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USGS Woods Hole Dive Team Deploys Samplers for Study of a Phosphorus Plume
Members of the U.S. Geological Survey (USGS)'s Woods Hole Science Center dive team (Dann Blackwood, Michael Casso, and Rick Rendigs) successfully completed emplacement and recovery of "seepage samplers" in the offshore sediment of Ashumet Pond in Falmouth, MA, on June 3-4, 2004. This reconnaissance project was conducted in collaboration with Denis LeBlanc, of the USGS Water Resources Discipline (WRD)'s Massachusetts District, in an effort to determine the extent and concentration of phosphorus contained within ground water that is flowing into the pond. The source of phosphorus is believed to be a sewage-treatment plant located on the Massachusetts Military Reservation. Phosphorus is one of a suite of nutrients that has been associated with increased algal blooms and potential eutrophication processes in lakes and estuaries. The nearshore area of high-nutrient ground-water flow into Ashumet Pond is readily defined by black discoloration on the pond-bottom sediment. The discoloration is believed to be a manganese oxide coating that precipitates under anaerobic conditions associated with the biodegradation of organic matter in sewage-treatment processes. USGS divers observed this discoloration as extending more than 100 ft from the shoreline to a water depth of more than 10 ft. The discoloration covers several hundred yards along the offshore area north of the public boat ramp. Results from the offshore seepage samplers indicate elevated concentrations of phosphorus out to a distance of 80 ft from the shoreline. Eight drive-point wells were also drilled into the pond sediment from a floating barge at two sites near the seepage-sampling area. The wells were drilled and sampled to maximum depths of 100 ft to delineate the vertical extent of the phosphorus plume within the offshore sediment. On the basis of these preliminary results, further sampling efforts are planned throughout the summer to determine and map the offshore concentration gradients of phosphorus entering the pond. Stay tuned!
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in this issue:
Phosphorus Plume Study Sea-Otter Numbers at Record High West-Central Florida Project Concludes South Florida Congressional Staff Tour Basics of the Basin Research Symposium USGS Recognized for ArcIMS Data |