To evaluate mobility of toxic elements and their potential ecological risk caused by seabird biovectors, the fractionation distributions of arsenic (As), mercury (Hg) and cadmium (Cd) were investigated in three ornithogenic sediment profiles from the Ross Sea region, East Antarctica. The results show residual As holds a dominant position, and Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions, indicating weak mobility of As and Hg. However, exchangeable Cd occupies a considerable proportion in studied samples, suggesting Cd has strong mobility. The preliminary evaluation of Sediment Quality Guidelines (SGQs) shows adverse biological effects may occur occasionally for As and Cd, and rarely for Hg. Using Risk Assessment Code (RAC), the ecological risk is assessed at moderate, low and very high for As, Hg and Cd pollution, respectively. The authors concluded that the findings show that organic matter derived from guano is the main factor controlling the mobility of Hg and Cd through adsorption and complexation.
Authors: Lou C, Liu X, Nie Y, Emslie SD. ;Science of the Total Environment. 2015 Aug 28;538:644-653. doi: 10.1016/j.scitotenv.2015.08.102.[Epub ahead of print] ;