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Soil enzyme activities are used as proxies for microbial mineralization of organically bound macro-elements including carbon (C), nitrogen (N), and phosphorus (P). Enzymes play key roles in hydrolyzing complex polymers into simple labile compounds. This study compares the activities of select extracellular enzymes including: alkaline phosphatase (monesterase), phosphodiesterase, β-glucosidase, and leucine aminopeptidase, in floc, recently accreted and underlying native soil of Stormwater Treatment Area-2 (STA-2). The STA-2 has been in use for 10 years supporting a combination of emergent and submerged aquatic vegetation cells. We hypothesized that enzyme activity will decrease with soil depth and enzyme activities will vary in emergent and submerged aquatic vegetation cells. Triplicate soil cores were obtained from the center of each cell and sectioned into floc, newly accreted, and native sections. Newly accreted soil is material accreted after the creation of the STA and native soil is peat deposited before the construction of the STA. Enzyme activities with depth were quantified using the microplate fluorimetric enzyme assay using 4-methylumbellerone (MUF) and its conjugates for alkaline phosphatase, phosphate diesterase, and β-glucosidase. Leucine aminopeptidase was quantified using 7-amino-4-methyl coumarin and its conjugate. Preliminary results show that in general, floc has the highest enzyme activity while enzyme activity decreases with soil depth until native soil is reached. Native soil does not follow the pattern of enzyme activity of newly accreted soil. Ongoing research includes soil characterization using potentially mineralizable N, microbial biomass C, N, and P, total C, N, and P soil moisture content, bulk density, and δ15N and δ13C for potential relationships. |