Spatial distribution and health risk of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in the water of the Luanhe River Basin, China

The objectives of this study were to investigate the contamination levels and dispersion patterns of heavy metals and polycyclic aromatic hydrocarbons (PAHs) and to estimate the risk to health effects within the Luanhe river basin of northern Hebei Province, China. Samples of water were collected from upstream to downstream locations, and also from the main tributaries of Luanhe river. After appropriate preparation, all samples were analyzed for eight metals (As, Hg, Cd, Cr, Pb, Cu, Zn, and Fe) and 16 PAHs. Mean concentrations of As, Cd, Cu, and Zn were within the permissible levels, but Hg, Pb, and Fe concentrations were exceeded at some sites. The results indicated that the metal levels of upriver sites were higher than lower river sites; the metal levels of the main river were higher than ones of the tributaries except for Goutaizi at Xiaoluanhe. Only seven out 16 PAH components, which were mostly three- to four-ring compounds, were detected. Predominance of three- to four-ring PAHs suggests relatively recent local sources of PAHs in the study area. The combined hazard index for all metals and PAHs was from 2.26E - 02 to 1.18E - 01, which was lower than 1, suggesting minimal risk to humans. Only Arsenic (As) was evaluated with potential carcinogenic risks of 7.27E - 06 to 2.50E - 05. The study represents the preliminary implementation of a well-defined methodology into the environmental management process and provides a scientific basis for the pollutant controlment order.