Using the bioindication method for determining air pollution by heavy metals

The results of studies of chemical pollution (Pb, Zn) of perennial grasses—Elymus repens L., Artemisia absinthium L., and Hypericum perforatum L.—on background plots and within the areas of impact of industrial enterprises in Kropyvnytskyi (Ukraine) are presented. It is noted that chemical pollution is the most dangerous. The activity of enterprises is considered, in the result of which heavy metals enter the air. Testing of plants (stems and leaves) was carried out at a distance of 10–100 m from the enterprises. The content of heavy metals in the aboveground part of plants was analysed by atomic absorption spectrophotometer in the laboratory of the Department of Exploratory and Ecological Geochemistry, IGMR NAS of Ukraine. The comparison of sorption properties of different plants in the same phases of development allowed plants with bioindication capabilities to be identified. The results of the analysis showed that plants most effectively accumulate the maximum amount of heavy metals from the atmospheric air at the end of the summer dormancy phase (second half of August). At this time the plant requires the minimum amount of nutrients that it takes from the soil. Stems and leaves of perennial grasses actively accumulate aerosols and fine dust on their surface due to plant secretions with the formation of a mucous film that actively adsorbs heavy metal ions. The background, minimum, and maximum content of heavy metals in plants is determined. Comparing the content of heavy metals in plant samples in the background and study plots, it was found that E. repens near industrial enterprises is the most effective bioindicator of air pollution. In order to determine the level of atmospheric air pollution using bioindication methods, the index of plant contamination (Sр) was proposed, which is the ratio of concentration coefficient of heavy metals and their amount. An assessment scale for atmospheric air pollution with heavy metals has been developed based on the contamination index (Sр) of bioindicator plants: the degree of pollution is 1–3—weak, 3–6—medium, 6–9—strong, more than 9—very strong. The proposed coefficients allow for conducting a situational assessment of atmospheric air pollution with heavy metals using bioindication methods.