Measured and modelled effects of temperature, dissolved oxygen and nutrient concentration on sediment-water nutrient exchange

Empirical models of sediment-water fluxes of NH sub(4) super(+), NO sub(3) super(-) and PO sub(4) super(3-) were formed based on published reports. The models were revised and parameters evaluated based on laboratory incubations of sediments collected from Gunston Cove, VA. Observed fluxes ranged from -18 (sediment uptake) to 276 (sediment release) mg NH sub(4) super(+)/m super(2)/day, -17 to -509 mg NO sub(3) super(-)/m super(2)/day, and -16.4 to 8.9 mg PO sub(4) super(3-)/m super(2)/day. The model and observations indicated release of NH sub(4) super(+) was enhanced by high temperature and by low DO. Uptake of NO sub(3) super(-) was enhanced primarily by high NO sub(3) super(-) concentration and to a lesser extent by high temperature and by low DO. Direction of PO sub(4) super(3-) flux depended on concentration in the water. Release was enhanced by low DO. No effect of temperature on PO sub(4) super(3-) flux was observed.