Modeling anaerobic dechlorination of polychlorinated biphenyls

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Çevre Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2012

Öğrenci: HALE DEMİRTEPE

Danışman: İPEK İMAMOĞLU

Özet:

This study aims to investigate the fate of polychlorinated biphenyls (PCBs) in sediments via using an anaerobic dechlorination model (ADM). PCBs are ubiquitous environmental pollutants, accumulated mostly in aquatic sediments. Significant attention was placed on the anaerobic dechlorination of PCBs since this process leads to the conversion of highly-chlorinated biphenyls to lower chlorinated ones, resulting in less toxic and more biodegradable congeners. An ADM was developed previously for the identification and quantification of anaerobic dechlorination pathways. In the present study, this model was improved and applied to laboratory and environmental sediment PCB data from Baltimore Harbor (BH), Maryland, USA, where PCB contamination has been recorded. The laboratory PCB data was from a 500 day microcosm study conducted with BH sediments which was used to validate the model, as well as to gather information on dominant dechlorination pathways affecting the sediments. ADM predicted the laboratory PCB data almost perfectly and subsequently very well predicted the environmental sediment PCB profiles. A complete identification and quantification of the anaerobic dechlorination pathways occurring in the BH sediments is achieved with this study for the first time. The significant similarity between the sediment sample PCB profiles and the model predicted profiles reveals that the BH sediments have undergone anaerobic dechlorination via a combination of previously identified dechlorination activities (N, P, M) with selective pathways. Model findings are consistent with microbial analysis of the sediments. Better understanding of anaerobic dechlorination mechanisms should aid in predicting natural attenuation of PCBs or developing bioremediation strategies for contaminated sites.