P E R G A M O N Atmospheric Environment 35 Supplement No. 1 (2001) $55-$62

ATMOSPHERIC ENVIRONMENT

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Trends in the atmospheric and hydrological cycle of sulphur at catchments in the Czech Republic

Jaroslav Fiala*, Mark Rieder, Miriam Dvo~-fikovfi, Hana Livorov~ The Czech Hydrometeorological Institute, Na rdabatce 17, 143 06 Praha 4 - Komo['any, Czech Republic

Received 3 May 2000; received in revised form 30 October 2000; accepted 7 November 2000

Abstract

The study is focused on the river basin of the upper Elbe and especially on the highly polluted area of northwestern Bohemia which is a part of the so-called Black Triangle area. A ten-year data set (1989-1998) of sulphur emissions, ambient air quality, atmospheric deposition and surface run-off has been evaluated. Substantial sulphur downward trend has been stated both for emissions and deposition which correlate well together. Relations between surface run-off and total deposition are discussed. Run-off chemistry of individual river basins is influenced by sulphur deposition and weathering of sulphur-rich heaps of lignite mines to a different degree. The ambient air quality has been improved in the Czech Republic, ambient air sulphur dioxide concentrations dropped and the total sulphur deposition has decreased to 50% of its value in 1989. © 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Sulphur emissions; Ambient air concentrations of sulphur dioxide; Atmospheric deposition; Throughfall; Surface run-off; Catchments; GIS mapping; Long-term trends; The Czech Republic

1. Introduction

There has been an overall downward trend in emis- sions from both stationary and mobile sources in the last decade in the Czech Republic. Reasons for this change include gradual economic changes, a number of emis- sion-reduction measures adopted by operators, mainly the implementation of an extensive desulphurization pro- gramme on large point combustion sources, gradual transformation of the fuel base (conversion from coal to natural gas) for all stationary source categories and replacement of vehicle fleets, particularly passenger cars.

In the Czech Republic the total emissions of sulphur have decreased since 1986 from 1089 to 222ktons in 1998. A similar systematic decrease has occurred for ambient air sulphur dioxide and total suspended partic- ulates (TSP) concentrations in most polluted regions of the Czech Republic, i.e. northwestern Bohemia, Prague and the Ostrava region. Annual concentrations of

* Corresponding author. Tel.: + 420-2-401-9801; fax: + 420- 2-4403-2468.

E-mail address: fialaj@chmi.cz (J, Fiala).

sulphur dioxide averaged through representative stations in northwestern Bohemia decreased from 78 ggm -3 in 1987 to 16 ggm 3 in 1998. Ambient air concentrations of sulphur dioxide show a descending trend in all regions of the Czech Republic. The same decrease of the annual weighted averages of sulphate concentrations in rain- water has been observed at the precipitation quality monitoring stations. Sulphates have decreased from 7 . 5 m g S O ~ - 1 - 1 i n 1987 t o 2 . 5 m g S O 2 1 - l i n 1998 on an average.

The responsibility for operation of the national air quality monitoring network lies with the Czech Hydro- meteorological Institute (CHMI). The CHMI is also a national institution that monitors abiotic and biotic components of an aquatic environment and evaluates the surface and ground water quality in the territory of the Czech Republic.

In this article, the development of total sulphur emis- sions for the river basin of the upper Elbe (roughly equal to the territory of Bohemia) is correlated with the trends of total sulphur deposition. These trends are also com- pared with sulphur run-off from selected catchment areas in the Czech Republic. This comparison will be used as

1352-2310/01/$-see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S1 352-23 1 0(00)005 16- 1

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a basis for empirical modelling and for balancing and verification of total atmospheric deposition, acidification loads and emission inventory.

The study is focused on catchment areas of the rivers Ohre and Bilina which flow through the west Bohemian part of the Black Triangle area. These catchment areas form a part of the river basin of the upper Elbe.

