Graduate Thesis Or Dissertation
 

Passive sampling devices as biological surrogates for evaluating seasonal bioavailability of hydrophobic organic contaminants in surface water

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/d217qs16w

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  • The seasonal distribution of bioavailable organochiorine contaminants in surface water and the potential environmental factors influencing their bioavailability were evaluated. The study was carried at the lower Willamette River at Portland Harbor, Oregon where surface water runoff varied according to season. Bioavailable water concentrations of DDTs and PCBs were determined using a polyethylene membrane containing passive sampling device (PSD), known as semipermeable membrane device (SPMD). Our findings indicated that the influence of river seasonality on the bioavailable distributions of organochiorine contaminants was compound- and site-specific. Bioavailable DDTs concentrations were strongly affected by the local historic use of DDTs and seasonal changes in river conditions. The dominance of bioavailable p,p'-DDD and large DDD/DDE ratios observed during low flow condition in summer suggest redistribution of p,p'-DDD into the water column and conditions favoring reductive dechlorination of p,p'-DDT to p,p'-DDD. In contrast, bioavailable dieldrin and PCB concentrations were significantly increased during high flow condition in fall, especially during episodic rainstorm events. While a discernable seasonal pattern for PCBs was observed along the 18-mile stretch study area, the seasonal pattern of dieldrin was only apparent at the sampling site downstream of an agricultural creek with historical use of dieldrin. The increase in bioavailable PCB concentrations and daily loads cOincident with high precipitation and sewer overflows in fall suggested a significant contribution of PCBs from precipitation input and urban storm water discharges to the surface water. Seasonal bioavailable concentrations of organochiorine compounds exceeded the national and the Oregon water quality criteria revealing the significance of considering realistic seasonal and site-specific influences on bioavailable organochiorine distributions when performing risk assessments. In addition, we developed the triolein-free polyethylene lay flat tubing (LFT) as an alternative in situ PSD. The LFT proved reliable and had the same benefits as SPMD, but was simpler, inexpensive and lacked interference from the triolein impurities. The LFT tended to accumulate compounds with high log K0 faster than SPMD. LFT sampling rates were estimated and modeled for 33 target analytes, including PAHs, PCBs, and organochiorine pesticides. The successful determination of field derived data illustrates the effectiveness and reliability of LIT for environmental monitoring.
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  • File scanned at 300 ppi (Monochrome, 256 Grayscale, 24-bit Color) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
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file details SethajintaninDoolalai2006.pdf 2017-08-08 Público Descargar