Spatial and temporal patterns of dissolved ammonium, manganese and silica fluxes from bottom sediments of Long Island Sound, U.S.A.

Comparisons at 3 stations show that NH₄ ⁺ and Si(OH)₄ fluxes generally agree within a factor of c2 or better with those calculated from pore water solute gradients. Si(OH)₄ fluxes are also consistent with reported opaline silica dissolution rates. Seasonal measurements show that fluxes vary directly with temperature and are highest in summer. The summer fluxes of all 3 solutes reflect depositional environment and correlated directly with the quantity of fine-grained material and percent organic matter in surface sediment. In addition, the ratio of NH₄ ⁺ released to organic matter present in the sediment decreases with increasing water depth.-from Authors