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采集了永定河及其支流清水河水样和表层沉积物各11个,并通过高速离心获得间隙水样10个.利用ICP-MS检测了上覆水中可溶性重金属(Cd、Cr、Cu、Hg、Mn、Ni、Pb、Zn)、间隙水中可溶性重金属(Cd、Cr、Cu、Mn、Ni、Pb、Zn)的含量以及沉积物中重金属(Cd、Cr、Cu、Hg、Mn、Ni、Pb、Zn)的总量;检测了样品的理化性质;分析了水体及沉积物间重金属的分配系数.结果表明,上游采样点水化学类型主要为Ca2+-Mg2+-HCO3-SO42-,而下游采样点水化学类型则主要为Na+-Mg2+-Cl--SO42-,上游和下游的水化学类型呈现明显的差异性;上覆水中Mn在位于下游的7号采样点含量超出生活饮用水卫生标准;间隙水中的重金属普遍高于上覆水含量;采用间隙水标准毒性单位(IWCTU)对间隙水重金属进行评价,发现Zn在大部分采样点(除2、5、11)及Pb在采样点6、7、8存在一定程度的毒性风险;Cd、Pb、Ni等3种重金属在附近有煤矿分布的采样点的上覆水和沉积物中含量都较高,需要特别注意的是Hg的分布也可能与煤矿开采有关.Pb、Cr、Mn等3种重金属在沉积物与上覆水中的分配系数比较大,而Hg、Cd、Zn则分配系数比较小;重金属在上覆水间隙水及沉积物中的分布关系为沉积物＞间隙水＞上覆水;分别对上覆水间隙水和沉积物中的重金属进行相关性分析及沉积物的主成分分析,发现Cd和Pb在间隙水和沉积物中均存在显著的相关性,沉积物中的Cd、Pb、Ni、Hg、Cu、Cr在第一主成分中具有较高的载荷值,推断这几种重金属具有相同的来源.

Eleven samples of water and surface sediment were collected in the Yongding River,with ten pore water samples obtained by high-speed centrifugation of the surface sediments.The dissolved heavy metals (Cd,Cr,Cu,Hg,Mn,Ni,Pb and Zn) in these samples were analyzed by Inductively Coupled Plasma-Mass Spectrometry,and relevant physicochemical properties were also determined.The partition coefficients of heavy metals between water and surface sediment were calculated.The results showed that the main hydrochemical type of the upstream part of the river in this research area was Ca2+-Mg2+-HCO3--SO24-,while that of the downstream part of the river was Na+-Mg2+-Cl--SO42-.Only the concentration of Mn in overlying water exceeded the limit for Drinking Water Quality.Concentrations of the heavy metals in pore water were generally higher than those in overlying water.According to assessment of heavy metals in pore water based on interstitial water criteria toxic units (IWCTU),Zn for all sampling sites (except site 2,5 and 11) and Pb for the three sites (site 6,7 and 8) had a toxic risk to aquatic organisms.Cd,Pb and Ni showed high concentrations in both overlying water and sediment collected at sampling sites where the coal mining activities were carried out.High concentrations of Hg near the coal mines should also be taken into account.Pb,Cr and Mn showed higher partition coefficient values while the values were lower for the other three heavy metals (Hg,Cd and Zn).The distribution of all heavy metals in overlying water,pore water and sediment was sediment ＞ pore water ＞ overlying water.Among heavy metals in overlying water,pore water and sediment,Cd and Pb in both pore water and sediment were significantly correlated.The principal component analysis (PCA) results for the heavy metals in sediment demonstrated that Cd,Pb,Ni,Hg,Cu and Cr were present in the first principal component,indicating that these heavy metals probably had similar source.