Research On The Estuarine Behavior Of Pharmaceuticals And Endocrine Disruptors Using Passive Sampling

Nowadays, water pollution has become a global issue. As a class of emerging polar contaminants, drugs and endocrine disrupting compounds (EDCs) are widespread in the aquatic environment. They can not only change the ecological environment, but also affect the organism’s endocrine system. As a passive sampler, Polar Organic Chemical Integrative Sampler (POCIS) has been developed rapidly because of its small size, light weight, easy operation, continuous sampling with no need for power whilst obtaining abundant information. In this study, a total of25antibiotics, EDCs and drugs were selected as the target substances. The sampling rates of POCIS for selected substances were obtained through the laboratory dynamic experiments. The influence of salinity, flow rate and the physiochemical properties was studied in the further research. Finally, the sampling rates obtained from validation in the field environment were used in the application of POCIS, so as to expand the use of POCIS for environmental monitoring.In this study, the traditional approach for detecting the target substances was improved, and the method of layout and elution for contaminants adsorbed in POCIS was established. The analytical methods were based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The recoveries of traditional method and the POCIS were69.7-124.2%(RSD<12.4%) and79.5-115.0%(RSD<8.8%), respectively. The limits of quantitation for POCIS were0.03-1.28ng/L.The sampling rates for the target contaminant were highly influenced by their physiochemical properties and aquatic environmental conditions. The flow-through system demonstrated that the uptake of selected compounds in POCIS in the study period followed a liner pattern, and the linear correlation coefficient was between0.920-0.990. The mean sampling rates (Rs) for sulfa antibiotics were the lowest and varied from0.020-0.049L/d; similar to macrolide, the Rs for chloramphenicol was0.048L/d; the Rs for pharmaceuticals varied form0.031L/d (Paclitaxel) to0.193L/d (Nimodipine). The influence of salinity and flow rate on POCIS was different, so their effect on the Rs was different. The Rs for most compounds of POCIS was increased2-4times with increasing water salinity. Except estriol and paracetamol, when the salinity was increased form0%o to14%o, the Rs was increased2-6times, particularly the Rs for sulfapyridine (SP) was increased6.5times. The variation of Rs for most target compounds was below50%when the salinity exceeded14%o. The Rs could be increased by2-4times when the flow rate was doubled, and the increase of Rs for chloramphenicol and macrolide was similar. In summary, the salinity and flow rate were considered to be the main factors affecting the Rs, and it can be deduced from the results that for most compounds the flow rate was more important than the salinity. Simultaneously, the effects of the physicochemical properties of the target substances, such as octanol-water partition coefficient (Kow), acidity dissociation constant (pKa) and molecular weight were studied. The results showed that in the presence of high salinity and flow rate, there was a positive correlation between Rs and log Kow, which was not observed in the presence of high pKa. The Rs for macrolides and EDCs were the highest when log Kow was equal to3.1-3.5. When studying the effect of molecular weight on Rs in different conditions, no relationship was established.A field validation experiments was carried out in Wusongkou in July,2013, and the Rs under field conditions was obtained. Following that, a continuous observation of21days was conducted in October, and in December in order to promote the application for POCIS another five days’ study was implemented in Shidongkou, Wusongkou and Bailing Harbor. The result shows that16kinds of pollutants were detected in Wusongkou, and most of their concentrations were low (50ng/L) and in small fluctuations. The liner correlation coefficient between the estimated value by POCIS and the mean concentrations is about0.8, indicating that POCIS was able to monitor the emerging contaminants. Because of the sharp decrease in temperature, there was a significant difference between them in December. The major type of contaminants was MLs and the main pollutant was erythromycin-H2O and DCF in these three regions. There was a good agreement between the estimated value and the mean concentrations measured by spot sampling in Shidongkou.The POCIS were applied in8coastal fish ponds for investigating the content of the emerging contaminants in2013. The total contents of the pollutants ranked as follows:Ningbo> Shantou> Zhoushan> Ningde> wenling> Lianyungang> Qingdao> Shenzhen. The major contaminants found in their fish ponds were diclofenac (DCF) and bis-phenol A, and the sulfa antibiotics also accounted for10%.In summary, the passive sampling following field validation experiment can accurately detect the content of the emerging contaminants. The passive sampling can be applied to different bodies of water, and with the combination of biomarkers, it can provide important ecotoxicological information on organic contaminants in the future.