Carbon Budget for the Mid-Slope Depocenter of the Middle Atlantic Bight

A mass budget was constructed for organic carbon on the upper slope of the Middle Atlantic Bight, a region thought to serve as a depocenter for fine-grained material exported from the adjacent shelf. Various components of the budget are internally consistent, and observed differences can be attributed to natural spatial variability or to the different time scales over which measurements were made. The flux of organic carbon to the sediments in the core of the depocenter zone, al a water depth of similar to 1000 m, was measured with sediment traps to be similar to 65 mg C m(-2) day(-1), of which 6-24 mg C m(-2) day(-1) is buried. Oxygen fluxes into the sediments, measured m with incubation chambers attached to a free vehicle lander, correspond to total carbon remineralization rates of 49-70 mg C m(-2) day(-1). Carbon remineralization rates estimated from gradients of C-org within the mixed layer, and from gradients of dissolved ammonia and phosphate in pore waters, sum to only similar to 4-6 mg C m(-2) day(-1).