Atmospheric Organic Nitrogen - Origin, Speciation, and Significance in Global Marine BiogeochemistryEPA 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: Michaud, Jayne
Project Period: August 1, 1999 through August 1, 2002
Project Amount: $93,700
RFA: STAR Graduate Fellowships (1999) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Academic Fellowships , Fellowship - Oceanography
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.
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.
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.