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:Long-term Ecological Monitoring in the National Parks of Poland KRYSTYNA GRODZINSKA Institute of Botany Polish Academy of Sciences Pollution of the environment is usually determined by means of physico-chemical methods, i.e., by recording concentrations of toxic ele- ments and their compounds in the air, water, and soil. It can also be determined by means of biological methods with the help of bioindicators (Lepp, 1981a and b; Manning and Feder, 198~, Martin and Coughtrey, 1982~. Biological methods are relatively simple, quick, and inexpensive. They also have a great advantage in that organisms themselves record toxic effect of the pollution. The intent of this chapter is to discuss the use of bioindicators as a tool in the long-term monitoring of ecosystems for pollution. The level of environmental pollution can be estimated according to changes in the geographical distribution of various groups of organisms, as well as their morphological, cytological, physiological, biochemical, and chemical changes. Three types of bioindicators are usually distinguished: . scales of indicator species, noting the presence or absence of each species; · true indicators, e.g., individual species that exhibit damage propor- tional to dose; and accumulators or collectors of potentially toxic materials with or without internal damage (Grodzinski and Works, 1981~. In assessments of environmental contamination by pollutants produced by industry and motor vehicles, bioindicators of the accumulator type are most frequently used (Martin and Coughtrey, 1982~. Various groups of organisms, both plant and animal, can be accumulators (Grodzinska, 1982~. Mosses are particularly effective accumulators of heavy metal (FoLkeson, . 232
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HU1lL4N EFFECTS ON THE TERRESTRIAL ENVIRONMENT 233 1979; Grodzinska, 1978; Groet, 1976; Hvatum et al., 1983; Ruhling et al., 1987; Steiness, 1980; and filler, 1971 and 1972~. Mosses also have several advantages as indicator organisms: . Many species have a vast geographical distribution, and they grow abundantly in various natural habitats, even in industrial and urban ag- glomerations. Mosses have no epidermis or cuticle; therefore, their cell walls are easily penetrable for metal ions. Mosses have no organs for uptake of minerals from the substrate; they obtain minerals mainly from precipitation and dry deposition. · Some species have layer structure, and annually produced organic matter forms distinct segments. Transport of minerals between segments is very poor because of the lack of vascular tissues. . Mosses accumulate metals in a passive way, acting as ion exchang- ers. · Mosses show the concentrations of metals as a function of the amount of atmospheric deposition. For these reasons, mosses are used to determine the current degree of contamination of the environment, in both very extensive and quite small areas. They are also used for monitoring levels of contamination over a certain period of time—years, decades, or even centuries (Grodzinska, 1982~. The use of mosses for long-term monitoring of environmental con- tamination by heavy metals is widespread in the Scandinavian countries (Gydeson et al., 1983; Ruhling and Tyler, 1969, 1971, 1973; Ruhling et al., 1987) and also in Poland (Grodzinska, 1978; Grodzinska et al., in prep.~. In this chapter, long-term monitoring of levels of contamination in Poland's national parks during the decade 1976-1986 is discussed. MATERIALS AND METHODS Poland has 14 national parks and several hundred nature reserves which occupy less then 1% of the area of the country (Figure 1~. They cover fairly small areas, from 1,600 to 22,000 hectares, and are located from the Baltic coast through the central lowlands and uplands to the mountains (Table 1~. Virtually all of these areas are under stress from both air and water pollution and tourism. The mosses Pleuro~uim schreberi Mitt. and Hylocomium splendens (Hedw.) Br.eur. were chosen as test species. The reasons for this choice were:
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234 ECOLOGICAL RISKS TABLE 1 General characterization of Polish national parks. No. Name of park Altitude above Annual sum of Area sea level (m) precipitation (mm) (ha) 1 Slowinski 0-56 619 18,247 2 Wolinski 0-115 581 4,844 3 Wielkopolski 55-132 501 5,198 4 Kampinos 60-106 500 35,482 5 Bialowieza 147-170 585 5,317 6 Roztocze 300-390 710 6,843 7 Swietokrzyski 260-611 560, 660 5,897 8- Ojcow 305478 791 1,592 9 Karkonosze 410-1,605 1,158 5,562 10 Babia Gora 800-1,725 960-1,400 1,741 11 Tatry 800-2,499 1,112-1,810 21,164 12 Gorce 600-1,310 900-1,220 5,945 13 Pieniny 420-982 805 2,328 14 Bieszczady 630-1,346 1,035 5,587 · both Pleurozium and Hylocomium are common species and occur in abundance in forest ecosystems through Poland; · Hylocomium has hi- to tripinnate stems, with a very distinct sep- aration between each year's shoot, which makes it easy to estimate the age of the sampled segments; Pleuroaum has unipinnate stems without any clear separation between the annual shoots. The green parts of this species represent usually two- to five-year increments, whereas the brown parts are older; · these species are more effective accumulators than others; · these species have been repeatedly used for estimates of environ- mental pollution in many countries (e.g., Rinne and Barclay-Estrup, 1980; Ruhling and Tyler, 1969, 1984; Ruhling et al., 1987~. Pleurozium schreben and Hylocomium splendens were collected from the same plots in 14 national parks in Poland twice in the autumns of 1976 and 1986. In each park the material was collected at several points in both central and border areas. Unwashed mosses were separated into young, green parts and old, brown parts, dried at 85°C, and wet digested in a 4:1 mixture of concentrated nitric and perchloric acid. Seven heavy metals (i.e., cadmium [Cd], chromium [Cr], nickel [Ni], lead [Pb], copper [Cu], zinc [Zn], and iron [Fe]) were identified spectro-photometrically using the Perkin-Elmer and Varian Techtron Atomic Absorbtion Spectrophotometer (AAS).
