Peroxyacetyl nitrate in eastern Scotland

• Published in: The Science of the total environment 2005-01, Vol.337 (1), p.213-222
• Main Authors: McFadyen, G.G., Cape, J.N.
• Format: Article
• Language: English
• Subjects: Applied sciences; Atmospheric pollution; Environmental Monitoring; Exact sciences and technology; Long-range transport; Nitrogen oxides; Oxidants, Photochemical - analysis; Ozone; Ozone - analysis; PAN; Peracetic Acid - analogs & derivatives; Peracetic Acid - analysis; Periodicity; Photochemical oxidants; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Rural Health; Scotland; Seasons; Wind
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2004.06.016

Peroxyacetyl nitrate (PAN) concentrations in air were sampled hourly from 1994 to 1998 at a rural site 15 km south-west of Edinburgh, in eastern Scotland. Annual average concentrations were between 0.1 and 0.15 nl l −1, with episodes up to 3 nl l −1 in long-range transported polluted air. PAN concentrations were approximately log-normally distributed. The concentrations measured are the result of a balance between photochemical production rates and removal by thermal decomposition and dry deposition. In general, there was a poor correlation between PAN and ozone concentrations at this rural site except during episodes of photochemical pollution, when the PAN/O 3 volume ratio exceeded 0.01. The PAN/NO x volume ratio had a median value of 0.015 but ranged up to 0.25. There was a pronounced seasonal maximum in PAN concentrations in late spring, and a strong diurnal cycle only in April–June, with a maximum at 1700 h. Individual episodes, with concentrations up to 3 nl l −1, could be traced over distances of ca. 1000 km, with rapid changes in concentration as the prevailing winds advected polluted air masses across the site.