Arsenic concentration, speciation, and risk assessment in sediments of the Xijiang River basin, China.

In order to acquire the spatial distribution, speciation, and risk assessment of arsenic (As), 18 sediment samples were collected in the middle and upper reaches (Nanpan River, Beipan River, Hongshui River, Diaojiang River, and Duliu River) of the Xijiang River basin, China. The chemical fractions of As in the collected sediments were mainly dominated by the residual fraction and the Fe (Mn, Al) oxide/oxyhydroxides fractions. The correlation analysis results showed that the chemical fraction of As in sediments had close correlations with Mn, good correlations with Fe and organic matter (OM), while weak correlations with Al and carbonate. In addition, it also showed that Diaojiang River basin was found to have an extremely high As pollution status and suffered from high ecological risk. Duliu River and Nanpan River had moderately polluted levels of As and showed a low ecological risk. The other sample sites of Xijiang River basin were uncontaminated of As. The assessment results from this study indicated that the different types of species present based on the chemical fractionation of As from the Xijiang River basin showed different risks. Graphical abstract.