Distribution and geochemical speciation of heavy metals in sediments from coastal area suffered rapid urbanization, a case study of Shantou Bay, China

► Shantou Bay was polluted majorly by Cd, Cu and Pb. ► Total and non-residual fractions of metals have a seaward decrease. ► Cd, Zn, and Mn were dominated in acid-soluble fractions. ► Pb and Cu were dominated in reducible (50%) and oxidable fractions respectively. ► Non-residual fractions of metals were ascribed to anthropogenic sources.