Sewage-Contaminated Groundwater -- Cape Cod, Massachusetts
The sample-freezing drive shoe
and a tank of liquid carbon dioxide (CO2
) in the background. The CO2
is used to freeze the very bottom of a core while it's still in the subsurface.
Field crew working to cap the bottom of the core liner after a successful coring attempt with the sample-freezing drive shoe. The sample-freezing drive shoe enables the recovery of full length cores even in unconsolidated sandy aquifers.
Closeup of the sample-freezing drive shoe and a core in a polycarbonate plastic liner removed from the core barrel. The frozen section at the bottom of the core prevents the core sample from dropping out of the core barrel when it's pulled up to the surface.
Close up of the sample-freezing drive shoe after retrieval from a borehole. Ice has accumulated on the outside of the drive shoe as a result of liquid CO2 that was pumped down into the drive shoe while still in the borehole. Freezing the bottom of the core enhances core recovery.
A handful of sand from aquifer sediments on western Cape Cod, MA. The surfaces of these quartz grains are covered by coatings containing iron and aluminum oxides and silicates. Arsenic in the coatings can be released by changes in chemical conditions.
Electron photomicrograph of a cross section of a quartz grain from sediments on Cape Cod, MA, shows coatings (white material at the surface). The coatings contain arsenic that can be released under changing chemical conditions.
scientists conducting a tracer test where clean, oxygenated groundwater was injected into an anoxic zone beneath the sewage infiltration beds. The tracer test was part of a study of the natural restoration of a subsurface sewage plume after the use of the infiltration beds (the source of the plume) was discontinued.
Divers from the USGS
Science Center for Coastal and Marine Geology, Woods Hole, Massachusetts, assisted with the installation of wells designed to better understand the upward hydraulic gradients beneath Ashumet Pond, Cape Cod, Massachusetts.
Seepage meters were deployed to measure fluxes of water and associated phosphorus concentrations discharging into Ashumet Pond, Cape Cod, Massachusetts. A National Association of Geoscience Teachers
student intern is connecting a seepage bag to the meter.
scientists installing diffusion samplers used to monitor the performance of a reactive barrier designed to remediate a phosphate plume discharging to Ashumet Pond, Cape Cod, MA.
scientists installing an experimental horizontal well to test its usefulness for monitoring the performance of a reactive barrier that was installed to remediate a phosphate plume discharging to Ashumet Pond, Cape Cod, Massachusetts.
The sediment along the shoreline of Ashumet Pond, Cape Cod, MA, before the installation of a permeable reactive barrier to remediate a plume of sewage discharging to the pond. The black color of the sediment is the result of manganese in the plume precipitating to manganese oxide when groundwater with very little dissolved oxygen encounters the oxygen rich pond water.
Shortly following the installation of a permeable reactive barrier, the sediment along the shoreline of Ashumet Pond, Cape Cod, MA, turned red, indicating the oxidation of the iron filings in the barrier. The barrier was constructed to remediate a phosphate plume discharging to the pond.
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