Diffusive nutrient flux at the sediment-water interface in Suma Park Reservoir, Australia

An initial assessment of the diffusive flux of soluble reactive phosphorus (SRP), ammonium N (NH4+) and nitrate N (NO3-) at the sediment-water interface in the Suma Park Reservoir was carried out in situ by means of passive sediment peepers. The purpose of the experiment was to measure the exchange rates of SRP, NW and NO3- between sediments and water and to assess their contribution to the nutrient budget in the reservoir, the main water supply of Orange, Australia. This field experiment indicated that SRP and NH4+ were diffused from the sediments to the overlying water at a rate of 0.1 +/- 0.07 and 1.7 +/- 1.2 mg m(-2) day(-1) respectively. On the other hand, NO3- was lost from the water column at the rate of 0.3 +/- 0.2 mg m(-2\) day(-1). The experiment demonstrated that dissolved nutrient flux at the sediment-water interface through molecular diffusion makes a significant contribution to the total nutrient budget in the reservoir and plays a critical role in the overall nutrient cycling and supporting the production of blue-green algae. It was evident that the bottom sediment acts both as a source and a sink for phosphorous (P) and nitrogen (N).