HR-ICP-MS研究丰水期黄河甘宁蒙段表层沉积物中重金属的形态分析与污染评价

Study on Speciation Analysis and Ecological Risk Assessment of Heavy Metals in Surface Sediments in Gansu,Ningxia and Inner Mongolia Sections of the Yellow River in Wet Season with HR-ICP-MS

为连续、系统地研究不同年份丰水期黄河甘宁蒙段表层沉积物中重金属的含量、污染状况和潜在生态风险,在前期工作的基础上,采用三级四步提取法（BCR）和高分辨电感耦合等离子体质谱（HR-ICPMS）对2012年丰水期黄河甘宁蒙段包头浮桥（S2）、石嘴山陶乐镇（S6）和乌金峡（S9）等10个采样点水体表层沉积物中Cd,Pb,Cr,Ni,Cu,V,Co,Zn和Mn九种重金属元素进行含量测定和形态分析,并对重金属元素的污染作出评价。结果表明：各重金属元素在每个采样点分布趋势相同,平均含量顺序依次为：Mn〉V〉Zn〉Cr〉Cu〉Ni〉Pb〉Co〉Cd;表层沉积物中重金属主要以残渣态形式存在,表明重金属的生物有效性低,对环境影响较小;地积累指数法（Igeo）的评价结果显示Cd元素的Igeo值最高,对环境污染程度较高,其余元素对环境影响较小,其中Mn元素影响最小;富集因子法（EF）评价结果表明,Cd和Cu元素在某些采样点表现为显著富集,尤其是Cd在S5点处EF值高达4.69,表明该点处Cd受人类活动影响较为明显,其余元素均为非富集元素,这与Igeo评价结果吻合;潜在生态风险指数法（RI）表明,黄河甘宁蒙段S1,S2和S5点的RI值在150~300之间,为中等危害范畴,其余各采样点RI值均小于150,为轻微危害。研究结果为相关部门提供可信的实验数据和理论依据,也为建立该河段泥沙-污染物输移数学模型和系统研究持久性有毒污染物迁移转化规律及环境评价提供技术支撑。

In order to continuously study the contents ,pollution condition and potential ecological risk of heavy metals in surface sediments in Gansu ,Ningxia and Inner Mongolia sections of the Yellow River in wet seasons in different years ,the speciation analysis of 9 kinds of heavy metals including Cd ,Pb ,Cr ,Ni ,Cu ,V ,Co ,Zn and Mn ,pollution condition and potential ecologi‐cal risk of heavy metals in surface sediments from 10 sampling sites like Baotoufuqiao （S2） ,Shizuishantaolezhen （S6） and Wu‐jinxia （S9） in Gansu ,Ningxia and Inner Mongolia sections of the Yellow River in 2012 wet season were studied with BCR se‐quential extraction and high resolution inductively coupled plasma‐mass spectrometry （HR‐ICP‐MS ） based on our previous works .The results implied that the order of heavy metals average contents in the 10 sediment samples were the same ：Mn〉V〉Zn〉Cr〉Cu〉Ni〉Pb〉Co〉Cd .In the sediments ,heavy metals mainly existed in the form of residual fraction ,which indicated that the bioavailability or environmental impact was low .Results of geo‐accumulation indices （Igeo ） showed that ICdgeo was the lar‐gest among the heavy metals with the strongest pollution ,while IMngeo was the smallest .Enrichment factor （EF） indicated that on‐ly Cd and Cu were enriched at some sampling sites .In S5 ,because EFCd reached 4 .69 ,Cd was affected by human activities obvi‐ously and the result was consistent with Igeo .Potential ecological risk index （RI） implied that the RI values in S1 ,S2 and S5 were between 150 and 300 ,which belonged to moderate polluting degree ,while others were less than 150 ,belonging to light pollution degree .The results of this paper could not only provide reliable experimental data and theoretical basis for the relevant departments ,but also supply the technical support for constructing mathematics model of sediments‐pollutants transport ,sys‐tematically researching the migration and transformation rule of persistent toxic substances and environmental assessment in these reaches .