US EPA

2489237 

Journal Article 

A 2,500-year history of anoxia and eutrophication in Chesapeake Bay 

Cooper, SR; Brush, GS 

1993 

Yes 

Estuaries
ISSN: 0160-8347 

16 

3B 

617-626 

English 

10.2307/1352799 

WOS:A1993ML72200005 

http://www.jstor.org/stable/1352799
Exit
 

Ongoing monitoring programs and historical data are not sufficient to establish anthropogenic effects on the ecology of Chesapeake Bay. However, stratigraphic records preserved in the sediments can be used to reconstruct both prehistoric and historic sedimentation and water conditions of the bay, including anoxia and eutrophication. Pollen, diatoms, total organic carbon (TOC), nitrogen, total sulfur, and an estimate of the degree of pyritization of iron (DOP) are being used as paleoecological indicators in dated sediment cores for the purpose of reconstructing a long-term environmental history of the bay. Analysis of the data indicates that sedimentation rates, anoxic conditions, and eutrophication have increased in the Chesapeake Bay since the time of European settlement. For example, since initial land clearance around 1760, sedimentation rates have increased from as low as 0.02 cm yr-1 to an average 0.22 cm yr-1, and TOC from 0.14 mg cm-2 yr-1 to a high 4.96 Mg CM-2 yr-1. Diatom community structure shows a steady decrease in overall diversity since 1760 and the centric:pennate ratio has increased significantly since 1940.