曼谷湾沉积物重金属元素的富集效应与生物有效性

摘要

2010年在曼谷湾(泰国湾北部)及其北部主要河口(湄干河、拉塞河、湄南河和邦巴功河)采集了46个表层沉积物样品,分析了样品中重金属元素(Cd、Co、Cu、Pb、Zn)的含量水平,并用Al均一化数据,获得消除了粒度效应的重金属地球化学特征.利用1mol/L的HCl对该区沉积物进行了处理,通过分析沉积物重金属在酸溶相和残渣相的分布,揭示其生物有效性.结果表明,曼谷湾周边河流沉积物中重金属元素含量明显高于曼谷湾；曼谷湾沉积物中重金属(Co、Cu、Pb、Zn)从北向南随着离岸距离的增加而增加,Cd没有明显分布规律；地累积指数显示Cd和Pb存在显著的地球化学富集特征.Cd和Pb在酸溶相中的比例相对较高,表明其生物有效性较高,易引发二次污染.%Forty-six surface sediment samples were collected from the Bangkok Bay (Upper/Northern Gulf of Thailand) and adjacent river-mouths (Mae Klong River, Tha Chin River, Chao Phraya River, and Bang Pakong River) in 2010. The geochemical characteristics of heavy metals (Cd, Co, Cu, Pb and Zn) were studied using Al as a reference element to normalize the grain-size effect. The biological availability was assessed based on heavy metal concentrations in acid-soluble and residual fractions after the bulk sediment samples were pretreated with 1mol/L HCl. The results showed that the concentrations of heavy metals in sediments of the river-mouths were higher than that of the Bangkok Bay. The concentrations of heavy metals increased in a seaward direction from north to south except Cd and geo-accumulation index indicates that Cd and Pb were significantly enriched in the sediments. Higher concentrations of Cd and Pb in the soluble fractions showed strong bioavailability which may easily cause secondary pollution.