WORKSHOP ON THE INTERCOMPARISON OF METHODOLOGIES FOR SOIL NOX EMISSIONS - SUMMARY OF DISCUSSION AND RESEARCH RECOMMENDATIONS

A workshop on the intercomparison of methodologies for soil NO(x) emissions was held on March 14-15,1994 at North Carolina State University (NCSU) in Raleigh, North Carolina, in preparation for a field experiment tentatively scheduled for May-June, 1995 involving measurement of rural site NO(x) emissions. The workshop was sponsored jointly by the U.S. Environmental Protection Agency (EPA) and NCSU. Representatives from several agencies will participate in the experiment, including the EPA, NASA, NOAA, DOE, NCAR, Atmospheric Science from the University of Maryland, and Atmospheric Sciences and Soil Sciences from NCSU. Approximately 50 workshop attendees, which included national experts on all aspects of flux measurement technologies, met for a day and a half to discuss techniques for measuring soil NO(x) (= NO + NO2) emissions and to suggest how to best incorporate these techniques into a field experiment to compare NO(x) measuring methodologies. The need for more knowledge in the area of soil NO(x) emissions is related to the uncertainty of the relationship between rural NO(x) emissions and the production of tropospheric ozone. In particular, the role of nitrogen-based fertilizers spread over rural agricultural areas in the production or emission of NO(x) is not well documented. To determine the best way to document and model these relationships, a full experimental comparison of NO(x) emission measurement techniques over a rural agricultural area is needed. Thus, it was recommended that a study of the intercomparison of methodologies for soil NO(x) emissions (both intensive field experiments and analysis) should be undertaken. The primary goal of this study will be to relate chamber techniques to micrometeorological flux estimates of NO(x). The study should include (i) an intensive four-to-six-week experiment for the intercomparison of methodologies for soil NO(x) emissions, (ii) and soil and air quality characterization of the experimental site.