Origin of calcium in marine aerosol over the arabian sea near the west Coast of India

We report the influence of soil dust on marine aerosols inferred from the analysis of aerosol samples collected on board research vessel ‘Gaveshani’ for a period of 11 days during May 1983 over the sea areas around the Indian subcontinent. The number distribution curve over the Arabian Sea was disturbed due to the presence of soil particles in the large size aerosols (r ⩾ 1 μm) as compared to that over the Bay of Bengal. The atmospheric concentration of non sea-salt calcium was positively correlated with the concentration of Fe. The Ca/Na ratios varied widely from the Arabian Sea to the Bay of Bengal with respect to ratio in sea-water. All the excess calcium in the marine aerosols is found to originate from the soil particles of the Arabian Desert and is transported towards the west coast of Indi

Spread of acid rain over India

Rain water and aerosol samples were collected at a few locations representative of urban and non-urban regions in India. Also, rain water samples were collected in and around a coal-fired power plant. All the rain water and aerosol samples were analyzed for major chemical components along with pH. The rain water at all the places of measurement, except near the industrial sources, has been found to be alkaline and was characterized by the presence of excess cations, particularly by Ca2+. The acid rain near the industrial sources was associated with excess anions, especially SO2- 4. The atmospheric aerosols at all the places of measurement were found rich with basic components, suggesting that the alkaline soil dust and fly ash are responsible at present for preventing the spread of acid rain in India. Rain water and aerosol samples were collected at a few locations representative of urban and non-urban regions in India. Also, rain water samples were collected in and around a coal-fired power plant. All the rain water and aerosol samples were analyzed for major chemical components along with pH. The rain water at all the places of measurement, except near the industrial sources, has been found to be alkaline and was characterized by the presence of excess cations, particularly by Ca2+. The acid rain near the industrial sources was associated with excess anions, especially SO4 2-. The atmospheric aerosols at all the places of measurement were found rich with basic components, suggesting that the alkaline soil dust and fly ash are responsible at present for preventing the spread of acid rain in India

Impact of alkaline particulates on pH of rain water in India

Rain water samples were collected over a period of a decade from 1974 in Pune, a city which is relatively free from industrial pollution. They were also collected at 4 places during 1974 in the region of Bombay which is highly industrialized. The samples were analyzed for major chemical components and pH. The ionic balance was computed. Samples were collected at Delhi during 1965 and 1966 and were analyzed for pH. The values were compared with those reported for 1978. The total suspended particulates (TSP) were measured at Delhi during 1980 and analyzed for water soluble components. The rain water at all the places except near the industrial source was not acidic and was characterized by the presence of excess cations, particularly Ca. The acid rain near the industrial source was associated with excess anions, especially sulphate. The difference between the cations and anions was inversely proportional to the H+ ion concentration. The pH of rain water at Delhi which was in the alkaline range during 1965 and 1966 remained alkaline even after a period of 12 yr when the city developed industrially. The TSP in the region was rich with the basic components, mainly Ca, suggesting that the alkaline property of the soil dust is mainly responsible for neutralizing the acidic effects resulting from the anthropogenic gaseous pollutants

Trace elements and sea salt aerosols over the sea areas around the Indian sub-continent

The nature and the characteristics of trace elements and sea salt aerosols in the ocean atmosphere around the Indian sub-continent was studied. For this purpose, concentrations of the total suspended particulates (TSP) as well as of its various chemical components together with their mass size distributions were measured on 11 days in May 1983. Over the sea regions around the sub-continent, sampling was done on board the research Vessel Gaveshani using a high volume air sampler and a multistage Andersen sampler. The concentrations of soil-origin elements (Al, Fe, Mn and Ca) were found to be at a maximum over the Arabian sea region suggesting the presence of dust particulates, transported from the Arabian peninsula. The near sea water ratio of CI/ Na was observed in giant size (> 2.5 μm dia) sea salt aerosols suggested that there was very little fractionation in these aerosols. The ratio value considerably decreased in the case of sub-μm sea salt particles. The chemical components originating from soil and from sea salt showed a unimodal distribution whereas those from anthropogenic sources showed a bimodal distribution

Long-term effects of pollutants on pH of rain water in North India

The ionic composition and pH of rainwater samples collected during the summer monsoon seasons of 1963 and 1965 at Agra and Delhi, respectively have been compared with those collected during the summer monsoon seasons of 1984 at both these cities. The pH values at Agra and Delhi have been found to have decreased by 2.8 (9.1-6.3) and 0.9 (7.0-6.1) units, respectively after the period of two decades during which the cities developed industrially to a great extent. The main cause for the decrease in the pH values is a significant increase of acidic components and decrease of soil-oriented components in the rain water. For the first time in India, long-term effects of pollutants on the pH of rain water have been observed but the effects are comparatively slow compared with those in western countries. The ionic composition and pH of rainwater samples collected during the summer monsoon seasons of 1963 and 1965 at Agra and Delhi, respectively have been compared with those collected during the summer monsoon seasons of 1984 at both these cities. The pH values at Agra and Delhi have been found to have decreased by 2.8 (9.1-6.3) and 0.9 (7.0-6.1) units, respectively after the period of two decades during which the cities developed industrially to a great extent. The main cause for the decrease in the pH values is a significant increase of acidic components and decrease of soil oriented components in the rain water. For the first time in India, long-term effects of pollutants on the pH of rain water have been observed but the effects are comparatively slow compared with those in western countries