杭州城区河道底泥重金属污染及潜在生态风险评价

Heavy Metal Pollution in the River Sediment in Hangzhou and Assessment of its Potential Ecological Risk

对杭州城区34条河道45个点位河道底泥进行采样,分析了pH及汞、砷、铅、铬、镉、铜、锌、镍等重金属含量,并进行污染及潜在生态风险评价。结果表明,监测点位的底泥为中性偏碱性,重金属含量分布不均,且范围波动很大,部分河道底泥重金属中汞、铅、镉、铬、锌、镍等有不同程度的超标,少数河道镉、铬、锌污染严重;按《农用污泥中污染物控制标准》(GB4284-84),超标的河道有13条,分别为沿山港、电厂河、西塘河、下塘河、上塘河、白石港、麦苗港、幸福河、永久河、北塘河、官河、史家桥河和南门江;总体上底泥重金属潜在生态风险顺序依次为汞>镉>铅>铜>砷>锌>镍>铬,汞和镉是主要的潜在生态风险因子,要特别关注沿山港、下塘河、上塘河及麦苗港的汞污染和沿山港、官河、史家桥河及南门江的镉污染问题;对于潜在生态风险危害程度轻微或中等,且达到《农用污泥中污染物控制标准》(GB4284-84)的河道疏浚底泥,具有农用的可行性。

River sediments were sampled from 45 points in 34 rivers in Hangzhou,which were analyzed for pH and contents of heavy metals including Hg,As,Pb,Cr,Cd,Cu,Zn and Ni.The assessment of pollution and potential ecological risk showed that the river sediments from the monitored points were neutral partial alkaline;the contents of heavy metals distributed uneven and varied very much;the heavy metals of Hg,Pb,Cd,Cr,Zn and Ni from a part of river sediments exceeded standard in differentdegrees and a few ones polluted by Cd,Cr and Zn seriously.According to the ＂Controlling standards for pollutants in agricultural sludge＂（GB4284-84）,there were 13 rivers exceeded the standards including Yanshan harbor,Dianchang river,Xitang river,Xiatang river,Shangtang river,Baishi harbor,Maimiao harbor,Xingfu river,Yongjiu river,Beitang river,Guan river,Shijiaqiao river and Nanmen river.The potential ecological risk of heavy metals ranked as HgCdPbCuAsZnNiCr,of which Hg and Cd were the main potential ecological risk factors.Special attentions should be paid on the Hg pollution in Yanshan harbor,Xiatang river,Shangtang river and Maimiao harbor and the Cd pollution in Yanshan harbor,Guan river,Shijia bridge river and Nanshan river.For those river where the sediments had low or medium level of potential ecological risks and reached the ＂Controlling standards for pollutants in agricultural sludge＂（GB4284-84）,they were available for agricultural utilization.