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NATIONAL DRY DEPOSITION NETWORK SECOND ANNUAL PROGRESS REPORT (1988)
Citation:
Edgerton, E., T. Lavery, M. Hodges, AND J. Bowser. NATIONAL DRY DEPOSITION NETWORK SECOND ANNUAL PROGRESS REPORT (1988). U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-90/020.
Description:
Progress in the National Dry Deposition Network during calendar year 1988 is presented. The network configuration and operating procedures for the field, laboratory, and data management center are described and data are summarized. Forty-three sites were operational at the close of 1988. Each site was equipped with sensors for measuring ozone and meteorological parameters required by inferntial dry depositon algorithms. Weekly average day/night concentration of sulfate, nitrate, sulfur dioxide, and nitric acid were measured using a three-stage filter pack. Sodium, potassium, calcium, magnesium and ammonium were measured during half of the year. Ambient concentration data for 18 sites operational throughout the year showed species-dependent variability from site to site, season to season, and day to night. Average SO-42- and HNO3 were highest during summer (10 and 3 ug/m respectively) and lowest during fall (4 and 1.8 ug/m3, respectively); SO2 and NO3 highest in winter (18 and 1.7 ug/m3, respectively) and lowest in summer (10 and 0.6 ug/ml). Day/night variability was generally low for SO-42- and NO3, but frequently pronounced for SO2 and HNO3. Approximations of annual dry deposition for SO2 plus SO2 and NO3 plus HNO3 suggest that fluxes are of the same order of magnitude as wet deposition at numerous sites. Application of one or more dry depositon algorithms is needed to refine such estimtes. Examination of ozone data showed numerous observations above 100 ppb mainly associated with stagnating high pressure.