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HUMAN EFFECTS ON THE TERRESTRIAL ENVIRONMENT Z35 -son 0 50 100 km FIGURE 1 Ideation of Polish national parks. 1-Slowinski, 2-Wolinski, 3-W~elkopolski, 4-Kampinos, S-Bialowieza, 6-Rozto~e, 7-Swietok~zyski, 8-Ojcow, 9-Karkonosze, 10-Babia Gora, 11-l~t~y, 1~Gorce, 1~Pieniny, 14-Bieszczady. RESULTS Significant differences were found in the levels of heavy metals in mosses representing particular parks (Figure 2~. The greatest difference among parlo; was found in the cases of lead, cadmium, and zinc (about ~5 timesy, with smaller differences in the case of chromium and nickel (2-3 times). Most of the heavy metals occurred in lowest concentrations in the mosses of the national parks in northern and eastern Poland; their highest concentrations were found in parks in the southern part of the country. In 1976, in the first group of parks, the concentration of cadmium was approximately 1 fig g~i, whereas in the second one it reached 6 fig gal. The respective accumulations of chromium were approximately 4 and 8 fig
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236 ECOLOGICAL RISKS g-l; nickel, approximately 3.5 and 7 fig g-l; lead, approximately 60 and up to 270 fig g-l; and zinc, approximately 70 and up to 300 fig g-1 (Figure 2~. In 1986, the cadmium content of mosses in the least contaminated national parks was about 0.5, and up to 2 fig g-1 in the mosses of the most contaminated parks. Perspective accumulations of chromium were approximately 3 and 8 fig go-; nickel, approximately 3 and 5 fig g-l; lead, approximately 40 and up to 100 fig g-l; and zinc, approximately 50 and 100 ,ug g- 1 (Figure 2~. In order to assess the general situation regarding the contamination of Polish national parks by heavy metals, a synthetic pollution index was used. It represents the mean, standardized contents of six elements (Cd, Cr. Ni, Cu. Pb, and Zn) in mosses. For example: Cd cone. in Ojcow National Parks Standardized value of Cd = - mean Cd cone. in 14 National Parks index = (Ojcow NP) = sum of standardized values of 6 heavy metals According to this index, parks were classified as being relatively clean, moderately contaminated, or heavily contaminated. The maritime parks and those in the eastern part of Poland were classified in the first category. The moderately polluted group is represented by parks in the central, lowland part of the country as well as some mountain parks. Parks located in the uplands and in the higher mountain ranges in southern Poland are the most polluted (Figure 3~. A change was found in the contamination of national parks by heavy metals over the last ten years. The present concentration in mosses of toxic metals such as cadmium, lead, and zinc has fallen twofold, while that of nickel, chromium, and iron is 20-26% lower than in 1976 (Table 2~. Except for iron and nickel, these differences are significant, and highly significant statistically (liable 3~. However, the changes in the contamination of mosses by heavy metals are different in particular parks. In those parks which were very heavily contaminated 10 years ago (e.g., Oj cow, Karkonosze, and Swietokrzyski), the mosses at present contain smaller quantities of heavy metals. In the three parks that were slightly and moderately contaminated in 1976 (e.g., Bialowieza, Bieszczady, and Kampinos), the level of concentration of heavy metals is similar to current levels, while in three other parks Entry, Pieniny, and Wielkopolski), it has increased considerably (Figure 4~. The differences in the concentration of heavy metals across Poland were much more pronounced in 1976 than in 1986. This is supported by the results of statistical analysis (Table 3~. In 1976, the differences were highly significant statistically for all the heavy metals, while they were highly significant only for chromium, copper, and lead in 1986 Cable 3~.
