Crude Oil Metabolites in Groundwater at Two Spill Sites

CATEGORY: GROUNDWATER METABOLITES
Crude Oil Metabolites in Groundwater at Two Spill Sites

Type	Journal Article
Author	Barbara A. Bekins
Author	Isabelle M. Cozzarelli
URL	http://onlinelibrary.wiley.com/doi/10.1111/gwat.12419/abstract
Publication	Groundwater
Date	March 1, 2016
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). Such values are more than 10 times higher than benzene and two to three times higher than Diesel Range Organics in the same wells. Based on 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. However, a review of toxicology studies suggests that polar metabolites of crude oil may pose a risk to aquatic and mammalian species. Altogether, the results suggest that at sites where residual sources are present, monitoring of NVDOC is warranted to evaluate the fates of plumes of hydrocarbon transformation products.