摘要:
2013年12月采集了重庆南山老龙洞地下河表层沉积物样品,利用电感耦合等离子体质谱仪(ICP-MS)、电感耦合等离子体发光质谱仪(ICP-OES)分析样品中 Mn、Pb、Cu、As 和 Cr 的含量,并用地累积指数法和潜在生态风险指数法对重金属的生态风险进行评估。结果表明:地下河表层沉积物存在重金属富集现象,富集程度依次为 Cr>Cu>Mn>Pb>As,其中 UGR0处重金属污染相对较严重;地下河表层沉积物重金属含量主要受总有机碳(TOC)控制,与沉积物 pH、粒径无显著相关性,TOC 也控制着重金属稳定度,影响着重金属的迁移性,进而影响上覆水水质;地累积指数法评价显示地下河表层沉积物重金属整体上处于轻度污染状态,潜在生态风险指数法评价表明老龙洞地下河表层沉积物重金属含量水平引发有害生物效应的可能性不大。
Abstract:
The surface sediment was collected from a karst subterranean river in Nanshan,Chongqing,in December 2013.These samples were analyzed by using Inductively Coupled Plasma Mass Spectrometry(ICP-MS)and Inductively Coupled Plasma Optical Emission Spectrometry(ICP-OES),respectively,to determine the content of heavy metals(Mn,Pb,Cu,As and Cr)in the sediments.Meanwhile,the geo-accumulation pollution index and potential ecological risk index were used to assess the ecological risk of heavy metals in sediments,so as to provide a scientific basis for the development of urban construction and protection of karst groundwater.Results showed that Mn,Pb,Cu,As and Cr are enriched in Laolongdong subterranean river sediments,with the enrichment of these heavy metals as Cr>Cu>Mn>Pb>As.It was TOC (total organic carbon)that controlled the sediments heavy metal contents,but not pH and particle size of sedi-ments.Meanwhile,TOC also controlled SAC (stability assessment code),which has an effect on the migra-tion of the heavy metals,and influences the quality of overlying water.In general,heavy metals in surface sediments from Laolongdong were in slightly-polluted state evaluated by geo-accumulation pollution index, and implied a low probability of toxic effect evaluated by potential ecological risk index.
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