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HUDSON EFFECTS ON THE TERRESTRIAL ENKIRONhIENT 237 a (1976) 119O 1 d SO- W_ _ ~ ,,,9 9-1 L11 19 cow it, l . ~'1 v FIGURE 2a Cd, Cr. Ni, Pb, Zn, (pa g-1 dw) concentrations in Pleurozium schreben in the Polish national parks The mean contents of metals in the green and brown parts of the mosses are indicated for both the central and the peripheral areas of the parks. A-1976, B-1986. Parks no. 1-14, as identified in Figure 1. The differences in the metals content between mosses in the central and border parts of the national parks were also determined. These were highly significant in 1976 for all the heavy metals analyzed, except cadmium. The metals also occurred in higher concentrations in mosses growing in the outer parts of parks. This situation changed in 1986. The mosses
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238 FIGURE 2b A (1976) ~ ti~1 ~> <\ 1 1 ECOLOGICAL RISKS l 19° , , 20~99 - Pb Zn 19 l me, 5 . it accumulated metals, except nickel, in similar quantities, both in the center and at the edges of the parks (Table 3~. In addition, highly significant statistical differences were found in concentrations of heavy metals between the younger, green and older, brown parts of mosses, both in 1976 and at present Amble 3~. These differences were much more pronounced in 1986. Finally, it was shown that Pleurozium schreberi and Hylocomium splen- dens accumulated cadmium, nickel, and chromium in similar quantities in 1976, but differed statistically in the level of accumulation of copper, lead,
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HUAL4N EFFECTS ON THE TERRESTRIAL E~IRONME~ B (1986) _540~ -50° FIGURE 2c 2~9 ~ — gso0- J 1,ug 9-1 111 A~O Cd Cr Ni zinc, and iron (Table 3). In 1986, four elements (Cd, Cu. An, and Fe) occurred in similar concentration in both mosses species, and three (Ni, Cr. and Pb) differed from them in concentration (Table 3~. DISCUSSION The contamination of Polish national parks by heavy metals, deter- mined by analyzing mosses, correlates well with the distribution of sources of industrial emissions in Poland (Kassenberg and Marek, 1986; Kassen- berg and Rolewicz, 1985~. The parks in the southern parts of Poland
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240 soo ECOLOGICAL RISKS l 19° B (1 986) sol I art' /i~ ,~ i ~~ \ N~-/J ~3 v:~-l\ 11 S ~ ~ ~~ ~~ 11 , ,~ ~~!~; : 20 ~'9. 9 -1 Lo 19° Pb Zn I FIGURE 2d are most polluted (e.g., Ojcow, Babia Gora, Tatry, Pieniny, Karkonosze, and Swietokrzyski). These parks lie within the range of emissions from the Silesian-Krakow, Legnica-Glogow, and Central Industrial regions. The moderately contaminated parks (i.e., Wielkopolski and Kampinos) are lo- cated at a considerable distance from the great industrial centers, but close to large cites such as Warsaw and Poznan. The cleanest parks (i.e., Slowinski, Wolinski, Bialowieza, Roztocze, and Bieszczady) lie in the least industrialized parts of Poland. The results show that the contamination of mosses with heavy metals has decreased noticeably during the last decade in the Ojcow, Swietokrzyski, and Karkonosze parks, but only slightly in three others, i.e., Kampinos, Bieszczady, and Bialowieza; contamination has increased in the mountain
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HUAL4N EFFECTS ON THE TERRESTRL4L ENKIRONM~ TABLE 2 Heavy metal concentration (ug go) in mosses in 14 Polish national parks (mean concentration over all parks). Pleurozium Hylocomiwn Element 1976 1986 1976 1986 Cd 1.80 0.94 2.27 0.92 Cr 6.58 5.51 7.19 4.63 Ni 5.10 4.21 4.62 3.25 Pb 108 59.0 92.3 45.4 Zn 132 73.5 122 65.1 Fe 1,870 1,598 1,768 1,352 ; TABLE 3 Statistical analysis of He difference between heavy metals concentrations in Pleurozi7~m (P) and Hylocomiwn (H). 