Organic Matter and Nutrient Cycling in a Coastal Plain Estuary: Carbon, Nitrogen, and Phosphorus Distributions, Budgets, and Fluxes

Abstract

Abstract Nutrient temporal and spatial distributions were evaluated, in addition to budgets and fluxes derived from the Land-Ocean Interaction in the Coastal Zone (LOICZ) biogeochemical model, to determine dissolved organic matter and inorganic nutrient distribution, flux, and fate in the Mullica River–Great Bay Estuary. Seasonal cycles were observed for dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) with increasing concentrations from spring to fall and maximum concentrations in summer/early fall. Annually, the estuarine system was a net source of DOC (+5 mol m−2 y−1), DON (+0.08 mol m−2 y−1), and dissolved inorganic phosphorus (DIP, +0.010 mol m−2 y−1), a net sink of dissolved inorganic nitrogen (DIN, −0.28 mol m−2 y−1), and in approximate balance of DOP (0.001 mol m−2 y−1). Overall, the upper estuary and mid-estuary served as net sinks for most nutrients, whereas the lower estuary served as a net source. Annual mean nutrient export from the lower estuary to the nearshore coastal r...