Abstract:
Sediment samples were collected in Campeche Sound in the southern Gulf of Mexico aboard R/V Justo Sierra cruise from 2004-05-17 to 2004-06-05 to study the impacts of oil-related activities on the seafloor. A total of 62 samples were collected from 13 to 1336 meters of water depth. The most abundant species showed signs of oil pollution, but it is unknown if the contamination is from natural or anthropogenic sources. Organic carbon and total hydrocarbon concentrations were measured, and an increase was found around oil platforms, natural seeps and just offshore of major rivers. Metal concentrations of Cadmium, Copper, Nickel, Barium, Arsenic, and Chromium were also measured and above the threshold effect level, indicating that these areas may be of ecological concern. This dataset supports the publication: Machain-Castillo, M. L., Ruiz-Fernández, A. C., Gracia, A., Sanchez-Cabeza, J. A., Rodríguez-Ramírez, A., Alexander-Valdés, H. M., … Hollander, D. J. (2019). Natural and anthropogenic oil impacts on benthic foraminifera in the southern Gulf of Mexico. Marine Environmental Research, 149, 111–125. doi:10.1016/j.marenvres.2019.06.006
Suggested Citation:
Maria Luisa Machain Castillo. 2020. Dataset for: Natural and anthropogenic oil impacts on benthic foraminifera in the southern Gulf of Mexico. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/9KQEPRR2
Data Parameters and Units:
Dataset consists of a folder of images of benthic foraminifera, a Readme, and an Excel spreadsheet describing abundance (Individuals/g), Species Richness Index (S), Fisher Alpha Index (α), Shannon Index (H’), Corg (%), Polycyclic aromatic hydrocarbons [PAH (µg kg-1)], Foraminifera with Chapopote Stains (%), and Foraminifera with Pyrite Infillings (%).
The file "DataBase GRIIDC con coordenadas y fechas 04dic2019.xlsx" includes - Sediment sample, latitude (degree N), longitude (degree W), Date of sampling, Depth (m), abundance (Individuals/g), Species Richness Index (S), Fisher Alpha Index (α), Shannon Index (H’), Corg (%), PAH (µg kg-1), Foraminifera with Chapopote Stains (%), Foraminifera with Pyrite Infillings (%), Species #, Species name. It also contains links to public depositories of other data such as trace metal concentrations in the southern Gulf of Mexico, results of factor analysis on foraminifera species association in sediments from the southern Gulf of Mexico, factor scores from the factor analysis on foraminifera species in sediments, and factor loadings from the factor analysis on foraminifera species in sediments.
Please note that trace metal concentrations in the southern Gulf of Mexico are not classified according to longitude and latitude but averages, standard deviations across 62 sampling sites are provided.
Correction note: In the worksheet "Table 3", date of sampling for June (Column D; Rows 5-18) are in the DD/MM/YYYY format and for May (Column D; Rows 19-66) are in MM/DD/YYYY format.
Methods:
Box core samples were collected with the aid of a Reineck box corer, 0.5m per side. The top 1 cm of sediment subsamples was carefully removed along with the water-sediment interface. Samples for foraminiferal and geochemical analysis were obtained with plastic spatulas and plastic bags, while samples for hydrocarbon analysis were obtained with stainless-steel spatulas and aluminum containers. Rose Bengal-stained 10% formalin (1g.L−1), buffered with borax was used to preserve foraminiferal samples. Further preservation of samples was by refrigeration at 4 oC.
Using a solution of hexane: dichloromethane (1:1) several PAHs were extracted with the aid of an ASE 300 accelerated solvent extractor. After concentration and purification with a packed column of sulfite, silica, alumina and granulated copper, an analysis was conducted with a GC-MS (Agilent Technologies 6890N/5973MS.
A Beckman Coulter 1S232 particle analyzer was used to obtain grain size by laser diffraction. The Walkley-Black (WB) method was used to estimate organic matter content. X-ray fluorescence spectrometry (XRF, Spectrolab Xepos-3) under He atmosphere was used to measure elemental composition.
Error Analysis:
Standard reference materials used for PAHs analysis was NIST 1941b (Organics in marine sediments). Accuracy was determined with the recovery of 85-110% of standard reference material. The detection limit was 0.5-1.0 ug/Kg
Reference materials used for elemental composition analysis were IAEA-158 and PAC-2 and acceptable recoveries were within the certified ranges.
Recoveries of anhydrous dextrose used to validate organic matter determination were 95-97%.
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