USGS CMG 03038 Metadata

Study of submarine ground water including borehole geophysics,
porewater squeezing, sediment sampling, ground-water sampling

On August 14-22 a USGS-led team undertook a complex subsurface field
effort to study the occurrence and chemistry of submarine ground water beneath
Chincoteague Bay, Maryland as a follow-up to earlier surface geophysical
studies.  The area was made famous by Marguerite Henry's 1947 children's book
(and later Disney movie), Misty of Chincoteague, about the wild ponies that live
on the adjacent barrier islands, Chincoteague and Assateague.  Chincoteague Bay
is experiencing nutrient over-enrichment that is of concern to its primary
managers, the National Park Service and the Maryland Department of Natural
Resources.  Submarine discharge of ground water recharged in agricultural areas
on land is suspected to be a major contributor of nitrogen to the bay.  Offshore
work consisting of drilling, geophysical logging, and sampling was performed
from a barge platform, and was augmented with onshore logging of existing wells.
The maximum drilling depth reached by the barge rig was 72 feet beneath the
sediment surface. The field team included John Bratton, Sarah Kelsey, and Dirk
Koopmans (USGS-GD-Woods Hole and contractors); David Krantz and Abby Norton
(University of Toledo); John Earle (USGS-WRD-Denver); and J.K. Bohlke and Craig
Tobias (USGS-WRD-Reston).  Drilling contractors from Hillis-Carnes Engineering
and a barge/tug pilot provided by Hi-Tide Marine Construction consistently
overcame difficult mechanical, geological, and meteorological conditions to get
the science done.  Special thanks go out to National Park Service colleagues
from Assateague Island National Seashore, Brian Sturgis and Carl Zimmerman, who
provided logistical support, shuttle boats, and lodging.  The fieldwork was
conducted safely and efficiently and produced excellent scientific results.
Noteworthy discoveries included the presence of a plume of fully fresh ground
water greater than 25 feet thick extending more than 1/2 mile offshore along the
western side of the bay (Public Landing), a similar plume at the northern end of
the bay (South Point), hypersaline brines underlying part of Assateague Island,
and a widespread buried peat present at the base of the bay's Holocene
sediments.  Downhole gamma and electromagnetic induction logs were obtained from
eight locations.  Ground water samples were collected from nine temporary
subestuarine wells, surface water was obtained from eight locations, and pore
water was squeezed from 35 sediment samples.  Additional analyses for age
dating, nutrients, and stable isotopes will be performed over the coming months.

Navigation Techniques: Garmin GPS 76, UTM, NAD27 CONUS. HI-TIDE MARINE CONSTRUX 
BARGE, HI-TIDE MARINE CONSTRUCTION, OCEAN CITY, MD

http://soundwaves.usgs.gov/2003/10/fieldwork2.html