Chemical composition of rainwater and dustfall at Bhubaneswar in the east coast of India

Chemical composition of rainwater and dustfall was studied in two different stations of Bhubaneswar, located in the east coast of India. A wet-only and a bulk collector were placed at Regional Research Laboratory (RRL), a suburban area, during 1995–1997 and in the State Botanical Garden (SBG), a rural forest area, during 1997–1998. Of the rain events, 93% recorded alkaline pH (>5.6) at RRL while at SBG, 57% of the rain events were alkaline and the rest were acidic. Non-sea salt (nss) Ca2+ and NH3 were the primary neutralizing agents of rainwater acidity at both the locations. Low concentrations of alkaline constituents in the dustfall are an important finding in this study under Indian conditions. The Cl−/Na+ ratio in rainwater at RRL was same as the seawater ratio (1.167) which indicates that sea salt contribution is local to RRL. It may be of indirect marine origin and resuspended locally. Rainwater samples were enriched with nss SO42−, nss Ca2+ and nss Mg2+ at both the sites. Most of the nss SO42− and NO3− were of anthropogenic origin, while a part of those might be soil derived.