浙江大洋水库沉积物重金属、营养盐生态风险评价

为评价大洋水库有机污染和重金属的潜在生态风险,于2013年3、6、9月对其沉积物Cu、Pb、Cd、Cr、Zn、As和Hg 7种重金属和碳、氮、磷的空间分布进行了研究。结果表明:沉积物Cu、Pb、Cd、Cr、Zn、As和Hg含量分别为19.50、86.19、0.41、2.44、126.7、3.46、0.36 mg/kg,有机碳(TOC)、总氮(TN)和总磷(TP)含量分别为7.30%、0.27%和0.099%,各种重金属和营养盐含量无空间差异;大洋水库重金属污染程度和潜在生态风险两种背景值评价方法间无差异或仅相差一个等级;以金衢盆地重金属背景值为参比,发现大洋水库沉积物处于中度重金属污染水平(Cd=10.53),7种重金属处于低污染到较高污染程度之间,其中Hg污染程度最高,Cr和As污染程度较低;大洋水库沉积物潜在重金属生态风险指数(RI)平均值为181.63,具有中等生态危害;各种重金属离子潜在生态风险由高到低依次为Hg、Cd、Pb、As、Cu、Zn、Cr,其中Hg具有中等到较高的生态风险,Cd为中等风险,其他重金属为低风险。研究表明,该水库存在严重的有机污染和较严重的有机氮污染。

Ecological risk assessment of heavy metals and nutrients in surface sediment of Dayang Reservoir,Zhejiang Province

The spatial distribution of heavy metals Cu, Pb, Cd, Cr, Zn, As and Hg and nutrients carbon, nitro-gen, and phosphorus in sediments were investigated in Dayang Reservoir in March, June and September in 2013 to evaluate their potential ecological risk ( PER) and organic pollution. The results showed that the concentrations of the heavy metals was 19. 50 mg/kg in Cu, 86. 19 mg/kg in Pb, 0. 41 mg/kg in Cd, 2. 44 mg/kg in Cr, 126. 7 mg/kg in Zn, 3. 46 mg/kg in As and 0. 36 mg/kg in Hg, and 7. 30% in total organic carbon (TOC), 0. 27% in nitrogen (TN) and 0. 099% in phosphorus (TP), without significantly spatial differences in the concentrations of the heavy metals and nutrients. There was no significant differences in PER and pollution degree of heavy metals between two background reference systems or only one grade differences. Compared with the background values of the Jinqu Basin nearby Dayang Reservoir, the sediment of the reservoir was found to be moderately polluted, with pollution parameter ( C d ) of 10 . 53 . The pollution made by the 7 heavy metals ranged from low level to relatively high level, the maximal pollution degree by Hg and the minimal by Cr and As, with an average PER index ( RI) of 181. 63, indicating that the reservoir sediment was within the real moderate risk. The order of the PER of the 7 heavy metals was ranged as Hg, Cd, Pb, As, Cu, Zn and Cr, with moderate to relatively high PER for Hg, mod-erate PER for Cd and low PER for the other five heavy metals. The organic matter index ( OI) and organic nitrogen index ( ON) analysis revealed that the reservoir was seriously polluted by organic materials and organic nitrogen.