Abstract:

This dataset contains particulate hydrocarbon information from the two mesocosm experiments in June and August, 2011. Two independent mesocosm experiments were carried out in June and August of 2011 at the Dauphin Island Sea Lab as previously described. Briefly, 200 L barrels were lined with Teflon bags and placed in 2000 L tanks with circulating water. Water was pumped into each mesocosm through an intake tube with a 6.35 mm screen from south of Dauphin Island 6 h (June) or 24 h (August) before the start of the experiments to coincide with high tide. Treatments were randomly assigned to each mesocosm, with each treatment present in each of the five 2000 L tanks. In each experiment, there were 4 treatments, with 5 replicates each (20 barrels in total). These data present the changes in particulate hydrocarbons over the incubation period (10 days in June and 7 days in August). Mesocosm experimental design is described in Ortmann et al (2012) Dispersed Oil Disrupts Microbial Pathways in Pelagic Food Webs, PLos ONE, 7(7) e42548. doi:10.1371/journal.pone.0042548. Please also see the associated paper Ortmann A. C., and Y. H. Lu (2015) Initial community and environment determine the response of bacterial communities to dispersant and oil contamination. Marine Pollution Bulletin 90, 106-114

Suggested Citation:

Ortmann, Alice C., and Yuehan Lu. 2015. Particulate hydrocarbons for mesocosm incubations. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7NS0RT3

Publications:

Ortmann, A. C., & Lu, Y. (2015). Initial community and environment determine the response of bacterial communities to dispersant and oil contamination. Marine Pollution Bulletin, 90(1-2), 106–114. doi:10.1016/j.marpolbul.2014.11.013

Ortmann, A. C., Anders, J., Shelton, N., Gong, L., Moss, A. G., & Condon, R. H. (2012). Dispersed Oil Disrupts Microbial Pathways in Pelagic Food Webs. PLoS ONE, 7(7), e42548. doi:10.1371/journal.pone.0042548

Purpose:

To characterize the changes in particulate hydrocarbons over time as a response of 4 treatments 1) control (no addition); 2) dispersant treatment; 3) oil treatment; 4) dispersed oil treatment.

Data Parameters and Units:

Date, sample type, time (day), particulate alkane (ng/L), standard deviation, standard error

Methods:

Two out of the 5 mesocosms for each treatment were sampled for particulate hydrocarbon analysis. All sampling and analysis apparatus to be in direct contact with samples were either combusted at 450 °C for 5 h (glass materials), or acid soaked (10% HCl) and thoroughly rinsed with Milli-Q water (plastic materials). At day 0 (t0) and day 10 (June) or day 7 (August) (tn), 2 L of water from ca. 10 cm below the surface was filtered through a 142 mm, 0.7 μm glass microfiber filter (Whatman GF/F). Filters were folded, placed in pre-combusted aluminum foil pouches, and put on ice for transportation. Samples were frozen within 6 h of collection. Hydrocarbon analysis followed the method described by Risdon et al. (2008) with modifications. The filters were shredded with solvent-washed forceps and mixed with Hydromatrix (Agilent Technologies) to remove water. Normal hexadecane-d34 (n-C16D34) was added as a surrogate prior to the extraction to standardize the extraction efficiency. Samples were then ultrasonically extracted with 4 ml acetone for 2 min at 20 °C to ensure that the surrogate was thoroughly mixed into the samples. Twenty ml of acetone:hexane (1:1, vol:vol) was then added to the samples, followed by two ultrasonic extractions for 10 min at 20 °C. Solvent-washed copper turnings were added to the extracts to remove sulfur. After storage at 4 °C overnight, the extracts were concentrated with gentle ultra-high purity (UHP) nitrogen stream, followed by addition of 3 ml acetone, 5 ml hexane, 4 ml Milli-Q water and a spatula of sodium chloride. The mixtures were manually shaken for 30 s and allowed to settle for 20 min, with the top hexane layer siphoned as the hydrocarbon fraction. The hydrocarbon fraction was then separated by silica column chromatography into aliphatic and aromatic hydrocarbon fractions, which were eluted by 10 ml of hexane and 12 ml of dichloromethane, respectively. Aliphatic fractions were quantified and identified using a Shimadzu GC-2014 gas chromatograph (GC), and compound identification was confirmed using an Agilent 6890 GC-5973MSD mass spectrometer. The GC oven was set at 50 °C, held for 1 min, and then increased by 6 °C min−1 to 310 °C and held for 15 min. Helium was used as the carrier gas at a flow rate of 1.48 ml min−1. The quantification of objective compounds was done by comparing their peak areas to the peak areas of n-C16D34, with the correction of instrumental responses of various compounds that were obtained by regularly running a mixture containing a C7–C40 saturated alkane standard mixture (Sigma–Aldrich) and n-C16D34. As the data were not normally distributed, comparisons of measured parameters across the treatments or different times points were conducted using a non-parametric Kruskal–Wallis test (for >=3 groups) or Mann–Whitney U test (for 2 groups). The significance level, α, was set at 0.05.

Instruments:

Shimadzu GC-2014 gas chromatograph (GC), and an Agilent 6890 GC-5973MSD

Individual Files: