Sedimentation Pulse in the NE Gulf of Mexico following the 2010 DWH Blowout

Authors

Gregg R. Brooks, Eckerd College
Rebekka A. Larson, Eckerd College
Patrick Schwing, University of South FloridaFollow
Isabel C. Romero, University of South FloridaFollow
Christopher Moore, Eckerd College
Gert-Jan Reichart, Utrecht University
Tom Jilbert, Utrecht University
Jeff P. Chanton, Florida State University
David W. Hastings, Eckerd College
Will A. Overholt, Georgia Institute of Technology
Kala P. Marks, Georgia Institute of Technology
Joel E. Kostka, Georgia Institute of Technology
Charles W. Holmes, Environchron
David Hollander, University of South FloridaFollow

Document Type

Article

Publication Date

7-14-2015

Keywords

Foraminifera, Geologic Sediments, Gulf of Mexico, Petroleum Pollution, Radioisotopes

Digital Object Identifier (DOI)

https://doi.org/10.1371/journal.pone.0132341

Abstract

The objective of this study was to investigate the impacts of the Deepwater Horizon (DWH) oil discharge at the seafloor as recorded in bottom sediments of the DeSoto Canyon region in the northeastern Gulf of Mexico. Through a close coupling of sedimentological, geochemical, and biological approaches, multiple independent lines of evidence from 11 sites sampled in November/December 2010 revealed that the upper ~1 cm depth interval is distinct from underlying sediments and results indicate that particles originated at the sea surface. Consistent dissimilarities in grain size over the surficial ~1 cm of sediments correspond to excess ²³⁴Th depths, which indicates a lack of vertical mixing (bioturbation), suggesting the entire layer was deposited within a 4-5 month period. Further, a time series from four deep-sea sites sampled up to three additional times over the following two years revealed that excess ²³⁴Th depths, accumulation rates, and ²³⁴Th inventories decreased rapidly, within a few to several months after initial coring. The interpretation of a rapid sedimentation pulse is corroborated by stratification in solid phase Mn, which is linked to diagenesis and redox change, and the dramatic decrease in benthic formanifera density that was recorded in surficial sediments. Results are consistent with a brief depositional pulse that was also reported in previous studies of sediments, and marine snow formation in surface waters closer to the wellhead during the summer and fall of 2010. Although sediment input from the Mississippi River and advective transport may influence sedimentation on the seafloor in the DeSoto Canyon region, we conclude based on multidisciplinary evidence that the sedimentation pulse in late 2010 is the product of marine snow formation and is likely linked to the DWH discharge.

Comments

Data used in this article are available for download.

Sediment Bulk Density, NE Gulf of Mexico, 2010-2013.

Sediment texture and composition, NE Gulf of Mexico, 2010-2013

Short-lived radioisotope geochronology

Rights Information

This work is licensed under a Creative Commons Attribution 4.0 License.

Citation / Publisher Attribution

PLoSOne, v. 10, issue 7, art. e0132341

Scholar Commons Citation

Brooks, Gregg R.; Larson, Rebekka A.; Schwing, Patrick; Romero, Isabel C.; Moore, Christopher; Reichart, Gert-Jan; Jilbert, Tom; Chanton, Jeff P.; Hastings, David W.; Overholt, Will A.; Marks, Kala P.; Kostka, Joel E.; Holmes, Charles W.; and Hollander, David, "Sedimentation Pulse in the NE Gulf of Mexico following the 2010 DWH Blowout" (2015). Marine Science Faculty Publications. 439.
https://digitalcommons.usf.edu/msc_facpub/439