淀山湖水生生物中有机氯化合物的浓度与富集特征

为研究淀山湖水生生物中有机氯化合物的浓度与富集特征,测定了该湖水生生物样品(铜锈环棱螺、日本沼虾、鱼类)中滴滴涕(DDTs)、六六六(HCHs)、六氯苯(HCB)、多氯联苯(PCBs)的浓度。研究结果显示,在所有生物样品中均检测到了DDTs、HCHs、HCB,各生物体内的有机氯农药含量有很大差异。在8种生物样品中,乌鳢体内的有机氯化合物含量最高,这可能与乌鳢处于较高营养级,且为肉食性鱼类,体内脂肪较多有关。∑DDTs、∑HCHs、HCB的含量范围分别是55~1 135、0.5~24、6.9~91ng/g lw,其中DDTs为最主要的有机氯农药。4,4’-DDE和α-HCH在各自同系物中所占比例最高,说明淀山湖历史上曾经使用过有机氯农药,而近期没有新的污染源输入。以铜锈环棱螺为参照,有机氯农药的生物放大系数(BMFs)范围是1.2(泥鳅)~23(乌鳢);PCBs的生物放大系数范围是5.9(河川沙塘鳢)~55(乌鳢)。亲脂疏水性、低生化降解速率导致有机氯化合物能在生物组织中富集并通过食物链逐级放大。研究结果表明,有机氯化合物会沿着食物链积累放大,可能会对人体健康存在潜在的威胁。

CONCENTRATIONS AND BIOACCUMULATION CHARACTERISTICS OF ORGANOCHLORINES IN AQUATIC ORGANISMS FROM DIANSHAN LAKE

In order to study the concentrations and bioaccumulation characteristics of organochlorines, DDTs, HCHs, HCB and PCBs were detected in a series of aquatic organisms collected from the Dianshan Lake, including pond snails, shrimps and several species of fish. The results showed that DDTs, HCHs, HCB were found in all biological samples, the concentrations of the analyzed organochlorine pesticides in different organisms differed greatly from each other. Among the eight species, snakehead had the highest concentrations of organochlorines. This might be due to that snakehead, as a carnivore species, lies at a higher trophic level and has higher body fat ratio. The ∑DDTs (sum of DDT, DDE, DDD) concentrations ranged from 55 to 1135 ng/g lw in the muscle, the ∑HCHs (sum of α HCH, β HCH, γ HCH, δ HCH) and HCB concentrations ranged from 0.5 to 24 ng/g lw to 6.9 to 91 ng/ lw, respectively. DDTs were the dominant OCPs measured in the samples. The 4, 4 DDE and α HCH were the most abundant congeners. As the predominant congener of DDTs, the 4,4 DDE showed the highest concentrations in all samples and accounted for a mean percentage of 76.6% of the sum DDTs. The (DDD+DDE) /DDT ratios in all the aquatic organisms were above 1, which indicated that there was no recent input of DDT in the sampling region. The profiles of DDTs and HCHs suggested a historical usage rather than contribution from recent sources. PCBs were detected in all organisms except pond snail. The concentrations of PCBs in the aquatic organisms were in the following order: snakehead > crucian > horn > bleeker > loach> günther > shimp > pond snail. Taking pond snail as the reference, the OCPs biomagnifications factors (BMF) of different aquatic organisms ranged from 1.2 (loach) to 23 (snakehead). Taking shrimp as the reference, the PCBs BMF of different aquatic organisms ranged from 5.9 (günther) to 55 (snakehead). The lipophilic nature, hydrophobicity and low chemical and biological degradation rates of organochlorines have led to their accumulation in biological tissues and the subsequent magnification of concentrations in organisms, progressing through the food chain. The abovementioned results indicated that the studied organochlorine compounds can be bioaccumulated and biomagnified along the food chain in the Dianshan Lake, which may pose a potential threat to human health