Abstract:

This dataset comprises sediment isotope data collected from the northern Gulf of Mexico seafloor on different cruises from 2010-05-01 to 2017-06-18. The data includes collection date and location, cruise and site name, core depth, percent, and radiocarbon dating.

Suggested Citation:

Jeffrey Chanton. 2019. Sediment organic isotope data collected in the northern Gulf of Mexico seafloor on different cruises from 2010-05-01 to 2017-06-18. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7Q52N7D

Publications:

Rogers, K. L., Bosman, S. H., Lardie-Gaylord, M., McNichol, A., Rosenheim, B. E., Montoya, J. P., & Chanton, J. P. (2019). Petrocarbon evolution: Ramped pyrolysis/oxidation and isotopic studies of contaminated oil sediments from the Deepwater Horizon oil spill in the Gulf of Mexico. PLOS ONE, 14(2), e0212433. doi:10.1371/journal.pone.0212433

Rogers, K. L., Bosman, S. H., Wildermann, N., Rosenheim, B. E., Montoya, J. P., Hollander, D., … Chanton, J. P. (2021). Mapping spatial and temporal variation of seafloor organic matter Δ14C and δ13C in the Northern Gulf of Mexico following the Deepwater Horizon Oil Spill. Marine Pollution Bulletin, 164, 112076. doi:10.1016/j.marpolbul.2021.112076

Purpose:

To characterize the isotopic composition of sedimentary organic matter in the northern gulf of mexico.

Data Parameters and Units:

Sample label, core depth (multiple units), Site name, Type: S= seep, NS+non-seep, collection date (mm/dd/yyyy), latitude (decimal degrees), longitude (decimal degrees), depth of station (m), delta 13C (per mil), delta 15N (per mil), percent carbon by weight (%), percent nitrogen by weight (%), D14C, Analysis number 14C only (Accession number = identifier number given by institution analyzing the sample where UGA = University of Georgia; OS = NOSAMS; CAMS Livermore national lab), Fraction modern (F modern), Fraction modern error (Fm Er), Age (years), Age error (years). Nd= not determined. Dates missing in excel files for cruises: DSH08 - 12/9/10, DSH10 - 12/9/10, PCB06 - 12/5/10.

Methods:

Surface sediment was collected and analyzed for delta 13C and D14C from 199 sites by multicore, over 7 years from 2010-2017 across the northern Gulf of Mexico. The surface 0 -1cm of all cores were collected and frozen until processing in the lab. The sediment was acid treated with 10% HCl, to remove carbonates, rinsed, freeze-dried, and ground. Sites were categorized as seep or non-seep according to map data compiled by MacDonald et al. (2015). Sediment was analyzed for delta 13C and percent Carbon using a Carlo-Erba elemental analyzer connected to a Finnigan MAT delta Plus XP Stable Isotope Ratio Mass Spectrometer (EA-IRMS) at the National High Magnetic Field Laboratory. For the natural abundance of radiocarbon, a subset of samples was combusted in quartz tubes at 850 degrees C for four hours and the resultant CO2 was purified cryogenically using the methods of Choi and Wang (2004). The purified CO2 was flame sealed in a 6 mm ampoule and sent to Woods Hole National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) or University of Georgia (UGA) for analysis of the natural abundance of radiocarbon. The radiocarbon signatures are reported in the D14C notation as described in Stuvier and Pollach (1977).

Instruments:

A Carlo-Erba elemental analyzer connected to a Finnigan MAT delta Plus XP Stable Isotope Ratio Mass Spectrometer (EA-IRMS) at the National High Magnetic Field Laboratory Woods Hole National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) or University of Georgia (UGA).

Error Analysis:

Analytical reproducibility averaged 0.2 per mil based on analysis of 20 replicate samples for 13C and 15N, and 0.1% and 0.05% for percent carbon and nitrogen. For 14C, replication of 17 sediment samples averaged 6.5 per mil.

Provenance and Historical References:

Choi Y, Wang Y. 2004. Dynamics of carbon sequestration in a coastal wetland using radiocarbon measurements. Global Biogeochem Cy 18(4), GB4016. DOI: 10.1029/2004GB002261 MacDonald IR, Garcia-Pineda O, Beet A, Daneshgar Asi S, Feng L, et al. 2015. Natural and unnatural oil slicks in the Gulf of Mexico. J Geophys Res: Oceans 120(12): 8364–8380. DOI: 10.1002/2015JC011062 Stuiver M, Polach HA. 1977. Reporting of 14C Data. Radiocarbon 19: 355–263.

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