Local Patterns of Sulphur Deposition Around Halifax/Dartmouth, Nova Scotia: 1979–83

Abstract

Five years of sampling support earlier findings that SO₂ emissions from Halifax/Dartmouth, Nova Scotia (population 270,000) cause wet sulphate deposition within 40 or 50 km of the city to be twice regional values. The urban effect is greatest within the city itself. Mean monthly sulphate concentrations in precipitation are usually more highly correlated among stations than is monthly deposition; the highest correlations are among concentrations in and around the city. Month to month variations in sulphate concentration in the city and at Oyster Pond (50 km east of the city) appear to be affected mainly by urban influences; those at St. Margaret’s Bay (25 km west of the city) appear to be affected by both urban and regional influences. The urban effect appears to have diminished somewhat during the 5 yr, possibly because the urban emissions have decreased by 35% since 1980.