Cornwell, J. C. UMCES, Horn Point Laboratory, cornwell@hpl.umces.edu
Owens, M. C. UMCES, Horn Point Laboratory, owens@hpl.umces.edu

 
BIOGEOCHEMICAL CONTROLS ON SEDIMENT-WATER PHOSPHORUS EXCHANGE IN LAKE CHAMPLAIN
 
Sediment-water exchange of soluble reactive P (SRP) in aquatic sediments is controlled by a number of physical, chemical and biological factors. In Lake Champlain, our study of sediment-water solute and gas exchange, pore water chemistry, and geochronology has provided some insight into the rates of P recycling. At most sites approximately 10% of sedimented P is recycled to the water column. In mesotrophic/eutrophic shallow water embayments with higher water column SRP and phytoplankton biomass, about 50% of sedimented P is recycled to the water column. Strong biogeochemical control of P fluxes arises from a dynamic Fe cycle which keeps freshly precipitated iron oxide concentrations relatively high and P concentrations low. Despite this active Fe cycling, P retention via burial can be low at some sites, particularly those with filter feeding mussels present. Explanations of site to site differences in P recycling in Lake Champlain must rely on more than geochemical distributions in solids and pore water; both physical and biological controls are clearly important.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: SS30TH0735S