241 F-VALUES AND LEVEL OF SIGNIFICANCE Species Central & border (P ~ H) Parts of mosses pans of parks Parks Years 1976 1986 1976 1986 1976 1986 1976 1986 76/86 Cd 131.68b 4.40 3.63 P 8.56 P 3.30 0.01 144.86 3.72a S.73a 0.08 H 9.58 Ha Ni 1.26 6.2Sa 48.93 Pa 43.81 pc 18.175 6.87a 33.516 5.33b 2.93 19.99 Hb 22.16 Hb Cr 0.81 7.36a 35.56 Pa 37.21 pc 31.916 1.88 27.726 2.15 S.59a 10.96 Ha 22.94 H. Cu 166.665 1.35 17.87 P 0.75 P 49.70b 2.58 61.555 2.51 5.14a 13.91 H. 4.48 H Pb g.gga g.5ga 14.41 Pa 41.90 pc 101.985 0.18 200.775 1.88 9.645 45.04 H. 54.23 He Zn 8.67a 1.29 3.98 P 43.23 pc 202.496 0.45 384.966 3.9Sa 9.37a 6.48 Ha 14.49 H. Fe 7.37' 1.04 38.93 Pa 56.15 pc 46.0C' 2.89 6~00, 4.48a 1.95 41.15 8.20 Ha a = P < 0.05 b = P < 0.01 c = P < 0.001 parks at ~try, Pieniny, and Babia Gora. The deposition of metallurgical dusts in 1976 was 173,000 tons (0.6 t/km~2) over the entire- area of Poland, and under 140,000 tons per year (0.4 t/km~2) in the period from 1980- 1984, but rose again in 1985 and 1986 to nearly 170,000 tons per year (GUS Statistical Yearbook, 1976-1986~. The decrease in the deposition of metallurgical dust was most pronounced in the large industrial regions (i.e., Silesia-Krakow, Legnica-Glogow, and the Central Region) and adjacent areas. In central and southern Poland, however, this change was quite small (GUS Statistical Yearbook, 1976-1986~. Changes in the amounts of heavy metals, as recorded by the analysis of
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242 ECOLOGICAL RISKS A (1 976) I (Eva. (Db. ~c. /_- . - 5 FIGURE 3a Pollution index values for the Polish national parks defined as a sum of standardized contents of heavy metals in mosses. a-relatively clean parks, lo-moderately polluted parks, c-heavily polluted parks. A-1976, B-1986. Parks no. 1-14 as identified in Figure 1. mosses in national parks, correlate well with changes in the total emission of dusts in the period from 1976-1986 in Poland. The mountain parks (Tatry, Babia Gora, and Pieniny) are the exception. These lie at Poland's southern borders, and consequently are exposed to additional heavy metals- from Czechoslovakia. Gydesen et al. (1983), Ruhling and Tyler (1984), and Ruhling et al., (1987) found an analogous decrease in the level of heavy metals in mosses in Scandinavia over the period 1968-1985. They cite data demonstrating a gradual decrease in emissions of metallic dusts in various countries of
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HUMAN EFFECTS ON THE TERRESTRL4L ENVIRONMENT _ B (1 986) :-( \2 \ A::::::} \ ~3 :4 ~9 ~ ~ I I 1 1 1 1 1 1 1 1 1 t I I 1 1 1 ~ . J , j . I I j I j I I I I ~ I , 1 1 1 1 1 1 1 T' I, I, ~ 'I ~ ~ ~ ~ ~ . ~ ~ ~ Sm 10 1111111 1111111111 / ~ J '] ~ ~1' 1 1 ~ ~ ~ '1rr TI! ~ V- ~ ~ ~ Nlilil 1111111~ 1 _~ IT 1 1 1 IN 1 1 1 1 : 1 1 1 1 ~ 1 1 ~ ~ ~ _ _ I ~ ~ ~ I` I ~ ~ ~ ~ ~ ~ ~ ~ U ,' ~ ~ ~L~' ~a. (3b. ~c. FIGURE 3b 243 western and central Europe. In Poland, there was also a decreasing trend in the emission of industrial dust during this period. This decrease was most pronounced in the early 1980s, due to a recession in heavy industry. Mosses reflected this trend with precision because their biomass accu- mulates dust from the previous 3 or 4 years. It has been noted that the differences in concentration between the younger, green and older, brown parts of mosses were greater in 1986 than in 1976. This reflects the low deposition of metallic dusts in the early 1980s (presently the brown parts of mosses) and slightly greater deposition in the mid-1980s (presently the green parts of mosses). While in some mountain parks (e.g., Karkonosze) forest decline has been observed over the last decade, it should be attributed to other, gaseous, pollutants such as SO2 and NO. The differences in the contamination of mosses by heavy metals among
