Project at a Glance
Title: Studies of dry acid deposition in the South Coast Air Basin intermethod comparison of procedures for nitric acid and ammonia
Principal Investigator / Author(s): Appel, B R
Contractor: Air and Industrial Hygiene Laboratory, California Department of Health Services
Contract Number: 4-147-32
Research Program Area: Atmospheric Processes
Topic Areas: Acid Deposition
A field study was performed at Claremont, CA to evaluate methods for the measurement of atmospheric nitric acid, fine particulate nitrate and gaseous ammonia. The methods employed for nitric acid were the automated, semi-continuous tungstic acid technique (TAT) and the denuder difference method (DDM). Ammonia was measured with the TAT, a filterpack and a manual denuder tube collection method.
The DDM for nitric acid appears to be accurate within about 20%, while the TAT is subject to large variability. Daytime results at Claremont generally show agreement between the TAT and DDM but TAT results are much higher at night. Similarly, TAT ammonia results are uncertain by about a factor of 2. Filter pack ammonia results are consistently too high by, on average, a factor of 1.5, compared to a relatively accurate, manual denuder tube collection technique.
For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893
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