2. Methods

2.1. National emission inventory

In the Czech Republic the ambient air pollution is caused largely by sources of air pollution located within the borders of the country. In northwestern Bohemia the largest point sources are situated in regions with poor atmospheric ventilation. Atmospheric emissions of basic pollutants (sulphur dioxide, particulate matter, nitrogen oxides, carbon monoxide and hydrocarbons) have been inventoried annually since the beginning of the 1980s in the Czech Republic. More than 2500 sources are regis- tered in the emission inventory database of large point sources and this database has been annually updated since 1982. In the case of point sources with thermal capacity larger than 150 MW, the data on emissions are based on obligatory continuous measurements since 1993. The atmospheric emissions from medium-sized sources are extracted from the annual Notification of Charges for Air Pollution as verified by the environment departments of district authorities. The emission inven- tory database for medium-sized sources contains more than 27,000 sources.

In the case of emission inventories from small area sources, a model based on the General Census has been completed. Its output includes information on the con- sumption of principal fossil fuels in households, which was updated in co-operation with regional fuel and en- ergy suppliers (gas distribution, power distribution and heat supply companies). The final output from the model consists of data on air emissions from household sources at the level of communities.

The emission inventory of mobile sources covers emis- sions from road, railway, water and air transport and in addition emissions from agricultural and forest machin- es. Geographical layering of emissions from mobile so- urces on Czech motorways and major roads allocates the value of average 24-h specific emission to each sec- tion of the road network for which the vehicle census is conducted.

2.2. Ambient air pollution monitoring

The backbone air-quality monitoring network of the Czech Republic, operated by CHMI, is based on contem- porary automated air pollution monitors for all basic

pollutants (802, NOx, TSP, PMlo, 03 and CO). In recent years, the automatic monitoring has been ex- tended by aromatic hydrocarbons. CHMI is responsible namely for the installation and operation of ambient air monitoring networks in the most polluted areas for the purposes of alert and regulatory system. Data from the automatic monitoring network are collected and transferred through data lines to regional processing computers for real-time processing and evaluation. In addition to CHMI air pollution monitoring networks, several other organisations, especially the Public Health Service, have also been contributing to the air pollution monitoring for a number of years in the Czech Republic. Manual monitoring networks of the CHMI and of other organisations serve as a complementary monitoring for territorial and long-term air-quality assessment.

The information on monitoring stations together with the type of their measurements is updated on an annual basis. Sulphur dioxide monitoring started in the late 1960s and now there are more than 400 monitoring stations in operation on the territory of the Czech Re- public. The location of stations in the study area can be seen in Fig. 1.

2.3. Monitoring of chemical composition of precipitation

Wet atmospheric deposition is monitored by several stations operated by CHMI, the Czech Geological Sur- vey (CGU) and the Water Management Research Insti- tute (VUV), as can be seen in Fig. 2. The stations of the CHMI are based on weekly wet-only measurements sampled by automatic collectors. Stations operated by the CGU and the VUV are based on monthly bulk sampling. Chemical analyses of precipitation samples include concentrations of SO 2-, NO~, H +, NH2, CI- , F - , Pb 2 +, Cd 2 +, and Ni 2 +. The deposition of these ions is monitored because of their material impact on the various spheres of the environment.

2.4. Water-quality monitoring

Surface water-quality monitoring started in 1963 with a sampling frequency of 12 samples per year. In the very beginning basic chemical parameters like sulphates were analysed, as well as indicators of the oxygen regime, additional chemical indicators and radiochemical indi- cators. The concentration of heavy metals has been monitored since 1980 with a sampling frequency of 12 samples per year. Hydrocarbons (PCB, PAH, etc.) and biological and microbiological parameters have been analysed since 1993 with the same frequency. Nowadays CHMI monitors surface water-quality at 263 sampling sites in the state water-quality monitoring network. These sampling sites are located along water courses important for water management. CHMI also monitors groundwater quality at 480 sites nationwide. The data

