Research introductionAlthough nitrogen is an essential building block of life, in soluble form, it is also is a key eutrophication and acidification agent. Thus, "reactive nitrogen" (any nitrogen compound available for biotic uptake) is a perfect example of the complexity in understanding and managing human alternations to biogeochemical and hydrologic cycles. Research in the Elliott Lab addresses critical scientific and societal issues that exemplify the complex interactions between hydrology, ecology, and human activities across spatial scales.
Our research program examines the tight coupling between human activities and reactive nitrogen distributions in atmospheric, terrestrial and hydrologic systems at multiple spatial scales using stable isotope biogeochemistry. These coupled relationships are being investigated in agricultural, energy production, transportation, and human-built environments to determine how best to manage inputs of reactive nitrogen to protect water quality, air quality, ecosystem and human health. Ongoing projects broadly address three research questions: |
The "Cascading" Impact of Nitrogen in the Environment
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How does human activity affect spatial patterns of atmospheric reactive N emissions & deposition?
Ongoing projects are redefining the use of "isoscapes" to assess sources of atmospherically deposited reactive nitrogen to landscapes, watersheds, regions, and continents. We are characterizing the isotopic composition of reactive nitrogen emissions from multiple land uses and human activities. This work, conducted in agricultural, urban, forested, energy production, and maritime settings, is aimed at filling knowledge gaps required for accurate isoscape interpretation. Reactive nitrogen deposition fluxes and isotopic composition are being examined in gases, particulate matter, precipitation, plant biomonitors, and an ice core to assess similarities in spatial and temporal patterns of emissions and subsequent deposition. Research projects are funded by the U.S. Department of Agriculture (CSREES Air Quality Program), grants from the Electric Power Research Institute (EPRI), and an NSF CAREER award.
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How does land use and hydrologic connectivity influence reactive nitrogen delivery to aquatic systems?
Ongoing projects seek to advance our understanding of the fate of non-point sources of reactive nitrogen in aquatic systems. Using triple nitrate isotopes, we are examining factors that control nutrient delivery in human-impacted landscapes and determining how hydrological connectivity is a critical factor for proper assessment of watershed nutrient budgets. Research projects are funded by the Pennsylvania Water Resources Research Institute (WRRI), the University of Pittsburgh, a small grant from the Nine Mile Run Watershed Association, and an NSF CAREER award.
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How do plants, forests, & ecosystems respond to anthropogenic alterations to the nitrogen cycle?
Ongoing projects investigate sources and mechanisms for changing ecosystem nutrient status in forested, near-road, and urban settings. We are examining inter-watershed controls on breakthrough of atmospheric nitrogen and assessing how N saturation status influences atmospheric nitrogen export in streamwater. Additionally, we seek to clarify the role of plant uptake in retention of atmospheric nitrogen. Research projects are funded by NSF (Hydrologic Sciences and Ecosystems Studies Cluster), U.S. Forest Service (Northern Global Change Research Program), and the Maryland Department of Natural Resources (Power Plant Research Program).