New analytical techniques allow unprecendented questions to be asked regarding nitrogen isotopes in atmospheric compounds.  This research explores the use of isotopes as additional tools for understanding sources of atmospheric nitrogen pollution in wet deposition, dry deposition, gaseous compounds, particulate matter, and vegetation.  Additionally, ongoing research associated with the Baltimore Long-Term Ecological Research (LTER) and the U.S. Forest Service explores CO₂ and NO_x sequestration by vegetation along an urban to rural gradient using stable isotope techniques.    

Papers and Published Abstracts:

Elliott, EM, Kendall, C, Wankel, SD, et al.  Nitrogen isotopes as indicators of NO_x source contributions to atmospheric nitrate deposition across the Midwestern and Northeastern United States.  In press.

Elliott, E.M., Kendall, C., Burns, D. A., Boyer, E. W., Harlin, K., Wankel, S. D., Butler, T. J., Carlton, R.  (2006), Nitrate Isotopes in Precipitation to Distinguish NOx Sources, Atmospheric Processes, and Source Areas in the United States, Eos Trans. AGU, 87(36), Jt. Assem. Suppl., Abstract H52B-01

Elliott, EM; Kendall, C; Harlin, K; Butler, T; Carlton, R; Wankel, SD.  2004.  Mapping the Spatial and Temporal Distribution of N and O Isotopes in Precipitation Nitrate across the Northeastern and Mid-Atlantic United States.  EOS Trans.  AGU, 85(47), Fall Meet. Suppl., Abstract H52B-02. 

Kendall, C, Elliott EM, and Wankel, SD.  2007.  Tracing Anthropogenic Inputs of Nitrogen to Ecosystems.  In Stable Isotopes in Ecology and Environmental Science (2^nd edition).  Lajtha, K and Michener, RH (eds.)  Blackwell Scientific Publications.

Presentations:

Elliott, EM.  Nitrogen isotopes in dry deposition:  Can CASTNET and passive samplers be used to partition contributions of NOx sources?  National Atmospheric Deposition Program 30th Annual Technical Meeting.  September 2007. Boulder, CO.  

Elliott, EM.   Stable isotope techniques for tracing NOx source contributions to nitrate deposition in the U.S.  U.S. EPA, Clean Air Markets Division, Washington D.C., June 2007. 

Elliott, EM.  Insights into Sources and Fate of Nitrogenous Emissions Using Stable Isotope Techniques.  Chesapeake Bay Scientific Advisory Committee, Workshop on Atmospheric Nitrogen Deposition, Binghamton University, New York, May 30, 2007.

Elliott, EM.  Understanding atmospheric nitrate sources to ecosystems and biogeochemical implications using stable isotopes.  University of Louisville, Department of Biology, April 2007.

Elliott, EM.  NO_x Sources, Source Areas, and Atmospheric Cycling In The United States.  National Atmospheric Deposition Program 29th Annual Technical Meeting.  October 2006. Norfolk, VA. 

Elliott, EM.  Using Nitrate Isotopes in Precipitation to Distinguish NOx Sources, Atmospheric Cycling, and Source Areas in the United States.  USGS Water Resources Division Research Seminar.  Menlo Park, CA.  May 2006.

Elliott, EM.  Nitrate isotopes in precipitation across the United States:  A new tool for distinguishing NO_x sources?.  7^th International Conference on Acid Deposition.  June 2005.  Prague, Czech Republic.     

Collaborators: 
Carol Kendall (USGS-Menlo Park), Beth Boyer (UC-Berkeley), Doug Burns (USGS-Albany), Scott Wankel (Harvard University), Tom Butler (Cornell University and IES), Karen Harlin (NADP), Gary Lear (US EPA CASTNET Program), John Hom (USFS- Northeastern Research Station).

2)  How does land use and landscape pattern, particularly in urban environments, affect nutrient dynamics in watersheds?
 

Ongoing research uses stable isotopes of nitrate in surface waters to examine the role of land use on nutrient sources to watersheds.  This is particularly important in urbanizing areas where normal hydrological flowpaths are complicated by human infrastructure.  This research is taking place in various geographic settings including:

USGS NAWQA, Effects of Urbanization on Stream Ecosystems

Baltimore Ecosystem Study Long-term Ecological Research site

New York watersheds study

Nine Mile Run watershed

Collaborators: 
Carol Kendall (USGS-Menlo Park), Cathy Tate (USGS-Denver), Lori Sprague (USGS-Lakewood), Elise Giddings (USGS-Raleigh), Brian Gregory (USGS-Atlanta), Sujay Kaushal (University of Maryland- Chesapeake Biological Lab), Doug Burns (USGS-Troy), Beth Boyer (UC-Berkeley), Dan Bain (University of Pittsburgh)

3)  How does land use history influence terrestrial nutrient cycling?  Can stable isotopes be used as long-term indicators of changing nitrate sources to watersheds?
 

Another focus of my research examines how long-term land use change and urbanization influence nutrient sources to watersheds. This research uses a combination of paleoecological techniques (pollen biomarkers), land use history, nutrient load reconstructions, and sediment isotope geochemistry.

Presentations:

Elliott, EM.  Innovative stable isotope tools for understanding human impacts to nitrogen biogeochemistry.  University of Pittsburgh, Department of Geology and Planetary Science, February 2006.

Elliott, EM.  Organic Nitrogen Isotope Stratigraphy, Palynology, and Sediment History of Freshwater Wetlands in the Chesapeake Bay Basin:  Comparison with Land Use History.  USGS Water Resources Division Research Seminar.  Menlo Park, CA.  November 2003. 

Papers and Published Abstracts:

Elliott, EM, Brush, GS.  2006.  Organic Nitrogen Isotopes Record Long-term Changes in Watershed Nitrogen Sources and Land Use.   Environmental Science and Technology. 40(9):  2910-2916.

Elliott, EM, Brush, GS.  2003.  Does d¹⁵N of Sedimented Organic Nitrogen Record Historical Changes in Nitrogen Source to Wetlands?  American Society of Limnology and Oceanography, Aquatic Sciences Meeting.  Abstract # SS2.04, Nitrogen Paleo-biogeochemistry.

Elliott, EM, Brush, GS.  2002.  Extending the Record:  Using Isotopes to Infer Changing Nitrogen Sources to Wetlands.  EOS Trans.  AGU, 83(19), Spring Meet. Suppl., Abstract #H31B-06. 

Elliott, EM, Brush, GS.  2001.  Historical Variations in Nitrogen Source to Wetlands.  Ecological Society of America Annual Symposium.  August, 2001.  Madison, Wisconsin.  Abstract #35, Session #19.      

Collaborators: 
Grace S. Brush (Johns Hopkins University), John Hom (USFS- Northeastern Research Station)