LONG-TERM RECORD OF AMMONIA AND AMMONIUM CONCENTRATIONS AT K-PUSZTA, HUNGARY

Air concentrations of gaseous ammonia (NH3) and aerosol ammonium (NH4) have been measured daily at K-puszta, Hungary, since 1981. The measu rements provide a unique time series of NH3 concentrations at a Europe an site, which together with the NH4+ concentrations allow an examinat ion of the long-term trends in these pollutants. The results are parti cularly relevant to examine the effect of expected reductions in ammon ia emissions on air concentrations. Between 1983 and 1393 reductions i n animal numbers and fertilizer use (particularly since 1989) have pro vided an estimated 50% reduction in NH3 emission for the country. An a nalysis of the air concentration data reveals strong daily, seasonal a nd inter-annual variation, but no discernible decrease in annual air c oncentrations for either NH3 or NH4+, or precipitation NH4+ also measu red at the site. The lack of reduction in concentrations may be due to changes in the emissions from other local sources or atmospheric chem istry and long-range transport, but probably also reflects the strong inter-annual variation. The results show that short term (<5 yr) relat ionships between livestock NH3 emission reductions and air concentrati ons at individual sites should not be expected, and that longer-term m easurements at many sites may be necessary to detect any trends. (C) 1 998 Elsevier Science Ltd. All rights reserved.