The concentrations of nine metals (As, Cr, Al, Cu, Pb, Zn, Ni, Mn, and Hg), in 23 water samples collected from four main types of water (well, surface river, subterranean stream and blue hole), in the Huixian karst wetland were determined and analyzed to investigate their distributions and health risks. A multivariate statistical analysis was used to study the distribution characteristics of the metals. A human health risk assessment model was developed to assess the health risks. The results found that the mean concentrations of metals in water from the Huixian karst wetland were in the order:Al > Mn > Zn > Cr > Ni > As > Hg > Cu > Pb. The maximum concentrations of Hg (1.08 μg·L-1) in the well water, Hg (0.78 μg·L-1) and Mn (259.00 μg·L-1) in the surface river water, and Hg (0.47 μg·L-1) and Al (300.00 μg·L-1) in the blue hole water all exceeded the corresponding standard limits. The metal concentrations in the subterranean stream samples were all within the regulated limits. For the nine metals, the well water and the subterranean stream water qualities were better than those of the surface river and the blue hole. The results of the multivariate statistical analysis showed that the concentrations of Cr, Ni, Cu, and Zn in the well water were mainly related to the regional geological background, while the concentrations of Al and Pb in the blue hole water were mainly affected by pyrite mining and residential activities. The concentrations of As and Mn in rivers may be affected by tourism activity, aquaculture and river sediments. The results of the health risk assessment on water through the drinking and skin penetration pathway indicated that the total health risks order was:well > subterranean stream > blue hole > surface river. The total health risks values of well water as drinking water for adults (6.11×10-5 a-1) and children (6.67×10-5 a-1) exceeded the maximum allowance level (5.0×10-5 a-1). Cr was the main metal element that causes carcinogenic risks. For drinking water safety, the concentrations of Hg and Cr in well water should be controlled before drinking.
Keywords: Huixian karst wetland; health risk; metals; multivariate statistical analysis; water.