The Influence of Nitrogen Deposition on Trace Gas Emissions of NOx, N2O and CO2 in Arid and Semiarid Ecosystems

EPA Grant Number: F13F31238
Title: The Influence of Nitrogen Deposition on Trace Gas Emissions of NOx, N2O and CO2 in Arid and Semiarid Ecosystems
Investigators: Eberwein, Jennifer Rae
Institution: University of California - Riverside
EPA Project Officer: Lee, Sonja
Project Period: September 22, 2014 through September 22, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Fellowship - Ecology , Academic Fellowships

Objective:

This study will investigate soil feedbacks to nitrogen deposition through analysis of soil trace gas emissions of NOx, N2O and CO2 along an anthropogenic nitrogen deposition gradient. Furthermore, this study will try to elucidate the mechanisms regulating that response through examination of microbial physiology and will contribute to further understanding of carbon and nitrogen interactions and soil trace gas emissions in arid environments.

Approach:

NOx, N2O and CO2 emissions are important contributors to air quality and terrestrial feedbacks to climate change. Knowledge gaps concerning interactions between the carbon and nitrogen cycles and changes in the ratio of carbon to nitrogen availability due to nitrogen deposition inhibit accurate predictions of the response of soil trace gas emissions to nitrogen deposition. This study will address that knowledge gap through a combination of laboratory incubations under controlled conditions and field observational data and manipulations of carbon and nitrogen availability. Furthermore, isotopic tracers and molecular techniques will be used to understand if changes in carbon and nitrogen alter soil emissions through changes in microbial physiology and/or shifts in microbial community composition.

Expected Results:

Nitrogen addition has the potential to increase soil emissions of NOx, N2O and CO2. The ratio of carbon to nitrogen availability is expected to be an important factor in regulating that response, due to associated changes in microbial physiology and/or community composition. This response is likely to be highly dependent on seasonal variations of soil moisture availability, plant activity and nitrogen deposition rates, with precipitation events following extended dry periods producing large pulses of microbial activity and corresponding emissions of NOx, N2O and CO2.

Potential to Further Environmental/Human Health Protection

Thorough understanding of ecosystem responses to nitrogen deposition is necessary to inform modelers so that terrestrial feedbacks to nitrogen deposition and climate change drivers can be accurately predicted. The results from this project will enhance understanding of carbon and nitrogen budgets in arid ecosystems and provide insight into interactions between the carbon and nitrogen cycles. Additionally, NOx represents important health implications and N2O and CO2 are major greenhouse gases. This research will provide valuable information to regulatory bodies so that ecosystem services provided by soils can be considered when emission standards are set.

Supplemental Keywords:

carbon dioxide, nitrogen cycling and deposition, soil biome

Progress and Final Reports:

  • 2015
  • Final