渤海表层沉积物中DDTs、PCBs及酞酸酯的空间分布特征

Spatial distribution characteristics of DDTs, PCBs and phthalates in surface sediments from Bohai Sea, China

利用第2次全国海洋污染基线调查数据,研究渤海表层沉积物中DDTs、PCBs和酞酸酯的空间分布特征.结果表明:DDTs和PCBs的高值样点主要分布于秦皇岛近岸、辽东湾近岸和渤海湾近岸海区;酞酸酯的最高值和次高值样点分别出现在莱州湾近岸和辽东湾近岸,而秦皇岛近岸海区的平均水平高于其它海区.目前,渤海表层沉积物中PCBs和酞酸酯的含量相对较低,对周边底栖生物尚未构成威胁.另一方面,DDTs组成的比值关系显示秦皇岛近岸、渤海湾近岸和辽东湾近岸海区近期出现DDTs的输入,并且DDTs含量已超出相应的生态效应低值区间的标志水平,具有一定的生态风险.在渤海海区大多数样点,DDTs的主要代谢产物为厌氧条件下的DDD.

Based on the data of the Second Survey of Marine Pollution Baseline, the distribution characteristics of DDTs, PCBs and phthalates in the surface sediments collected from 66 sampling sites in Bohai Sea were studied. According to geographical distribution, the studied area was classified into 6 sub-areas, including 5 coastal areas (Liaodong Peninsula, Liaodong Bay, Qinhuangdao, Bohai Bay and Laizhou Bay) and 1 outer sea area. After pretreatment procedures, such as extraction, purification, separation and concentration, DDTs and PCBs were determined using gas chromatograph equipped with electron capture detector (GC-ECD), and phthalates using gas chromatograph mass spectrometer (GC-MS). The analytical results indicated that: (1) the range of DDTs concentrations in the offshore areas of Liaodong Peninsula, Liaodong Bay, Qinhuangdao, Bohai Bay and Laizhou Bay were 0.4～1.5, 0.4～3.9, 0.4～12.1, 0.4～4.6 and 0.4～1.1 (ng·g^(-1)), respectively, and 0.3～0.8ng·g^(-1) in the outer sea area; (2) the range of PCBs concentrations in the offshore areas of Liaodong Peninsula, (Liaodong Bay,) Qinhuangdao and Bohai Bay were no detection～1.1, no detection～3.7, no detection～7.7 and no detection～5.1ng·g^(-1), respectively, and the contents of PCBs in the Laizhou Bay coastal area and in the outer sea were lower than the detection limits; and (3) the range of phthalates' concentrations in the offshore areas of Liaodong Peninsula, Liaodong Bay, Qinhuangdao, Bohai Bay and Laizhou Bay were 1.2～19.9, 1.2～460.4, 117.6～319.9, 1.2～190.6 and 9.5～481.3 (ng·g^(-1)), respectively, and 1.2～189.5ng·g^(-1) in the outer sea area. In view of the average concentration, the maximum values of DDTs (2.0ng·g^(-1)), PCBs (2.1ng·g^(-1)) and phthalates (236.3ng·g^(-1)) were all presented in the coastal area of Qinhuangdao. Moreover, the concentration ratios of DDT to its corresponding metabolites (DDD+DDE) were higher than 1 at the sampling sites in the offshore areas of Qinghuangdao, Liaodong Bay and Bohai Bay, which demonstrated some recent inputs of DDT nearby. The main degradation product of DDT was DDD under the anaerobic conditions. Currently, the concentrations of PCBs and phthalates in the surface sediments were relatively low, and did not exert negative impact on the surrounding benthic community yet. On the other hand, the contents of DDTs were greater than the corresponding guidelines of effect range low (ERL), which suggested possible occurrence of local ecological risk.