Date of Award

10-27-2016

Document Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

First Advisor

Dr. Weixing Zhu

Abstract

Humans have altered nitrogen (N) cycling on a global scale, and elevated nitrogen levels are characteristic of urban ecosystems. The major reasons that N is higher in cities include imports of food, fuel and fertilizer. High N export from both point- and nonpoint-sources is common in large cities. While N cycling has been studied in large urban areas, less is known about its cycling in medium-sized cities, such as Binghamton, N.Y. We found that point-source N exported from the Binghamton-Johnson City Wastewater Treatment Plant (B-JC WWTP) was greater than nonpoint-source N exported from eight urban streams to the Susquehanna River, which runs through the Binghamton area. The point-source N fluxes we measured from the B-JC WWTP were high because its function was impaired during the study, causing major environmental impacts on the Susquehanna River. Nonpoint-source N exported from eight urban streams was low, and comparable to N exported from streams of forested watersheds in the region. In an experiment in a roadside ecosystem, experimental deposition of N and road salt (NaCl) did not affect N cycling in roadside soils. However, NaCl negatively impacted C mineralization and soil respiration in situ. In a final experiment, we found that the microbial community of urban stream sediment had the capacity to substantially reduce NO3- through denitrification.

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