Nonvolatile dissolved organic carbon and diesel range organics concentrations measured in 2016 at the Bemidji crude oil study site

The Bemidji crude oil spill site is a long-term USGS study site to understand the fate of crude oil in the shallow subsurface. A description of the site can be found at https://mn.water.usgs.gov/projects/bemidji. In 2014 concentrations of non-volatile dissolved organic carbon (NVDOC) were three times higher than diesel range organics (DRO) in the contaminant plume*. This is important because most of the NVDOC in the plume is composed of partial transformation products of compounds from the crude oil that are not reflected in a DRO analysis. In 2016 we conducted a campaign to determine if DRO values continue to reflect only a fraction of the NVDOC. These data are the results of that campaign. A total of 25 wells were sampled for DRO and NVDOC in August, 2016. Three wells with long term records were included in the sampling: 530B, 515B, and 9316D. Wells sampled in 2016 but not in 2014 include two wells located 14 m from a down gradient lake (1217B and 1217C) and one well in the zone sprayed by oil (956).
*Earlier measurements referenced here can be found in: Bekins, B. A., Cozzarelli, I. M., Erickson, M. L., Steenson, R. A., and Thorn, K. A., 2016, Crude Oil Metabolites in Groundwater at Two Spill Sites: Groundwater, v. 54, no. 5, p. 681-691