干旱区生态环境知识资源中心

Dew samples were collected between October 2007 and February 2008 from a suburban site in Agra. pH, conductivity, major inorganic ions (F-, Cl-, NO (3) (-) , SO (4) (2-) , Na+, K+, Ca2+, Mg2+, and NH (4) (+) ), and some trace metals (Cr, Sn, Zn, Pb, Cd, Ni, Mn, Fe, Si, Al, V, and Cu) were determined to study the chemistry of dew water. The mean pH was 7.3, and the samples exhibited high ionic concentrations. Dew chemistry suggested both natural and anthropogenic influences, with acidity being neutralized by atmospheric ammonia and soil constituents. Ion deposition flux varied from 0.25 to 3.0 neq m(-2) s(-1), with maximum values for Ca2+ followed by NH (4) (+) , Mg2+, SO (4) (2-) , Cl-, NO (3) (-) , Na+, K+, and F-. Concentrations of trace metals varied from 0.13 to 48 mu g l(-1) with maximum concentrations of Si and minimum concentration of Cd. Correlation analysis suggested their contributions from both crustal and anthropogenic sources.