ACCUMULATION AND DISTRIBUTION OF Pb, Cu, Zn AND Cd IN SUNFLOWER (Helianthus annuus L.) GROWN IN AN INDUSTRIALLY POLLUTED REGION / ACUMULACION Y DISTRIBUCION DE Pb, Cu, Zn Y Cd EN EL GIRASOL (Helianthus annuus L.) CULTIVADO EN LA REGION INDUSTRIALMENTE POLUCIONADA / ACCUMULATION ET DISTRIBUTION DE Pb, Zn ET DE Cd DANS LE TOURNESOL (Helianthus annuus L.) CULTIVÉ DANS LES RÉGIONS DE POLLUTION INDUSTRIELLE

Abstract

SUMMARYInvestigations conducted during last years showed serious violations of ecological equilibrium in many agricultural regions.Crops produced in these regions are commonly used as food and feed. It has been established that the content of heavy metals in the soils and agricultural crops grown nearby the metallurgical factories is much above the admissible concentration. Micro-particles of Pb, Cu, Zn and Cd separated in the atmosphere by aerosols, accumulate in the soil, plants and water areas. From the studied heavy metals the coarse particles of Zn commonly pile in soil nearby the contaminator, and the heavier particles of Pb are distributed by the prevailing winds. These elements accumulate shallow in the upper layer and confined to quantity move down. The irregular contamination of soil around certain factory is in great part dependent on turbulent movement of air, windlessness and the condition of fluctuating atmosphere - inversion. Contamination with heavy metals is most oftenly in according with areas. Maximum accumulation is found out on boundary areas in a distance at about 1000 m from the factory called the area of accumulation, and 15 000 m away from the factory called area of distraction. Commonly, on this area is grown one of the specific for Bulgaria culture - the sunflower. This needs solving of many problems connected with studying the accumulation and depous of localization of heavy metals in sunflower grown on contaminated soil, as well as their influence upon soil fertility.