Peroxyacetyl nitrate in eastern Scotland.
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.
McFadyen
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Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian EH26 0QB, UK.
Cape
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D004784:Environmental Monitoring; D010083:Oxidants, Photochemical / Q000032:analysis*; D010126:Ozone / Q000032:analysis; D010463:Peracetic Acid / Q000031:analogs & derivatives* / Q000032:analysis*; D010507:Periodicity; D012423:Rural Health; D012606:Scotland; D012621:Seasons; D014919:Wind
D010083:Oxidants, Photochemical; D010126:Ozone; D010463:Peracetic Acid; C004185:peroxyacetyl nitrate