Skip to main content
U.S. flag

An official website of the United States government

Antropogenically induced changes in sediment and biogenic silica fluxes in Chesapeake Bay

January 1, 2003

Sediment cores as long as 20 m, dated by 14C, 210Pb, and 137Cs methods and pollen stratigraphy, provide a history of diatom productivity and sediment-accumulation rates in Chesapeake Bay. We calculated the flux of biogenic silica and total sediment for the past 1500 yr for two high-sedimentation-rate sites in the mesohaline section of the bay. The data show that biogenic silica flux to sediments, an index of diatom productivity in the bay, as well as its variability, were relatively low before European settlement of the Chesapeake Bay watershed. In the succeeding 300-400 yr, the flux of biogenic silica has increased by a factor of 4 to 5. Biogenic silica fluxes still appear to be increasing, despite recent nutrient-reduction efforts. The increase in diatom-produced biogenic silica has been partly masked (in concentration terms) by a similar increase in total sediment flux. This history suggests the magnitude of anthropogenic disturbance of the estuary and indicates that significant changes had occurred long before the twentieth century.

Publication Year 2003
Title Antropogenically induced changes in sediment and biogenic silica fluxes in Chesapeake Bay
DOI 10.1130/0091-7613(2003)031<0071:AICISA>2.0.CO;2
Authors Steven M. Colman, J.F. Bratton
Publication Type Article
Publication Subtype Journal Article
Series Title Geology
Index ID 70026063
Record Source USGS Publications Warehouse
USGS Organization Woods Hole Coastal and Marine Science Center