Application of the RUSLE for Determining Riverine Heavy Metal Flux in the Upper Pearl River Basin, China

A novel model was developed to estimate heavy metal flux at regional scale by using the Revised Universal Soil Loss Equation (RUSLE) to estimate soil erosion. This model was then used to estimate the fluxes of heavy metals including Zn, Cu, Cr, Ni, Cd, and As in three mono-lithologic regions in upper Pearl River Basin including carbonate rock (CR) basin, black shale (BS) basin, and basalt (BT) basin. Results show that the total annual erosions of the watershed were 8.56 × 10 5 t a −1 , 3.26 × 10 6 t a −1 , and 5.09 × 10 5 t a −1 in CR, BT, and BS basins, respectively. The heavy metal flux was lowest for Cd (0.87 kg km −2 a −1 , 0.46 kg km −2 a −1 , and 1.07 kg km −2 a −1 in CR, BS, and BT basins, respectively). The heavy metal flux was highest for Zn in CR basin (16.29 kg km −2 a −1 ), Cr in BS basin (27.25 kg km −2 a −1 ) and Cu in BT basin (259.59 kg km −2 a −1 ). These findings have important implication to understand transport and distribution of heavy metals in the Pearl River Basin, and make regulations for controlling of non-point source heavy metal pollution.