Effect of Corexit 9500A on Mississippi Canyon crude oil weathering patterns using artificial and natural seawater
During the 2010 Deepwater Horizon oil well blowout in the Northern Gulf of Mexico (GoM), the application of 6.97 million litres of chemical dispersants was used at the well-head and on the sea surface to promote oil degradation and weathering of the Mississippi Canyon 252 (MC252) crude oil. Chemical...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2017-03-01
|
| Series: | Heliyon |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2405844016306235 |
| _version_ | 1828196309666889728 |
|---|---|
| author | Gregory M. Olson Heng Gao Buffy M. Meyer M. Scott Miles Edward B. Overton |
| author_facet | Gregory M. Olson Heng Gao Buffy M. Meyer M. Scott Miles Edward B. Overton |
| author_sort | Gregory M. Olson |
| collection | DOAJ |
| description | During the 2010 Deepwater Horizon oil well blowout in the Northern Gulf of Mexico (GoM), the application of 6.97 million litres of chemical dispersants was used at the well-head and on the sea surface to promote oil degradation and weathering of the Mississippi Canyon 252 (MC252) crude oil. Chemical dispersants encourage microbial degradation by increasing the surface area of the spilled oil, which also increases its bioavailability. However, the net beneficial effects of using chemical dispersants on spilled oil and their effects on weathering are not completely elucidated in contemporary literature. The use of simulated environmental conditions in replicate laboratory microcosm weathering experiments were employed to study the weathering of oil and the effects of dispersants on oil weathering. Fresh MC252 oil was evaporatively weathered 40% by-weight to approximate the composition of oil seen in surface slicks during the 2010 spill. This surface oil was then well mixed with two types of seawater, autoclaved artificial seawater, the abiotic control, and Gulf of Mexico seawater, the biotic experiment. Four different weathering combinations were tested: 10 mg of oil mixed in 150 ml artificial seawater (OAS) or natural (i.e., GoM) seawater (ON) and 10 mg of oil with dispersant mixed with 150 ml of artificial seawater (OASD) or natural (i.e., GoM) seawater (OND). For the treatments with dispersant (OASD and OND), the dispersant-to-oil ratio (DoR) was 1:20. The experiment was carried out over 28 days with replicates that were sacrificed on Days 0, 0.5, 3, 7, 14, 21 and 28. For the OAS and OASD treatments, abiotic weathering (i.e., evaporation) dominated the weathering process. However, the ON and OND treatments showed a dramatic and rapid decrease in total concentrations of both alkanes and aromatics with biodegradation dominating the weathering process. Further, there were no identifiable differences in the observed weathering patterns between microcosms using oil or oil treated with dispersant. In the biotic weathering microcosms, the relative degree of individual polycyclic aromatic hydrocarbon (PAH) depletion decreases with an increase in rings and within a homolog series (increased alkylation). The n-C17/pristane and n-C18/phytane ratios rapidly decreased compared to the abiotic weathering experiments. The C2-dibenzothiophenes (DBT)/C2-phenanthrenes (D2/P2) and C3-DBTs/C3-phenanthrenes (D3/P3) ratios initially remained constant during the early stages of weathering and then increased with time showing preferential weathering of the sulfur containing compounds compared to similar sized PAH compounds. These ratios in the abiotic microcosms remained constant over 28 days. Additionally, twenty-four quantitative MC252 oil biomarker ratios were evaluated to determine if their usefulness as oil source-fingerprinting tools were compromised after significant weathering and dispersant augmentation. |
| first_indexed | 2024-04-12T09:59:14Z |
| format | Article |
| id | doaj.art-fbbb0b882d8e4e888f05d8970c6e24f4 |
| institution | Directory Open Access Journal |
| issn | 2405-8440 |
| language | English |
| last_indexed | 2024-04-12T09:59:14Z |
| publishDate | 2017-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Heliyon |
| spelling | doaj.art-fbbb0b882d8e4e888f05d8970c6e24f42022-12-22T03:37:36ZengElsevierHeliyon2405-84402017-03-013310.1016/j.heliyon.2017.e00269Effect of Corexit 9500A on Mississippi Canyon crude oil weathering patterns using artificial and natural seawaterGregory M. Olson0Heng Gao1Buffy M. Meyer2M. Scott Miles3Edward B. Overton4Department of Environmental Sciences, 1273 Energy, Coast and Environment Building, Louisiana State University, Baton Rouge, LA 70803, USALouisiana Department of Transportation and Development, 1201 Capitol Access Rd., Baton Rouge, LA 70802, USADepartment of Environmental Sciences, 1273 Energy, Coast and Environment Building, Louisiana State University, Baton Rouge, LA 70803, USADepartment of Environmental Sciences, 1273 Energy, Coast and Environment Building, Louisiana State University, Baton Rouge, LA 