The biodegradation of oil and the dispersant Corexit 9500 in Arctic seawater

Thesis (Ph.D.) University of Alaska Fairbanks, 2017As oil and gas production continues in the Arctic, oil exploration and shipping traffic have increased due to the decline of Arctic sea ice. This increased activity in the Arctic Ocean poses a risk to the environment through the potential release of oil from cargo ships, oil tankers, pipelines, and future oil exploration. Understanding the fate of oil is crucial to understanding the impacts of a spill on the marine ecosystem. Previous oil biodegradation studies have demonstrated the ability of Arctic and sub-Arctic microorganisms to biodegrade oil; however, the rate at which oil degrades and the identity of indigenous oil-degrading microorganisms and functional genes in Arctic seawater remain unknown. In addition to oil, it is also important to understand the fate and effects of chemicals potentially used in oil spill response. Corexit 9500 is a chemical dispersant that is pre-approved for use in sub-Arctic seawater and is likely the dispersant of choice for spill responders in Arctic offshore environments. Currently no literature exists concerning the biodegradation of Corexit 9500 in Arctic seawater. Here we investigate the fate of oil, chemically dispersed oil, and the chemical dispersant, Corexit 9500, in laboratory mesocosms containing freshly collected Arctic surface seawater. The objectives of these experiments were to calculate the extent and rate of biodegradation (based on GC/MS & LC/MS/MS analysis) and to identify bacteria (determined using 16S rRNA gene sequencing) and genes (based on GeoChip 5.0 microarray) potentially involved in the biodegradation process. Indigenous microorganisms degraded both fresh and weathered oil, in both the presence and absence of Corexit 9500, with oil losses ranging from 36-41% within 28 days and 46-61% within 60 days. The biodegradation of the active components of Corexit 9500, which are dioctyl sodium sulfosuccinate (DOSS) and non-ionic surfactants, was also measured after 28 days. Biodegradation of DOSS was 77% in offshore seawater and 33% in nearshore seawater. Non-ionic surfactants were non-detectable after 28 days. Taxa known to include oil-degrading bacteria (e.g. Oleispira, Polaribacter, and Colwellia) and oilbiodegradation genes (e.g. alkB) increased in relative abundance in response to both oil and Corexit 9500. These results increase our understanding of oil and dispersant biodegradation in the Arctic and suggest that some bacteria may be capable of biodegrading both oil and Corexit 9500. We also sought to understand baseline abundances of taxa known to include oildegrading bacteria and functional genes involved in oil biodegradation in an offshore oil lease area. Aerobic oil-degradation genes (based on GeoChip 5.0 microarray) and taxa (determined using 16S rRNA gene sequencing) known to include oil-degrading bacteria were identified in seawater from the surface, middle, and bottom of the water column. Bacterial community structure differed significantly by depth (surface water vs. bottom water), while the relative abundance of major functional gene categories did not differ with depth. These findings support previous observations that two different water masses contribute to a stratified water column in the summer open-water season of the oil lease area, but indicate that potential function is fairly similar with depth. These results will contribute to understanding the potential for oil biodegradation throughout the Arctic water column and the fundamental microbial ecology of an offshore oil lease area. Together, these mesocosm experiments and in situ studies address important data gaps concerning the fate of spilled oil and Corexit in Arctic seawater. These results provide novel insight into the ability of Arctic bacteria to biodegrade crude oil and Corexit 9500, and suggest similarities between Arctic and temperate deep-sea environments in regards to taxa and functional genes that respond to oil and Corexit

Rhizoremediation of diesel contaminated soil using Salix alaxensis

Thesis (M.S.) University of Alaska Fairbanks, 2010"An outdoor pot study and a microcosm study were conducted to evaluate the potential for Salix alaxensis (felt leaf willow) to rhizoremediate diesel-contaminated soil. The pot study was conducted for 96 days during an Alaskan interior summer with S. alaxensis grown in soil contaminated with diesel fuel oil #2. The concentration of diesel range organics (DRO) and the most probable number (MPN) of diesel degrading microorganisms in the rhizosphere were measured initially and compared to final values. A microcosm study was also performed with crushed willow roots to simulate root turnover, in which the abundance of diesel degrading microorganisms was also determined. It was hypothesized that treatments containing willow and fertilizer would foster the greatest abundance of diesel degrading microorganisms and thus would provide the largest decrease of diesel range organics. In the pot study, growth of S. alaxensis resulted in the largest decrease of DROs, although treatments amended with fertilizer contributed to a significant increase in MPN of diesel degrading microorganisms. The microcosm study indicated that the addition of crushed willow roots to contaminated soil produced a similar abundance of diesel degrading microorganisms as the addition of salicylic acid. The findings suggest that S. alaxensis can be a useful plant for rhizoremediation of diesel-contaminated soil"--Leaf iii1.1. Petroleum contamination -- 1.2. PAH biodegradation -- 1.3. Genetics and gene regulation -- 1.4. Cometabolism -- 1.5. Phytoremediation and rhizoremediation -- 1.6. The rhizosphere -- 1.7. Rhizodegradation of of petroleum -- 1.8. The role of plant secondary compounds in rhizoremediation of aromatics -- 1.8.1. Salicylate induces PAH degradation -- 1.8.2. Salicylate contributes to cometabolism -- 1.9. Studies of petroleum rhizoremediation -- 1.10. Evaluating the rhizoremediation potential of Salix alaxensis -- 1.11. Willows in rhizoremediation -- 1.12. Thesis objectives and hypothesis -- 2. Rhizoremediation of diesel contaminated soil using Salix alaxensis -- 2.1. Introduction -- 2.2. Methods -- 2.2.1. Plant material -- 2.2.2. Soil preparation and characterization -- 2.2.3. Experimental design -- 2.2.4. DRO concentration analysis -- 2.2.5. Soil microbial enumeration -- 2.2.6. Microcosm study -- 2.2.7. Statistical analysis -- 2.3. Results -- 2.3.1. Plant biomass -- 2.3.2. Most probable number results -- 2.3.3. Removal of diesel range organics -- 2.4. Discussion -- 2.5. Conclusion -- 2.6. Figures -- 2.7. Tables -- 2.8. References -- Conclusions -- References

