Chemical composition (precipitation quality) and atmospheric deposition have been monitored in the long term at relatively large number of stations in the Czech Republic. In 2007 the Air Quality Information System (ISKO/AQIS) database obtained data on precipitation quality from 54 localities in total (16 ČGS, 15 CHMI, 14 VÚLHM, 3 VÚV TGM and 6 HBÚ AV ČR, see Fig. III.1). Further, data from 6 Polish and 5 German boundary areas were submitted. Most of the CHMI stations measure wet-only samples in weekly interval (monthly interval was switched over to weekly interval in 1996 in line with the EMEP methodology). In 1997 the weekly precipitation sampling, �bulk� type, (with non-specified contains of dustfall) for heavy metals analysis was introduced at these stations. In the localities of other organizations monthly sampling (or irregular sampling) is used for measuring concentrations in precipitation (�bulk�type) in the open area (or throughfall). The detailed information on individual localities and sampling types is presented in Table III.4.
Tables III.5 and III.6 contain average values of the chemical composition of atmospheric precipitation and the values of the 2007 annual wet deposition.
Wet deposition charts were compiled for selected ions on the basis of all-round chemical analyses of wet only precipitation samples, specifically for SO₄^2- - S, NO₃^-- N, NG₄⁺- N, H⁺ (pH), F^- and Cl ^-, and the maps of wet deposition with an undefineable amount of dry deposition (�bulk� sampling) for Pb, Cd and Ni were also created.
The above ions were selected to represent deposition fields with regard to their considerable impact on the various spheres of the environment. Wet deposition charts for each of the ions were derived from the field of ion concentrations in precipitation (based on annual mean concentrations weighted by precipitation totals calculated from the data observed), and from the field of annual precipitation totals which was generated on data from 750 precipitation gauging stations, taking into account the altitude�s effect on precipitation amount. When constructing wet deposition fields, results of wet-only samples analysis are preferred to �bulk� samples with dustfall, and weekly samples are preferred to monthly samples. Data from the network stations operated by ČGS, VÚV TGM and VÚLHM based on monthly �bulk� sampling with dustfall (see Table III.4) are modified by empirical coefficients expressing the individual ions� ratios in �wet-only� and �bulk� samples (values for each of the ions from 0.74 for NH₄⁺ to 1.06 for H⁺) for the purpose of the development of the wet deposition charts. The fact that in case of H+ cations the ratio is higher than 1, can be explained in the following way: the solid particles contained in the �bulk� type samples react with hydrogen cations, which results in their decreasing concentration [31].
In addition to wet deposition, also dry and total deposition charts are included for sulphur, nitrogen and hydrogen ions. Dry sulphur and nitrogen deposition was calculated using fields of annual mean SO₂ and NO_x concentrations for the Czech Republic, and the deposition rates found in [21] for SO₂ 0.7 cm.s^-1/0.35 cm.s^-1, and NO_x 0.4 cm.s^-1 / 0.1 cm.s^-1, in case of forested/unforested area. Total deposition charts were produced by adding S and N wet and dry deposition charts. The wet hydrogen ion deposition chart was compiled on the base of pH values measured in precipitation. Dry hydrogen ion deposition reflects SO₂ and NO_x deposition based on stechiometry, assuming their acid reaction in the environment. The total hydrogen ion deposition chart was developed by summation of wet and dry deposition charts.
The average deposition fluxes of S, N and H are presented in the table III.1.

