Crude Oil Contamination in the Shallow Subsurface: Bemidji, Minnesota
scientists collecting a groundwater sample from a well at the USGS
Bemidji Crude-Oil Spill Research Site, Minnesota. The scientists monitored in real time the dissolved oxygen, pH, specific conductance, and temperature of the water as the well is pumped so they can know when to collect a representative sample. USGS
scientists measured concentrations of oil breakdown products at greater concentrations than parent compound
. Photo Credit: Jared Trost, USGS
Map of surface oil areas resulting from the pipeline rupture at the Bemidji Crude Oil Spill Research Site, Minnesota
. The map delineates areas where the oil pooled in the subsurface, where oil drained, where oil sprayed from the rupture, and where soil was removed.
Oblique areal view of the crude oil spray area at the pipeline rupture site. USGS
scientists and others have been studying the long-term fate of the spilled crude oil.
Conceptual model of the subsurface contaminant plume's microbial geochemistry. The model shows the right to left progression of what electron acceptors are being used by subsurface microbial communities to degraded dissolved oil constituents in groundwater.
Collecting vapor samples from contaminated areas in the unsaturated zone. The USGS
scientist is using a syringe to extract air from a small sampling tube that extends into the subsurface.
scientists cutting a frozen core for later biogeochemical analysis. Freezing the core keeps the natural pore fluids in place. The scientists have been studying the natural attenuation of a plume of dissolved constituents in groundwater that resulted from a crude oil spill.
A scientist operating a gas chromatograph in an onsite laboratory. The onsite laboratory enables the scientists to make measurements quickly so sampling plans can be adjusted on the fly.
Installing a tensiometer in the unsaturated zone prior to a tracer test. Tensiometers are used to measure water pressure in the unsaturated zone.
scientist measuring hydrogen gas in groundwater samples in the onsite laboratory at the Bemidji Crude Oil Spill Research Site, Minnesota. Hydrogen is an important intermediate compound that is both produced and consumed during biodegradation. The hydrogen gas concentrations can help identify the types of microbial communities that are degrading contaminants.
scientists conducting a subsurface tracer test at the Bemidji Crude Oil Spill Research Site, Minnesota. The scientists use tracer tests to study subsurface contaminant transport processes.
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