广东大中型水库底泥重金属含量特征及潜在生态风险评价

广东省45宗大中型水库底泥重金属含量分析评价结果表明:除Cr外,广东省大中型水库底泥中Cu、Zn、Pb和Cd含量均高于广东省土壤重金属含量背景值.广东省四大地理区域中,粤北地区大中型水库底泥Cu、Zn、Pb和Cd平均含量均为最高,分别为89.71、321.21、154.95mg/kg和1.46mg/kg;其次是粤东和粤中地区;粤西大中型水库底泥Cu、Zn、Pb和Cd平均含量均为最低,但Cr平均含量居四大区域之首,为130.81mg/kg.粤东和粤北大中型水库底泥重金属富集系数以Cd最高;粤中和粤西大中型水库底泥重金属富集系数则以Cu最大.总体而言,粤北大中型水库底泥重金属具有很强的潜在生态风险,粤东和粤中大中型水库底泥重金属潜在生态风险程度为中等;粤西大中型水库底泥重金属属于轻微生态风险程度.结果说明,广东省大部分地区大中型水库底泥的重金属潜在生态风险主要是由于底泥中Cd的潜在生态风险系数过高所造成.人为生产活动,特别是矿产开采造成的污染是广东省大中型水库底泥重金属潜在生态风险等级提高的主要原因.

Heavy metal contents analysis and potential ecological risk appraisal to sediments of large and medium |scaled reservoirs in Guangdong Province

To evaluate the potential ecological risks of heavy metals in sediment of large and medium|scaled reservoirs in Guangdong province, the contents of Cu, Zn, Pb, Cd and Cr in sediments of 45 reservoirs were analyzed. The results showed that Cu, Zn, Pb and Cd contents in sediment were higher than the soil background values of Guangdong province except for Cr. The mean concentrations of Cu, Zn, Pb and Cd in sediment of reservoirs in northern area of Guangdong province were the highest which was 89.7, 321.21, 154.95 and 1.46mg/kg, respectively, followed by those in eastern and central areas, and the lowest in western area, however, Cr content was the highest in sediment of reservoirs in western area which was 130.81mg/kg. The enrichment factor of Cd was the highest in sediment of reservoirs in eastern and northern areas while that of Cu was the highest in sediment of reservoirs in western and central areas. In general, the potential ecological risk of heavy metals in sediment of reservoirs was very strong in northern area of Guangdong province, moderate in eastern and central areas, and slight in western area. The potential ecological risk of heavy metals in sediment of large and medium|scaled reservoirs in most areas of Guangdong province resulted from high potential ecological risk factor of Cd in sediment. Anthropogenic activities, especially mining, were the main reason for elevated potential ecological risk of heavy metal in sediment of large and medium|scaled reservoirs in Guangdong Province.