Reports
Physiographic distribution of interstitial waters in Chesapeake Bay
1988, Hill, J.M.
Report of Investigations 49
Abstract
The Chesapeake Bay can be divided into three major physiographic regions based on basin structure and sediment characteristics. These regions are:
- The Northern Bay - a shallow region (ave. depth = 3m) dominated by fluvial inputs of freshwater and sediment;
- The Middle Bay - characterized by a deep axial channel, stratified water column, and fine sediments, and;
- The Southern Bay - a shallow region (ave. depth = 9m) composed of very coarse sediments (sand and silty sands).
Examination of the interstitial water compositions within each of these regions shows a strong relationship between the physical setting and the geochemical state of the sediment. Major relationships found are:
- Northern Bay - pore water chemistry varies in response to variations in fluvial inputs, and dissolved total sulfide concentrations are below detection due to the large degree of dilution of seawater in this area;
- Middle Bay - sediments highly sulfidic, in equilibrium with elemental sulfur. The composition of the pore waters is seasonally stable except at the transition between the Northern and Middle Bay where some fluvial influence is found, and;
- Southern Bay -low carbon content of the sediment maintains low reaction rates thus metabolite levels are low and there is minimal depletion of sulfate.
