澳门水域水体有机氯农药的垂线分布特征

Vertical distribution of organochlorine pesticites (OCPs) in Macao coastal waters

对澳门水域水柱不同水深水体进行垂线采样,根据水样颗粒相和溶解相有机氯农药(OCPs)的定量分析结果,探讨水体中OCPs的垂线分布特征.结果表明,OCPs总量变化范围为25 1～67 5ng·L-1,六六六总量为8 7～27ng·L-1;DDTs总量是8 7～29 8ng·L-1;DDT (DDE+DDD)垂线分布表明,水柱上层样品的DDT (DDE+DDD)>1,说明目前可能仍有新使用的DDT农药进入该水域;据OCPs在颗粒相和溶解相中的分配及其垂线分布表明,水体中悬浮颗粒物主要以沉降和水平迁移输运为主;聚类分析结果亦表明,中层、上层水样的关联程度相对较高,与底部界面水的相关性较低,揭示OCPs在表层沉积物与水体间的垂向交换、迁移较弱,水环境受表层沉积物再次释放OCPs的影响较小.

The organochlorine pesticides (OCPs) in water column from Macao coastal waters were analyzed quantitatively, based on USEPA 8000 series methods and under quality assurance and quality control (QA/QC). The results were as follows: (1) The total (particulate plus dissolved phase) OCP concentrations in Macao were between 25.1?ng·L^(-1) and 67.5?ng·L^(-1); ranges of the HCHs concentrations were 8.7～27?ng·L^(-1) and the total DDTs levels were from 8.7?ng·L^(-1) to 29.8?ng·L^(-1); (2) The dissolved phase concentrations of HCHs in Macao coastal waters ranged from 5.7?ng·L^(-1) to 22.3?ng·L^(-1). However, the DDTs levels in dissolved phase ranged from 0.5～2.7?ng·L^(-1). The HCHs levels in particulate phase in Macao costal waters ranged 51.7～3653?ng·g^(-1), and the DDTs concentrations in particalate phase were 180～16236?ng·g^(-1); (3)The concentrations of DDTs and the ratios of DDT/(DDE+DDD) decreased with increasing of depth in the water colum. The DDT/(DDE+DDD) ratios in the upper water samples (surface and 0.2H) are higher than 1 and it suggested that there are still fresh inputs of DDT into the Macao coastal waters; (4)The concentrations of OCPs in particulate phase and the partition coeffients (logK_p) between particulate phase and dissolved phase were decreasing with increasing depth, indicating predominant deposition process and horizontal transportation for particles in water colunm; (5) Three clusters were classified by cluster analysis. The interface samples, which statistical distance is relatively far from the middle and upper sampling locations, it indicated that the vertical transportation of OCPs was not significant, and the influence of OCPs from the surface sediment on the water column is also not significant.