Date of Award

2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Natural Resources

First Advisor

Reddy,Gudigopuram Bhaskar Dr.

Abstract

Increased swine production in North Carolina has resulted in higher waste production. Continuous application of swine wastewater from lagoons to agricultural land can pose surface and ground water pollution. Constructed wetland (CW) treatment is an alternate to the lagoon spray field system that reduces the nutrients concentration through physical, chemical and biological mechanisms. One of the biological processes in the CW is enzymatic activity which plays a major role in releasing nutrients from organic substances. The objectives of this research were to investigate the activity of soil enzymes at different depths of CW treated with swine wastewater and to assess the relationship between the enzyme activity and nutrient concentration. One continuous marsh (CM) and one marsh-pond-marsh (MPM) wetland cells were studied, which were in operation for the last ten years treating swine wastewater. The activities of dehydrogenase, urease, phosphatase, arylsulfatase, and β-glucosidase were significantly higher in the soil surface layer (0-3 cm) than lower depths (6-12 cm). Enzyme activities were higher in marsh soils of CM than pond soils of MPM. There was no significant difference in enzyme activity between inlet and outlet of CM and MPM. No significant relationship was found between the enzyme activity and nutrient concentration. Urease, phosphatase and arylsulfatase activity were correlated to soil C and N, whereas, β-glucosidase activity was correlated to soil C. The results suggest that lower enzyme activity is required for these wetlands to achieve high nutrient removal efficiency.

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