Application of sediment traps to assess downward flux and settling velocity in New Croton Reservoir, Westchester County, New York

Temporal and spatial patterns are presented for metalimnetic and near-bottom sediment trap collections of particulate phosphorus (PP), chlorophyll (Chl), particulate organic carbon (POC), and suspended solids, during the stratified periods of 1999 and 2000 in the New Croton Reservoir. The contribution of non-phytoplankton particles (tripton) to the PP pool caused a decoupling of the downward fluxes of Chl and PP. These contributions were manifested in the stoichiometry of trap collections and the higher estimates of settling velocity (SV) of PP compared to Chl. Tripton represented 73–89% of the deposited phosphorus. Water column concentrations and sediment deposition generally decreased in the downstream direction in the reservoir. Comparisons of deposition of near-bottom to metalimnetic traps at two sampling stations, and transmissometry data indicate that resuspension occurs. These findings have direct bearing on the successful simulation of water quality models.