广州市河涌沉积物及底栖生物体内的重金属含量及分布

CONCENTRATIONS AND DISTRIBUTION OF HEAVY METALS IN SEDIMENTS AND BENTHIC ORGANISMS FROM SEWAGE STREAM IN GUANGZHOU CITY

本文报道了广州市河涌沉积物及底栖生物的重金属含量及分布状况。应用 WFX- IF2型原子分光光度计对 2 1个采样点沉积物及底栖生物样品中 Cd、Cu、Zn、Pb、Cr和 Ni的含量进行了测定 ,并使用标准物作了对照分析。结果显示 :沉积物中 Cd、Cu、Zn、Pb、Cr、Ni的平均含量分别为 5.61、30 2 .1 2、72 7.0 3、1 63.37、67.70、84.58μg/ g干重 ;底栖生物中 Cd、Cu、Zn、Pb、Cr、Ni的平均含量分别为 0 .78、2 9.2 0、2 68.38、1 0 .75、3.89、3.44μg/ g干重。结果表明 :广州市河涌已受到不同程度的重金属污染 ,受污染最严重的是赤岗涌、海珠涌和棠下涌。工业活动是造成污染的主要原因。河涌中的水栖寡毛类与沉积物中的重金属含量显著相关 (P<0 .0 1 ,P<0 .0 5) ,可以作为 Cu、Cr、Ni的良好指示生物。

It is well known that heavy metals have a great ecological significance due to their toxicity and accumulative behaviour playing a prominent role in aquatic ecosystems. Toxic trace metals occur in all compartments in the sewage streams in many large cities of water environment, and become a potential hazard for hydrobios and man. The main objective of the present study is to investigate the concentrations and distribution of heavy metals in sediments and benthic organisms (aquatic oligochaetes) from sewage stream in Guangzhou city. Sediment and aquatic oligochaetes samples were collected from 21 sites in seven sewage stream in Guangzhou from February to May, 2002. The samples were homogenized, freeze dried and digested by nitric acid. They were tested for their cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb),chromium (Cr)and nickel (Ni) concentrations (based on dry weight) by flame atomic absorption spectrophotometry. Analytical methodologies used were confirmed by reference to certified standard material (Standard Oyster Tissue 1556a and Buffalo River Sediment). The results showed that the average concentrations of Cd, Cu, Zn, Pb, Cr and Ni in sediments were 5.61, 302.12, 727.03, 163.37, 67.70, 84.58 μg/g (dry weight basis); and 0.78, 29.20, 268.38, 10.75, 3.89, 3.44 μg/g (dry weight basis) in benthic organisms, respectively; and the great difference occurred in sediments and benthic organisms in different sampling sites. It indicated that all streams in Guangzhou have been polluted by heavy metals in different degree, which was mostly affected by human actions. Chigang stream, Haizhu stream and Shangxia stream are the most serious. Industry activities are responsible for the pollution mainly. The concentrations of heavy metals in benthos (aquatic oligochaetes) is remarkably correlated with that in sediments ( P<0.01,P <0.05), so the former can be used as bio indicator of Ni, Cu and Cr. The sewage sludge in Guangzhou streams used as agricultural fertilizer is basically safe in concentrations of heavy metals.