Graphic Yearbook 2013
IX. ATMOSPHERIC DEPOSITION IN THE CZECH REPUBLIC
Atmosperic deposition is the flow of substances from the
atmosphere towards the Earth’s surface (Braniš, Hůnová 2009).
This is an important process contributing to self-cleaning of
air, however, on the other hand it enables the pollutants’
entering to other components of the environment. Atmospheric
deposition is divided into wet deposition and dry deposition.
Wet deposition is connected with the occurrence of atmospheric
precipitation (vertical deposition: rain, snow, and horizontal
deposition: fog, rime), and therefore it has an episodic
character. The dry component represents the deposition of gases
and particles through different mechanisms and it is a
continuous process.
The quantification of total atmospheric deposition is very
important for the study of its effects on the environment. There
is a significant difference in the quantification of individual
components with regard to the level of difficulty of the method
and reliability of the obtained results. Wet vertical deposition
is relatively easiest to measure (Krupa 2002), while there is no
available method for the direct measurement of dry deposition,
and thus it is necessary to estimate it with the use of various,
usually relatively complicated approaches (Wesely, Hicks 2000;
Kumar et al. 2008). Nevertheless, the most difficult measurable
component of atmospheric deposition is horizontal deposition (e.g.
Krupa 2002; Klemm, Wrzesinsky 2007). It is measured only
exceptionally and actual deposition, with regard to this
component, is usually significantly underestimated (Bridges et
al. 2002; Hůnová et al. 2011).
Atmospheric deposition in Europe has decreased significantly
over the recent twenty years, however, in a number of regions it
still continues to be a problem (EEA 2011). Chemical composition
(precipitation quality) and atmospheric deposition have been
monitored in the long term at relatively large number of
stations in the Czech Republic. Time trends and changes in
spatial distribution of major components of deposition, i.e.
sulphur and nitrogen, for the whole period of the carried out
measurements were published (Hůnová et al. 2004; 2014).
In 2013 the Air Quality Information System (ISKO/ AQIS) database
obtained data on precipitation quality from 42 localities in
total (13 ČGS, 14 CHMI, 8 VÚLHM and 6 HBÚ AV ČR. Further, data
from 5 German localities) in boundary areas were submitted by
LfULG. 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. Since 2011 the
analyses of heavy metals at CHMI stations have been carried out
from wet-only precipitation sampling, “bulk” type sampling was
closed down. 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 IX.4.
Wet deposition charts were compiled for selected ions on the
basis of all-round chemical analyses of wet only precipitation
samples, specifically for SSO42--S, NO3--N,
NH4+-N, H+ (pH), Cl-,
F- , Pb2+, Cd2+ and Ni2+.
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 and VÚLHM based on monthly “bulk” sampling
with dustfall (Table IX.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 (Ranalli et al. 1997).
In addition to wet deposition, also dry deposition charts are
presented for sulphur, nitrogen, hydrogen ions, lead and cadmium.
The maps of total annual deposition are presented 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
(Dvořáková et al. 1995).
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 IX.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 (64–87 % of precipitation totals in an open area
for the year 2013). 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 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 (Dvořáková et al. 1995).
In 2013 the colour range in legends to deposition maps was
changed due to very low deposition levels of most evaluated
pollutants, for which the previous colour range was not
convenient any more.
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 2013 for the territory of
the Czech Republic was slightly above the long-term normal;
it amounted to 727 mm in the average, which represents 108 %
of the long-term normal (for the years 1961–1990). As
compared with the year 2012 (689 mm) the total precipitation
was higher.
- 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 the year 1999
with the exception of lower depositions in 2003, when there
was recorded subnormal total precipitation (516 mm, i.e. 77
% of the long-term normal). The decreasing trend has
continued since 2005 until today. In 2013 the level of wet
sulphur deposition in the territory of the Czech Republic
amounted to 22,136 t (as compared with 24,664 t in 2012). In
2013, the highest values of wet sulphur deposition were
recorded in the mountainous areas, and namely in the Krušné
hory Mts., the Moravskoslezské Beskydy Mts., the Jeseníky
Mts. and the Krkonoše Mts. (Fig. IX.2).