Tab. III.1 Average deposition fluxes of S, N and H in the Czech Republic, 2007

Throughfall sulphur deposition chart was generated for forested areas from the field of sulphur concentrations in throughfall and a verified field of precipitation, which was modified by a percentage of precipitation amounts measured under canopy at each station (47–114 % of precipitation totals for the year 2007). In 2007 the map was created with the use of a new, more detailed layer of forests, with the total area amounting to 22 000 km². Throughfall deposition generally includes wet vertical and horizontal deposition (from fogs, low clouds and rime) and dry deposition of particles and gases in forests. In case of sulphur, its circulation within the forests is negligible; it should provide a good estimate of total deposition.
The maps of heavy metals wet deposition (with an undefineable amount of dry deposition) for Pb, Cd and Ni were derived from concentrations of these metals in �bulk� precipitation samples with dustfall at individual stations. The fields of dry deposition of Pb and Cd contained in SPM (dry Pb and Cd deposition) were derived from the fields of these metals� concentrations in the ambient air (or on the basis of air pollution field of annual average of PM₁₀ concentrations and values of IDW interpolation of the shares of the respective metal in dust). The deposition rate of Cd contained in SPM was taken as 0.27 cm.s^-1 for a forest and 0.1 cm.s^-1 for unforested terrain; the figures for Pb are 0.25 cm.s^-1 for a forest and 0.08 cm.s^-1 for unforested terrain [21].
The data on precipitation quality are controlled routinely using the method of ion balance calculation (the difference between the sum of cations and the sum of anions in the sample should meet the allowable criteria which differ slightly in various organizations).
Another control is carried out by comparing the calculated conductivity and the measured conductivity which both should also meet the allowable criteria.
Analysis of the blank laboratory samples is also used and blank field samples are monitored and assessed continuously. This enables the control of work during sampling and the control of changes occurring due to transport, manipulation, storage and preparation of the samples prior to the chemical analysis.

