Reports
The surficial sediments of Chesapeake Bay, Maryland: Physical characteristics and sediment budget
1988, Kerhin, R.T., Halka, J.P., Wells, D.V., Hennessee, E.L., Blakeslee, P.J., Zoltan, N., and Cuthbertson, R.H.
Report of Investigations 48
Abstract
The characterization of the bottom sediments and identification of patterns of erosion and deposition were integral tasks of the Toxics program outlined by the Environmental Protection Agency's Chesapeake Bay Program. As part of the program, the physical and chemical characteristics of the bottom sediments and the patterns of erosion and deposition were measured and mapped.
Seventy-five percent of the sediments sampled were sand and silty clay according to the sediment classification of Shepard (1954). Sand and silty clay were generally distributed along the nearshore margins and axial channels, respectively. Zones of mixed sediments occur as isolated pockets. Some of these pockets have been identified as exposures of pre-Holocene sediments.
The total carbon content was completely dominated by the organic carbon fraction of the sediments. The organic carbon content was strongly associated with fine-grained sediment, reaching a maximum of 10.5%. The highest organic carbon content was found in the northern Bay, decreasing southward. Sulfur content ranged from 0.01 to 2.00%, averaging 0.58%. Sulfur content generally increased southward.
Several distinct patterns of erosion and deposition were identified: l) extensive areas of Bay floor erosion, 2) deposition and erosion exceeding 2.4 meters/century in the axial channel, and 3) variable patterns at the confluence of major tributaries. The northern and lower middle Bay were sites of deposition, but erosion was predominant in the upper middle Bay.
A sediment budget showed a net deficit of sediment deposited on the Bay floor. For sand, 585x106 tonnes/century was contributed from the various sources with 524x106 tonnes/century recorded as accumulation. This was a net deficit of sand accumulation at 60xl06 tonnes/century. For the silt/clay fraction, the sources contributed 388x106 tonnes/century while accumulation was recorded at 281x106 tonnes/century, for a net deficit of silt/clay accumulation at -l08x106 tonnes/century. The sediment budget indicates that sand and silt/clay is being exported into the Virginia Chesapeake Bay or tributaries.
Downloads and Data
Report of Investigations 48 (pdf, 43 MB)RI 48, plate 1 (pdf, 1.5 MB)RI 48, plate 2 (pdf, 1.5 MB)RI 48, plate 3 (pdf, 1.5 MB)RI 48, plate 4 (pdf, 1.5 MB)RI 48, plate 5 (pdf, 1.4 MB)RI 48, plate 6 (pdf, 1.4 MB)RI 48, plate 7 (pdf, 1.7 MB)RI 48, plate 8 (pdf, 1.3 MB)