Biomonitoring of some heavy metal contaminations from a steel plant by above ground plants tissue

Abstract

Soil and plants growing in the vicinity of industrial areas display increased concentrations of heavy metals and give an indication of the environmental quality. The contamination source for aluminum, iron, nickel and lead in the Botanical garden of Mobarakeh Steel Company was recognized by analyzing the leaves and topsoil of two evergreen species: Quercus brantii and Ligustrum vulgare. Availability of the studied elements for plants was investigated by measuring their total and extractable concentration inthe soils. For ensuring air borne source of these metals, plant tissues were washed with distilled water. Plant available heavy metals of the soils were few in comparison with the total values which were related to the high pH value and the CaCO₃ percentage in the soils around each plant. On the other hand, significant differences were obtained between the washed and unwashed leaves in both species indicating metal contaminations from the atmosphere. Significant differences were detected between the contaminated and background site samples in both plants for Al, Fe and Ni. In addition, the leaves of L. vulgare accumulated more elements partially than Quercus brantii. Difference in the accumulation potentials of the plants were related to the diversity of the physical and chemical properties of the leaves and the type of elements. The enrichment ratio of plants (C_contaminated/C_background) was calculated and it indicated that, the Fe in both plants was moderately enhanced by anthropogenic activities.

Key words: Industrial contamination, Quercus brantii, Ligustrum vulgare, enrichment factor.