THE RADIOACTIVE CONTAMINATION OF SOUTHWEST SPITSBERGEN TERRITORY

Transkrypt

1 Marek Reszka, Jerzy Szezy pa Department of Radiochemistry Institute of Chemistry Maria Curie-Sklodowska University Lublin, Poland Wyprawy Geograficzne na Spitsbergen UMCS, Lublin 1991 y^t THE RADIOACTIVE CONTAMINATION OF SOUTHWEST SPITSBERGEN TERRITORY INTRODUCTION The ecological impact of nuclear explosions at the Chernobyl Nuclear Power Station catastrophe in 1986 gave the world its first real encounter with a severe nuclear accident and its implication for all mankind. Significant pollution of the environment was detected in the whole Europe. Our preliminary investigations of the radioactive contamination of polar environments were carried out in summer 1990 during the 5-th Polar Expedition organized by Maria Curie-Skłodowska University (UMCS) Lublin, Poland. Soil and plant samples were collected from sites in the southern part of Bellsund in Western Spitsbergen. The low quality sandy soil, eolian deposits, as well as more fertile loams and peats, were prepared according to international standard methods. A sample of soil, which dates from 17-th century, was taken from an excavation at the sea shore. Lichens, mosses, and a few vascular plant species were picked up from their sites in tundra and the mountains in the vicinity of bird colonies. The measurements of two samples of plants from the vicinity of Murmansk (Soviet Union) and some data for samples collected in the Eastern Poland territory are presented for comparison. GENERAL CHARACTERISTIC OF THE AREA OF STUDIES Spitsbergen with its arctic climate, lack of the compact plant cover is often named the arctic desert. During short summer only 15% of the territory is uncovered. Preceding warming up of the global climate results in retracting of glaciers, exposing new nival moraine terraces. The main area of studies was Calypsostranda, the maritime plain constituting a system of uplifted marine terraces and mountain chain surrounding the Recherche Fiord. Its surface is built of Quaternary formations, fluvioglacial sands and gravels, boulder clays SOILS. 179

2 and marine loams. The more detailed characteristic of Spitsbergen soils can be found in other papers (Klimowicz, Uziak 1987; Melke, Chodorowski, Uziak 1989). On the basis of the previous studies these soils can be divided in a few groups depending on their level of development (age), mineral composition, and localization (Melke, Chodorowski, Uziak 1989; Uggla, 1981). The following order was proposed: 1 weathered rocky soil, 2 initial soil, 3 brown soil, 4 gley soil, 5 peat soil, 6 alluvial soil, 7 fossil soil. Intense corrosion of rocks, niveo-eolian processes during winter and accumulation of dust in summer forms the first group of soil. The samples of this kind were collected in hollows within moraines and fore fields of glaciers. As was expected, this material showed almost no radioactivity resulting from its low adsorption ability but mainly because of intense washing by glacier rivers. The next set of sa!mples was taken on dry tundra plains and can be classified as brown soil. These soils were formed on well permeated sands and gravels of marine terraces create a shallow layer under poor vegetation. The more complex soil gley is formed on boulder clays. The samples of this soil were collected in the more wet zones of tundra, gentle slopes of hills and river banks. The richest, peat soil, can be found in damp areas of peat bogs near small tundra lakes, under the compact layer of mosses. It has relatively small density because of the great amount of weathered and decayed parts of plants. It is supposed that presence of bird colonies has a profound influence on formation of this soil. A few samples were taken from accessible mountains; Wijkanderberget, Klokkefjellet, Maria Theresa (up to 560 m altitude). At Cap Smith, at the sea shore, the retreating glacier revealed a layer of dark soil under moraine stones. Some findings from this excavation allowed this soil to be dated from 17th century (Krawczyk, Reder, 1989). This site was covered by glacial ice until The soil samples were taken from under the stone coat. All samples were collected according to IAEA standardized methods, then dried and the fraction over 2 mm was removed by sieving. After estimating the density, the radioactivity of each sample was measured using a model 5500B, Beckman Gamma Counter. Results are presented in Table 1. PLANTS. Due to the minute area of soil, the plant cover of Spitsbergen is extremely poor. The short season of vegetation, which lasts from July to August, strong (up to 20 m/s) winds, and low temperatures make the polar environment very severe. Arctic flora of this region consists mainly of numerous species of algae, lichens and mosses and a few small vascular, alpine type plants. A more detailed description of Spitsbergen flora can be found in other papers (Rzętkowska, 1987). Algae and lichens appear as a first form of life on areas exposed by retracting glaciers on rocky moraines. Producing some organic acids, they contribute in 180