70803, USADepartment of Environmental Sciences, 1273 Energy, Coast and Environment Building, Louisiana State University, Baton Rouge, LA 70803, USADuring the 2010 Deepwater Horizon oil well blowout in the Northern Gulf of Mexico (GoM), the application of 6.97 million litres of chemical dispersants was used at the well-head and on the sea surface to promote oil degradation and weathering of the Mississippi Canyon 252 (MC252) crude oil. Chemical dispersants encourage microbial degradation by increasing the surface area of the spilled oil, which also increases its bioavailability. However, the net beneficial effects of using chemical dispersants on spilled oil and their effects on weathering are not completely elucidated in contemporary literature. The use of simulated environmental conditions in replicate laboratory microcosm weathering experiments were employed to study the weathering of oil and the effects of dispersants on oil weathering. Fresh MC252 oil was evaporatively weathered 40% by-weight to approximate the composition of oil seen in surface slicks during the 2010 spill. This surface oil was then well mixed with two types of seawater, autoclaved artificial seawater, the abiotic control, and Gulf of Mexico seawater, the biotic experiment. Four different weathering combinations were tested: 10 mg of oil mixed in 150 ml artificial seawater (OAS) or natural (i.e., GoM) seawater (ON) and 10 mg of oil with dispersant mixed with 150 ml of artificial seawater (OASD) or natural (i.e., GoM) seawater (OND). For the treatments with dispersant (OASD and OND), the dispersant-to-oil ratio (DoR) was 1:20. The experiment was carried out over 28 days with replicates that were sacrificed on Days 0, 0.5, 3, 7, 14, 21 and 28. For the OAS and OASD treatments, abiotic weathering (i.e., evaporation) dominated the weathering process. However, the ON and OND treatments showed a dramatic and rapid decrease in total concentrations of both alkanes and aromatics with biodegradation dominating the weathering process. Further, there were no identifiable differences in the observed weathering patterns between microcosms using oil or oil treated with dispersant. In the biotic weathering microcosms, the relative degree of individual polycyclic aromatic hydrocarbon (PAH) depletion decreases with an increase in rings and within a homolog series (increased alkylation). The n-C17/pristane and n-C18/phytane ratios rapidly decreased compared to the abiotic weathering experiments. The C2-dibenzothiophenes (DBT)/C2-phenanthrenes (D2/P2) and C3-DBTs/C3-phenanthrenes (D3/P3) ratios initially remained constant during the early stages of weathering and then increased with time showing preferential weathering of the sulfur containing compounds compared to similar sized PAH compounds. These ratios in the abiotic microcosms remained constant over 28 days. Additionally, twenty-four quantitative MC252 oil biomarker ratios were evaluated to determine if their usefulness as oil source-fingerprinting tools were compromised after significant weathering and dispersant augmentation.http://www.sciencedirect.com/science/article/pii/S2405844016306235Environmental scienceAnalytical chemistry |
| spellingShingle | Gregory M. Olson Heng Gao Buffy M. Meyer M. Scott Miles Edward B. Overton Effect of Corexit 9500A on Mississippi Canyon crude oil weathering patterns using artificial and natural seawater Heliyon Environmental science Analytical chemistry |
| title | Effect of Corexit 9500A on Mississippi Canyon crude oil weathering patterns using artificial and natural seawater |
| title_full | Effect of Corexit 9500A on Mississippi Canyon crude oil weathering patterns using artificial and natural seawater |
| title_fullStr | Effect of Corexit 9500A on Mississippi Canyon crude oil weathering patterns using artificial and natural seawater |
| title_full_unstemmed | Effect of Corexit 9500A on Mississippi Canyon crude oil weathering patterns using artificial and natural seawater |
| title_short | Effect of Corexit 9500A on Mississippi Canyon crude oil weathering patterns using artificial and natural seawater |
| title_sort | effect of corexit 9500a on mississippi canyon crude oil weathering patterns using artificial and natural seawater |
| topic | Environmental science Analytical chemistry |
| url | http://www.sciencedirect.com/science/article/pii/S2405844016306235 |
| work_keys_str_mv | AT gregorymolson effectofcorexit9500aonmississippicanyoncrudeoilweatheringpatternsusingartificialandnaturalseawater AT henggao effectofcorexit9500aonmississippicanyoncrudeoilweatheringpatternsusingartificialandnaturalseawater AT buffymmeyer effectofcorexit9500aonmississippicanyoncrudeoilweatheringpatternsusingartificialandnaturalseawater AT mscottmiles effectofcorexit9500aonmississippicanyoncrudeoilweatheringpatternsusingartificialandnaturalseawater AT edwardboverton effectofcorexit9500aonmississippicanyoncrudeoilweatheringpatternsusingartificialandnaturalseawater |