Nutrient distributions and transport in Long Island Sound

Abstract

Inorganic nitrogenous nutrient (NH 3, NO 2, NO 3) distributions and transport in Long Island Sound are investigated for both winter and summer conditions with a steady state, one dimensional mass balance model. Nutrient budgets based on horizontal exchange, lateral input from sewage and agricultural sources, and first order biochemical uptake (utilization minus regeneration) are computed for each of 13 regions in the Sound. All nutrient concentrations, principally ammonia, peak sharply in the upper East River where a strong point source exists. Concentration distributions and uptake rates are consistent with previous studies of the nitrogen cycle and productivity of the Sound. However, this paper stresses horizontal exchange and sewage as important and hitherto neglected components of the nutrient budgets in various regions. Estimates of the loss of nitrogen to the sediment are presented for the western, central and eastern regions, from the Sound to the ocean at the eastern end, and into New York Harbor from the upper East River. Sewage effluents are shown to be the prime external source of nutrients for the Sound.