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244 E10 1 2 3 4 ECOLOGICAL RISKS _, ·~- ::: :-: . :-- .. ·:- ·. . .. . .- . : ·. .- :: . ·.- 6 10 11 12 FIGURE 4 Changes in moss contamination by heavy metals in Polish national parks. a- pollution index value in 1976, lo-pollution index value in 1986. Parks: 1-Slowinski, 2-Wolinski, 3-Pieniny, 4-Bialowieza, S-Wielkopolski, 6-Bies~czady, 7-Kampinos, S-lit~y, 9-Babia Gora, 10-Swietok~zyski, 11-Karkonosze, 12-Ojcow. particular parks were very clear in 1976. At present they are less distinct. This can be explained by the creation of other, local sources of emission of metallic dusts in central and northeastern Poland. Current decreases in the concentration of heavy metals in mosses between the central and outer parts of parks demonstrates that entire park areas are now subjected to the pressure of emissions; hence, the functioning of the ecosystems of these parks is currently at greater risk The contamination of mosses by heavy metals in Poland is especially great when compared with Scandinavia (Ruhling and Tyler, 1973, 1984; Ruhling et al., 1987~. The most endangered Polish parks have two to four times as much cadmium, nickel, lead, iron, zinc, and chromium than do the most heavily polluted parts of Sweden and Norway. As compared with the clean parts of northern Scandinavia, the heavily contaminated Polish national parks had three to five times as much nickel and zinc, over 70 times as much cadmium, and over 10 times as much lead and chromium in 1976. In 1976, the mosses from the cleanest parks in Poland accumulated about
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HUMAN EFFECTS ON THE TERRESTRL4L ENVIRONME~ 245 twice as much iron, zinc, chromium, and nickel; six times as much lead; and over 10 times as much cadmium as the mosses in northern Scandinavia. In 1986, the seriously contaminated Polish parks were three to five times more polluted, and the cleanest parks about twice as polluted, by these heavy metals than northern parts of Scandinavia. MANAGEMENT RECOMMENDATIONS Management of Polish national parks must take two special circum- stances into consideration: the relatively small park areas and the heavy contamination of the air and water. The various types of protected areas in Poland such as national parks, nature reserves, and landscape parks presently cover 3.9 million hectares, which represents 10% of the total area of the country (GUS Statistical Yearbook, 1986~. Most are grouped in the southern part of the country, where the natural landscape is most varied. At the same time, southern Poland is the most industrialized and under the greatest stress from industrial emissions. The value of the Polish national parks is reflected by the fact that three of them (Babia Gora, Bialowieza, and Slowinski) were declared UNESCO biosphere reserves. National parks in Poland and central Europe are small, many times smaller then those of North America, the USSR, and even Scandinavia. The idea behind the establishment of such small national parks in the very heart of industrialized Europe is to protect the diversity of ecosystems and species rather than regenerate to the original climax. Therefore, management of Polish national parks must include practical measures to allay the affects of air pollution until such time as the emission of gases and dusts can be controlled. These parks can, however, serge well for studies of long-term changes in the ecosystem. The network of national parks in Poland and other European countries can be utilized for monitoring long-term changes caused by air pollution. These parks are small and exposed to local and global air pollution. This study supports the use of mosses (~PIeurozium schreberi and Hylocomium splendens) as very sensitive bioindicators (bioaccumulators) for air pollution by heavy metals. They can be used easily for ecological monitoring on various scales and areas. However, the procedures for sampling moss and subsequent laboratory analysis must be unified (Grodzinska, 1984~. REFERENCES Folkeson, L" 1979. Interspecies calibration of heavy metal concentrations in nine mosses and lichens: Applicability to deposition measurements. Water, Air and Soil Pollution 11:15~260. Grodzinska, K 1978. Mosses as bioindicatom of heavy metal pollution in Polish national parks. Water, Air, and Soil Pollution 9.8~97.
