Nitrite in dew, fog, cloud and rain water: An indicator for heterogeneous processes on surfaces

• Published in: Atmospheric research Vol. 87; no. 3; pp. 200 - 212
• Main Authors: Acker, Karin, Beysens, Daniel, Möller, Detlev
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2008; Elsevier
• Subjects: Applied sciences; Atmospheric chemistry; Atmospheric pollution; Cloud; Dew; Exact sciences and technology; Nitrite; Nitrous acid; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Rain; France; Europe; Germany; France, Aquitaine, Bordeaux; Rain; Nitrite; Atmospheric chemistry; Nitrous acid; Cloud; Dew; Surface reaction; Water drop; Clouds; Pollutant behavior; Nitrites; Nitrogen compounds; Urban area; Photochemical reaction; Diurnal variation; Rural area; Air pollution; Fog; Hydrometeor; Heterogeneous reaction
• ISSN: 0169-8095; 1873-2895
• DOI: 10.1016/j.atmosres.2007.11.002

Nitrite was measured in atmospheric liquid phase samples between 1998 and 2005 to investigate the heterogeneous formation of nitrous acid in the lower atmosphere, as well as to assess the quality of water recovered from dew. The samples were collected during ground-based cloud field experiments at different German mountain sites (Brocken, Schmücke, and Hohenpeissenberg) and at a site south of the Bordeaux urban area (France). Concentrations found in Bordeaux dew samples (up to 2800 μg l − 1 ) are comparable to those found elsewhere in urban fog and dew water and considerably higher than those detected in cloud water or rain. Particulate nitrite (and nitrate) as well as HNO 2 (HNO 3) data in air masses from a foothill site of Mt. Schmücke, before involved in cloud processing, are also presented. In clouds at Mt. Brocken, both the interstitial HNO 2 gas and the aqueous phase nitrite concentration have been measured simultaneous. Significant deviations from Henry's law have been observed, indicating that a calculation of HNO 2 from measured solute nitrite concentrations in bulk samples will overestimate the gasphase concentration. Besides the heterogeneous HNO 2 production on wetted surfaces with contact to atmospheric air, a fraction of nitrite measured in cloud droplets or dew will arise from the dissolution of gasphase HNO 2, the particle scavenging processes or the dissolution of surface substrates. HNO 2 is a dominant hydroxyl radical source during daytime due to its effective photolysis and after water evaporation the released nitrite can significantly contribute to the total OH production and therefore to photochemical smog conditions in the lower atmosphere.