珠江三角洲河流及南海近海区域表层沉积物中有机氯农药含量及分布

Distribution of organochlorine pesticites (OCPs) in surface sediments in Pearl River Delta and its adjacent coastal areas of South China Sea

利用GCECD检测了珠江三角洲主要河流、珠江河口及南海近海岸带共计50个表层沉积物中的有机氯农药,主要检测出DDTs、HCHs和七氯等农药.有机氯农药含量范围为0.176～12.85ng·g-1,分布特征为珠江、东江>西江>珠江口>南海近海;南海样品的含量随着离岸距离的增加而下降.与1997年的样品相比较,珠江三角洲河流中有机氯农药含量明显下降,主要原因是有机物的降解作用.但DDTs农药仍然对该区生物造成潜在的负面影响.DDTs农药的组成特征表明,除西江有新近使用的DDT外,其余区域以农药残留为主.DDTs主要以还原产物为主,但随传输距离的增加,氧化产物逐渐成为主要组分.有机质含量与有机氯农药间的相关性分析表明,有机质在控制有机氯农药在沉积物中的分布上起着重要作用.

Organochlorine pesticites （OCPs） （ mainly HCHs, DDTs and heptachlor） were measured in 50 surface sediment samples from rivers of Pearl River Delta and its nearby South China Sea. Total OCPs concentration varied from 0. 176-12.85 ng/g. The OCPs concentration in the sediments follows the sequence： Zhujiang River, Dongjiang River 〉 Xijiang River 〉 Pearl River Estuary 〉 South China Sea. A decrease in OCPs concentrations with distance from the estuary to open sea could be observed in South China Sea. Although present organochlorine pestieites had decreased in Zhujiang River and Xijiang River as compared to 1997, adverse biological effects of OCPs might occasionally occur in rivers of Pearl River Delta according to effects-range guideline. The ratios of DDT/ （ DDD＋DDE） for the sediment demonstrated that new DDT still be used in watershed of Xijiang River. DDD was major component of DDTs in rivers of Pearl River Delta, the Pearl River estuary and nearshore of South China Sea. In offshore regions, DDE became major component of DDTs. TOC and OCPs concentrations were correlated, which suggested that organic carbon played an important role in determining the level of OCPs in the sediment.