Similarly, dry sulphur deposition recorded its most significant decrease between the years 1997 and 2000. In the following years the field of dry deposition remained more or less at the same level, which is coherent with SO2 concentrations in the ground-level ambient air (Fig. IX.20). In 2013 dry sulphur deposition in the territory of the CR reached 27,178 t and the highest values were recorded in the Krušné hory Mts. (Fig. IX.3).
The field of total sulphur deposition represents the sum of wet and dry depositions and it shows the total sulphur deposition amounting to 49,314 t for the Czech Republic’s territory for the year 2013 (Table IX.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. Since 2007 the value of total sulphur deposition has ranged around 50,000 t of sulphur for the Czech Republic’s territory (Fig. IX.20). The total sulphur deposition reached the maximum values in the Krušné hory Mts. area and Ostrava area (Fig. IX.4).
- The throughfall sulphur deposition reached in 2013 the
maximum values in the mountainous areas (Fig. IX.5). 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. Rime 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 lasting several years (Tesař et al. 2000; Tesař et al.
2005). 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- contained in suspended particles. Based on the data on sulphates concentration in aerosol for the year 2013 from two stations (Churáňov and Košetice) and on the application of the deposition rate 0.25 cm.s-1 (Dvořáková et al. 1995) dry deposition of S from SO42- reached the average value 0.06 g.m-2.year-1 for forested areas (Churáňov = 0.042 g.m-2.year-1, Košetice = 0.076 g.m-2.year-1). 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 (Draaijers et al. 1997).
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 forested area 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 (Table IX.3). Throughfall sulphur deposition on the forested surface of the Czech Republic reached the amount of 19,723 t in 2013.
- Wet deposition of both reduced (N/NH4+) and
oxidized (N/NO3-) forms of nitrogen
decreased in comparison with the year 2012. The maximum
values of wet deposition of oxidized forms were reached in
the territory of the Orlické hory Mts. (Fig. IX.6), while
the maximum values of wet deposition of reduced forms were
recorded in the territory of the Vysočina region, the Krušné
hory Mts. and the Krkonoše Mts. (Fig. IX.7). The highest
values of total wet nitrogen deposition (the sum of wet
depositions of N/NH4+ and N/NO3-)
were recorded in the area of the Krušné hory Mts., the
Krkonoše Mts., the Orlické hory Mts., the Hrubý Jeseník Mts.
and the Šumava Mts. (Fig. IX.8).
- The development of dry deposition of oxidized forms of
nitrogen had a declining trend up to the year 2002 (when the
value reached 48 % of the value of the average for the years
1995–1997). Afterwards, a slight increase was recorded in
several years (2004, 2006 and in the period 2007–2011).
These fluctuations are connected with the limit values of NOx
in the troposphere. In 2013 dry deposition in the territory
of the CR slightly increased. The highest values were
reached in big cities and along major communications (Fig.
IX.9).
In 2013 the total nitrogen deposition reached 69,693 t of N. year-1 for the area of the CR (Table IX.2). It is apparent that in comparison with the year 2012 (75,133 t.year-1) it decreased. The highest values of total nitrogen deposition were reached in the the Krušné hory Mts. and the northeastern part of the Ústí nad Labem region (Šluknovský výběžek), in big cities (Prague, Brno, Ostrava) and along the most loaded communications, mainly the D1 highway (Fig. IX.10).
- Wet deposition of hydrogen ions has markedly decreased
over the recent 15 years; it reached the lowest value in
2011. In 2013 there continued a slight increase of wet
deposition, probably due to the increasing annual total
precipitation since the year 2012. In 2013 the value of
annual wet deposition of hydrogen ions in the territory of
the CR amounted to 680 t.year-1 (as against 568 t in the
year 2012). The highest values were reached in the territory
of the Krkonoše Mts., the Jizerské hory Mts., the Orlické
hory Mts., the Krušné hory Mts., the Hrubý Jeseník Mts., the
Moravskoslezské Beskydy Mts. and the Šumava Mts. (Fig.
IX.11). 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 Moravia-Silesia region (Fig. IX.12). 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. IX.20).
