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 2008 the Air Quality Information System (ISKO/AQIS) database
obtained data on precipitation quality from 54 localities in total (16 ÄŚGS, 15
CHMI, 14 VĂšLHM, 3 VĂšV TGM and 6 HBĂš AV ÄŚR, 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 content 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 2008 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 SO42-- S, NO3--
N, NH4+- 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 ÄŚGS, VĂšV and
VĂšLHM 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 NOx concentrations for the Czech Republic, and the deposition rates for
SO2 0.7 cm.s-1/0.35 cm.s-1, and NOx 0.4 cm.s-1/0.1 cm.s-1, for the
forested/unforested areas [21].
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 NOx 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.
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 (49–115 % of precipitation totals for the
year 2008). 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 2008 for the territory of the Czech Republic was
below the long-term normal; it amounted to 619 mm in the average, which
represents 92 % of the long-term normal (for the years 1961–1990). As compared
with the year 2007 the total precipitation was slightly lower, which corresponds
with a slight decrease of wet deposition of all monitored ions.
-
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 connection with
higher precipitation totals, in the mountainous areas (the Jizerské hory Mts.,
the Krkonoše Mts., HrubĂ˝ JesenĂk Mts. and MoravskoslezskĂ© Beskydy 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 further decreased, which resulted from the reduction of air pollution
concentrations due to more favourable meteorological and dispersion conditions.
In 2008 the levels of dry deposition were comparable with the previous year. The
field of total sulphur deposition represents the sum of wet and dry depositions
and it shows the total sulphur deposition amounting to 46,325 t for the Czech
Republic’s territory for the year 2008 (see Table III.2). The decrease of the
total deposition was caused by the decrease of dry sulphur deposition, due to
lower air pollution SO2 concentrations as well as by the decrease of wet
deposition due to lower annual total precipitation. 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. In 2008 there was recorded the lowest total sulphur deposition as
compared with the previous years. The total sulphur deposition reached the
maximum values in the Krušné hory Mts. area.
-
The throughfall sulphur deposition field, similarly as in the previous year,
reached the maximum values in the Orlické hory Mts. and the Krušné 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 SO42- of suspended particles. Based on the data on
sulphates concentration in aerosol for the year 2008 from three stations (Prague
4-Libuš, Svratouch and Košetice) and on the application of the deposition rate
0.25 cm.s-1 [21] dry deposition of S from SO42- reached the average value
0.18
g.m-2.year-1 for forest areas. Due to the limited number of localities
monitoring the sulphates concentrations in aerosol, this is a very rough
estimate.
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 SO42- of suspended particles) can reach, because in
sulphur, unlike other pollutants, the inner circulation in vegetation is
negligible.
In 2008 the layer from the geodatabase ZABAGED of the Czech Office for
Surveying, Mapping and Cadastre –ČÚZK (a finer grid 500x500 m) with the total
forests area achieving 26,428 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 2008 (see Table III.3). Throughfall sulphur
deposition on the forested surface of the Czech Republic reached the amount of
30,197 t in 2008, i.e. there was a slight increase as compared with the previous
three years. The fact that the total wet and dry deposition of S decreased as
compared with the previous year suggests the increased influence of horizontal
deposition in 2008.
-
The map of wet deposition of nitrates and ammonia ions shows, similarly as in
the previous year, the highest values in the territory of the Krkonoše Mts.
(again the locality HĹ™ĂbÄ›cĂ) and in the HrubĂ˝ JesenĂk Mts. The increased values
of total wet nitrogen deposition were recorded mainly as a result of the
influence of higher deposition of ammonia ions also in the area of Orlické hory
Mts. The total wet deposition of the oxidized forms of nitrogen in the territory
of the Czech Republic is comparable with the previous year (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.
In 2008 the total nitrogen deposition reached 69,180 t of N (ox+red).year-1 for
the area of the Czech Republic (see Table III.2), which is comparable with the
year 2007. The highest values of total nitrogen deposition were reached in the
Krkonoše Mts. (locality HĹ™ĂbÄ›cĂ) and in the JizerskĂ© hory Mts., KrušnĂ© hory
Mts., HrubĂ˝ JesenĂk Mts. and OrlickĂ© hory Mts.
-
The wet deposition of hydrogen ions reached, similarly as in the previous
years, the maximum values in the Krkonoše Mts. (localities Modrý potok and
HĹ™ĂbÄ›cĂ). The map of dry deposition of hydrogen ions shows the similar character
as in the previous year when a slight decrease of values was recorded. The
maximum values were reached in the Krušné hory Mts. 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 NOx–N. Fig. III.21 shows again a slight decrease of total deposition
of hydrogen ions in 2008, this time as a result of decrease of wet deposition of
H+.
