Sulphate Aerosol at Delhi in Relation to the Associated Chloride Component

Abstract

Using the Millipore filter technique, measurements have been made of the concentration of sulphate aerosols in ground air layers at Delhi during 1962-63. The aerosol content, on the average, is found to be high during winter (5.52 ?gm m?3) and low during summer (2.76 ?gm m?3) and the monsoon season (3.0 ?gm m?3). In contrast to chloride aerosol, the sulphate concentration is about twice as large in winter but only about half as large in the other periods. It also undergoes a wider range of variation in its day-to-day content than does chloride during winter, but during the monsoon the trend is just the opposite. The pattern of variation of the sulphate aerosol content is not closely associated with that of the chloride. Details of particle distributions also appear to be unrelated to details of concurrent weather.