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246 ECOLOGICAL RISKS . 1982. Monitoring of air pollutants by mosses and tree bark. Pp. 3342 in the Proceedings of the International Workshop, "Monitoring of Air Pollutants by Plants: Methods and Problems," L. Steubing and HJ. Jager, eds. Osnabruck (F RG), September 24-25, 1981. The Hague, Boston, and London: Dr. W. Junk Publishers. . 1984. Bioindicators of environmental deterioration. Pp. Z7-34 in Forest Ecosystems in Industrial Regions, W. Grodzinski, J. Weiner, and P.F. Maycock, eds. Ecological Studies 49:1-277. Berlin/Heidelberg/New York~okyo: Springer Verl. Grodzinska, K., B. Godzik, and G. Szarek, in preparation. Heavy metal accumulation in Polish national parks: Changes over ten years. Grodzinski, W., and T.P. Yorks. 1981. Species and ecosystem level bioindicators of airborne pollution: An analysis of two major studies. Water, Air, and Soil Pollution 16:33-53. Groet, S.S. 1976. Regional and local variations in heavy metal concentrations of bryophytes in the northeastern United States. Oikos 27:445-456. GUS (Statistical Yearbook of the General Statistical Department). 1976-1986. Warszawa. Gydesen, H., K Pilegaard, L Rasmussen, and A. Ruhling. 1983. Mosses analyses used as a mean of surveying the atmospheric heavy metal deposition in Sweden, Denmark, and Greenland in 1980. National Swedish Environment Protection Board Bulletin 1670:1-44. Hvatum, O.O., B. Bolviken, and E. Steinnes. 1983. Heavy metals in Norwegian ombrotrophic bogs. Pp. 351-356 in Environmental Biogeochemistry, R. Hallberg, ed. Ecol. Bull. (Stockholm) 35. Kassenberg, ~, and MJ. Marek. 1986. Ekologiczne aspekty przest~zennego zagospodarowa- nia kraju (Ecological aspects of the spatial development of the country). Warszawa: PWN (State Scientific Publishers), pp. 1-174. Kassenberg, A., and C. Rolewicz. 1985. P~zestrzenna diagnoza ochrony srodowiska w Polsce (Spatial diagnosis of environmental protection in Poland). Komitet Przestnennego Zagospodarowania Kraju. PAN. Studia 89:1-125. Warszawa: PW (State Economic Publishers), Ekon (Committee on Spatial Development of the Count~y of the Polish Academy of Sciences). Lepp, N.W. 1981a, ed. Effect of heavy metal pollution on plants. Vol. 1. Effect of trace metals on plant functions. London: Applied Science Publishers, Ltd. . 1981b, ed. Effect of heavy metal pollution on plants. Vol. 2. Metals in the environment. London: Applied Science Publishers, Ltd. Manning, WJ., and W.A. Feder. 1980. Biomonitoring air pollutants with plants. London: Applied Science Publishers, Ltd. Martin, M.H., and PJ. Coughtrey. 1982. Biological monitoring of heavy metal pollutions. London: Applied Science Publishers, Ltd. Rinne, R.J.K, and P. Barclay-Estrup. 1980. Heavy metals in a feather moss—Pleurozium schreben and in soils in Northwest Ontario, Canada. Oikos 34:43-54. Ruhling, A., L" Rasmussen, K Pilegaard, A. Makinen, and E. Steinnes. 1987. Sunrey of atmospheric heavy metal deposition in the Nordic countries in 1985 monitored by moss analyses. Nord 21:144. Ruhling, A., and G. Tyler. 1969. Ecology of heavy metals- a regional and historical pollution study. Bot. Notiser 122:248-259. . 1971. Regional differences in the deposition of heavy metals over Scandinavia. J. Appl. Ecol. 8:497-507. . 1973. Heavy metal deposition in Scandinavia. Water Air and Soil Pollution 2:445-455. , , . 1984. Recent changes in the deposition of heavy metals in Northern Europe. Water, Air, and Soil Pollution 22:173-180. Steinnes, E. 1980. Atmospheric deposition of heavy metals in NoIway studied by analysis of moss samples using neutron activations analysis and atomic absorption spectrometry. J. Radioanal. Chem. 58:387-391. Tyler, G. 1971. Moss analysis: A method for surveying heavy metal deposition. Pp. 129-132 in the Proceedings of the 2nd International Clean Air Congress, Washington, D.C. . 1972. Heavy metals pollute nature, may reduce productivity. Ambio 1,2:29-52.
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