TRACE-ELEMENT AND MAJOR ION COMPOSITION OF WET AND DRY DEPOSITION IN ANKARA, TURKEY

Daily, wet-only precipitation samples collected over a two year period were analyzed for SO42-, NO3-, Cl-, NH4+, H+, Ca, Mg, K, Na, Al, Cu, Cd, Cr, Zn, V and Ni. Weekly dry-deposition samples collected on petri -dishes over the same period were analyzed only for major ions. Concen trations of ions and elements in Ankara precipitation are comparable w ith concentrations reported in literature for other urban areas. Howev er, the wet deposition fluxes are the lowest among literature values, owing to small annual precipitation in the region. Although, annual av erage pH in precipitation is 4.7, episodic rain events with fairly low pH's were observed. Approximately half of the acidity in Ankara preci pitation is neutralized in the winter season, while the acidity is com pletely neutralized by airborne soil particles that are rich in CaCO3 in the summer precipitation. The SO42- and NO3- contributes approximat ely equally on the free acidity in winter. Main forms of SO42- and NO3 - in precipitation are CaSO4 and Ca(NO3)(2), respectively. Crustal ele ments and ions have higher concentrations during summer season, while anthropogenic ions and elements did not show well-defined seasonal cyc les. The lack of industrial activity in Ankara has profound influence on the temporal behavior of elements and ions. (C) 1997 Elsevier Scien ce Ltd.