SUMMARY OF SEDIMENT CHEMISTRY RESEARCH AT OLD WOMAN CREEK, OHIO

Sediments are important at Old Woman Creek National Estuarine Research Reserve (OWC) and similar environments because suspended sediments provide a medium for the transport of many nutrients and toxic substances and bottom sediments may serve as either a sink or source of these substances, can influence estuarine productivity and water quality, can serve as substrates for much of the wetlands microscopic and macroscopic flora and fauna, and can contain a record of past conditions at the depositional site. Previous research at OWC has determined that the major sources of sediment supplied to the estuary are from soils and tills and the Berea Sandstone in the drainage basin. These sediments and their associated chemical species are primarily delivered to the estuary during storm events and the majority of the suspended sediment that washes into OWC is trapped and accumulates at the bottom of the estuary. Some postdepositional mobilization and sediment-water exchange of metals such as cadmium (downcore transport) and nutrients such as silica (release from sediments) has been observed and fluxes calculated. Groundwater seepage into the estuary varies with annual rainfall and is greatest near the estuary perimeter. Solute fluxes resulting from groundwater seepage are generally small compared to total fluxes as measured using bottom chambers. Benthic macroinvertebrates may contribute significantly to internal recycling. Both field measurements and computer simulations indicate that the water and solute budgets are controlled, in part, by a barrier sandbar which sometimes separates the estuary from Lake Erie.