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Title: The weathering of oil after the Deepwater Horizon oil spill: insights from the chemical composition of the oil from the sea surface, salt marshes and sediments
Award ID(s):
0752105
NSF-PAR ID:
10023366
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Environmental Research Letters
Volume:
7
Issue:
3
ISSN:
1748-9326
Page Range / eLocation ID:
035302
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  1. Abstract

    The GuLF STUDY, initiated by the National Institute of Environmental Health Sciences, is investigating the health effects among workers involved in the oil spill response and clean-up (OSRC) after the Deepwater Horizon (DWH) explosion in April 2010 in the Gulf of Mexico. Clean-up included in situ burning of oil on the water surface and flaring of gas and oil captured near the seabed and brought to the surface. We estimated emissions of PM2.5 and related pollutants resulting from these activities, as well as from engines of vessels working on the OSRC. PM2.5 emissions ranged from 30 to 1.33e6 kg per day and were generally uniform over time for the flares but highly episodic for the in situ burns. Hourly emissions from each source on every burn/flare day were used as inputs to the AERMOD model to develop average and maximum concentrations for 1-, 12-, and 24-h time periods. The highest predicted 24-h average concentrations sometimes exceeded 5000 µg m−3 in the first 500 m downwind of flaring and reached 71 µg m−3 within a kilometer of some in situ burns. Beyond 40 km from the DWH site, plumes appeared to be well mixed, and the predicted 24-h average concentrations from the flares and in situ burns were similar, usually below 10 µg m−3. Structured averaging of model output gave potential PM2.5 exposure estimates for OSRC workers located in various areas across the Gulf. Workers located nearest the wellhead (hot zone/source workers) were estimated to have a potential maximum 12-h exposure of 97 µg m−3 over the 2-month flaring period. The potential maximum 12-h exposure for workers who participated in in situ burns was estimated at 10 µg m−3 over the ~3-month burn period. The results suggest that burning of oil and gas during the DWH clean-up may have resulted in PM2.5 concentrations substantially above the U.S. National Ambient Air Quality Standard for PM2.5 (24-h average = 35 µg m−3). These results are being used to investigate possible adverse health effects in the GuLF STUDY epidemiologic analysis of PM2.5 exposures.

     
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    Olive (Olea europaea) is an important crop in Europe, with high cultural, economic and nutritional significance. Olive oil flavor and quality depend on phenolic secoiridoids, but the biosynthetic pathway of these iridoids remains largely uncharacterized.

    We discovered two bifunctional cytochrome P450 enzymes, catalyzing the rare oxidative C‐C bond cleavage of 7‐epi‐loganin to produce oleoside methyl ester (OeOMES) and secoxyloganin (OeSXS), both through a ketologanin intermediary. Although these enzymes are homologous to the previously reportedCatharanthus roseussecologanin synthase (CrSLS), the substrate and product profiles differ.

    Biochemical assays provided mechanistic insights into the two‐step OeOMES and CrSLS reactions. Model‐guided mutations of OeOMES changed the product profile in a predictable manner, revealing insights into the molecular basis for this change in product specificity.

    Our results suggest that, in contrast to published hypotheses,in plantaproduction of secoxy‐iridoids is secologanin‐independent. Notably, sequence data of cultivated and wild olives point to a relation between domestication and OeOMES expression. Thus, the discovery of this key biosynthetic gene suggests a link between domestication and secondary metabolism, and could potentially be used as a genetic marker to guide next‐generation breeding programs.

     
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