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"%.,i

m31

N ~ 30 - 4o 40 - 5o 50 - 6o

]mm 60 - 70 > IHr

Fig. 1. Location of monitoring stations with the values of SO2 concentrations in the given classes and fields of sulphur dioxide concentrations in 1997 in the upper Elbe river basin.

c o n c e n t r a t i o n s in p rec ip i t a t i on [mg.1-1]

- I < 0.75 _-1 0.75 - 1.0

1.0 - 1.25 1.25 - 1.5

N 1.5 -2 .0 [ ] 2 .0 -2.5 [ ] > 2 . 5

ring stat ion

,m. sampler

n. sampler dated sampler

Fig. 2. Location of monitoring stations with the values of sulphate concentrations in rainwater in the given classes and fields of sulphate concentrations in rainwater in 1997 in the upper Elbe river basin.

are stored in the Hydroecological information system in an ORACLE database at the CHMI.

2.5. Air-quality inJormation system of the Czech Republic

Data from all systematically operated monitoring net- works in the Czech Republic are collected in the air

pollution database of the Air-Quality Information Sys- tem (AQIS) operated and managed by the Air-Quality Protection Division of the CHMI. Using state-of-the-art information technologies AQIS has been operating and undergoing development since 1992 as an integrated sys- tem for nation-wide comprehensive assessment of the

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Fig. 3. Map of emission fluxes from 5 x 5 km in the Czech Republic.

state and development of air pollution. The system fea- tures capabilities for collecting, archiving and assessing data from automatic and manually operated ambient air pollution monitoring networks in the Czech Republic, for storing and processing data on emissions and air pollution sources and for archiving and processing data on chemical composition of precipitation. Within the scope of the nation-wide processing the data quality control is implemented in AQIS including the regular verification of the plausibility of data and elimination of implausible and erroneous data from the delivered batches.

The emission, air pollution and wet deposition databases of AQIS are the basis for regular annual and long-term assessment and estimates of territorial loads from air pollution (Fiala et al., annually since 1993). Along with the evaluation of emissions, air pollution and atmospheric deposition trends, another main task of the regular assessment is the mapping of pollutant concen- trations fields and mapping of wet and dry atmospheric deposition using the tools of geographical information systems (Arc/Info).

3. Results

For the purposes of the study, the selected territory of assessment is restricted to the river basin of the upper Elbe. This river basin comprises also the river basins of

Ohre and Bilina selected for the comparisons of sulphur run-off and sulphur deposition.

3.1. Mapping o f ambient air concentration fields and deposition fluxes of sulphur

The Creation of maps of annual sulphur dioxide con- centrations (Fig. 1) is based on monitoring data from station networks with the application of"kriging", which is a statistical method for objective interpolation (Journel and Hujibrets, 1981). In areas with insufficient density of measurement the annual sulphur concentrations have been estimated with the application of dispersion and statistical model SYMOS '97 (System for Modelling of Stationary Sources; Bubnik et al., 1998) where detailed spatially desegregated sulphur emissions are used (Fig. 3). Fields of sulphur dioxide concentrations are the bases for the evaluation of dry deposition fields constructed using the dependence of deposition velocities on the type of vegetation cover. Deposition rates for sulphur dioxide 7 and 3.5mms -1 for forested and non-forested areas, respectively, were used (Sehmel, 1980; Walcek et al., 1986).

Wet sulphur deposition maps are prepared by means of GIS applications using the fields of sulphate-weighted average concentrations in rainwater (Fig. 2) and the field of precipitation totals. These data are from more than 750 precipitation-measuring stations, taking into ac- count the altitude's effect on precipitation quantity. Average concentrations were modified by empirical

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Fig. 4. Map of total deposition of sulphur in 1997 in the upper Elbe river basin.

