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THE IMPACTS OF ANTHROPOGENIC PROCESSES ON THE NITROGEN BUDGET OF A POND**

Abstract

Levee-style ponds are constructed to impound water and prevent flooding. While humans benefit from the flooding mitigation downstream, it leaves streams with slow moving water that doesn’t allow for proper recharge of the aquifers and can disrupt nutrient cycles. Nitrate, a producer-available form of nitrogen (N), is often a limiting nutrient in aquatic ecosystems. Nitrate can enter a pond through a variety of fluxes, including surface runoff and biomass decay. Factors such as landscaping clippings, leaf litter, fertilizer and even stocked fish can add nitrate to a system. Weather and climate changes also have the potential to alter nitrate levels. In our observational study of the Lockerly Arboretum levee-constructed pond system located in Milledgeville, Baldwin County, Georgia, we assessed the nitrogen budget of the system, and the impacts of landscaping practices and fish stocking. Nitrate concentration was assessed on water samples collected from each of our four sites using a HACH colorimeter. Two sites were located within the pond itself, one was located upstream in a feeder creek, and one was located downstream under the levee.  Dissolved oxygen (DO), pH, and electrical conductivity (EC) were measured using EXtech field meters in situ at all four study sites. The feeder stream site had the highest nitrate measurements (average 1.64 mg/L) of all locations, likely due to sunlight being a limiting factor for photosynthesis in this shaded area, and the substantial addition of allochthonous biomass. Measurements of pH, DO, and EC changed as the temperature dropped from summer to fall, supporting our nitrate results as nitrate can be influenced by temperature, oxygen, and electrical conductivity. We plan to conduct hydrological assessments of the site, as this study continues to progress.

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