Document Type

Senior Honors Project

Publication Date

4-2012

Abstract

The Dew Drop pond, located on the St. Catherine University campus in St. Paul, Minnesota has two functions: (a) to be a beautiful area to the campus for students’ enjoyment and (b) the filtration and removal of nutrients and sediment from runoff before it is transferred to the Mississippi River. This study was conducted to evaluate the effect of runoff from the St. Catherine University campus has on the pond, which is filling in and experiencing summer algal blooms. Sediment cores were collected from varying areas of the pond (west buffer (n=4), east buffer (n=3), no buffer (n=3), east island (n=2), west island (n=2)) and segmented into two or three layers based on visual distinction of texture and color in the sediment. Samples were extracted using 2M KCl and 0.5M NaHCO3, shaken 1 hour, and filtered using Whatman 42 filter paper. Extracts were analyzed for ammonium (NH4-N), nitrate (NO3-N), soluble reactive phosphorus (SRP), dissolved organic carbon (DOC), and total dissolved nitrogen (TDN). Following statistical analyses of one-way ANOVA, results show significantly higher concentrations of NH4-N and TDN in the east island region (29404.71mg/kg (p<0.01), 32248.15mg/kg (p<0.05) respectively), of SRP in the east buffer region and the middle layer of sediments (2236.50mg/kg (p<0.01), 1678.32mg/kg (p<0.05) respectively), and of DOC in the top layer of the sediments (36.91mg/g (p<0.05)). Though no statistical difference was present for NO3-N data, values were much lower than NH4-N. Comparison to similar studies performed in river floodplains, wetlands, and retention basins demonstrate that the Dew Drop pond has high nutrient concentrations, indicating the potential for continuation of eutrophication, and this is likely decreasing its ability to efficiently store water and remove nutrients from the runoff before entrance to the river. Recommendations include the dredging of the pond to remove nutrient stored sediments, as well as planting a sustainable and effective buffer zone of native, perennial grasses and shrubs to limit the runoff of excess nutrients into the pond and erosion of the banks.

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