9416807 Giblin This project will compare the stoichiometric relationships among benthic fluxes of oxygen, carbon, sulfur, nitrogen and phosphorous from sediments in a variety of lakes. Investigators will use a comparative ecosystem approach and a process-based diagenetic model to examine the factors which control regeneration of nitrogen and phosphorus from sediments. They will examine how the release of nitrogen and phosphorus changes in lakes across gradients of organic matter deposition, water chemistry, sediment chemistry and bottom water oxygen concentration. The data to be examined include: multi-year data sets from Lakes in the Hubbard Brook, Northern Lakes and Arctic LTER sites; shorter term data sets from about 50 temperate and arctic lakes; data from several experiments where carbon inputs to the sediments and overlying water chemistry were manipulated in intact sediment cores; and data from two whole lake fertilization experiments. Investigators will use this data to generate improved conceptual and numerical models of the controls of nutrient release from freshwater sediments. These models will provide tools for the management of water quality in lakes and estuaries.
