A Preliminary Study On Organochlorine Pesticides In Demersal Organisms From The Pearl River Estuary And In Water And Sediments From Two Tibetan Lakes

Organochlorine pesticides are of great concern for their negative impact on the wildlife and human health. Bioconcentration and long-range atmospheric transport are two important characteristics of their environmental behavior. In this paper, we collected 52 demersal organism samples from Pearl River Estuary and measured the concentrations of HCHs and DDTs in these demersal organisms. The analysis of stable nitrogen and carbon isotope ratios of biota was used to characterize a demersal organism's trophic position and carbon source, respectively. To evaluate the situation of environment pollution in Tibet, concentrations of OCPs were also determined in water and sediments from two Tibetan lakes, Lake Yamzho Yumco and Lake Co Ngoin. In addition, we conducted an investigation in recoveries of PCBs by clean-up with silica gel/aluminia column chromatography, gel-permeation chromatography (GPC), and multi-layer silica gel column.The result showed:1 The demersal organisms from the Pearl River estuary were seriously polluted by DDTs and HCHs. On a lipid content basis, total HCH concentrations ranged from 21.97 to 3925.87 ng/g lipid, and total DDT ranged from 1981.74 to 42490.78 ng/g lipid; HCHs in shell, shrimp and crab had levels higher than DDTs in fish, on the contrary, DDTs in fish had levels higher than HCHs in shell, shrimp and crab. No obvious law was among the concentration of DDTs and HCHs in the same organisms from different locations. Compared to National Standard (GB2763-81), our data are in the range of standard. But compared to other similar studies, contamination of DDTs in Pearl River estuary is more serious.2 The total HCH and DDT concentrations in the organisms from Outer Linding (B-C) and Inner Linding (F-G) water areas were well explained by trophic position inferred by 15N, but no relationship was found between the total HCH and DDT concentrations and I5N in the organisms from DE water area, indicating heterogeneity in water mass and biota in the Pearl River estuary. At present, this phenomenon has not been reported yet. Slopes for log tDDT versus 15N are 0.08 (Outer Linding, B-C) and 0.02 (Inner Linding, F-G), these are comparable with other tropic areas, but different from temperate zones reported by other studies. This showed that bioconcentration of OCs in the tropic zone or sub-tropic zone is relatively weak as compared to those in the water bodies in temperate and frigid zones.3 Organochlorine pesticides (OCPs) in water and sediments from two Tibetan lakes, Lake Yamzho Yumco and Lake Co Ngoin, were analyzed by GC-ECD. The results showed that the two pristine Tibetan lakes were significantly contaminated by OCPs. The occurrence of a variety of OCPs, the absence of an up-profile decreasing trend around the surface layer, as well as the higher concentrations of OCPs in Lake Yamzho Yumco compared to the northern Lake Co Ngoin may probably suggest a significant long-range atmospheric transport (LRAT) of OCPs by air flows from Bay of Bengal to Tibet. It should be noted that the DDTs and HCHs concentrations in water and sediments from the two Tibetan lakes were even within the range of those in eastern China regions, indicating an accumulation of OCPs in Tibetan lacustrine environment, which may exerta long-term negative impact on the wildlife in Tibet.4 The result of recoveries of PCBs showed that the recoveries of PCBs after GPC clean-up are all high, and no significant difference was among the recoveries of PCBs with different chlorine atoms. This indicated the method that GPC was used to remove lipid could not affect the recoveries of PCBs.