title: Precipitation chemistry and occurrence of acid rain over Dhanbad, coal city of India.
abstract: The present study investigated the chemical composition of wet atmospheric precipitation over Dhanbad, coal city of India. The precipitation samples were collected on event basis for three years (July 2003 to October 2005) at Central Mining Research Institute. The precipitation samples were analyzed for pH, conductivity, major anions (F, Cl, NO(3), SO(4)) and cations (Ca, Mg, Na, K, NH(4)). The pH value varied from 4.01 to 6.92 (avg. 5.37) indicating acidic to alkaline nature of rainwater. The pH of the rainwater was found well above the reference pH (5.6), showing alkalinity during the non-monsoon and early phase of monsoon, but during the late phase of monsoon, pH tendency was towards acidity (<5.6 pH) indicating the non-availability of proper neutralizer for acidic ions. The observed acidic events at this site were 91, (n = 162) accounting 56% for the entire monitoring months. The (NO(3) + Cl)/SO(4) ratio in majority of samples was found below 1.0, indicating that the acidity is greatly influenced by SO(4). The calculated ratio of (Ca + NH(4))/(NO(3) + SO(4)) ranges between 0.42-5.13 (average 1.14), however in most of the samples, the ratio is greater than unity (>1.0) indicating that Ca and NH(4) play an important role in neutralization of acidic ions in rainwater. Ca and SO(4) dominate the bulk ionic deposition and these two ions along with NH(4) accounts 63% of the annual ionic deposition.
authors.affiliation: Environmental Management Group, Central Mining Research Institute, Council of Scientific & Industrial Research, Dhanbad, India. singhak@yahoo.com
authors.forename: Abhay Kr
authors.initials: AK
authors.lastname: Singh
authors.forename: G C
authors.initials: GC
authors.lastname: Mondal
authors.forename: Suresh
authors.initials: S
authors.lastname: Kumar
authors.forename: K K
authors.initials: KK
authors.lastname: Singh
authors.forename: K P
authors.initials: KP
authors.lastname: Kamal
authors.forename: A
authors.initials: A
authors.lastname: Sinha
mesh_terms: D015258:Acid Rain / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis*; D000838:Anions / Q000032:analysis; D002412:Cations / Q000032:analysis; D011232:Chemical Precipitation; D002947:Cities; D003031:Coal / Q000032:analysis*; D004553:Electric Conductivity; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D007194:India
chemical_list: D015258:Acid Rain; D000393:Air Pollutants; D000838:Anions; D002412:Cations; D003031:Coal