During the past decades of years, the widespread restrictions and ban on the use of legacy persistent organic pollutants (POPs) such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) around the world have resulted in gradual decrease in their concentration in various environmental media. As an open sea area, the Northwest Pacific Ocean is far away from the continental area without obvious pollution point source, the ocean currents play an important role in the transportation and diffusion of POPs. In this study, the surface waters (2−5 m) and subsurface waters (150 m) in the Kuroshio area of the Northwest Pacific Ocean were collected and analyzed for dissolved OCPs and PCBs. The results showed that the concentrations of HCHs, DDTs, CHLs and PCBs in the surface waters ranged from 30.7 pg/L to 68.8 pg/L, 6.16 pg/L to 23.8 pg/L, 1.07 pg/L to 5.75 pg/L and 49.8 pg/L to 124 pg/L, respectively; the concentrations in the subsurface waters ranged from 27.3 pg/L to 68.4 pg/L, 7.06 pg/L to 14.1 pg/L, 0.518 pg/L to 10.1 pg/L and 34.1 pg/L to 68.4 pg/L, respectively. The concentration levels of OCPs in different water bodies were comparable, which may be related to the huge water body and internal homogeneity of the Kuroshio. The ratios of the various isomers of HCHs indicated that the sea area was dominated by lindane input, while the ratio of DDTs and CHLs showed that the DDTs and CHLs in the waters of the sea area were mainly derived from the residues of legacy. PCBs were dominated by tri-PCBs and tetra-PCBs, which consistented with the use of PCBs in East Asia. The large volume and uniform internal distribution of Kuroshio water mass have an important impact on the vertical distribution of pollutants, that is, the concentration and composition of OCPs in water at different depths are similar. At the same time, Kuroshio brings high temperature and high nutrient salt water masses, forming potential risks to the enrichment of pollutants in the marine organisms.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |