Ambient air quality at a coastal site in rural North-West England

Abstract

Air quality data obtained at a rural site in North-West England are presented. Concentrations of SO 2, NO 2, NO and O 3 were measured continuously, whilst 24h-average concentrations of NO 3 −, SO 4 2−, NH 4 +, Na +, K +, Ca 2+, Mg 2+ and Cl − were determined. Excluding pollutants from a nitric acid/ammonium nitrate fertiliser works within 2 km of the main measuring sites, the upper decile of hourly concentrations was for SO 2, 19 ppb; NO 2, 22 ppb and O 3, 52 ppb during the period May–September 1977. The upper decile of 24h concentrations was for SO 4 2−, 12 μg m −3; NO 3 2−, 4 μg m −3 and NH 4 +, 4 μ gm −3. The concentrations measured are typical of those reported for rural and semi-rural sites in Europe and North America. The results are interpreted in terms of local and synoptic scale meteorological influences, and it is concluded that the highest concentrations of the pollutants SO 2, NO 2, NO 3 −, SO 4 2− and NH 4 + are generally associated with regional transport of polluted air masses, rather than with more local sources. Predictably, Na +, Mg 2+ and Cl − have their source in marine aerosol, whilst K + and Ca 2+ are predominantly soil-derived. A study of total pollutant deposition showed values typical of rural sites in Britain.