Transport of heavy metals in the Huanghe River estuary, China

Surface water samples were taken from the Huanghe River estuary in May and September 2009. Pb, Cu, Zn, Cd, As and Hg in dissolved and particulate phase, and physicochemical indexes of the water were determined to study the transport of metals. The results show that dissolved metals in river water increased significantly in 2009 compared to late 1980, and metal content in suspended particulate matter in the river is still low compared to the world river average. At the estuary, the levels of particulate heavy metals decrease seaward with increasing salinity and have significant positive correlation with suspended particulate matter (SPM) levels. The concentrations of dissolved Pb, Cu, Zn and As decrease as salinity levels increase, but the levels of dissolved Cd and Hg increase seaward with increasing salinity. The correlation analysis shows that SPM, salinity and DO are the important factors that controlled the spatial distribution of heavy metals. There is inverse linear relationship between metals' log (KD) for Pb, Cu, and Zn values and SPM. This relationship may be caused by Particle Concentration Effect (increased colloid concentration in the filtered fraction in proportion to the quantity of suspended particles). SPM, salinity, pH and DO have significant (p < 0.01) correlation with KD (partitioning coefficient) of Pb and Cu. SPM has also significant (p < 0.05) correlation with KD of Zn and Hg, and salinity has significant (p < 0.05) correlation with KD of Zn and As. However, the KD of Cd has no relation to the physicochemical indexes which means the behavior of Cd in estuary is different. SPM and salinity are main parameters affecting the variance of KD in the estuary. Pollution and decrease of SPM in the upper reaches of the Huanghe have affected the transport behavior of trace elements at the estuary compared 1980.