Abstract:

The data set list the decay rates of saturated hydrocarbons measured during the standardized sediment-oil-agglomerate (sSOA) experiment. In this experiment, 100 sSOAs produced from agglomerates washed-up at Pensacola Beach/Florida were buried in the upper 50 cm of the sandy beach at Pensacola Beach/Florida. Five pairs of sSOAs contained in stainless steel teaballs were attached to a 50 cm long vertical PVC pipe, such that pairs of sSOAs were positioned a 10, 20, 30, 40 and 50 cm sediment depth. sSOA degradation was followed over 3 years. The sSOA arrays were deployed on October 22nd, 2010, and then retrieved with surrounding sediment at seven monthly to bimonthly intervals for approximately one year and thereafter at three larger intervals until the final sampling on 16 December 2013 (2 Dec10, 19 Jan 11, 2 Mar 11, 21 Apr 11, 16 Jun 11, 28 Jul 11, 14 Sep 11, 10 Jan 12, 26 Oct 12, 16 Dec 13). One parameter monitored was saturated hydrocarbon content of the sSOAs. The decay rates calculated from the saturated hydrocarbon concentration decrease over time are reported in this data set.

Suggested Citation:

Markus Huettel, Ioana Bociu. 2019. Standardized sediment-oil-agglomerate (sSOA) experiment: Decay rates of saturated hydrocarbons for initial (0.5-year) and total 3-year period listed by carbon number (C15-C40). Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-wjj4-dq16

Publications:

Bociu, I., Shin, B., Wells, W. B., Kostka, J. E., Konstantinidis, K. T., & Huettel, M. (2019). Decomposition of sediment-oil-agglomerates in a Gulf of Mexico sandy beach. Scientific Reports, 9(1). doi:10.1038/s41598-019-46301-w

Purpose:

After Deepwater Horizon oil contaminated Gulf sandy beaches, quantitative information on the degradation rates of sediment-oil-agglomerates (SOAs) embedded in Gulf of Mexico beach sands was not available, partly because the continuous washing up of SOAs onto the beach (e.g. as released from natural and anthropogenic sources and submerged oil mats) makes the determination of the exact time point when SOAs became buried in the beach difficult. To address this question, a three-year in-situ experiment was initiated that quantified the degradation of standardized MC525-SOAs (sSOAs) buried in a Pensacola sandy beach. The use of sSOAs allowed following the degradation of a known source material that was buried at a known time point, and direct comparison of sSOA composition at the times of burial and after excavation.

Data Parameters and Units:

The decay rate constants are listed in per day (d-1).

Methods:

A ~200 mg aliquot of each sSOA was weighed and extracted in an accelerated pressurized solvent extractor (Buchi SpeedExtractor E-914) according to the US EPA Method 3545A modified for in-cell extract clean-up. Extraction recovery averaged 102% (1SD=31.7). The resulting 40 mL DCM-solution was concentrated in a Buchi Syncore Analyst and transferred to n-hexane producing a 1 mL hydrocarbon extract. The extracts were analyzed on an Agilent 7890A gas chromatograph J&W (Agilent Select PAH GC Column (30 m x 0.25 mm x 0.15 µm)) equipped with an Agilent 7000 Triple Quadrupole mass spectrometer. Alkanes from 10 to 40 carbons in length were evaluated. Decay rates were calculated from the time series using first order kinetics.

Instruments:

Buchi SpeedExtractor E-914, Agilent 7890A gas chromatograph, Agilent 7000 Triple Quadrupole mass spectrometer.

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