Chemistry data associated with shoreline sediment and soil samples collected in the Gulf of Mexico from April 2010 through December 2012

This report contains shoreline sediment and soil chemistry data, and provides additional context for the posted dataset, including information about the collection, analysis, and organization of the data. This data posting differs from other recently published datasets relating to the Gulf of Mexico in several respects: This Shoreline Sediment and Soil Chemistry dataset focuses only on information related to petroleum-related chemical constituents and associated parameters in sediment and soil samples. Chemical compounds that are not present in oil (such as polychlorinated biphenyls, pesticides, and halogenated volatiles) are not included in this dataset. This dataset includes data from independent studies performed by BP contractors. BP has been working to produce and organize these independent data, and has engaged outside consultants to perform quality assurance and quality control (QA/QC) checks. As a result, these data have not previously been publicly accessible. • This dataset combines results from fourteen NRDA studies and four Response studies to create a unified data file. Certain Response data have been adjusted for surrogate recoveries as described below. Before posting, extensive work was done to verify some aspects of the posted information (e.g., positional coordinates and field data transcriptions). The focus of this data posting is chemistry data associated with shoreline sediment and soil samples collected in both federal and state jurisdictional waters in the Gulf of Mexico from April 2010 through December 2012. Additionally, sediment/soil-associated aqueous samples (e.g., leachates) are also provided in this data posting. More than 15,000 shoreline sediment and soil samples with associated chemistry analyses are included in this data posting. These samples were collected at more than 4,000 sampling stations during 18 studies. These studies can be classified into four general categories: NRDA Cooperative—Studies conducted as part of the NRDA which were agreed to and executed cooperatively by the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Interior (DOI), and/or other Trustees, and BP. BP NRDA Independent—Studies conducted by BP independently to develop data to support and inform the NRDA. Trustee Independent—Studies conducted by NOAA, DOI, and/or other Trustees independently to develop data to support and inform the NRDA. Response (non-NRDA)—Studies conducted by BP and/or government representatives under the direction of the Unified Area Command and in association with activities performed in response to the DWH accident (the Response). The chemical parameters provided in this data posting include: Parent and alkylated polycyclic aromatic hydrocarbons (PAHs), Saturated hydrocarbons (SHC), Total petroleum hydrocarbons (TPH), including parameters reported as total extractable material (TEM) and total extractable hydrocarbon (TEH), Benzene, toluene, ethyl benzene, and xylenes (BTEX) and other volatile hydrocarbons classified as paraffins, isoparaffins, aromatics, naphthenes, and olefins (PIANO), Geochemical biomarkers (sterane and triterpane), where available Metals, Total Organic Carbon (TOC), Percent moisture or percent solids, Grain size parameters. The chemical analyte lists are generally consistent between studies for the standard PAH, SHC, and BTEX compounds. However, portions of the dataset also include analysis of the extended PIANO volatile hydrocarbon list, TPH, or geochemical biomarkers. Additionally, NRDA PAH analyses include an extended list of parent and alkylated decalins, benzothiophenes, naphthobenzothiophenes, and several other PAHs and related chemicals that were not included in Response analyses. This dataset includes data associated with natural field samples, along with the associated field-collected quality control samples, such as field replicates, equipment blanks, field blanks, and trip blanks. Laboratory duplicate samples are provided, where available. No other laboratory quality control samples (e.g., laboratory blanks and spike samples) are included in this data posting. The Trustees developed an approach for screening sediments for the potential presence of oil using analysis by gas chromatography/flame ionization detection (GC/FID) and visual inspection of the resulting chromatograms. Through this visual inspection of the chromatograms, screened samples were categorized by comparing the amount of oil (of any source) present in the sample, if any, to the abundance of naturally-occurring organic matter (NOM) as determined by the chromatographic character of the extractable hydrocarbons. The Trustees developed the following four classification levels: A = Oil is present in excess of NOM, B = Oil is present in comparable abundance to NOM, C = Trace oil is present but is exceeded by NOM, D = No obvious oil, overwhelmingly comprised of NOM. All samples classified by Trustee representatives in the preliminary screening phase as Category A, B, or C were sent for further laboratory analysis to aid with characterizing the source of the oil present in the sediments. A subset of the Category D samples was also sent for further laboratory analysis. Within this Shoreline Sediment and Soil Chemistry dataset posting of approximately 15,500 analytical samples, only 4 samples have TPH screening classification levels available on the Trustees website.