EVALUATION OF AMMONIA EMISSIONS FROM SWINE OPERATIONS IN NORTH CAROLINA

摘要

Historically, the primary methods available for determining emissions from large area sources were point-sampling techniques employing flux chambers or evacuated canisters followed by analysis of the appropriate gas samples. These techniques can produce accurate results when conducted within a statistical framework and when an iterative approach to sampling is adopted. However, point-sampling techniques are expensive, time consuming, and open to the risks of missing significant emissions from a non-homogenous source. Remote sensing techniques are now available for quantifying emissions from large, heterogenous area sources, such as municipal wastewater treatment facilities, waste lagoons, and surface coal mines. These techniques produce a path-integrated concentration, typically reported in units of parts per million-meter (ppm-m), of the species of interest, eliminating concern over source heterogeneity. Open-path Fourier transform infrared (OP/FTIR) spectroscopy is one of the remote sensing techniques which, within the last decade, has received wide attention. Extensive development and optimization work of a mobile OP/FTIR system for analyzing emissions from area sources was performed in the early 1990's by Kansas State University, the University of Kansas, and the U. S. Environmental Protection Agency. Further comparative studies between OP/FTIR and canister sampling were conducted by Russwurm et al. and by Carter et al. Somewhat broader treatments of the subject were produced by Minnich et al. and by Kagann et al. Recently, papers have been published by Piccot et al. and Kirchgessner et al. describing a validation of the single-path OP/FTIR technique using methane emissions and SF tracer releases from area sources. The validation included a comparison to evacuated canister samples taken simultaneously with the OP/FTIR data. OP/FTIR techniques have been successfully applied to the measurement of methane emissions at western U.S. coal mines. Piccot et al. have also described a medium scale test of the plane-integrated technique for analyzing emissions from a simulated volume source. In this series of tests, over 90% of the runs measured emissions within 20% of known emissions, and half of the tests were within 10%. The use of OP/FTIR is also documented in a paper by Thorneloe et al." describing the single-path OP/FTIR technique applied to methane, tropospheric ozone precursors, and nitrous oxide. The data presented in this paper are from the initial phase of a study to extend the application of the plane-integrated method to agricultural sources of fine particulate precursors. All of the information was gathered with the classical single-beam approach to develop a baseline to which the performance of the plane-integrated technique can be compared.