Michael Kalina

Ten years trends (1984–1993) in the precipitation chemistry in central Austria

Abstract Since 1984, wet precipitation samples have been collected from five sampling sites in the eastern Alpine region of Austria. The chemical analysis performed included pH, NH4+, Na+, K+, Ca2+, Mg2+, Cl−, NO3− SO42− and precipitation amount. These data were used to determine the 10 years (1984–1993) trends in precipitation chemistry and deposition for all major ions. The statistical data treatment by the use of least-squares linear regression revealed a significant decrease of sulfate and hydrogen ion concentrations and depositions at all sites in consideration (above 65% for hydrogen ion and over 33% for sulfate concentration and 40% for hydrogen and 36% for sulfate deposition). An effort is made to explain the acidity decrease not only by the parallel decrease of sulfate concentration but by the participation of the other constituents of the wet precipitation events. It has been found that when the hydrogen ion concentration decrease is stronger than that of sulfate ion concentrations a compensation mainly by ammonium ion concentration increase is achieved. On the contrary, when the hydrogen ion concentration decrease is weaker than sulfate concentration decrease, a calcium ion concentration decrease is present for the sites in consideration. The results obtained indicate that the precipitation chemistry in Central Austria follows the global trends of controlled reduction of atmospheric acidity.

Scavenging ratios for sulfate, ammonium and nitrate determined at Mt. Sonnblick (3106 m a.s.l.)

Abstract For a time period of two years scavenging ratios were calculated for the high alpine site Mt. Sonnblick. Annual average values are 2.6×10 6 , 1.4×10 6 and 1.8×10 6 for total nitrate, sulfate and ammonium, respectively, when the scavenging ratios are calculated based on overall monthly averages. Two other calculation methods (based on ‘paired’ monthly averages and on single days) are discussed in the paper. Higher scavenging ratios are observed for the beginning of the cold season (October–January) than for the summer months (June–September) the respective ratios being in the range of 3 to 5. Precipitation sulfate was found to be formed predominately by particulate sulfate (89–96%) while reactive gas-phase scavenging of sulfur dioxide is only of minor importance (4–11%). Precipitation nitrate on the other hand is predominantly formed by gas-phase scavenging of nitric acid (88–96%) and particulate nitrate contributes to a lesser extent (4–12%). The first estimate for ammonium in precipitation indicates that particulate ammonium accounts for 49–79%, while ammonia forms the remaining 51–21%. An equation was derived to interrelate the scavenging ratio of sulfate to the scavenging efficiency of particulate sulfate into cloud droplets. The comparison showed very satisfactory agreement in respect to the absolute values as well as to the annual variations.

Altitude-dependent wet, dry and occult nitrogen deposition in an Alpine Region

From November 1995 to October 1996 and from October 1997 to September 1998, samples of wet precipitation, cloud water, as well as of reactive gases and particulate matter, were collected at three elevational levels (920 m, 1280 m and 1758 m a.s.l.) in Achenkirch, Austria. The samples were analysed for ammonium and nitrate in wet precipitation and in cloud water, for ammonia, nitric acid and nitrogen dioxide in the gas phase and for particulate ammonium and particulate nitrate in aerosol. Total nitrogen deposition was calculated combining measured concentrations in wet, dry and occult depositions with the corresponding deposition fluxes. Two multilayer deposition models were used for the calculation of dry and occult deposition. The total nitrogen input in 1995/96 was estimated to be 29 kg N ha−1a−1 at the Christlumkopf station (1758 m), 20 kg N ha−1a−1 at the Christlumalm station (1280 m) and 28 kg N ha−1a−1 at the Talboden station (930 m). Respective data for the 1997/98 observation period were 31 kg N ha−1a−1 at the Christlumkopf station (1758 m) and 18 kg N ha−1a−1 at the Mühleggerköpfl station (920 m). Critical Loads of nitrogen for coniferous forests were exceeded significantly near-source regions represented by areas of intense agricultural use and at high elevation sites.

Long-term assessment of the wet precipitation chemistry in Austria (1984-1999).

