicity coefficient for potential ecological risk assessment

The potential ecological risk index (RI), proposed by the Swedish geochemist Hakanson, has been widely used for quantitatively evaluating the pollution degree caused by various pollutants. As an emerging contaminant, tungsten (W) poses ecological risks to the environment, and the quantitative assessment of the risk is of extraordinary significance. However, the lack of a determined W toxicity coefficient has limited the use of the RI in evaluating the W pollution degree. In this study, the toxicity coefficient of W (= 2.00) was calculated based on Hakanson’s theory, then verified via a case study conducted by 23 sediment samples in Taojiang River near a W mining area in southern Jiangxi. The risk factor ( E w ) and geoaccumulation index ( I geo ) of W, and RI and Nemerow comprehensive pollution index (NCPI) of eight heavy metals at each sampling site were calculated and compared, respectively. The results showed consistent correlations and trends of pollution levels for the investigated sites, which means the rationality of assigning a toxicity coefficient of 2.00 for W. These results can contribute to the use of the RI method for the scientific evaluation of W pollution levels.