Concentration and fractionation of trace metals in surface sediments of intertidal Bohai Bay, China

► Cd, Cr, Cu, Ni, Pb and Zn were measured in sediments of intertidal Bohai Bay. ► Sediment grain size plays a key role in controlling the heavy metal geochemistry. ► Sediments with high clay and silt content have been polluted to various degrees. ► Cr prominently contributes the most to the contamination. ► The combination of the six studied metals may have a 21% probability of being toxic.