Results

• The precipitation in the year 2007 for the territory of the Czech Republic was above the long-term normal; it amounted to 755 mm in the average, which represents 112 % of the long-term normal (for the years 1961–1990). As compared with the year 2006 the total precipitation was slightly higher (by 47 mm).
• Wet sulphur deposition decreased after 1997 below 50,000 t and this trend continued up to 1999. Since 2000 the profound decrease had not continued and the values remain more or less at the level of 1999 with the exception of lower depositions in 2003, where the precipitation total was markedly subnormal. The highest values of sulphur wet deposition were recorded in the Jizerské hory Mts. and in the Krkonoše Mts.
  Dry sulphur deposition the most significant decline of which was recorded in the year 1998 (the value decreased by 45 % in comparison with the average value for the period 1995–1997), continued to decline in 1999–2000. In 2000–2006 the deposition field remained at the same level, which is coherent with SO₂ concentrations in the ground-level ambient air. In 2007 the dry sulphur deposition recorded a marked decrease, resulting from the reduction of air pollution concentrations due to more favourable meteorological and dispersion conditions. The field of total sulphur deposition is the sum of wet and dry depositions and it shows the total sulphur deposition amounting to 52,043 t for the Czech Republic's territory for the year 2007 (see Table III.2). The decrease of the total deposition was caused by the decrease of dry sulphur deposition. After the previous decrease from the values markedly above 100,000 t, in 2000–2006 the sulphur deposition remained within the range from 65,000 to 75,000 t per year with the exception of the year 2003 which was markedly below normal as for the precipitation (see Fig. III.21). The value of total deposition in 2007 almost reached the value of the year 2003. The total sulphur deposition reached the maximum values in the Krušné hory Mts. area.
• The throughfall sulphur deposition field reached the maximum values in the Krušné hory Mts. and in the Orlické hory Mts. In some parts of the mountains in the Czech Republic the values of throughfall deposition reach, in the long-term, higher values than the values of the total sulphur deposition determined as the sum of wet (only vertical) and dry deposition from SO₂. The increased contribution can be attributed to deposition from fog, low clouds and rime (horizontal deposition) which is not included in total summary deposition because of uncertainties. Hoarfrost and fog are normally highly concentrated and may significantly contribute to sulphur and other elements� deposition in mountainous areas and areas with frequent fogs (valley fogs, fogs near water courses and lakes). The problem is in a very erratic character of this type of deposition from place to place where some uncertainties may occur when extrapolating to a wider area. For sulphates, the deposition from fogs and rime in the mountain areas is stated in the range 50–90 % of the �bulk� type deposition in the average for a longer period (several years) [32, 33]. In some individually assessed years the relation of the sulphates deposition from fog and rime and �bulk� type deposition exceeded even 100 %.
  Further, the throughfall deposition includes also the contribution from dry deposition of S from SO₄^2- of suspended particles. Based on the data on sulphates concentration in aerosol for the year 2007 from two stations (Prague 4-Libuš, Svratouch) and on the application of the deposition rate 0.25 cm.s^-1 [21] dry deposition of S from SO₄^2- reached the average value of 0.1 g.m^-2.year^-1 for forest areas. Due to the fact that sulphates concentration in aerosol was available only from two localities in 2007, this is a very rough estimate. Nevertheles, it is apparent that with regard to the values of throughfall deposition or total deposition of S the contribution of S from SO₄^2- in suspended particles is negligible.
  The map of throughfall deposition can be regarded as an illustration what values the total sulphur deposition (including the horizontal deposition and dry deposition of S from SO₄^2-.of suspended particles) can reach, because in sulphur, unlike other pollutants, the inner circulation in vegetation is negligible. In 2007 the new, more detailed layer of forests achieving 22,000 km² was used for the calculation of throughfall deposition. Therefore, also total values of througfall deposition since 2001 were recalculated with the use of the new layer of forests, in order to carry out the comparison with the year 2007 (see Table III.3). Throughfall sulphur deposition on the forested surface of the Czech Republic reached the amount of 23,662 t in 2007.
• The map of wet deposition of nitrates and ammonia ions shows the highest values in the territory of the Krkonoše Mts. (locality Hříběcí). Higher values of wet deposition of nitrates, connected mainly with higher total precipitation, were recorded in the mountainous areas, and namely in the Jizerské hory Mts., in the Krušné hory Mts., in the Orlické hory Mts., in the Hrubý Jeseník Mts. and in the Šumava Mts. Higher values of wet deposition of ammonia ions were recorded in the the Krušné hory Mts., in the Orlické hory Mts., in the Hrubý Jeseník Mts., in the Šumava Mts., in the Český les Mts. and in the Moravskoslezské Beskydy Mts. The total wet deposition of the oxidized forms of nitrogen in the territory of the Czech Republic decreased, as compared to the previous years, mainly due to the decrease of dry NOx deposition caused by more favourable meteorological and dispersion conditions (see Fig. III.21). Dry deposition of oxidized forms of nitrogen was declining up to the year 2002 (when the value reached 48 % of the value of the average for the years 1995–1997). Afterwards, a certain stagnation was recorded, the value of deposition for the Czech Republic ranged between 14,105 t and 20,622 t. The lowest value (14,205 t) was reached in the year 2007.
  In 2007 the total nitrogen deposition reached 70,611 t of N (ox+red). year^-1 for the area of the Czech Republic (see Table III.2), which represents a significant decrease in comparison with the previous years. The highest values of total nitrogen deposition were reached in the Krkonoše Mts. (locality Hříběcí) and in the Lužické hory Mts., the Orlické hory Mts., the Krušné hory Mts. and in the Hrubý Jeseník Mts.
• The wet deposition of hydrogen ions reached the maximum values in the Krkonoše Mts. (localities Hříběcí and Modrý potok), the Jizerské hory Mts., the Krušné hory Mts. and the Šumava Mts. The map of dry deposition of hydrogen ions shows the decrease of its values. In the second half of the 90�s of the last century both wet and dry depositions of hydrogen ions decreased by 50 % per the whole area of the Czech Republic, the decrease of dry deposition of hydrogen ions values was in coherence with the decrease of dry deposition of SO₂–S and NO_x–N. Fig. III. 21 shows an apparent decrease of dry deposition of hydrogen ions in 2007 in coherence with the decrease of SO₂ and NO_x deposition.
• After the year 2000 when the distribution of leaded petrol was finished the values of wet deposition of lead ions markedly decreased. The field of wet deposition for the year 2007 is in the majority of the territory of the Czech Republic similar as in the years 2004 and 2005. The maximum deposition was recorded in the territory of the Jizerské hory Mts. More significant increase of deposition above 10 mg.m^-2.year^-1 in 2006 in the Jizerské hory Mrs., the Orlické hory Mts. and the Žďárské vrchy Mts. was not confirmed. The map of dry lead deposition is similar as in the previous years.
• The wet deposition of cadmium in 2007 did not reach such marked increase in the area of the Jizerské hory Mts. as in the previous years. The values decreased below 0.25 mg.m^-2.year^-1. A slight decrease (below 0.5 mg.m^-2.year^-1) was recorded already in 2006. On the contrary, the values of dry deposition of cadmium ions were higher as compared with the remaining part of the Czech Republic, similarly as in the previous years, in the Liberec Region, which was caused by local pollution. Long-term increased cadmium concentrations in the ambient air are also measured in this area. Significant emission source from the glassworks is one of the probable reasons of this situation.
• The 2007 map of wet annual deposition of nickel ions did not confirm the increase of deposition from the year 2006 in the area of the Jizerské hory Mts. and the Krkonoše Mts. The maximum values (1.5–2 mg.m^-2.year^-1) were reached in the locality Hradec Králové-observatoř and in the Krkonoše Mts., near the locality Hříběcí.
• The highest values of the deposition of fluoride ions were recorded in the Jizerské hory Mts. The maximum levels of wet deposition of chloride ions were recorded in the Krkonoše Mts. and in the Jizerské hory Mts.
  The development of annual wet deposition of the main elements as measured at selected stations in the Czech Republic (Fig. III.23) shows stagnation instead. The decrease of sulphate deposition was substantial not only at the exposed stations as Ústí n.L., Prague-Libuš or Hradec Králové but it was also obvious at the background stations Košetice and Svratouch. The decrease was substantial at the station Ústí n.L. where the wet sulphate deposition decreased by 60 % after 1995 and where the decrease of other substances (NO₃^-, NH₄⁺, Pb₂⁺) was also obvious.
  With the development of sulphur and nitrogen deposition the development of the proportion of both elements can be observed in atmospheric precipitation connected with the development of emissions of individual pollutants. Since the second half of the 90�s a slight increase of nitrates and sulphates proportion has been observed. The development of this proportion over the recent 10 years for the CHMI stations is shown in Fig. III.22.