-
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 2008 is in the majority of the territory of the Czech
Republic similar as in the previous years with the exception of the year 2006
which recorded more significant increase of deposition above 10 mg.m-2.year-1 in
2006 in the Jizerské hory Mts., the Orlické hory Mts. and the Žďárské vrchy Mts.
The map of dry lead deposition is similar as in the previous years.
-
The wet deposition of cadmium in 2008 was comparable with the previous year.
The map shows a slight increase of the areas with the lowest deposition (below
0.05 mg.m-2.year-1) connected with lower precipitation total. 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. Slightly
higher values of dry cadmium deposition were recorded also in Ostrava.
-
The 2008 map of wet annual deposition of nickel ions confirmed the increase of
deposition recorded already in the year 2006 in the area of the Jizerské hory
Mts. and the Krkonoše Mts. The maximum values (3–4 mg.m-2.year-1) were reached
in the locality ModrĂ˝ potok and UhlĂĹ™ská.
-
The highest values of the deposition of fluoride ions were recorded in the
Krkonoše Mts. The maximum levels of wet deposition of chloride ions were
recorded also in the Krkonoše Mts. and further in the Jizerské hory Mts., Hrubý
JesenĂk Mts. and the MoravskoslezskĂ© Beskydy Mts.
The development of annual wet deposition of the main elements as measured at
selected stations in the Czech Republic (Fig. III.23) after the decrease of wet
deposition of several components (mainly sulphates, hydrogen ions and lead ions)
in the second half of the 90’s, shows stagnation instead. The decrease of
sulphate deposition was substantial not only at the exposed stations as ĂšstĂ
n.L.-Kočkov, Prague 4-Libuš and Hr. Král.-observatoř but it was also obvious at
the background stations Košetice and Svratouch. The decrease was substantial at
the station ĂšstĂ n.L.-KoÄŤkov 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 11 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,
2008
Tab. III.2 Estimate of the total annual deposition of the given elements
on the area of
the Czech Republic (78,841 sq. km) in tonnes, 2008
Tab. III.3 Estimate of the total annual deposition of sulphur on the forested
part of the Czech Republic (26,428 sq. km) in tonnes, 2001–2008
Tab. III.4 Station networks monitoring atmospheric
precipitation quality and atmospheric deposition, 2008
Tab. III.5 Average annual concentrations of principal
pollutants in atmospheric precipitation at stations in the Czech Republic, 2008
Tab. III.6 Annual wet atmospheric deposition at
stations in the Czech Republic, 2008
Fig. III.1 Station networks monitoring atmospheric precipitation quality and
atmospheric deposition, 2008
Fig. III.2 Fields of annual wet deposition of sulphur (SO42–S),
2008
Fig. III.3 Fields of annual dry deposition of sulphur (SO2–S), 2008
Fig. III.4 Fields of annual total deposition of sulphur, 2008
Fig. III.5 Fields of annual throughfall deposition of sulphur, 2008
Fig. III.6 Fields of annual wet deposition of nitrogen (NO3-–N),
2008
Fig. III.7 Fields of annual wet deposition of nitrogen (NH4+–N),
2008
Fig. III.8 Fields of annual total wet deposition of nitrogen, 2008
Fig. III.9 Fields of annual dry deposition of nitrogen (NOx–N), 2008
Fig. III.10 Fields of annual total deposition of nitrogen, 2008
Fig. III.11 Fields of annual wet deposition of hydrogen ions, 2008
Fig. III.12 Fields of annual dry deposition of hydrogen ions corresponding to SO2
and NOx deposition, 2008
Fig. III.13 Fields of annual total deposition of hydrogen ions, 2008
Fig. III.14 Fields of annual wet deposition of fluoride ions, 2008
Fig. III.15 Fields of annual wet deposition of chloride ions, 2008
Fig. III.16 Fields of annual wet deposition of lead ions, 2008
Fig. III.17 Fields of annual dry deposition of lead, 2008
Fig. III.18 Fields of annual wet deposition of cadmium ions, 2008
Fig. III.19 Fields of annual dry deposition of cadmium, 2008
Fig. III.20 Fields of annual wet deposition of nickel ions, 2008
Fig. III.21 The development of annual deposition of sulphur (SO42-–S, SO2–S)
and oxidated forms of nitrogen (NO3-–N, NOx–N)
and hydrogen in the Czech Republic, 1995–2008
Fig. III.22 The development of the ratio of nitrate/sulphate concentrations in
atmospheric deposition (expressed as ÎĽeq. l-1) at the CHMI stations,
1998–2008
Fig. III.23 The development of annual wet deposition at selected stations in
1991–2008, Czech Republic
