黄河下游水体悬浮颗粒物中金属元素的地球化学行为

Geochemistry of metals in the suspended particles in the lower reach of the Huanghe

为调查黄河下游颗粒物的风化状况以及重金属变化规律及其污染程度,于2009年6～7月调水调沙期间（每日）及2010年4月至2011年11月（每月中旬）对垦利浮桥水体颗粒物进行采样调查.样品经消解后采用ICP-AES测定其中Al、Na、K、Ca、Fe、Mn、Cu、Zn、Cr、Ni、V的含量.采用化学风化指数（CIA）来衡量硅酸盐的化学风化程度,结果表明,黄河流域颗粒物化学风化程度为中等,近30年来颗粒物化学风化程度没有明显变化.黄河下游颗粒物中重金属（Cu、Zn、Cr、Ni、V）浓度呈现出冬季高夏季低的变化规律,调水调沙期间重金属浓度降低后期略有回升,这一变化规律主要是受泥沙的稀释及颗粒物粒径等因素影响.重金属富集因子（EF）的计算表明,黄河下游Zn具有中等程度的污染,其他元素无明显污染.提取3个因子对黄河下游颗粒物的化学组成因素进行分析,颗粒物主要受风化的影响,同时也受径流量以及人类活动的影响.

Suspended particulate matter（SPM） samples were collected at Kenli in the lower reach of the Huanghe daily during the water-sediment regulation event（WSRE） in June-July 2009 and monthly from April 2010 to November 2011. The concentrations of metal elements（Al, Fe, Mn, K, Na, Ca, Cr, Cu, Ni, V, Zn） were determined by ICP-AES after digestion. The chemical weathering of suspended particles and the distributions of particulate heavy metals and their pollution status in the lower reach of the Huanghe are presented in this manuscript. Chemical index of alteration（CIA） is widely used to assess the degree of silicate weathering of the particles in the drainage basin. The CIA results in the lower reach of the Huanghe indicate that the chemical weathering of the partilces is moderate and there＇s nosignificant variation compared with historical data. The concentrations of particulate heavy metals（Cr, Cu, Ni, V, Zn） were higher in winter than in summer and were lower during the WSRE than the later stage. The seasonal and daily variations were mainly caused by the dilution of resuspended particulate matter and the grain-size effect. Enrichment factor（EF） results showed that Zn was moderate polluted while other heavy metals remained at natural levels. Three factors are extracted to explain the chemical composition of particulate matter, which are chemical weathering, variations of riverine runoff and human activity.