海口城市水体底泥中重金属含量分布、形态特征及环境质量评价

Distribution, speciation, and environmental quality assessment of heavy metals in sludge of water bodies of Haikou City

分析了海口市19个水体59个底泥样品中重金属的含量和形态,并进行环境质量评价。结果表明:海口城市周边水体底泥的Cr、Ni、Cu、Cd元素含量高于市区底泥;而Hg、Pb、Zn元素含量分布则表现出市区高于周边的规律。As未表现出空间差异。海口底泥中Cu、Pb、Zn以残渣态为主(占40%左右);Cr、Ni、Hg、As四种元素以残渣态为主(占60%以上);Cd元素形态则以离子交换态为主(占30%以上),除残渣态之外的其余形态所占比例和高于80%。环境质量评价结果表明,海口城市底泥中As、Cd、Cu三种元素的含量较低,基本上符合海洋沉积物质量(GB18668-2002)一、二级标准。而Cr、Ni和Hg、Zn、Pb五种元素含量稍高,周边底泥中Cr、Ni两元素含量符合或超过三级标准,市区底泥中Hg、Zn、Pb元素含量分别符合二、三或超三级标准。

Distribution and speciation of heavy metals including Cu, Zn, Cd, Ni, Cr, Pb were determined in 59 sludge samples of 19 waterbodies in Haikou. The results showed that concentrations of Cr, Ni, Cu, and Cd in sludge of peri-urban areas were higher than those of urban, while higher concentrations of Hg, Pb, and Zn were found in urban areas. Cu, Pb, and Zn in sludge in Haikou City existed mainly in the form of residual, which accounted for 40% of the total content. Cu, Pb, and Zn in Fe-Mn bound and humic acid phases accounted for 30% of the total content. Cr, Ni, Hg, and As in sludge also existed mainly in the form of residue, which accounted for more than 60% of the total content. However, Cd existed mainly in the form of exchangeable phase, which accounted for more than 30%, and all phase（except for residue） accounted for more than 80%. Environmental quality assessment indicated that concentrations of As, Cd, and Cu in sludge in Haikou City were low, according with Level I or II of GB 18668—2002. However, concentrations of Cr, Ni, Hg, Zn, and Pb were relatively high. Concentrations of Cr and Ni in sludge of peri-urban areas met or exceeded Level III of GB18668-2002 while concentrations of Hg, Zn, Pb in urban areas met Level II, III and exceeded Level III of GB 18668-2002, respectively.