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 2010 the Air Quality Information System (ISKO/AQIS)
database obtained data on precipitation quality from 50 localities in total (16
ÄŚGS, 15 CHMI, 12 VĂšLHM, 1 VĂšV TGM and 6 HBĂš AV ÄŚR, see
Fig. III.1). Further, data from 5 German
localities in 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). Further, from 1997
to 2010 the weekly precipitation sampling, “bulk” type (with non-specified
content of dustfall), for heavy metals analysis was carried out at these
stations. Beginning from 2011 the analyses of heavy metals at CHMI stations will
be carried out from wet-only precipitation sampling. 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.
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 (55–100 % of
precipitation totals for the year 2011). 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 2011 for the territory of
the Czech Republic was below the long-term normal; it amounted to 627 mm in
the average, which represents 93 % of the long-term normal (for the years
1961–1990). As compared with the year 2010 the total precipitation markedly
decreased.
-
Wet sulphur deposition decreased after 1997 below 50,000
t and this trend continued up to 1999. In 1999–2005 the values remained more
or less at the level of 1999 with the exception of lower depositions in 2003
when there was recorded subnormal total precipitation. Starting from 2005
the decreasing trend continued, in 2011 the level of wet deposition in the
territory of the Czech Republic reached the second lowest level (right after
the year 2003) due to lower concentrations of sulphates measured in most
localities and lower total precipitation In 2011, the highest values of wet
sulphur deposition were recorded in the mountainous areas (the Jizerské hory
Mts., the Krkonoše Mts., the HrubĂ˝ JesenĂk Mts. and the MoravskoslezskĂ©
Beskydy Mts.).
Dry sulphur deposition recorded its most significant decline in the year
1998 (the value decreased by 45 % in comparison with the average for the
period 1995–1997), and 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. Beginning from 2008 the levels of dry deposition
remained at the level of the year 2007, the slight increase in 2010 was
connected with the growth of the measured SO2 concentrations. In
2011 dry sulphur deposition slightly decreased again due to lower SO2
concentrations. The field of total sulphur deposition represents the sum of
wet and dry depositions and it shows the total sulphur deposition amounting
to 45,101 t for the Czech Republic’s territory for the year 2011 (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.20–21). Since 2007 the value of total sulphur
deposition has 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, similarly as in the
previous years, 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 2011
from two stations (Svratouch 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 0.08 g.m-2.year-1 for
forested 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 18,691 t in 2011.
-
The map of wet deposition of reduced (N/NH4+)
and mainly oxidized (N/NO3-) forms of nitrogen shows
their apparent decrease in comparison with the year 2010 caused by lower
total precipitation. The maximum values of wet deposition of oxidized forms
were reached, similarly as in the previous year, in the territory of the
Orlické hory Mts. (the locality U dvou louček), the values of wet deposition
of reduced forms were recorded also in the Orlické hory Mts. (the locality
Luisino ĂşdolĂ). The highest values of total wet nitrogen deposition were
recorded in the area of Orlické hory Mts., and further in the Jizerské hory
Mts., the HrubĂ˝ JesenĂk Mts. and the Ĺ umava Mts. The total wet deposition of
the oxidized forms of nitrogen amounted to 17,164 t in for the area of .the
Czech Republic. 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.
During the recent two years dry deposition on the territory of the Czech
Republic has been slightly increasing
In 2011 the total nitrogen deposition reached 64,387 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 Orlické hory Mts., Jizerské
hory Mts. and Moravskoslezské Beskydy Mts.
-
The wet deposition of hydrogen ions markedly decreased,
over the recent 15 years it reached the lowest values partly due to the
lower total precipitation and partly due to higher pH levels at individual
stations. The highest values were reached in the territory of the Jizerské
hory Mts. Krkonoše Mts., OrlickĂ© hory Mts., HrubĂ˝ JesenĂk Mts. and the
Moravskoslezské Beskydy Mts. and Šumava Mts. 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. and in the territory of
the Moravian-Silesian Region. 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 marked decrease of wet deposition of hydrogen ions in 2011 in
comparison with the previous years.