The aim of the present study was to determine the long-time trends in concentrations and depositions of major ions in wet precipitation samples collected at 11 sampling sites from the Austrian precipitation chemistry network in the period 1984-1999. The analytical results were treated by the use of least square linear regression method. It is shown that a serious decrease of sulfate (between 30% and 60% for the period) and hydrogen ion (between 60% and 102% for the period) concentrations and depositions is achieved at almost all sampling sites and in most of these cases the linear trend proves to be statistically significant. Nitrogen containing ions and base cations do not reveal a distinct trend of changing and in the majority of the sites the linear models are not adequate. In principle, an overall slight concentration and deposition decrease for these major ions is observed (up to 30% for the period of observation) but some substantial exceptions are also found (site Haunsberg or site Lobau). The changes in chloride concentration and deposition, too, do not indicate significant linear trend and, in general, are decreasing for the period of monitoring. In order to give some explanation of the exceptional behaviour of some of the major ions in several sites, an additional comparison with Austrian emission data (sulfur dioxide, nitrogen oxides, ammonium) and with data from five EMEP sites from neighbouring countries is performed. A significant West-East trend of acidity increase is found as well as a good correlation with the emission trends. Therefore, both transboundary and specific local factors could be substantial factors in the wet precipitation chemistry in the region.

Investigations of nitrogen fluxes and pools on a limestone site in the Alps

In the North Tyrolean Limestone Alps a site was investigated over a four-year period (1998–2001) in order to assess the nitrogen saturation status, the nitrogen budget (quantification of the net uptake of nitrogen by the canopy and of the nitrogen mineralization, nitrogen uptake from roots and N2O emission rates, proof of the origin of nitrate in the soil water with stable isotope analyses), and the effects of the actual nitrogen input on ground water quality. The main goals were to quantify the nitrogen input rate, the nitrogen pools in above-ground and below-ground compartments, nitrogen turnover processes in the soil as well as the output into the groundwater and into the atmosphere. The findings are based on continuous and discontinuous field measurements as well as on model results.While nitrogen input exceeded the Critical Loads of the WHO (1995), nitrogen deficiency and nutrient imbalances were verified by needle analyses. The atmospheric input of inorganic nitrogen was higher than the nitrogen output in 50 cm soil depth. A tracer experiment with15N helped to prove that not more than half of the applied nitrate could be discharged. This allows the conclusion that nitrogen is stored in the system and that the site cannot yet be said to be saturated with nitrogen. The same result was also obtained by modelling. In addition, it was proved that the nitrogen discharge did not stem from deposition but from processes within the system.

Time trends in the concentrations of lead in wet precipitation from rural and urban sites in Austria

Trend and time series analysis of concentrations of lead in wet precipitation at different rural and urban sampling sites in Austria, collected during intervals of 6-12 years (between 1984 and 1995) is performed. A substantial decrease of the lead concentrations for all sites in consideration is observed similar to observations in Germany, Sweden and North sea and western Atlantic regions. Reductions in rural sites between 60 and 80% in 10 years and around 90% in 10 years in urban areas are found. This trend correlates with the reduction of lead emissions from combustion of gasoline. The seasonal deconvolution model of the data set reveals a typical seasonality with lead concentration peaks in summer and spring for the rural sites and winter peaks for urban sites. The average annual lead concentration in the rural region for 1995 was 1.25 micrograms/l, in the urban region 2.25 micrograms/l.

Lead Concentration in Wet Deposition Results of a Ten Year Time Series in Saltzburg, Austria

Since 1984 wet precipitation is sampled in Salzburg, Austria, by a wet only technique on a daily basis to get information about the seasonal and temporal trends of ionic concentrations and wet deposition loads. Today 4 sampling sites are operated being part of the Austrian wet precipitation network. Annual volume weighted mean concentrations of lead in wet precipitation have decreased from 4.3 to 2.8 μg/l at Nussdorf (520 m a.s.l., 1984-1993), from 3.6 to 0.9 μg/l at Werfenweng (940 m a.s.l., 1984-1993), from 2.6 to 1.8 μg/l at Kolm Saigurn (1600 m a.s.l., 1990-1993) and from 5.0 to 1.9 μg/l at Sonnblick (3106 m a.s.l., 1988-1993). The decrease of the lead concentration in wet precipitation is well correlated with the reduction of lead emissions due to combustion of leaded gasoline. The correlation coefficients for the 4 sampling sites range from 0.69 to 0.87, respectively. The highest deposition loads for lead in Salzburg are found at the Sonnblick sampling site with values between 70 and 29 g/ha (1988-1993) caused by the memorable precipitation depth at the high elevated site. The decadal reduction of the wet deposition load of lead in Central Austria is in the order of 50-70%.