title: Crude Oil Metabolites in Groundwater at Two Spill Sites.
abstract: Two groundwater plumes in north central Minnesota with residual crude oil sources have 20 to 50 mg/L of nonvolatile dissolved organic carbon (NVDOC). These values are over 10 times higher than benzene and two to three times higher than Diesel Range Organics in the same wells. On the basis of previous work, most of the NVDOC consists of partial transformation products from the crude oil. Monitoring data from 1988 to 2015 at one of the sites located near Bemidji, MN show that the plume of metabolites is expanding toward a lakeshore located 335 m from the source zone. Other mass balance studies of the site have demonstrated that the plume expansion is driven by the combined effect of continued presence of the residual crude oil source and depletion of the electron accepting capacity of solid phase iron oxide and hydroxides on the aquifer sediments. These plumes of metabolites are not covered by regulatory monitoring and reporting requirements in Minnesota and other states. Yet, a review of toxicology studies indicates that polar metabolites of crude oil may pose a risk to aquatic and mammalian species. Together the results suggest that at sites where residual sources are present, monitoring of NVDOC may be warranted to evaluate the fates of plumes of hydrocarbon transformation products.
authors.affiliation: babekins@usgs.gov.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Bekins
authors.affiliation: U.S. Geological Survey, 12201 Sunrise Valley Dr., Reston, VA, 20192.
authors.forename: Isabelle M
authors.initials: IM
authors.lastname: Cozzarelli
authors.affiliation: U.S. Geological Survey, 2280 Woodale Dr., Mounds View, MN, 55112.
authors.forename: Melinda L
authors.initials: ML
authors.lastname: Erickson
authors.affiliation: San Francisco Bay Regional Water Quality Control Board, 1515 Clay St., Oakland, CA, 94612.
authors.forename: Ross A
authors.initials: RA
authors.lastname: Steenson
authors.affiliation: U.S. Geological Survey, Denver Federal Center, MS-408, Building 95, Lakewood, CO, 80225.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Thorn
mesh_terms: D060587:Groundwater; D006838:Hydrocarbons; D008910:Minnesota; D010578:Petroleum; D014874:Water Pollutants, Chemical
chemical_list: D006838:Hydrocarbons; D010578:Petroleum; D014874:Water Pollutants, Chemical