Mechanisms of intrinsic bioremediation of gas condensate hydrocarbons in saturated soil

Applied Biochemistry and Biotechnology - The addition of gas condensate hydrocarbons to saturated soil from a gas production site stimulated sulfate reduction under anaerobic and oxygen-limiting...     

Rapid acquisition technique for MR elastography of the liver

Magnetic resonance elastography (MRE) of the liver is a novel noninvasive clinical diagnostic tool to stage fibrosis based on measured stiffness. The purpose of this study is to design, evaluate and validate a rapid MRE acquisition technique for noninvasively quantitating liver stiffness which reduces by half the scan time, thereby decreasing image registration errors between four MRE phase offsets. In vivo liver MRE was performed on 16 healthy volunteers and 14 patients with biopsy-proven liver fibrosis using the standard clinical gradient recalled echo (GRE) MRE sequence (MREs) and a developed rapid GRE MRE sequence (MREr) to obtain the mean stiffness in an axial slice. The mean stiffness values obtained from the entire group using MREs and MREr were 2.72 ± 0.85 kPa and 2.7 ± 0.85 kPa, respectively, representing an insignificant difference. A linear correlation of R² = 0.99 was determined between stiffness values obtained using MREs and MREr. Therefore, we can conclude that MREr can replace MREs, which reduces the scan time to half of that of the current standard acquisition (MREs), which will facilitate MRE imaging in patients with inability to hold their breath for long periods.     

The potential for intrinsic bioremediation of BTEX hydrocarbons in soil/ground water contaminated with gas condensate

Applied Biochemistry and Biotechnology - Gas condensate liquids contaminate soil and ground water at two gas production sites in the Denver Basin, CO. A detailed field study was carried out at...     

A case study of the natural attenuation of gas condensate hydrocarbons in soil and groundwater

Applied Biochemistry and Biotechnology - Condensate liquids have been found to contaminate soil and groundwater at two gas production sites in the Denver Basin operated by Amoco Production Co....     

Oxidation of hydrogen sulfide by an enrichment from sour water coproduced with petroleum

We have previously demonstrated that the chemoautotroph and facultative anaerobeThiobacillus denitrificans may be readily cultured aerobically or anoxically in batch and continuous reactors on hydrogen sulfide under sulfide-limiting conditions. A sulfide-tolerant strain ofT. denitrificans (strain F) was isolated by enrichment and recently used in a successful field test of a microbial process for the treatment of sour water coproduced with petroleum at an Amoco Production Co. site in Wyoming. Prior to the initiation of this field test, it was determined that the sour water at this site contained low concentrations of indigenous autotrophs, which could grow on thiosulfate as an energy source. Samples of this sour water have now been used to produce an enrichment culture for sulfide oxidizers. This enrichment has been characterized with respect to hydrogen sulfide oxidation, response to oxygen, pH and temperature optima, and sulfide tolerance. The enrichment was shown to be strictly aerobic and to grow on sulfide as an energy source with complete oxidation of sulfide to sulfate. The enrichment has a tolerance of sulfide comparable to that ofT. denitrificans strain F. However, the enrichment has a higher optimum temperature (35°C) than strain F and was shown to oxidize sulfides over a much broader range of pH values (3.5–10).

     

Intrinsic bioremediation of gas condensate hydrocarbons

Condensate liquids have been found to contaminate soil and ground water at two gas production sites in the Denver Basin operated by Amoco Production Co. These sites have been closely monitored since July 1993 to determine whether intrinsic aerobic or anaerobic bioremediation of hydrocarbons occurs at a sufficient rate and to an adequate end point to support a no-intervention decision. Ground water monitoring, soil gas analysis, and analysis of soil cores suggest that bioremediation is occurring at these sites by multiple pathways, including aerobic oxidation, sulfate reduction, and methanogenesis. Results of over two years of monitoring of ground water and soil chemistry at these sites are presented to support this conclusion.