Long-term record of ammonia and ammonium concentrations at K-puszta, Hungary

Air concentrations of gaseous ammonia (NH3) and aerosol ammonium (NH+4) have been measured daily at K-puszta, Hungary, since 1981. The measurements provide a unique time series of NH3 concentrations at a European site, which together with the NH+4 concentrations allow an examination of the long-term trends in these pollutants. The results are particularly relevant to examine the effect of expected reductions in ammonia emissions on air concentrations. Between 1983 and 1993 reductions in animal numbers and fertilizer use (particularly since 1989) have provided an estimated 50% reduction in NH3 emission for the country. An analysis of the air concentration data reveals strong daily, seasonal and inter-annual variation, but no discernible decrease in annual air concentrations for either NH3 or NH+4, or precipitation NH+4 also measured at the site. The lack of reduction in concentrations may be due to changes in the emissions from other local sources or atmospheric chemistry and long-range transport, but probably also reflects the strong inter-annual variation. The results show that short term (<5 yr) relationships between livestock NH3 emission reductions and air concentrations at individual sites should not be expected, and that longer-term measurements at many sites may be necessary to detect any trends.