HEAVY METALS INPUT TO THE NIEPOŁOMICE FOREST (S POLAND): CHANGES DURING 20 YEARS

G. Szarek-Łukaszewska, K. Grodzińska, S. Braniewski, W. Szafer Institute of Botany,

Polish Academy of Sciences, Lubicz 46, 31-512 Kraków, Poland, e-mail Szarek@ib-pan.krakow.pl

ABSTRACT

The Niepołomice Forest is a large forest complex (110 km²) situated in southern Poland 10 to 30 km to the east of the urban industrial Kraków agglomeration and steelworks, which was built up on the outskirts of the city in 1950. Due to prevailing westerly winds, the forest is affected by pollutants emitted by both the steelworks and the city. The level of heavy metal contamination in the Niepołomice Forest was described using a sensitive bioindicator - the moss Pleurozium schreberi. Concentrations of metals in moss collected in the Niepołomice Forest in 1998 (77 sites) were (in mg/kg) Cd - 0.71, Cr - 2.4, Cu - 8.6, Fe - 673, Pb - 12.7, Zn - 61. Concentrations of heavy metals in moss in the Niepołomice Forest decreased in time. As compared with the relatively clean area in north - eastern Poland (Puszcza Białowieska), the concentration of Fe was 2-9 fold and Pb 4-6 fold higher in the Niepołomice Forest in 1975, while in 1998 4 fold and 2 fold, respectively. In both 1975 and 1998 the highest concentrations of heavy metals in moss were found in the western part of the Niepołomice Forest and along the roads inside the forest complex.

INTRODUCTION

The Niepołomice Forest is a large forest complex situated in southern Poland 10-30 km to the east of the urban-industrial Kraków agglomeration and about 70 km from the largest heavy industry region in Poland (Upper Silesia) (Fig. 1). In the fifties a huge steelworks was built at the eastern margins of Kraków. Its production was based on the old technology of the thirties. The Niepołomice Forest came under the strong influence of pollutants emitted by the steelworks as well as power stations, thermal power plants and other small industrial works constructed at the same time in Kraków.

In the early seventies the steel production in the steelworks was about 7 million tons per year, while SO₂ and dust emissions were 160,000 tons and 140,000 tons, respectively (Weiner et al. 1997). In mid seventies the first effects of these industrial emissions were observed in the Niepołomice Forest. In this period the forest became an object of intense ecological research (among others Grodziński et al. 1984). As a result of political and economic transformations in Poland at the end of the eighties industrial production considerably declined. Steel production in the steelworks was only 3 million tons, and SO₂ and dust emissions fell to 50,000 and 40,000 tons, respectively (Weiner et al. 1997). Simultaneously drainage system carried out for years in the forest caused the lowering of the ground water table. Forest management changed as well.

This situation created a unique possibility to repeat studies on the response of forest ecosystems of the Niepołomice Forest to all external influences. In 1998 an extensive program entitled „Natural and anthropogenic effects upon the functioning of forest ecosystems - 50 years of changes in the Niepołomice Forest” (Weiner J., Grodzińska K., Szwagrzyk J.) was prepared. The objective of this program was, among others, to determine the present input of airborne pollutants and changes in this input during the past decades. The presented work is part of this research and it concerns the assessment of heavy metals contamination of the Niepołomice Forest, as based on the commonly used bioindicator, the moss Pleurozium schreberi (among others Wolterbeek et al. 1995; Grodzińska et al. 1999).Characteristics of the Niepołomice Forest (climate, substratum, soil, vegetation) are given in the Table 1.

METHODS

Samples of Pleurozium scherberi (Brid.) Mitt. were collected from 77 localities through out the Niepołomice Forest between June nad July 1998 (Fig. 1).The samples were taken within coniferous and mixed forests - in southern part of the Niepołomice Forest only; at least 100 m from roads crossing the forest complex. Green parts of unwashed mosses were dried at 70^oC. Samples were digested in the mixture of acids (1 HNO₃: 4 HClO₄ vol.). Concentrations of heavy metals (Cd, Cr, Cu, Fe, Pb, Zn) were measured by AAS (Varian 20BQ) with atomization in air-acetylene flame. The heavy metal levels were shown on countour map (kriging method) and circles maps which were drawn by use of Surfer sofftware.

RESULTS AND DISCUSSION

In 1998 concentrations of heavy metals (in mg/kg) in Pleurozium schreberi from the Niepołomice Forest were 0.71 Cd, 2.4 Cr, 8.6 Cu, 673 Fe, 12.7 Pb and 61 Zn. In comparison with „clean” areas of north-eastern Poland, these values were almost twice as high in case of Pb, Zn and Cu, three times as high for Cr, and seven times as high for Cd. A comparison of heavy metals concentrations in mosses from the Niepołomice Forest with their concentrations in mosses from the forests of strongly industrialized Upper Silesia shows that in case of Cd, Pb and Zn the Niepołomice Forest is much less polluted. This result reflects differences in the amounts of pollutant emission in these areas.