3 decomposition of the rock bed. It is well known that owing to their developed surface, lichens can adsorb many elements from their surroundings. Thus, they are widely used as indicators of environment contamination by heavy metals and radioactive elements (Beckett, Boileau, 1982; Jóźwik, 1989, 1990). Liverworts as the dominant species of lichens in Bellsund area were picked for radioactivity measurements. Mosses form a group of more complex plants. They can be found in wet zones of tundra plains and at the feet of mountains with bird communities. Due to the accumulation of the bird excrements, the moss colonies are particularly luxuries. This group of plants is also well known as pollutant sensitive. The most developed plants can be found in the wide areas of dry, grassy tundra. They form a mosaic like conglomeration of many species growing in less compact groups. Grass clumps with weak, thin blades can be found in a damp places on the glacier river banks. Plant roots were removed and the remaining samples were dried and crumbled and then their radioactivity was measured. The average results, showing the gamma radioactivity level of Cs-137 are presented in Table 2. Similarly to data obtained from other areas, mosses are the most radioactively contaminated group of plants. The level of pollution depended on the altitude of the sample collection as well as its exposition to wind and water. The less intense radiation than in mosses can be found in vascular plants having very compact structures which help them to hold the particulates. The samples which consist of leaves and flowers were the cleanest of all. The amount of radioactivity of Spitsbergen plants was compared with that of similar plants taken from Poland. (Szczypa, Solecki 1990; Proches, Pinglot 1986). Two samples of tundra plain vegetation were collected 200 km east of Murmansk in November They reveal a quite unexpectedly high level of contamination, about four times greater than for similar mosses at Spitsbergen and much higher than in Poland. These results are included in Table 2. SUMMARY Far away from human activity Spitsbergen has not avoided radioisotope contamination from Chernobyl fallout. The first radioactivity was observed»at Svalbard on May 4 in snow precipitation. The fresh snow samples showed that the pollution was in the same order as that during atmospheric nuclear test 1963 (Porches, Pinglot 1986; Holsworth 1984, Cunningham, Sago 1990). Many papers prove that Chernobyl fallout was world wide disaster with its effects reaching as far as the South Pole (Phillipot, 1990). All samples were measured in the Department of Radiochemistry UMCS with a Beckman Gamma Counter (Cs-137 window). 181

4 No radioactivity was detected at Spitsbergen in the glacier ice and in water. Despite the six times greater distance from Chernobyl to Spitsbergen, than to Poland the contamination of polar plants and soils is almost the same in range. The sorption properties of soil have a dominant effect on the retention of the radioactive elements. The more developed soils reveal the higher level of radioactivity. The samples of soils located in water courses were less contaminated because of intense washing. The more exposed soils on the top of the mountains and on the wide opened plains were more polluted. The measured radioactivity of samples from excavation was slightly above the background level. It was probably because of the good permeability of upper layers and contamination the soil by seeping water. As one could expect, lichens and tundra mosses adsorb and accumulate many elements from their environment. The radioactive elements were found in all of them. The level of contamination is comparable with that found in Poland. Content of the studied radioisotopes in plants depend on the species of plants and place of growing. Samples of perennial lichens and mosses contain more activity than samples of fresh flowers and leaves of vascular plants. The remarkably high level of radioactivity of the two samples picked up near Murmansk as well as other data (Kwapuliński, 1975; Cunningham, Sago 1990) suggest that atmospheric nuclear explosions in the vicinity in previous years played a significant role in radioisotope contamination of the polar region. REFERENCES Beckett P. J., Boileau L. J., 1982: Lichens and Mosses as Monitors of Industrial Activity. Envir. Pollut. 4, 69. Cunningham W. P., Sago В. IV., 1990: Environmental Science A Global Concern., C. Brown Publishers. G., 1984: Atm. Envir : Metale ciężkie w roślinach tundry spitsbergeńskiej rejon Bellsundu. Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Jóźwik Z., 1990: Heavy metals in the tundra plants of the Bellsund region, Spitsbergen. II. Blomlidalen, Dyrstadflya and Lognedalen, Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Klimowicz Z., Uziak S., 1987: Gleby na obszarze Calypsostrandy (Spitsbergen Zachodni). XIV Sympozjum Polarne, Lublin. Krawczyk A., Reder./.: Pozostałości osadnictwa sezonowego w północno-zachodniej części Ziemi Wedela Jarlsberga. Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Kwapuliński J., 1975: Skażenia promieniotwórcze na wybranych terenach południowej Polski. Wyd. Śląsk Katowice. Measurements of Radionuclides in Food and the Environment. A Guidebook. International Atomic Energy, Vienna, Holsworth Jóźwik Z., 182

