engleski

Fluoride content in soil and vegetation

Until the war the production of aluminium was 75.000 tons per year and emission of fluorides 17 kilograms per ton. Gaseous fluorides, particularly hydrogen fluoride, are among the most phytotoxic air pollutants and have been a threat to vegetation on a local or regional scale in the highly industrialised countries (Klumpp, Domingos, and Klumpp, 1996). Relatively few studies have been directly concerned with the effects of fluoride-containing particles on plants, and it has been generally assumed that this form of airborne fluoride is much less phytotoxic than the gaseous. Most particulate fluorides (cryolite, calcium fluoride, sodium fluoride) are stable compounds that do not hydrolyze readily with vapour in the atmosphere. Therefore, their removal from the atmosphere is controlled by dry and wet deposition. Climatic conditions are important in determining the effects of deposited particulate emissions on plants and animals. Light rains may deposit fluorides from the atmosphere on vegetation whereas heavy rains may partially wash off fluoride dusts from vegetation to soil. In arid regions, the dusts may accumulate on vegetation and be ingested by grazing animals. In areas of heavy precipitation, plants may take up washed-off fluorides from the soil. It has been estimated that >90% of natural fluoride in soil is insoluble or tightly bound to soil particles. The mobility of fluorides in soil is enhanced if the solubility of fluorides is increased, either by increased acidity or by formation of soluble complexes. The purpose of this study was to determine the accumulation of fluoride in two plant species (Pinus halepensis and Olea europea) and in the soil in the vicinity of aluminium reduction plant, which was destroyed during the aggression on Croatia 1991.

fluorides; soil; vegetation

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