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 2009 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 2009 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 (51–98 % of precipitation totals for the
year 2009). 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 2009 for the territory of the Czech
Republic was above the long-term normal; it amounted to 744 mm in the
average, which represents 110 % of the long-term normal (for the years
1961–1990). As compared with the year 2008 the total precipitation was
slightly higher, which corresponds with a slight increase 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., the Orlické hory Mts., the
HrubĂ˝ JesenĂk Mts. and the 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. Since 2008 the levels of dry deposition have remained
at the level of the year 2007. The field of total sulphur deposition
represents the sum of wet and dry depositions and it shows the total sulphur
deposition amounting to 49,491 t for the Czech Republic’s territory for the
year 2009 (see Table III.2). 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). Since 2007 the value of total sulphur deposition have ranged around
50,000 t of sulphur for the Czech Republic’s territory. 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. 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 2009 from two stations (Prague
4-Libuš and Košetice) 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 0.07
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 SO4-2 of suspended particles) can reach, because in
sulphur, unlike other pollutants, the inner circulation in vegetation is
negligible.
Since 2008 the throughfall deposition is calculated with the use of 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. Therefore, also total values of throughfall
deposition since 2001 were recalculated with the use of the new layer of
forests, in order to carry out the comparison with the data after the year
2007 (see Table III.3). Throughfall sulphur deposition on the forested
surface of the Czech Republic reached the amount of 26,193 t in 2009.
-
The map of wet deposition of nitrates showed in 2009, 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 OrlickĂ© hory Mts. The highest level
of the deposition of ammonia ions was recorded also in the Krkonoše Mts. (the
locality HĹ™ĂbÄ›cĂ) and in the JizerskĂ© hory Mts. (the locality UhlĂĹ™ská). The
highest values of total wet nitrogen deposition were recorded in the area of
JizerskĂ© hory Mts., the Krkonoše Mts. and the HrubĂ˝ JesenĂk Mts. The wet
deposition of the oxidized forms of nitrogen in the territory of the Czech
Republic has slightly increased as compared 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 ranges between 14,105 t and
20,622 t. As compared with the previous year, it also slightly increased,
which is probably caused by a very slight increase of NOx concentrations.
In 2009 the total nitrogen deposition reached 63,844 t of N (ox+red). year-1
for the area of the Czech Republic (see Table III.2). The highest values of
total nitrogen deposition were reached in the Jizerské hory Mts. and the
Krušné hory Mts.
-
The wet deposition of hydrogen ions reached, similarly as in the
previous years, the maximum values in the Krkonoše Mts. (locality HĹ™ĂbÄ›cĂ).
The map of dry deposition of hydrogen ions shows the similar character as in
the previous years. 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 a slight increase of dry, wet and total deposition of hydrogen
ions in 2009 in comparison with the previous two years.
-
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 2009 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 2009 was comparable with the previous
year. There was recorded a slight increase in the Jizerské hory Mts. in the
locality Souš. In comparison with the year 2008 the values of dry deposition
of cadmium ions did not exceed the value 0.25 mg.m-2.year-1 throughout the
territory of the Czech Republic.
-
The 2009 map of wet annual deposition of nickel ions shows the apparent
decrease of the values in the the Jizerské hory Mts. and the Krkonoše Mts.,
where there were recorded the maximum values of 2008. In 2009 the maximum
values were measured in the locality U dvou koček in the Orlické hory Mts.
-
The highest values of the deposition of fluoride ions were recorded in
the Orlické hory Mts. The highest levels of wet deposition of chloride ions
were recorded in the Jizerské hory Mts. and also for the first time in 2009
in the locality Podbaba.
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 12 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,
2009
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, 2009
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, 2001–2009
Tab. III.4 Station networks monitoring atmospheric
precipitation quality and atmospheric deposition, 2009
Tab. III.5 Average annual concentrations of principal
pollutants in atmospheric precipitation at stations in the Czech Republic, 2009
Tab. III.6 Annual wet atmospheric deposition at
stations in the Czech Republic, 2009
Fig. III.1 Station networks monitoring atmospheric precipitation quality and
atmospheric deposition, 2009
Fig. III.2 Fields of annual wet deposition of sulphur (SO42–S),
2009
Fig. III.3 Fields of annual dry deposition of sulphur (SO2–S),
2009
Fig. III.4 Fields of annual total deposition of sulphur, 2009
Fig. III.5 Fields of annual throughfall deposition of sulphur, 2009
Fig. III.6 Fields of annual wet deposition of nitrogen (NO3-–N),
2009
Fig. III.7 Fields of annual wet deposition of nitrogen (NH4+–N),
2009
Fig. III.8 Fields of annual total wet deposition of nitrogen, 2009
Fig. III.9 Fields of annual dry deposition of nitrogen (NOx–N),
2009
Fig. III.10 Fields of annual total deposition of nitrogen, 2009
Fig. III.11 Fields of annual wet deposition of hydrogen ions, 2009
Fig. III.12 Fields of annual dry deposition of hydrogen ions corresponding to SO2
and NOx deposition, 2009
Fig. III.13 Fields of annual total deposition of hydrogen ions, 2009
Fig. III.14 Fields of annual wet deposition of fluoride ions, 2009
Fig. III.15 Fields of annual wet deposition of chloride ions, 2009
Fig. III.16 Fields of annual wet deposition of lead ions, 2009
Fig. III.17 Fields of annual dry deposition of lead, 2009
Fig. III.18 Fields of annual wet deposition of cadmium ions, 2009
Fig. III.19 Fields of annual dry deposition of cadmium, 2009
Fig. III.20 Fields of annual wet deposition of nickel ions, 2009
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, 1995–2009
Fig. III.22 The development of the ratio of nitrate/sulphate concentrations in
atmospheric deposition (expressed as ÎĽeq. l-1) at the CHMI stations,
1998–2009
Fig. III.23 The development of annual wet deposition at selected stations in
1991–2009, Czech Republic