45

4O

35

30 o

¢~ 25

2o

1986 1989 1990 t991 1992 1993 1994 t995 1996 1997 1998

900

800

700

SOD

500 ~'~

400

300 =~

200 ¢n

100

70

6 9

50

~40

o~ 30

20

t0

. . . . . . . . . . .

t987 1998 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998

~RUN OFF libel DRY DEPOSITION ~ / ~TOTAL DEPOSITION lem WET DEPOSITION

EMISSION, NW.Bohemia

I00 f Fig. 5. Annual trends in sulphur run-off, wet, dry and total deposition and sulphur emissions in the given river basins.

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200

180

160

Sulphur Emission vs Total Deposition Elbe

l y = 6 , 7 5 8 7 x , 27,?.'I 88

R" =0,8483

I I

140

?, 12o ¢~

oo

40

2O

.wJ~

100 200 300 400 500 600 700 800 900

S-Emissionsf ktons

Fig. 6. Correlation of total emissions and total deposition of sulphur for the upper Elbe river basin.

coefficients expressing the individual ions' ratios in bulk and wet-only samples (values for each of the ions vary from 0.94 to 1.35) to facilitate the use of bulk precipita- tion data.

Maps of total deposition of sulphur were produced by means of map algebra by adding wet and dry sulphur deposition maps (Fig. 4).

The estimated total deposition of sulphur is in corre- spondence with the estimations of total deposition of sulphur taken by throughfall measurements in forested areas. Throughfall deposition generally includes wet ver- tical and horizontal deposition and dry deposition of particles and gases in vegetation canopy. In the case of sulphur, whose circulation within the canopy is negligible throughfall deposition should provide a good estimate of total deposition. For forested areas throughfall sulphur deposition maps have been generated 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 forest canopy at each station (Fig. 2). The throughfall deposition of sulphur corresponds well with the total deposition calculated by summing up wet and dry sulphur depos- ition (Table 1).

By the described procedure maps of dry, wet and total deposition have been created for the individual years of the period 1989-1998. The amount of dry, wet and total deposition of sulphur for the assessed territory

Table 1 Comparison of throughfall and total sulphur deposition, the upper Elbe catchment area

Type of deposition assessment ktons

Throughfall sulphur deposition 29,354 Total (wet + dry) sulphur deposition 25,931 in forested areas

were calculated from the prepared maps using GIS tools (Table 2).

3.2. Long-term trends

For the given river basins the sulphur depositions, total emissions and run-off of sulphur are summarised in Table 2 for the period 1989-1998. Annual trends in sulphur run-off, wet, dry and total deposition and sul- phur emissions in given river basins are depicted in Fig. 5. Close correlation can be shown for sulphur emissions and total deposition of sulphur (Fig. 6).

4. Conclusions

Deposition maps reveal the heaviest load caused by sulphur deposition in a broader mountainous area of

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Table 2 Depositions, total emissions and run-off of sulphur in 1989-1998 in tons of S

$61

Year 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998

Elbe river basin Wet deposition 49,000 45,082 48,017 42,867 49,260 42,416 44,100 39,569 37,191 35,000 Dry deposition 1,31,000 99,315 1,16,686 81,710 84,313 61,481 58,461 64,834 56,399 45,000 Total deposition 1,80,000 1,43,669 1,63,989 1,23,951 1,32,836 1,03,708 1,02,477 1,04,138 93,592 80,000 Run-off 3,19,291 2,28,780 1,90,038 2,54,987 1,99,891 2,85,895 3,85,518 3,02,519 2,46,781 2,07,639 Emissions, Bohemia 8,21,000 7,81,744 7,40,406 6,31,983 5,82,333 5,34,573 4,67,285 3,98,220 2,90,335 2,00,000

Ohre river basin Wet deposition 4300 3611 3304 3420 3575 4198 3874 3364 2786 2100 Dry deposition 18,100 13,969 16,783 11,487 12,944 9129 8374 9660 7069 6000 Total deposition 22,400 17,506 20,043 14,854 16,461 13,338 12,220 12,980 9854 8100 Run-off 46,454 40,110 36,669 42,789 36,952 51,465 57,897 40,090 41,089 49,261 Emissions, NW-Bohemia 5,90,000 5,20,070 4,60,349 3,99,598 3,75,603 3,55,709 3,13,410 2,54,761 1,41,356 99,000

