Assessing the Nitrogen and Phosphorus Loading in the Alabama (USA) River Basin Using PLOAD Model

Pollutant loadings in two watersheds, Mulberry and Catoma were assessed using the pollutant loading (PLOAD) model and model results were compared with those obtained from field sampling followed by laboratory analysis. The PLOAD model was used to determine water pollutants including total nitrogen (TN), total phosphorus (TP), orthophosphate (PO 4 3- ), nitrite (NO 2 – ) and nitrate (NO 3 – ) in two watersheds, Mulberry and Catoma that are part of the Alabama River Basin. Results revealed that both Mulberry and Catoma watersheds had TN and TP values that exceeded the US Environmental Protection Agency (EPA) limits set for rivers and streams. The TN and TP values were in the range of hypertrophic for lakes, and eutrophic for rivers. The PLOAD model results were in agreement with analytical results. We conclude that PLOAD is a valid model for determining pollutant loading in watersheds and provides a relatively faster and cheaper method of assessing impairment of watershed bodies compared to conventional methods.