The spatial distribution of heavy metals pollution of the Niepołomice Forest in 1998 was shown in Figure 2. Pollution zones were delimited using an index, as proposed by Grodzińska (1978). The western part of the forest, lying closest to the Kraków agglomeration and bordering on country towns, villages and a transit highway with heavy vehicular traffic, was most polluted by heavy metals (index > 2). The forest is cut by many local roads with light motor traffic (vehicles of local people, tourists, forest service), which results in elevated concentrations of heavy metals, and particularly Pb, in mosses.

The heavy metal contamination of Pleurozium schreberi in the Niepołomice Forest in 1998 was compared with that in 1975 (Makomaska 1978); 15 sample plots where moss samples were collected on both dates were taken into account. A ratio of the metal concentration in mosses from the Niepołomice Forest to its concentration in mosses from the Białowieża Forest, which was a control site in both 1975 and 1998, was used for comparison. The two elements (iron, lead) were chosen to illustrate the problem (Fig. 3). Iron is an element originating mostly from metallurgical industry emissions and coal burning. The sources of airborne lead are leaded petrol combustion, emissions from non-ferrous metal smelters and local coal firing (Kabata-Pendias, Pendias 1993).

In 1975 almost the whole area of the Niepołomice Forest was very polluted by heavy metals; Fe and Pb concentrations were about 3-9 and 4 times, respectively, higher than those in the Białowieża Forest. In that time dust emissions from the Kraków agglomeration were very high, amounting to 140,000-160,000 tons per year (Weiner et al. 1997). The Niepołomice Forest was also influenced by pollutant emissions from distant Upper Silesia with its hundreds of industrial works (metallurgical works, chemical and cement plants, power stations) (Grodziński et al. 1984).

Twenty years later heavy metal concentrations in mosses fell considerably in the whole area of Niepołomice Forest. They were less than twice for Pb and four times for Fe as high as in the clean Białowieża Forest. This decline in heavy metal pollution of the Niepołomice Forest was caused by a fall in the amount of dust emission and improvement of industrial technologies. Dust emission from the Kraków agglomeration was only 20,000 tons in 1995 (Weiner et al. 1997). In the seventies and the nineties the airborne deposition with heavy metals dust in the Niepołomice Forest contained 3090 and 786 mg/m²/year Fe, 27 and 12.4 mg/m²/year Pb, respectively (Manecki et al. 1981; Turzański et al. 1999). After the industrial recession of the eighties and the earlier part of the nineties, industrial production has increased. SO₂ and NO₂ contents in the atmosphere have been growing for a few years; an increase in the amount of dust, mainly alkaline, is much slower (Turzański et al. 1998). The proportion of emitted gases to dusts has changed, which is a dangerous phenomenon leading to increasing acidification of the environment. The preliminary results of studies on the input of elements with atmospheric precipitation to the Niepołomice Forest show that precipitation pH decreases. In the eighties pH of atmospheric precipitation was 5.3, while now 4.6. A balance of elements, which has also been studied, will show whether the present small heavy metals input to the Niepołomice Forest threatens the functioning of the forest ecosystem.

REFERENCES

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Table 1. Characteristics of the Niepołomice Forest (Grodziński et al. 1984)

Location	49^o59’-50^o07’ N 20^o3’ - 20^o28’ E
Area	110 km2
Altitiude a.s.l	184 - 212 m
Bedrock	Pleistocene fluvioglacial sands underlain by or interlayered with sediments, fertile alluvia of Wisła river, coehesive, very fine sands and heavy loams with sand or sandy-loam intercalations in bottom layer
Soil	grey brown (lessive) podzolic soils, brown, podzolized, gleyed soils, old warp soil
Wind	mainly from western quadrants
Precipitation (annualy)	700 mm
Air temperature	+8.2oC (VII - 18.5^oC, I i II -3.0^oC)
Vegetation period	218 days
Forest (vegetation)	mixed oak-pine forest (Pino-Quercetum), oak-hornbeam forest (Tilio -Carpinetum)
Main tree species	pine (Pinus sylvestris), oak (Quercus robur, Q. petraea)

Fig. 1. Location of the Niepołomice Forest and sampling sites of moss (Pleurozium scherberi)

Fig. 2. Variability of the pollution index values in the Niepołomice Forest. The index is defined as: Index_j=S(x_ij-x_i)/x_i where i - content of heavy metal in j - point, x - average content of i - heavy metal in all sites in the Niepołomice Forest (Grodzińska 1978)

Fig. 3. The ratio of concentration of Fe, Pb in the moss Pleurozium scherberi in the Niepołomice Forest to that in the „clean area” (Białowieża National Park) in 1975 and 1998. Concentration accepted for th clean area: 286 mg/kg Fe, 20 mg/kg Pb in 1975 (Makomaska 1978) and 301 mg/kg Fe, 9.6 mg/kg Pb in 1998.