Dispersant marker chemistry data associated with water column samples collected in the Gulf of Mexico from May 2010 through July 2012

This report contains dispersant marker water 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 published datasets relating to the Gulf of Mexico in several respects: It includes data from independent BP studies that have not previously been available to the public. It combines dispersant marker test results from 38 NRDA studies and 11 Response studies into one data file. These data reflect extensive efforts to verify and correct the positional information (i.e., coordinates and depths of each sample collected), where necessary. The focus of this data posting is dispersant marker chemistry data associated with water column samples collected in both federal and state jurisdictional waters in the Gulf of Mexico from May 2010 through July 2012. This data posting is supplemental to the water chemistry data set for petroleum-related compounds in water samples, which was posted separately (data posting reference ID W-01v01). More than 15,000 water samples with associated chemistry analyses, collected at more than 4,300 sampling stations, are included in this posting. These samples were collected during 49 studies, using more than 100 sampling cruises and surveys. 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 the following dispersant markers: Dipropylene glycol n-butyl ether (DPnB), Glycol ethers, Dioctyl sodium sulfosuccinate (DOSS), 2-Butoxyethanol, Propylene glycol. Dispersant markers are chemicals present in the Corexit dispersant formulations used in response to the Deepwater Horizon accident. Analyses of these chemicals are performed to evaluate the potential presence of Corexit in environmental samples. This dataset includes data associated with natural field samples for whole water and for Payne filter and filtrate pairs (Payne et al. 1999), 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. To verify the quality of these data, data validation, to assess the data’s completeness, correctness, and compliance with applicable analytical method requirements, and data verification, to verify the quality of field sample attributes, were conducted.