PHOSPHORUS BIOGEOCHEMISTRY

Phosphorus has been identified as one of the two key limiting nutrients in Chesapeake Bay. Phosphorus limitation occurs during the spring in the upper Chesapeake Bay and throughout much of the year in tidal freshwater habitats. Three projects are addressing phosphorus cycling in the Chesapeake Bay: a sediment N and P project in the Patuxent River, a sediment P project on the Potomac River, and a suspended P project on the Potomac River. In the Patuxent, we are concerned with the effect of salinity and temperature on the release of P from sediments. Sediment sampling is being carried out across salinity gradients. In the Potomac, we are 1) assessing the role of elevated pH on P release from bottom sediments and 2) the chemistry and bioavailability of phosphorus in suspended sediments. In the Potomac, we are working with the modeling community in refining the phosphorus component in the water quality model.