Tab. III.1 Average deposition fluxes of S, N and H in the Czech Republic, 2007

Tab. III.2 Estimate of the total annual deposition of the given elements in the Czech Republic (78,841 sq. km) in tonnes, 2007

Tab. III.3 Estimate of the total annual deposition of sulphur on the forested part of the Czech Republic (22,000 sq. km) in tonnes, 2001–2007

Tab. III.4 Station networks of precipitation and atmospheric deposition, 2007

Tab. III.5 Mean annual concentrations of ions in atmospheric precipitation at stations in the Czech Republic, 2007

Tab. III.6 Annual wet atmospheric deposition at stations in the Czech Republic, 2007

Fig. III.1 Station networks monitoring atmospheric precipitation quality and atmospheric deposition, 2007

Fig. III.2 Fields of annual wet deposition of sulphur (SO₄^2- - S), 2007

Fig. III.3 Fields of annual dry deposition of sulphur (SO₂ - S), 2007

Fig. III.4 Fields of annual total deposition of sulphur, 2007

Fig. III.5 Fields of annual throughfall deposition of sulphur, 2007

Fig. III.6 Fields of annual wet deposition of nitrogen (NO₃^- - N), 2007

Fig. III.7 Fields of annual wet deposition of nitrogen (NH₄⁺ - N), 2007

Fig. III.8 Fields of annual total wet deposition of nitrogen, 2007

Fig. III.9 Fields of annual dry deposition of nitrogen (NO_x - N), 2007

Fig. III.10 Fields of annual total deposition of nitrogen, 2007

Fig. III.11 Fields of annual wet deposition of hydrogen ions, 2007

Fig. III.12 Fields of annual dry deposition of hydrogen ions corresponding to SO₂ and NO_x deposition, 2007

Fig. III.13 Fields of annual total deposition of hydrogen ions, 2007

Fig. III.14 Fields of annual wet deposition of fluoride ions, 2007

Fig. III.15 Fields of annual wet deposition of chloride ions, 2007

Fig. III.16 Fields of annual wet deposition of lead ions, 2007

Fig. III.17 Fields of annual dry deposition of lead, 2007

Fig. III.18 Fields of annual wet deposition of cadmium ions, 2007

Fig. III.19 Fields of annual dry deposition of cadmium, 2007

Fig. III.20 Fields of annual wet deposition of nickel ions, 2007

Fig. III.21 Annual deposition of sulphur (SO₄²–S, SO₂–S) and oxidated forms of nitrogen (NO₃^-–N, NO_x–N) and hydrogen in the Czech Republic, 1995–2007
Fig. III.22 The development of the ratio of nitrate/sulphate concentrations in atmospheric deposition (expressed as μeq.^-l ) at the CHMI stations, 1998–2007

Fig. III.23 Annual wet deposition at selected stations between 1991 and 2007, the Czech Republic