- After the year 2000, when the distribution of leaded
petrol was finished, the values of the deposition of lead
ions markedly decreased. Wet deposition of lead slightly
increased in 2013 in the whole territory of the CR as
compared with the year 2012. The highest values were reached
in the territory of the Moravskoslezské Beskydy Mts., the
Hrubý Jeseník Mts. and the Orlické hory Mts. (Fig. IX.15). Dry deposition of lead ions reached the similar level in
2013 as in 2012 when the highest values were reached in the
area of Ostrava and the Moravskoslezské Beskydy Mts. (Fig.
IX.16).
- Both wet and dry deposition of cadmium ions increased as
compared with the year 2012 (Figs. IX.17 and
IX.18). The
most marked increase of wet deposition values was recorded
in the locality U dvou louček in the Orlické hory Mts. (from
0.261 mg.m-2.year-1 in 2012 to 1.261 mg.m-2.year-1 in 2013). However, the cause of this relatively marked increase has
not been sufficiently explained yet.
- The annual wet deposition of nickel ions slightly
increased in 2013 in comparison with the year 2012. The
highest values were reached in the locality Pluhův bor. This
was probably caused by very specific undersoil (serpentine)
with high content of nickel and magnesium (Krám et al.
2009). Higher levels of wet deposition of nickel ions were
recorded also in the territory of the Jizerské hory Mts.,
the Krušné hory Mts., the Slavkovský les Mts., the Český les
Mts. and the Šumava Mts. (Fig. IX.19).
- Wet deposition of chloride ions decreased as compared with the year 2012. This decrease, however, might have been influenced by the end of the measurements in the locality Podbaba (VÚV TGM) in 2013, where the highest levels of wet deposition of chloride ions were recorded in the previous years. Similarly as in other monitored pollutants, wet deposition of chloride ions within the CR reaches the highest values in the mountainous areas (Fig. IX.14).
The development of annual wet deposition of the main elements
as measured at selected stations in the Czech Republic
(Fig.
IX.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.
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 (Fig. IX.21). Since the
second half of the 90’s a slight increase of nitrates and
sulphates proportion has been observed at some stations.
Tab. IX.1 Average deposition fluxes S, N and H in the Czech Republic, 2013
Fig. IX.1 Station networks monitoring atmospheric
precipitation quality and atmospheric deposition, 2013
Fig. IX.2 Fields of annual wet deposition of sulphur (SO42- - S),
2013
Fig. IX.3 Fields of annual dry deposition of sulphur (SO2 - S),
2013
Fig. IX.4 Fields of annual total deposition of sulphur, 2013
Fig. IX.5 Fields of annual throughfall deposition of sulphur,
2013
Fig. IX.6 Fields of annual wet deposition of nitrogen (NO3- - N),
2013
Fig. IX.7 Fields of annual wet deposition of nitrogen (NH4+ - N),
2013
Fig. IX.8 Fields of annual total wet deposition of nitrogen,
2013
Fig. IX.9 Fields of annual dry deposition of nitrogen (NOx–N),
2013
Fig. IX.10 Fields of annual total deposition of nitrogen, 2013
Fig. IX.11 Fields of annual wet deposition of hydrogen ions,
2013
Fig. IX.12 Fields of annual dry deposition of hydrogen ions
corresponding to SO2 and NOx deposition, 2013
Fig. IX.13 Fields of annual total deposition of hydrogen ions,
2013
Fig. IX.14 Fields of annual wet deposition of chloride ions,,
2013
Fig. IX.15 Fields of annual wet deposition of lead ions, 2013
Fig. IX.16 Fields of annual dry deposition of lead, 2013
Fig. IX.17 Fields of annual wet deposition of cadmium ions, 2013
Fig. IX.18 Fields of annual dry deposition of cadmium, 2013
Fig. IX.19 Fields of annual wet deposition of nickel ions, 2013
Fig. IX.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, 1995–2013
Fig. IX.21 The development of the ratio of nitrate/sulphate
concentrations in atmospheric deposition (expressed as µeq. l-1) at the CHMI stations, 1998–2013
Fig. IX.22 The development of annual wet deposition at selected stations in 1991–2013, Czech Republic
