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Grantee Research Project Results

Grantee Research Project Results

Atmospheric Organic Nitrogen - Origin, Speciation, and Significance in Global Marine Biogeochemistry

EPA Grant Number: U915635
Title: Atmospheric Organic Nitrogen - Origin, Speciation, and Significance in Global Marine Biogeochemistry
Investigators: Mace, Kimberly A.
Institution: Texas A & M University
EPA Project Officer: Boddie, Georgette
Project Period: August 1, 1999 through August 1, 2002
Project Amount: $93,700
RFA: STAR Graduate Fellowships (1999)
Research Category: Aquatic Ecosystems , Academic Fellowships , Fellowship - Oceanography

Description:

Objective:

The goals of this research project are to: (1) measure total organic nitrogen (N) and total inorganic N in rain, bulk, and particle size-separated aerosols; (2) measure specific forms of atmospheric organic nitrogen (AON) to include urea and amino acids, and to relate them to total organic N as determined in goal number 1; (3) compare historical and present-day concentrations of organic N in ice core samples to determine the influence of human-induced change on organic N totals; (4) evaluate biomass burning as a potential source of organic N; and (5) evaluate the N isotope signatures of total organic N to ascertain possible sources.

Approach:

Sites for the study include an atmospheric sampling tower-based background monitoring station located at Cape Grim, Tasmania, Australia; an atmospheric sampling tower located on the windward coast of Oahu, Hawaii; an atmospheric sampling tower located on the Turkish Mediterranean coast; and wet and dry season samples collected from a biomass burning region in central Amazonia, Brazil. Samples will be analyzed for total inorganic and organic N. The organic portion of samples will be determined primarily by ultraviolet (UV) oxidation using a Metrohm 705 UV digestor (Metrohm, Switzerland). Other methods, such as persulfate digestion, also will be evaluated. Amino acids will be determined by a dabsyl chloride (DABS-Cl) method for high performance liquid chromatography (HPLC). Urea will be determined using both an ion chromatography (IC) method and a standard colorimetric method. N isotopes will be evaluated on a number of samples and possibly for individual organic species within the organic N pool. Ice core samples from Greenland will be analyzed using the methodology above to determine whether AON is a predominantly anthropogenic component.

Expected Results:

Expectations concerning the origin of organic nitrogen in the atmosphere are premature at this time. It is likely that many different sources contribute to the composition of the organic N fraction, and that these sources are largely the result of land use patterns.

Supplemental Keywords:

tropospheric, marine, aerosol, precipitation, nitrogen, organic, atmosphere, oceanography, measurement methods, aquatic, chemical transport., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Geochemistry, Oceanography, Aquatic Ecosystem, Monitoring/Modeling, Biochemistry, Environmental Monitoring, Ecology and Ecosystems, fate and transport, monitoring, atmospheric dispersion models, atmospheric nitrogen, estuarine research, atmospheric measurements, environmental measurement, ecosystem monitoring, nitrogen cycling, biogeochemcial cycling, marine biogeochemistry, high performance liquid chromatography, dissolved organic nitrogen, atmospheric chemistry

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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