Bilina river basin Wet deposition 1300 995 1066 1104 1053 1467 1228 1070 836 820 Dry deposition 6700 5034 5558 3971 4540 3437 3002 2949 2572 1950 Total deposition 8000 6028 6624 5075 5593 4934 4233 4018 3400 2770 Run-off 38,207 28,928 24,810 20,512 27,596 23,524 22,874 19,361 21,049 21,561 Emissions, NW-Bohemia 5,90,000 5,20,070 4,60,349 3,99,598 3,75,603 3,55,709 3,13,410 2,54,761 1,41,356 99,000

northwestern Bohemia, namely the Ore Mrs., the Giant Mts. and the Jizersk6 Mts., a part of the Black Triangle area (Fig. 4). The distributions of both nitrogen and hydrogen ion deposition fields are quite similar (Fiala et al., 1993). The areas with the highest deposition loads correspond well with those under the heaviest load of ambient air pollution and at the same time with those where forests are damaged to the highest degree (Moldan and Schnoor, 1992; Moravcik and Cerny, 1995).

Deposit ion trend diagrams (Fig. 5) show the prevailing contribution of dry deposition to the total deposition of sulphur in the heavily polluted areas of the Czech Republic. Due to the decrease of sulphur emissions, the dry deposition contribution to the total deposition of sulphur has decreased from about 70-80% at the end of the 1980s to the 55-60% more recently. The total sulphur deposition has decreased to 50% of the level in 1989.

Differences between the total deposition and through- fall deposition of sulphur could be caused by the fact that the total deposition (evaluated as the sum of dry and wet deposition) does not include the horizontal (occult) deposition and dry deposition of sulphates in particles. Especially in mountainous areas the contribution of horizontal deposi t ion, can be sig- nificant. Hoarfrost, rime, and fog are normally highly concentrated (Porkert, 1999) and thus they may contribute to the deposition of sulphur and other ele- ments.

Total sulphur depositions and emissions are well cor- related in the studied catchment areas (Figs. 5 and 6). The interpretation of relations between surface run-off and total deposition in the studied catchments is more com- plicated. This comparison reveals that besides the atmo- spheric deposition the prevailing contribution to the surface sulphur run-off is likely formed by weathering of pyrites in sulphur-rich heaps of open-pit lignite mines. In a small and pollution-loaded catchment area of the Bi- lina river the contribution of atmospheric deposition is more significant and the sulphur run-off, total deposition and emissions are more correlated.

R e f e r e n c e s

Bubnik, J., Keder, J., Macoun, J., Manak, J., 1998. SYMOS '97 Model Description CHMI, Prague (only in Czech at present time).

Fiala, J., et al., 1993. Air pollution in the Czech Republic. CHMI, Prague. Regularly published annual report (in English).

Journel, A.G., Hujibrets, C.J., 1981. Mining Geostatistics. Aca- demic Press, London.

Moldan, B., Schnoor, J., 1992. Czechoslovakia: examining a critically ill environment. Environmental Science and Technology 26, 14-21.

Moravcik, J., Cerny, J., 1995. Forest die-back affected regions of the Czech Republic. Acidification in the Black Triangle Re- gion, 11-18, Fifth International Conference on Acidic De- position, Science and Policy. Goteborg, Sweden, 26-30 June 1995.

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Porkert, J., 1999. Some results of long-term hoarfi-ost re- search in the Orlicke hory Mts., the Czech Republic, and comparisons with hoarfi'ost from north-eastern Finland. Acta Universitatis Carolinae Environmentalica 12, 117-146.

Sehmel, G.A., 1980. Particle and gas dry deposition: a review. Atmospheric Environment 14, 983-1011.

Walcek, CJ., et al., 1986. SO 2, sulphate and HNO 3 deposition velocities computed using regional landuse and meteorologi- cal data. Atmospheric Environment 20, 949-964.