The Studies On The Analysis Method Of The Semi-permeable Permeation Device Sampling Polychlorinated Biphenyls In Environmental Media And The Absorption Dynamics

Polychlorinated biphenyls（PCBs）are a class of typical persistent organic pollutants that are extremely harmful to the marine environment and are usually low in the environment,making it difficult for detection.In this paper,an analysis method consisting of Semi-permeable Membrane Device（SPMD）enrichment,ultrasonic extraction（UE）,gel permeation chromatography（GPC）cleanup and Gas Chromatography（GC-ECD）was established and optimized for detecting 27 PCBs congeners,and then was applied in analyzing the SPMDs deployed in sediment,seawater and atmospheric samples.The PCBs concentrations in the pore water of sediments were calculated and compared with those obtained using two theoretical models.The in situ static absorption experiments of SPMD-enriched PCBs were carried out to obtain the absorption dynamics parameters.The main results are as follows:The recoveries of PCBs were compared with those of the PCBs from SPMD tubes by the methods of the organic solvent dialysis（OSD）and ultrasonic extraction（UE）.It was found that the recoveries of the two methods were almost identical at the high concentration group（recoveries of OSD and UE were in the range of 65%～148%and 58%～152%,respectively）,while the ultrasonic extraction method was superior to the organic solvent dialysis method.Besides,the ultrasonic extraction method has obvious advantages in time and solvent saving.The effluent from 11 to 17 min was separated and purified by gel permeation chromatography to obtain the best separation efficiency.The enrichment equilibrium time of 27 PCBs in SPMD was determined by laboratory enrichment experiments.The distribution of most of the PCB congeners between SPMD tubes and seawater reached equilibrium in 10 days.The measured SPMD/water partition coefficient(K_SPMD)was calculated using SPMD and water concentration ratios at equilibrium,and then compared with two theoretical models proposed by Hofmans and Booij,respectively.It was found that the actual measured K_SPMDvalues were lower than those of two theoretical models,but they were significantly positively correlated with the octanol/water partition coefficient(K_OW)of PCBs（R²=0.82,p<0.01）,and there was a significant linear relationship between the measured K_SPMDvalues and theoretical values（R²=0.88,p<0.01）.The K_SPMDdetermined in the laboratory would lay the foundation for further popularization of SPMD.The total amount of PCBs(C_sed)in the sediments,the concentrations of PCBs in the pore water(C_w-sed,organic carbon content correction method),the total content of PCBs in the pore water(C_pw,centrifugation)and the dissolved PCBs(C_w-SPMD)were analyzed.The results showed that the C_pwvalue was significantly higher than that of C_w-sedand C_w-SPMD.Therefore,taking into account the bioavailability,the use of the PCBs in sediment or pore water in the total amount for ecological risk assessment would cause the risk to be overestimated.Consequently,the dissolved PCBs were more reasonable for the risk assessment instead of the total concentrations in pore water and sediment.In addition,the method was applied to the determination of PCBs in the Arctic seawater and the atmosphere（seawater and atmospheric contents were nd～90.1 pg/L and nd～34.8pg/m³,respectively）.The detection rate of 27 PCBs was more than 40%.Comparing with the legacy of PCBs in other areas of the world,the PCBs levels in the region was still at a relatively lower level.