Document Type

Thesis

Date of Award

10-27-2016

Keywords

Biological sciences, Earth sciences, Biogeochemistry, Nitrogen, Roadside, Urban ecology, Urban ecosystem, Urban streams

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

First Advisor

Dr. Weixing Zhu

Subject Heading(s)

Biological sciences; Earth sciences; Biogeochemistry; Nitrogen; Roadside; Urban ecology; Urban ecosystem; Urban streams; Biology; Ecology and Evolutionary Biology

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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