Chemical composition of the inorganic fraction of cloud-water at a high altitude site in West India
2014 (English)In: Atmospheric Environment, ISSN 1352-2310, Vol. 88, 59-65 p.Article in journal (Refereed) Published
Data from a ground-based cloud-water collection system intercepting water from clouds at a mountain field station, Sinhagad near Pune in India are presented. This study was part of an Indo-Swedish Collaboration Project on Atmospheric Brown Cloud-Asia (ABC-A). Cloud-water and rainwater (wet-only) samples were collected during June 2007-Dec. 2010. Concentrations of major anions and cations were determined. Ion concentrations were generally higher (NO3-, about 8 times; SO42- and K+, 5 times; NH4+ times and Cl-, Na+, Ca2+, Mg2+ 3 times) in cloud-water samples than in rainwater samples collected during the same days. The average pH of cloud-water samples was 6.0 with about 20% of the values below 5.6 and only 4% less than 5.0. Despite high concentrations of SO42- and NO3- the cloud water samples were on average not more acidic than rainwater samples. This is different from most of the other studies of cloud-water composition which have noted a substantially higher acidity (i.e. lower pH) in cloud-water than in rainwater. The slightly alkaline (pH > 5.6) nature of the cloud-water samples is mainly due to the presence of soil derived calcium carbonate in quantities more than enough to neutralize the acids or their precursors. A separation of the cloud-water data into trajectory groups showed that samples in air-masses having spent the last few days over the Indian sub-continent were in general more acidic (due to anthropogenic emissions) than those collected during days with air-masses of marine origin. A high correlation mutually between Ca2+, Na+, NO3- and SO42- makes it difficult to estimate the contribution to SO42- from different sources. Anthropogenic SO2- emissions and soil dust may both give important contributions.
Place, publisher, year, edition, pages
2014. Vol. 88, 59-65 p.
rainwater, inorganic ions, acidic deposition, pH
Meteorology and Atmospheric Sciences
Research subject Atmospheric Sciences
IdentifiersURN: urn:nbn:se:su:diva-101085DOI: 10.1016/j.atmosenv.2014.01.039ISI: 000335104300007OAI: oai:DiVA.org:su-101085DiVA: diva2:698838
FunderSida - Swedish International Development Cooperation Agency