SPATIAL DISTRIBUTION OF PHOSPHORUS AND NITROGEN IN A WETLAND ENVIRONMENT

The experimental objective was to collect nutrient data from the water column in a wetland located in Cedar River (Iowa) watershed to observe any trends, if present. The parameters observed consisted of: Cl^-, NO₃^-, SO₄^2- (concentrations measured by Dionex Dx-100 Ion Chromatograph and Dionex 4270 Integrator), Total P concentrations (persulfate digestion method and ascorbic calorometric method) for shallow and deep water samples, pH, Dissolved Oxygen, Conductivity, and Total Dissolved Solids (measured by field instruments). The wetland was observed buffering: pH, Conductivity, Total Dissolved Solids, Nitrate, Chloride, and Sulfate for shallow and deep water sample analysis. Total P concentrations differ both spatially and temporally for the sampled dates in June and July. This could be due in part to the wetland's buffering capacity, the phosphorus cycle in relation to increased pH (as pH increases, PO₄^3- is released from the sediment), and the dilution of P in rainwater. Stratification was not expected to occur due to the shallow water depth of the wetland; however, Total P concentrations differed for shallow and deep water samples in both June and July. In June, there is a 70.6 µg/L difference for shallow and deep Total P averages. Shallow water P analysis have a range of 645-939 µg/L in comparison to Deep water P analysis range of 735-1200 µg/L. Spatially, Total P at depth in June is a decreasing concentration trend from the inflow to the outflow. Temporally, shallow water P samples increased by 368 µg/L from June to July. Similarly, deep water P samples increased by 265 µg/L. Shallow water P samples in July ranged from 931 to 1380 µg/L. Deep water P samples ranged from 853 to 1347 µg/L. Spatially, both shallow and deep water samples showed an increasing trend in Total P concentration. Concentrations of P in sediment show an increasing trend from inflow to outflow as well. The mass calculation resulted in 32,300 kg of P present in the lake sediment. The water volume was calculated to be 7.2 x 10⁴ m³. The Total P in the water is 61.21 kg for June, and 85.38 kg for July. Nitrate in water for June was calculated to be 303.51 kg, and in July the Nitrate was too diluted to be picked up by the Ion Chromatograph.