Biodegradation of Naturally Occurring Substances in Produced Water - Revision of data for the DREAM model

A literature review was conducted to obtain more reliable primary (biotransformation) and ultimate (biomineralization) biodegradation rates for compounds in produced water for the DREAM model, than the current biodegradation data. During the literature review, it became apparent that many compounds lacked quality ultimate biodegradation rates, which is preferred in the model. Therefore, ultimate biodegradation rates for these compounds were estimated based on their primary biodegradation rates and a FACTOR. These data and calculations are described in the report below. Calculated ultimate biodegradation rates are compared to rates found in the literature. This report also includes two separate Excel spreadsheets that summarize the prima ry and ultimate biodegradation data obtained during the literature review and their corresponding experimental details. A Q10 approach was applied to calculated ultimate biodegradation rates to display rates at three relevant temperatures (5, 13, and 20°(). The ultimate biodegradation rates included in this report will substantially improve the DREAM model, but the majority of these rates are extrapolated estimates. Additional biodegradation tests are recommended to correlate these calculations with laboratory experiments.StatoilpublishedVersio

Dual-polarized chipless humidity sensor tag

In this letter, a miniaturized, flexible and high data dense dual-polarized chipless radio frequency identification (RFID) tag is presented. The tag is designed within a minuscule footprint of 29 × 29 mm2 and has the ability to encode 38-bit data. The tag is analyzed for flexible substrates including Kapton® HN DuPont™ and HP photopaper. The humidity sensing phenomenon is demonstrated by mapping the tag design, using silver nano-particle based conductive ink on HP photopaper substrate. It is observed that with the increasing moisture, the humidity sensing behavior is exhibited in RF range of 4.1–17.76 GHz. The low-cost, bendable and directly printable humidity sensor tag can be deployed in a number of intelligent tracking applications

Oil type and temperature dependent biodegradation dynamics - Combining chemical and microbial community data through multivariate analysis

Abstract Background This study investigates a comparative multivariate approach for studying the biodegradation of chemically dispersed oil. The rationale for this approach lies in the inherent complexity of the data and challenges associated with comparing multiple experiments with inconsistent sampling points, with respect to inferring correlations and visualizing multiple datasets with numerous variables. We aim to identify novel correlations among microbial community composition, the chemical change of individual petroleum hydrocarbons, oil type and temperature by creating modelled datasets from inconsistent sampling time points. Four different incubation experiments were conducted with freshly collected Norwegian seawater and either Grane and Troll oil dispersed with Corexit 9500. Incubations were conducted at two different temperatures (5 °C and 13 °C) over a period of 64 days. Results PCA analysis of modelled chemical datasets and calculated half-lives revealed differences in the biodegradation of individual hydrocarbons among temperatures and oil types. At 5 °C, most n-alkanes biodegraded faster in heavy Grane oil compared to light Troll oil. PCA analysis of modelled microbial community datasets reveal differences between temperature and oil type, especially at low temperature. For both oils, Colwelliaceae and Oceanospirillaceae were more prominent in the colder incubation (5 °C) than the warmer (13 °C). Overall, Colwelliaceae, Oceanospirillaceae, Flavobacteriaceae, Rhodobacteraceae, Alteromonadaceae and Piscirickettsiaceae consistently dominated the microbial community at both temperatures and in both oil types. Other families known to include oil-degrading bacteria were also identified, such as Alcanivoracaceae, Methylophilaceae, Sphingomonadaceae and Erythrobacteraceae, but they were all present in dispersed oil incubations at a low abundance (< 1%). Conclusions In the current study, our goal was to introduce a comparative multivariate approach for studying the biodegradation of dispersed oil, including curve-fitted models of datasets for a greater data resolution and comparability. By applying these approaches, we have shown how different temperatures and oil types influence the biodegradation of oil in incubations with inconsistent sampling points. Clustering analysis revealed further how temperature and oil type influence single compound depletion and microbial community composition. Finally, correlation analysis of degraders community, with single compound data, revealed complexity beneath usual abundance cut-offs used for microbial community data in biodegradation studies