| One sampling site was set in the mainstream of the Yellow River,near the drinking water source in Kaifeng City, 15 in Hei Reservoir, 16 in Liu Reservoir, 1 in the water entrance to the 1st Waterworks in Kaifeng City. Besides, 3 tap water samples were collected at different times of the day from the 1st Waterworks. So the system of upper source water - source water - tap water is formed. Three Erythroculter dabryi of similar size were collected from the field of Hei Reservoir and Liu Reservoir, respectively. Concentrations of NH3-N, volatile phenol, As, Cd, Pb, Cu, Zn, Mn, Ni, and Cr6 + in water samples were determined, and that of Cu, Pb, Zn, Mn, Ni, As and Cd in muscle tissue of Erythroculter dabryi were analyzed. Bioconcentration factors of heavy metals in the fish body were calculated. A health risk assessment was conducted for exposure to contaminants via drinking water ingestion, bathing and fish consumption pathways. The main conclusions drawn are as follows:(1) Concentrations of NH3-N, volatile phenol, Cr6+, Cu, Zn, Mn, As, Cd, Pb and Ni in the upper source water samples were higher than that in the source water and tap water ones, that in samples form the water entrance equal to that in the source water ones, and the higher level of contaminants in the upper source water, the greater decrease. The result shows that concentrations of NH3-N, Zn, Mn, Pb and Ni had no significant differences between Hei Reservoir and Liu Reservoir (p > 0.05), but there was a significant difference in concentrations of volatile phenol, Cr6+, Cu, As and Cd (p <0.05). The upper source water and source water are at Grade III, whereas tap water is at Grade I. Pollution levels of the mainstream of the Yellow River have a major impact on source water quality.(2) Concentrations of Cu, Zn, Mn, As, Cd, Pb and Ni in muscle tissue of Erythroculter dabryi of the Water Source were 1.61 2.13, 16.26 22.65, 0.38 0.49, 0.03 0.05, 0.03 0.05, 0.22 0.31, 0.14 0.22μg·g-1, respectively. Zn content is the highest; Cu comes second; Cd and As were the lowest. Heavy metals content in order were Zn> Cu> Mn> Pb> Ni> Cd, As. Significant accumulation of heavy metals has occurred in Erythroculter dabryi of the Water Source. BCF of Zn is the highest, suggesting the strongest accumulation ability. BCF in order was Zn> Pb> Cd> Cu> Ni> Mn> As. There was no significant difference in bioconcentration factors of heavy metals in muscle tissue of Erythroculter dabryi of Hei Reservoir and Liu Reservoir (p> 0.05).(3) Concentrations of heavy metals via individual exposure pose no non-cancer hazard to people who currently consume fish from the Water Source. Arsenic caused the geatest health risk via consumption of fish, because it was a leading contributor to non-cancer risk with 28.86% 41.66%. THQ values decrease in the order of As> Pb> Zn> Cu> Cd> Ni> Mn. In addition to THQCd> THQCu, Liu Reservoir was in accordance with Hei Reservoir. A mixture of heavy metals poses no non-cancer hazard to people, because the HIsF value was 0.19 0.24, not exceeding the risk control standards 1. As causes significant cancer risk via consumption of fish because values of TR exceeded of 1×10-6. In short, arsenic is not only a leading contributor to non-cancer risk, but also causes a significant cancer risk.(4) The drinking water pathway is the major route of exposure of human. Exposures of contaminants in source water decrease in the order of NH3-N>Cu>Zn>Mn>Cr6+>As>volatile phenol>Ni>Pb>Cd, whereas that in tap water decrease in the order of NH3-N>Mn>As>Zn>Cu>Ni>Pb>volatile phenol>Cd>Cr6+. Cancer risk indexes of contaminants in source water decrease in the order of As> Cr6+> Cd> Pb> Cu> Ni> Mn> Zn, whereas that in tap water decrease in the order of As> Cd> Pb> Ni> Cu> Mn > Zn> Cr6+. The drinking water pathway poses significant cancer risk, not dose bathing. Whether drinking or bathing, health risks of exposure to tap water pollutants are smaller than the source water. Arsenic is a major carcinogen, with the contribution 98.78% 99.07%.(5) A mixture of contaminants poses no non-cancer risk via drinking water ingestion, bathing and fish consumption pathways, with the values of HI 3.91×10-3 5.84×10-1 and the values of HIs 7.64×10-1. The drinking water pathway mainly poses cancer and non-cancer risk, with the contribution 72.76% and 86.57%, respectively. Fish consumption pathway comes second, and bathing hardly poses health risk. Arsenic is a major carcinogen, by which the contribution to HIs accounted for 76.35%. Cancer index of arsenic was 2.64×10-4 via above 3 pathways, showing that pollution by arsenic should be taken seriously enough. In summary, arsenic is not only a heavy pollutant causing the greatest health risk, but also a major carcinogen and non-carcinogen via multi-pathway exposure. |
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