Sampling of nitrates in ambient air

Fogwater chemistry in an urban atmosphere

“…In the absence of adduct formation the equilibrium partial pressures of CH20 calculated from fogwater data range from 16 ppb to 76 ppb, which are reasonable values for the Los Angeles atmosphere [Grosjean, 1982] [Appel, 1981].…”

PM10and PM2.5Compositions in California's San Joaquin Valley

“…The nitrate concentrations in this study were often double that of sulfate. The high nitrate concentrations were well above any contribution from the known biases in the nitrate measurement methods (e.g., Appel et al, 1980Appel et al, , 1981Forrest et al, 1980). Tracer (SF,) releases during winter showed that 50% of the tracer gas remained in the SJV 60 hours after its release.…”

Determination of Nitric Acid in Ambient Air by Gas Chromatography/Photoionization Detection after Collection in a Denuder

“…They concluded that interference in a denuder was negligible for particle transit times < 1.0 s. Forrest et al 2 came to the same conclusion when studying this phenomenon. Loss of particulate nitrate by deposition was investigated by Appel et al 16 for a denuder transit time of 0.3 s. Using 0.2 ± 0.1 nm and 2 ± 1 /urn particles, no losses were observed at room temperature and 20 or 60% RH, even when the transit time was doubled. Deposition losses for ambient particles were determined by measuring the particle number concentration upstream and downstream of a denuder.…”