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THE STATE OF THE FOREST ECOSYSTEM IN AN AREA OF OIL SHALE MINING AND PROCESSING 1. CHEMICAL COMPOSITION OF TREES AND ENVIRONMENT

1999; Estonian Academy Publishers; Volume: 16; Issue: 3 Linguagem: Inglês

10.3176/oil.1999.3.07

1736-7492

M Mandre, K Ots, J Rauk,

Engineering and Environmental Studies

The state of Norway spruce stands on a ferritory influenced by air pollution from oil shale mining and processing was investigated in 1996-1998.Sample plots were selected in different directions from the industrial centre of Kohtla- Jirve (Ida-Viru County, North-East Estonia).After a decrease of the emission of oil shale fly ash and a lower total concentration of pollution from industrial enterprises, the chemical composition of needles and shoots still showed latent injuries and deviations in the biochemical state of trees.Also the soil humus horizon, subsoil water and precipitation were still notably alkaline.Introduction О1 shale mining and processing are the most important industries in Estonia.Before 1990 the whole economic activity was characterized by intensive and unbalanced production and serious social-economic and ecological problems.Negligent attitude towards environmental protection has led to the pollution of ecosystems in many areas of Noirth-East Estonia.The state of the atmosphere depends first of all on prolonged emissions from the industrial enterprises.Over 40 years oil shale mining and processing in the area of Kohtla-Jirve, the main industrial centre in Ida-Viru County, has brought about several ecological problems like changes in the state of forests [l], soil, surface and ground water [2].Pollutants emitted from stationary sources of oil shale processing and chemical plants in Kohtla-Jirve have a multicomponental chemical character.They consist of hazardous gaseous components, soil particles and aerosols.The proportion of alkaline ash in the pollution complex has changed from year to year, making up 16-30 %.Gaseous pollutants have predominated in air pollution complexes: SO, has made up 42-56 %, CO B-lo % and NO, 2 %.From oiganic pollutants 30 % of aromatic and 60 % of aliphatic hydrocarbons have been established [3,4].Ida-Viru County is one of the most forested areas in Estonia, making up more than 10 % of all forest land [s].Essential forest damages from human pressure were observed during the period of intensive industrial activity in Ida-Viru County [3, 6, 7].Estonian forest monitoring showed that 14 % of young spruce had only I-2-year-old needles [6, 8] and in autumn 1992 only current year needles were found on numerous pines [9].The reduction in the emission of pollutants has led to a decrease in air pollution in North-East Estonia.Nevertheless, several problems such as alkalization of the environment, high concentrations of accumulated pollutants ш е substrate, starting neutralization processes in the environment caused by diminishing concentrations of dust and ash in pollution complexes, should be studied thoroughly.Special attention should be paid to estimating changes taking place in forest ecosystems as several forests are commercial forests or protected forests and parks in this region.The main aim of integrated monitoring in the forests is to determine the state of forest today.A detailed investigation of forest sample plots in different directions from the industrial town of Kohtla-Jarve was carried out by the authors of this paper.The aim of our investigations was to estimate the state of the forest ecosystem and trees in 1996-1998, the period of rapid decrease in air pollution in an area that used to be highly polluted.The object of our study was Norway spruce (Picea abies L.), one of the prevailing tree species in Estonian forests. Study Area and MethodsThe research was carried out in the neighbourhood of Kohtla-Jarve and Johvi towns, North-East Estonia, in 1996-1998.