珠江口沉积物中重金属及其相态分布特征

DISTRIBUTIONAL CHARACTERISTICS OF HEAVY METAL AND ITS AVAILABLE PHASES IN SEDIMENTS FROM ZHUJIANG RIVER MOUTH

分析了在珠江口采集的21个表层柱状沉积物样品重金属(Cu、Pb、Zn、Cr、Cd、As、Hg)的分布特征,并采用连续提取法,首次较系统地对该区沉积物中重金属元素的相态进行了研究。结果表明,珠江口表层沉积物中Zn、Cr、Cu、Cd等重金属含量呈现由西北逐渐向东南递减的变化特点,而Pb、As、Hg等重金属元素的含量分布无明显规律。重金属的相态分布表现为,Cu、Cd以吸附相为主,Cr、Hg以铁锰氧化物和有机结合相为主,Pb、Zn和As则表现为相对较为均匀地分布在3个或4个相态中,其中Pb以有机相稍占优势,Zn以铁锰氧化物相稍占优势,As则以水相稍占优势。重金属含量及相态分布的影响因素主要为污染源的排放(人为因素)和珠江口的水动力条件(自然因素),如强径流和弱潮所引起的沉积物粒度组成、海水、底质的盐度以及pH、Eh等。

The distributional characteristics of heavy metals (Cd, Cr, Cu, Pb, Zn, As, Hg) in the top sediments of twentyone cores from the Zhujiang River Mouth were analyzed, and their existing phases were also studied by a sequential chemical extraction method. The results showed that the contents of Zn, Cr, Cu and Cd decreased gradually from northwest to southeast, while those of Pb, As and Hg showed no apparent rule. As to the available phases, Cd and Cu mainly existed in absorptive phase, Cr and Hg were mainly combined to FeMn oxides or in organic phases, and Pb, Zn and As existed in three or four phases in a relative even ratio, among of them, Pb had a slightly advantage in organic phase, Zn in FeMn oxides phase, and As in aqueous phase. The anthropogenic pollutant discharges and hydrodynamic conditions are thought to be the two main factors affecting the heavy metal distribution and its existing phases in sediments.