A Technical Webinar Series
Background/Objectives
Monitored natural attenuation of petroleum hydrocarbons has become the remedy of choice
in the United States and internationally. This approach requires evidence of effective
retardation processes to address public and regulatory concerns. Less well-understood are
the secondary effects of these processes. Of particular concern is the release of trace metals
and arsenic from sediment into groundwater in aquifers affected by petroleum releases.
Approach/Activities
Working at an intensively studied site near Bemidji, Minnesota, United States Geological
Survey (USGS) scientists and collaborators focused on the question of whether naturally
occurring arsenic in the glacial aquifers might be mobilized in the presence of hydrocarbon
because of chemical interactions involving iron hydroxides, which also occur naturally. To
address this question, arsenic concentrations were measured and reactions modeled for
several years in groundwater and in sediment from the hydrocarbon plume at Bemidji.
Results/Lessons Learned
In this long-term field study, we found that changes in geochemistry from the natural
breakdown of petroleum hydrocarbons underground can promote the chemical release
(mobilization) of naturally occurring arsenic into groundwater. This geochemical outcome
can result in potentially significant arsenic groundwater contamination, predicted to last
for centuries.
About The Presenter
This webinar will take place on September 29th at 12:30 PM EST.
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Phone Conference ID: 668 054 796#