Non-carcinogenic risk assessment of eight metals in the source groundwater of Shaying River basin. 
Because of serious pollution of river water, people living along the Shaying River in China exploit the groundwater as a drinking water resource.  Various pollutants including heavy metals have been detected in the groundwater at depths up to 200 m. To perform a non-carcinogenic risk assessment, the hazard index (HI) was determined for several metals present in the groundwater.  High resolution inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectroscopy were used to measure the levels of Hg, Fe, Mn, Zn, Cd, Cr, Cu and Pb in source groundwater of eight tap water treatment plants (WTPs) during a 3-year period (2007-2009).  Zn was present at the highest concentration of up to 101.2 μg l(-1) and Cd contributed the most (57.8%) to the HI in the WTPs, followed by Mn (14.3%) and Cr (13.1%).  Both hazard quotients of individual metals and HI of total non-carcinogenic risk in each WTP were below 1.0, suggesting that the water posed negligible health risk on local residents.  Temporal and spatial comparisons showed that high HIs tend to occur in low water periods (i.e., summer), and the City Pressure Station (Fuyang City) had the highest HI, followed by Yingnan Pressure Station (Yingnan Country) and Taihe WTP (Taihe Country).  This study provides benchmark information useful for regulatory authorities to control the discharge of metals into the Shaying River Basin, and serves as a basis for comparison to other river systems in the world.