NOAATs Atlantic Margin Sediment Flux Study

Abstract

ABSTRACT Continental margin sedimentation (COMSED) has recently become an area of emphasis within the National Oceanic and Atmospheric Administration. In a combined Government-university-industry operation off the northeast U.S., quantitative parameters f sediment flux and dispersion are being studied. Previous geological investigations on the Atlantic continental shelf have described bottom sediments and current directions on a regional scale; C0MSED will define detailed bottom morphology, shallow stratigraphy, bottom sediment movement, and geochemistry. The initial area of interest is the continental shelf from Long Island, N.Y., to Cape Hatteras, N.C. Some university studies of the North Carolina, Virginia, and Delaware coasts have already been done. Investigations are now being under taken on New York-New Jersey shelf as part of NQAA' s Marine Ecosystems Analysis (MESA) environmental study. NOAA's initial plans in the NewYork sector call for three shelf transects from the shoreline to the upper continental slope off Long island, new york harbor, and new Jersey. Each transect contains three study areas of approximately 300 square nautical miles each representative of the nearshore, mid-shelf, and shelf-edge environments. However, due to budget restrictions, work in 1973 will be confined to an intensive study of the apex of the New York bight centered around Ambrose Light. The program is planned in three phases: I. Description of sediment parameters: grain.size and composition, bottom morphology, shallow stratigraphy and geochemistry; II. Analysis of the hydraulicregime by current meter and wave refraction studies, and III. Examination of the bottom sediment flux and the flux ofsignificant geochemical parameters by radioactive tracers and other dynamic measurement techniques. Introduction Continental shelf studies are increasingly attracting geologisis as they attempt to define more precisely the distribution of sediments and track their movement. The increased environmental and ecological interest in the marine area by the general public has added considerable emphasis to this work such that community problems may be studied in addition to working on long-standing questions in the basic research area. The COMSED (continental margin sedimentation) project will attempt to provide geological data by serving as the focus of cooperative work between several government agencies, universities, and private contractors. Project Background The Atlantic continental shelf is presently used as a source of mineral resource (sand and gravel), living resource (shellfish and finfish), waste disposal (sewer-sludge, dredge spoil, cellar dirt, and acid waste dumpsites), recreation (swimming, boating and fishing), and more recently, as proposed sites for offshore nuclear power plants and deep-water ship terminals. The northeast Atlantic shelf was chosed for the initial area of study because of population demands for these often conflicting multiple uses. The New York bight area, extending from the-eastern tip of Long Island southward to Cape May, New Jersey, wait chose-n-in particular because of high demand for basic environmental data. The area is unique geoiogically in having the Hudson shelf valley cutting across the entire shelf from its edge to nearly the shoreline.