【摘要】 采用高分辨电感耦合等离子体质谱（HR-ICP-MS）和地积累指数法(I_geo)对黄河甘肃、宁夏和内蒙古自治区连续三段表层沉积物中重金属（Cr,Pb,Cd,Cu,Zn和Ni）的空间分布和季节性波动（丰水期、枯水期和平水期）以及污染状况进行系统研究分析,研究结果表明:内蒙古段三个季节中沉积物重金属含量都高于甘肃和宁夏段,同时,除Cd外,丰水期所有点的沉积物重金属含量都高于枯水期和平水期,而枯水期和平水期的重金属含量相近。I_geo结果显示丰、枯水期的Cd,Cu和Cr元素的I_geo值在内蒙古段最高,而在甘肃段最低;所有重金属的I_geo值在丰水期高于枯水期,除Cd外,都在平水期降低,而I_geo^Cd在平水期各采样点明显上升;丰水期的甘肃段、枯水期的甘肃和宁夏段以及平水期的所有采样点中的Pb,Zn和Ni的I_geo值都小于0,表明这些元素在这些点几乎无污染。就研究区域而言,内蒙古段的重金属含量以及生态风险最高,Cr,Cd和Cu是最具有潜在风险的三个元素;就研究季节而言,丰水期的重金属含量和潜在风险高于枯水期和平水期,可能是跟丰水期沉积物的pH和总有机碳（TOC）含量较高有关。相关性分析（CCA）用来探究重金属与pH/TOC间的关系以及重金属的潜在来源。CCA的结果表明Pb,Cu,Zn和Ni互相相关,并且这四种元素容易受到周围环境pH和TOC的影响,除此之外,Cr,Cd以及TOC三者相关,且这两种元素受到人类活动影响较严重。该研究工作可为研究区域表层沉积物重金属在不同季节的环境行为提供有效的信息,同时,研究重金属、pH和TOC之间的相关性可有效揭示重金属的潜在来源。更多还原

【Abstract】 Spatial distribution,seasonal variations and pollution conditions of 6 heavy metals（Cr,Pb,Cd,Cu,Zn and Ni） in sediments in three different seasons（wet,dry and normal） from Gansu province,Ningxia and Inner Mongolia Autonomous Regions of the Yellow River were studied using high resolution inductively coupled plasma-mass spectrometry（HR-ICP-MS）,geo-accumulation index(I_geo),respectively.The results indicated that content of heavy metals in all three seasons of Inner Mongolia sediment samples were higher compared to Ningxia and Gansu sections,and except Cd,the other metals concentrations in wet season are relatively higher,and they are lower and approximated in dry and normal seasons.I_geo showed that high I_geo values of Cd,Cu and Cr were found in Inner Mongolia region in wet and dry seasons,and the low I_geo values of the three metals were obtained in Gansu region For season,the I_geo values of all study metals were higher in wet season than dry season,and they were decreased in normal season except Cd,while I_geo^Cd were high in all sampling sites in normal season indicating the strong anthropogenic sources there.I_geo values of metals including Pb,Zn and Ni were below 0 in wet season of Gansu,in dry season of Gansu,Ningxia regions and in normal season of all study regions,respectively,indicating a safer level.The results of spatial distribution and I_geoof study heavy metals suggested that higher total metal concentrations and potential risks were found in Inner Mongolia reaches of the Yellow River,and Cr,Cd and Cu were being more significant with the strong anthropogenic sources among all study metals.Considering the three different seasons,except normal season,the higher metal concentrations and potential risks for metals in sediments were observed in wet season than dry season,since the higher pH values of the sedimentary samples in wet season can help to promote adsorption and precipitation of heavy metal in sediments,meanwhile,the higher total organic carbon（TOC） values in sediments in wet season were also beneficial to the adsorption of heavy metals since the affinity between TOC and metal cations.Besides,the coast sediments with variety pollutants were brought into the river by rainfall in summer,which may also contribute to the rapid enrichment of heavy metals in sediments in wet season than dry season.The correlation among heavy metals and other variables and potential sources for heavy metals were evaluated by correlation coefficient analysis（CCA）.The results of CCA revealed that Pb,Cu,Zn and Ni showed a significant correlation with each other,and they would be easily influenced by pH and TOC.Furthermore,Cr showed a correlation with Cd and TOC and reflected a strong anthropogenic source.The present work could provide new information on the metals behavior in surface sediments and reflect the sediment geochemistry in the regions in the three seasons,whilst the study of element interrelationships,including pH and TOC gave the available information on their possible origins.更多还原