5 Melke J., Chodorowski J., Uziak S., 1989: Kształtowanie się gleb na obszarze Dyrstad i Logne w rejonie Bellsundu (Spitsbergen Zachodni). Wyprawy Geograficzne na Spitsbergen, UMCS Lublin. Phillipot J. C., 1990: Fallout in Snow. Nature, 348, 21. Porches M., Pinglot J. F., 1986: The Northerly Extent of Chernobyl Contamination. Nature 323, 676, Rzętkowska A., 1987: Wstępna charakterystyka roślinności rejonu Calypsostranda. XIV Sympozjum Polarne, Lublin. Szczypa ]., Solecki J., 1990: Estimation of Radiochemical Contamination of Eastern Part of Poland. International Symposium on Post Chernobyl Environmental Radioactivity Studies in East European Country! Kazimierz, Poland. Uggla H., 1981: Gleboznawstwo rolnicze. PWN Warszawa. STRESZCZENIE Od końca II Wojny Światowej do 1980 roku przeprowadzono w atmosferze około 450 wybuchów jądrowych. W roku 1986 awaria elektrowni atomowej w Czernobylu spowodowała uwolnienie do atmosfery znacznych ilości pierwiastków promieniotwórczych i rozprzestrzenienie ich na rozległe tereny północnej półkuli. Od kilku lat tematem badań Zakładu Radiochemii UMCS są skażenia roślin i gleb na terenie wschodniej Polski. W lecie 1990 roku w ramach wyprawy geograficznej UMCS terenem badań zostało objęte południowo-zachodnie wybrzeże Spitsbergenu. Posługując się na miejscu przenośną aparaturą dozymetryczną nie stwierdzono skażenia lodu ani wody w rzekach lodowcowych. Próbki glebowe i roślinne pobrane były z dostępnych miejsc w promieniu 20 km wokół bazy na wybrzeżu fiordu Bellsund. Do badań pobrano próbki materiału pochodzenia eolicznego, gleb brunatnych, glejowych oraz torfu. Spod wału morenowego pobrano próbkę gleby pochodzącą z XVII wiecznego siedliska. Ze względu na ubogą szatę roślinną zebrano około 20 gatunków flory polarnej głównie mchów i porostów oraz drobnych roślin kwiatowych. Poziom aktywności zebranych próbek został zmierzony w Zakładzie Radiochemii UMCS przy pomocy spektrometru gamma firmy Beckman (w zakresie energii CS-137). Stwierdzono duże wahania w wielkości skażenia wynikające z rodzaju i miejsca pobrania próbki. Dla porównania zamieszczone zostały wyniki pomiarów gleb i roślin ze wschodniej Polski a także dwie próbki z okolic Murmańska (ZSRR). Sugeruje się, że stosunkowo duże skażenie obszarów Spitsbergenu jest nie tylko wynikiem awarii w Czarnobylu ale także sąsiedztwa poligonów na Nowej Ziemi i przeprowadzanych tam eksplozji jądrowych. 183

6 Tab. 1. The average level of soils contamination of West Spitsbergen No. Plant Location Activity [Bq/kg] 1. Ciadonia rangiferna Wijkanderberget Cetraria Ciadonia rangiferna Klokke pass Briophyta (mosses) tundra near Scott river Briophyta (mosses) - и Saxifraga opposit. Dyrstad valley Silene acaulis Snatcherpynten shore Briophyta (mosses) Dyrstad valley Briophyta (mosses) foot of Bohlinrygen Saxifraga opposit. Renard moraines Saxifraga opposit Briophyta (mosses) Calypso tundra Briophyta (mosses) Reisletta plain Briophyta (mosses) Jarnbekken slope Briophyta (mosses) Obserwatoriefijelet slope Briophyta (mosses) -» Papaver daheianum Calypso tundra Saxifraga opposit. Scott river estuary Dryas pctopetala Blomli tundra, Salix polaris Klokke plain (hus) Poa alpina Blomli slope Deschampsia caespitosa Scotta river estuary Poa alpina Wydrzyca river valley Poa alpina Klokke valley Eriophorum Maria-Theresa slope Cerastium alpinum Klokke plain 75 The average level of grass contamination in Poland befofe the Chernobyl fallout Bq/kg The level of mosses contamination in Poland in Bq/kg The level of contamination of vascular plant taken from Murmańsk vicinity 973 -"- The level of contamination of a moss sample taken from Murmańsk vicinity "-

7 Tab. 2. The average level of radioisotope contamination of plants at West Spitsbergen 2 No Type of sample and Activity [Bq/kg] [Bq/m ] its location 1. eolian - Renard glacier moraine ablation - Renard gl. moraine ablation - Scotta gl. foreland ablation -Renard gl. sandr ablation - moraine of Blomli valley ablation - Recherch gl. foreland ablation - moraine of Dyr-stad valley eolian - Tiorn valley eolian - Wijkander pass gley - Klokke pass ll.gley - Snatcherpynten valley gley - Scott river banks brown soil - Maria-Theresa slope gley - foot of Observatoriefjelet peat - Klokke plain peat - Reinsletta valley , peat - Klokke plain (hus) peat - Calypso plain peat - Observatoriefjelet slope excavated sample from Cap Smith The average level of soil contamination in Poland before Chernobyl fallout. 481 Bq/kg The maximum level of soil contamination in Poland in May Bq/kg 185

8 oo CTs Rochesterpynten Renardodden Fig. 1. Location of studied area and distribution of soil samples.

9 Fig. 2. Location of studied area and distribution of plant samples.