Geochemistry of Middle Chesapeake Bay Sediments from Upper Cretaceous to Present

Abstract
Sediment samples obtained from eight drill cores (surface to −300 ft.) taken at the site of the new Chesapeake Bay bridge near Annapolis, were analyzed for elemental and mineralogical composition. Optical emission spectrography, X-ray spectrometry, and other techniques were utilized to obtain data on the concentration and distribution of the following elements: Si, Al, Na, K, Ca, Mg, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Pb, C, H, N and S. These data and the associated mineralogical information indicate heavy metal-clay mineral associations. Metals of environmental interest, e.g., lead (60 to <1 ppm), copper (54 to <10 ppm), cobalt (355 to 16 ppm), nickel (58 to 5 ppm), and vanadium (135 to 40 ppm), are enriched at the surface relative to the deeper sediments. Most of the heavy metals are 2–3 times less concentrated in these sediments than in the sediments of Baltimore Harbor, long a site of active metal loading.