Abstract:

This data set contains the sediment collection sites from the October-November 2012 NOAA Gordon Gunter cruise. The collection dataset lists the lat/long, depth, temp, oxygen, and salinity for each sediment grab. The other datasets list the raw numbers of meiofauna animals (nematodes and copepods), metals analysis, PAH analysis,organic carabon data, and granulometry analysis for the sites.

Suggested Citation:

Landers, Stephen C.. 2014. Dataset for: Sediment chemistry and meiofauna from the Northern Gulf of Mexico continental shelf. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N70P0WX5

Publications:

Martinec, C. C., Miller, J. M., Barron, N. K., Tao, R., Yu, K., Stewart, P. M., … Landers, S. C. (2014). Sediment Chemistry and Meiofauna from the Northern Gulf of Mexico Continental Shelf. International Journal of Oceanography, 2014, 1–10. doi:10.1155/2014/625718

Jones, C. M., Sharma, J., Miller, J. M., Stewart, P. M., & Landers, S. C. (2016). Nematode assemblages of the northern Gulf of Mexico continental shelf. Proceedings of the Biological Society of Washington, 129(1), 24–37. doi:10.2988/0006-324x-129.q1.24

Purpose:

To determine meiofauna trends and sediment characteristic trends along the continental shelf in the Gulf of Mexico.

Data Parameters and Units:

Nematodes and copepods are reported as raw counts and # of individuals per 15.19 cm^2 and # of individuals/10cm^2; PAH concentrations (ppb, parts per billion); Metal concentrations [Al, Fe, Pb, Ni, Ba, Cr, Cu, V, Zn, Ca, Sr] (mg/kg); Granulometry [coarse, medium sand, fine sand, very fine sand, silt/clay] (% of total sediment); Organic carbon (% of total sediment); Latitude (decimal degrees) Longitude (decimal degrees) Depth (meters) Temperature (degrees Celsius) Oxygen (mg) Salinity

Methods:

Sediment samples were collected using a Shipek® grab sampler aboard the NOAA ship Gordon Gunter along the northern GOM continental shelf and slope in Oct-Nov 2012. 130 samples were obtained from 26 sites for meiofauna and sediment analysis. Meiofauna samples were centrifuged with Ludox® to concentrate the meiofauna. Meiofauna were counted under a stereomicroscope at Troy University. Sediment PAHs were determined using Soxhlet extraction with methylene chloride (EPA 3540C) and a Shimadzu GCMS. Metals and organic carbon were analyzed at the LSU Central Analytical Instruments Research Laboratory. Metals were determined by ICP EPA 200.7. Organic carbon was determined using EPA 9060. Granulometry was determined using a Geotech Sand Shaker Mechanical Sieve at Jacksonville State University.

Instruments:

Meta data information on PAH analysis All continental shelf sediments were extracted for polycyclic aromatic hydrocarbons (PAH) analysis with the best available quality assurance (QA) and quality control (QC) as followings: Sediment extraction Each sediment was extracted using a Soxhlex extraction apparatus with dimethylene chloride (DCM). Protocol is adapted from the EPA method 3540c. Each sediment was divided into three sub-samples (named replicate 1, replicate 2 and spike). Three sets of Soxhlet extraction system were used simultaneously for each sub-sample respectively. Each sub-sample is mixed with sodium sulfate (sediment/sodium sulfate ratio about 1/2) to remove sediment moisture for maximum performance of extraction by DCM. The spike sub-sample was amended with 1 mL 1 ppm PAH standard for calculation of extraction recovery rate each time. The extraction system is equipped with a temperature controlled water circulation system for condenser and concentrator to minimize temperature variations in the laboratory during the 20-hour extraction period. Final volume of the extract is 1 mL, representing approximately 10 times of original PAH concentration in the sediment. The sediment dry weight is determined and all PAH results are express in dry weight basis. PAHs and their reference standards The following 27 PAHs are quantified for each sediment. Since no particular target PAH is pre-determined, a broad spectrum PAH components are included to capture as much information (both petrogenic and pyrogenic PAHs) as possible. The standard is purchased from Absolute Standards, Inc. (http://www.absolutestandards.com/). Benzo(e)pyrene Biphenyl Dibenzofuran Dibenzothiophene 2,6-Dimethylnaphthalene 1-Methylnaphthalene 2-Methylnaphthalene 1-Methylphenanthrene 2,3,5-Trimethylnaphthalene Perylene Acenaphthene Acenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(g,h,i)perylene Carbazole Chrysene Dibenzo(a,h)anthracene Fluoranthene Fluorene Indeno(1,2,3-cd)pyrene Naphthalene Phenanthrene Pyrene Analytical instrument: The laboratory at Troy University is equipped with a Schimadzu GC/MS (GC-2010-mass spectrometry) for the PAH analysis. The GC/MS has been calibrated for petroleum hydrocarbon analysis, including capillary column selection, flow control and temperature programming. For each analysis, a batch file is generated to run sample in the following sequence: DCM/PAH standard/Replicate 1/Replicate 2/Spike/Replicate 2/Replicate 1/DCM This batch analysis (8 runs x 1 hour/each run) ensures that the two replicate sub-samples run twice with either standard or spike (with 1 mL standard in it) ahead to calibrate the retention time for each PAH component. The solvent run before and after the samples ensures the GC/MS in the best condition for the sample analysis. Calculation: PAH components are quantified from the GC/MS data analysis. Results represent the means of four analyses (two replicates x two runs). Extraction recovery rate is determined by the recovery of added standard in the spike. Results are reported after correction according to the determined recovery rate each time. The final results are reported in ppb based on the dry weight of the sediment. External reference laboratory: For further QA/QC, 4 sediment samples will be randomly selected for analysis of PAHs by an external reference laboratory. Central Analytical Instruments Research Laboratory 312 M.B. Sturgis Hall Louisiana State University Baton Rouge, LA 70803

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