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Effect of Nutrient Amendments on Indigenous Hydrocarbon Biodegradation in Oil-Contaminated Beach Sediments

Department of Chemical and Environmental Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260

View larger version (22K): [in a new window]   Fig. 1. Schematic diagram of sediment irrigation system.

View larger version (28K): [in a new window]   Fig. 2. Concentration of (a) NH3–N, (b) NO3–N, and (c) total P in leachate from oil-spiked control and treated sediments. For Inipol (Ip) samples treated with Ip only, the total organic nitrogen was determined as ammonia nitrogen using a Kjeldahl method, meaning there is no NO3–N data in (b). C, control; Ip, Inipol; Os, Osmocote; SN, soluble nutrients.

View larger version (26K): [in a new window]   Fig. 3. Dehydrogenase activity of microbial biomass in oil-spiked control and treated sediments. Mean and standard deviation of duplicates are shown. C, control; INTF, 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazoliumchloride (INT)-formazan; Ip, Inipol; Os, Osmocote; SN, soluble nutrients.

View larger version (32K): [in a new window]   Fig. 4. Gas chromatograph–mass spectrometry (GC–MS) data of oil residue extracted from sediment before experiment on Day 0 and the control and six treated sediments on Day 45. Peak identification of hydrocarbon components is shown in GC–MS data of oil residue on Day 0. The y axes of all graphs are in the same range. C, control; Ip, Inipol; Os, Osmocote; SN, soluble nutrients.

View larger version (29K): [in a new window]   Fig. 5. Gas chromatograph–mass spectrometry (GC–MS) data of the biomarker C30–17(H), 21ß(H)-hopane in commercial standard (a) and oil residue (b). The MS spectra of C30–17(H), 21ß(H)-hopane is shown in (c).

View larger version (33K): [in a new window]   Fig. 6. Gas chromatograph–mass spectrometry (GC–MS) data of oil residue extracted from leachate of control on Days 0 and 7. Peak identification of hydrocarbon components is shown in GC–MS data of oil residue on Day 0.

View larger version (60K): [in a new window]   Fig. 7. Total amounts of aliphatics (n-C12 to n-C33, pristane, and phytane) relative to hopane and normalized by initial values in oil-spiked control and treated sediments on Days 0, 15, 30, and 45. Mean and standard deviation of duplicates are shown. C, control; Ip, Inipol; Os, Osmocote; SN, soluble nutrients.