Effect of ethanol and biodiesel addition on the movement and biodegradation of volatile petroleum hydrocarbons in the subsurface

The microbial degradation of typical volatile petroleum hydrocarbons in an aerobic sandy soil was studied with and without the blending of 10 percent ethanol (E10) or 20 percent biodiesel (B20) in batch microcosms and minilysimeters. In the head-space of the mini-lysimeters all volatile compounds remained above the analytical detection limits over 92 days except toluene in the pure petroleum hydrocarbon mixture (PP) and ethanol in E10. The mass percentage of each petroleum hydrocarbon compound remaining at the end of the experiments was comparable for all fuel mixtures, except for m-xylene, which was significantly less reduced in E10 as compared to PP and B20. Total cell counts at the end of the experiments were highest for E10 and lowest for PP. DGGE analysis revealed a distinct microbial community structure for each fuel mixture. Batch studies confirmed these observations, in particular slower degradation of toluene in the presence of ethanol. Inorganic nutrient addition to the batch systems resulted in higher total cell counts, more rapid microbial degradation rates and more similar microbial community structures. Under aerobic conditions, competition for scare inorganic nutrients seems to be the most plausible reason for slower monoaromatic hydrocarbon biodegradation in the presence of more readily degradable biofuel.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Predicting the effects of biochar on volatile petroleum hydrocarbon biodegradation and emanation from soil: a bacterial community finger-print analysis inferred modelling approach

We investigated the response of the dominant bacterial taxa in gravelly sand to the addition of biochar and/or mixtures of volatile petroleum hydrocarbons (VPHs) using denaturing gradient gel electrophoresis (DGGE) and sequencing of cut bands. Biochar addition alone had only weak effects on the soil bacterial community composition in batch study samples, while VPH addition had strong effects. Indirect effects of biochar on soil bacterial communities were apparent in column study samples, where biochar-enhanced sorption affected VPH spreading. Following VPH addition, cell abundance increased by no more than a factor of 2 and several Pseudomonas spp. became dominant in soil with and without biochar. We present a VPH fate model that considers soil bacterial biomass dynamics and a nutrient limited soil biomass carrying capacity. The model simulates an apparent lag phase before the onset of a brief period of intensive VPH biodegradation and biomass growth, which is followed by substantially slower VPH biodegradation, when nitrogen needs to be recycled between decaying and newly formed biomass. If biomass growth is limited by a factor other than the organic pollutant bioavailability, biochar amendment may enhance VPH attenuation in between a VPH source below ground and the atmosphere by reducing the risk of overloading the soil's biodegradation capacity

Fatty acid composition, anti-inflammatory and analgesic activities of Hibiscus sabdariffa Linn. seeds

Hibiscus (H.) sabdariffa (commonly known as “Karkadeh” in Arabic) is widely used in various pharmacological applications in Sudan. The present study was carried out to investigate the anti-inflammatory and analgesic activities of H. sabdariffa seed extracts using rat models. In acute anti-inflammatory models, oral administration of petroleum ether extract of H. sabdariffa seeds inhibited the hind paw edema (p<0.01) which was induced by carrageenan. The petroleum ether extract exhibited significant (p<0.01) inhibition of vascular permeability in rats induced by intraperitoneal injection of acetic acid (0.6%). In cotton pellet granuloma method, the petroleum ether extract of H. sabdariffa seed showed significant inhibition of granuloma. The extract reduced (p<0.001) abdominal constrictions which was induced by injection of acetic acid (0.7%). Analysis of seed oil of H. sabdariffa using Gas Chromatography revealed the presence of three fatty acids; these were linolelaidic acid, arachidic acid, and palmitic acid. In conclusion, H. sabdariffa seeds possess anti-inflammatory and analgesic activities in rat model