-
After the year 2000 when the distribution of leaded
petrol was finished the values of the deposition of lead ions from “bulk”
sampling markedly decreased. Similarly as in other pollutants, lead
deposition decreased in the whole territory of the Czech Republic due to
lower total precipitation in 2011. The highest values were reached in the
territory or the Jizerské hory Mts., Krkonoše Mts., Orlické hory Mts., Hrubý
JesenĂk Mts., MoravskoslezskĂ© Beskydy Mts. and the Ostrava area.
-
The deposition of cadmium from “bulk” sampling markedly
decreased as compared with the year 2010. The highest values were reached in
the territory of the Orlické hory Mts. (the locality U dvou louček). The map
of dry deposition of cadmium ions shows also the marked decrease in
comparison with the previous year due to lower concentrations of cadmium.
-
The 2011 map of annual deposition of nickel ions from
“bulk” sampling shows again the apparent decrease due to lower total
precipitation. The highest values were reached in the territory of the
Jizerské hory Mts., Krkonoše Mts., Krušné hory Mts., Slavkovský les Mts.,
ÄŚeskĂ˝ les Mts. and Ĺ umava Mts.
-
The highest levels of wet deposition of chloride ions
were recorded similarly as in the previous years 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.22) 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 apparent both at the
relatively exposed suburban stations and at the background stations, e.g.
Košetice and Svratouch. The decrease was substantial at the station Ústà n.L.-Kočkov 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 at some stations The development of this
proportion over the recent 12 years for the CHMI stations is shown in
Fig. III.21.
Tab. III.1 Average deposition fluxes of S, N and H in the Czech Republic,
2011
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, 2011
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, 2001–2011
Tab. III.4 Station networks monitoring atmospheric
precipitation quality and atmospheric deposition, 2011
Fig. III.1 Station networks monitoring atmospheric precipitation quality and
atmospheric deposition, 2011
Fig. III.2 Fields of annual wet deposition of sulphur (SO42–S),
2011
Fig. III.3 Fields of annual dry deposition of sulphur (SO2–S),
2011
Fig. III.4 Fields of annual total deposition of sulphur, 2011
Fig. III.5 Fields of annual throughfall deposition of sulphur, 2011
Fig. III.6 Fields of annual wet deposition of nitrogen (NO3-–N),
2011
Fig. III.7 Fields of annual wet deposition of nitrogen (NH4+–N),
2011
Fig. III.8 Fields of annual total wet deposition of nitrogen, 2011
Fig. III.9 Fields of annual dry deposition of nitrogen (NOx–N),
2011
Fig. III.10 Fields of annual total deposition of nitrogen, 2011
Fig. III.11 Fields of annual wet deposition of hydrogen ions, 2011
Fig. III.12 Fields of annual dry deposition of hydrogen ions corresponding to SO2
and NOx deposition, 2011
Fig. III.13 Fields of annual total deposition of hydrogen ions, 2011
Fig. III.14 Fields of annual wet deposition of chloride ions, 2011
Fig. III.15 Fields of annual wet deposition of lead ions, 2011
Fig. III.16 Fields of annual dry deposition of lead, 2011
Fig. III.17 Fields of annual wet deposition of cadmium ions, 2011
Fig. III.18 Fields of annual dry deposition of cadmium, 2011
Fig. III.19 Fields of annual wet deposition of nickel ions, 2011
Fig. III.20 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, 1995–2011
Fig. III.21 The development of the ratio of nitrate/sulphate concentrations in
atmospheric deposition (expressed as ÎĽeq. l-1) at the CHMI stations,
1998–2011
Fig. III.22 The development of annual wet deposition at selected stations in
1991–2011, Czech Republic
