PROCESSES AFFECTING CONCENTRATIONS OF AEROSOL STRONG ACIDITY AT SITES IN EASTERN ENGLAND

Concentrations of aerosol strong acidity and related species have been measured at sites in eastern England using a sampler in which ammonia is pre-separated by a denuder. High concentrations occurred at a coastal site and were associated with air advected over the North Sea. At inland sites, ammonia concentrations were higher and the aerosol was more substantially neutralized. Daytime concentrations of aerosol H+ exceeded those measured at night, despite higher daytime levels of ammonia, presumably due to more effective production of H2SO4 during daytime hours. Concentrations of acidic aerosols were within the range 0-178 neq m-3, well below those observed at many eastern North American sites with lower concentrations of ammonia.