مشخصات پژوهش

عنوان	Effect of crude oil-induced water repellency on transport of Escherichia coli and bromide through repacked and physically-weathered soil columns
نوع پژوهش	مقاله چاپ‌شده در مجلات علمی
کلیدواژه‌ها	Water repellency Repacked soil Weathered soil Crude oil Preferentialflow Tension infiltrometer
چکیده	Knowledge of the transport and fate of pathogenicEscherichia coli, especially in the areas contaminated with crude oil, is required to assess contamination of shallow groundwater resources. The present study aims to investigate the effect of crude oil-mediated water repellency on the movement of nalidixic acid-resistantEscherichia colistrain (E. coliNAR) and bromide (Br) as an inert tracer in two soil types. The soils were contaminated at three levels of 0, 0.5 and 1% w/w of total petroleum hydrocarbons (TPHs) using crude oil. Steady-state saturatedflow in the soil columns was controlled using a tension infiltrometer. Leaching experiments were conducted through the columns of repacked (un-weathered) and physically-weathered clay loam (CL) and sandy loam (SL) soils. The columns leachate was sampled at specific times for 4 pore volumes. The shape of breakthrough curves for theE. coliNAR and Br depended on soil texture and structure and the TPHs level. Preferentialflow in the crude oil-mediated water-repellent soils facilitated the transport of contaminants especially E. coli NAR. Filtration coefficient and relative adsorption index of bacteria were greatest in the repacked CL soils and were lowest in the weathered SL soils. Discontinuity of soil pores and lowerflow velocity resulted in greaterfiltration ofE. coliNAR in the repacked CL soil than other treatments. Physical weathering induced the formation of aggregates which reduced soil particle surfaces available for retention of water-repellent oil and contaminants. Movement of both bacteria and Br tracer in the weathered SL soil with 1% TPHs was higher than other treatments. Thisfinding was attributed to low specific surface area, continuity of the pores and water repellency-mediated preferential pathways in the weathered SL soil columns. Ourfindings implied that shallow groundwater resources could be very sensitive to microbial contamination particularly in the oil-mediated water-repellent soils.
پژوهشگران	اعظم مرادی (نفر اول)، محمدرضا مصدقی (نفر دوم)، الهام چاوشی (نفر سوم)، آزاده صفادوست (نفر چهارم)، محسن سلیمانی (نفر پنجم)