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Comparison of annular denuder and filter pack collection of HNO3 (g), HNO2((g), SO2 (g), and particulate-phase nitrate, nitrite and sulfate in the south-west desert

1991; Elsevier BV; Volume: 25; Issue: 8 Linguagem: Inglês

10.1016/0960-1686(91)90013-w

1878-2124

Cynthia L. Benner, Delbert J. Eatough, Norman L. Eatough, Prem S. Bhardwaja,

Groundwater and Isotope Geochemistry

During the 15 January–4 February 1986 SCENES Special Study, a comparison study was conducted to determine atmospheric HNO3 (g), HNO2 (g), SO2 (g), and particle-phase nitrate, nitrite and sulfate sampled with annular diffusion denuder and filter pack sampling systems for 12-h periods. The results of the ion chromatographic analyses of the denuder and filter extracts from the annular denuder system showed that an average of 88% of the total nitrate measured was HNO3 (g), 97% of the total nitrite was HNO2 (g), and 91% of the total sulfur was present as SO2 (g). Analyses of the various gas-phase species collected by replicate annular denuder systems indicated that a precision of ± 3% to ± 18% was achieved using these denuders. The good agreement in HNO3 (g) concentrations observed between the filter pack and the denuder (r2=0.873, slope=1.06±0.03, intercept=0±3.5 nmol m−3) results from the fact that the majority of the atmospheric nitrate consisted of HNO3 (g), which minimized any positive artifact in HNO3(g) due to loss of HNO3(g) from particles collected in the filter pack. The particulate-phase nitrate correlation between the two sampling systems was not as good (r2=0.709, slope=0.519±0.045, intercept =0±1.2 nmol m−3) because the lower percentage of nitrate present as the particulate species was more affected by the loss of particulate nitrate during sampling with the filter pack.