BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 1 Using High Plant Species as Indicators For The Accumulation of Lead From Polluted Air Julian Shehu, Alfred Mullaj, Ardian Maci, Alma Shehu Department of Crop Production, Faculty of Agronomy and Environment, Agricultural University of Tirana, Albania Abstract Environmental contaminants enter the plant cells from air, soil and water. In most phytoremediation processes great attention has been paid to the cleaning up of soil and water, even though the research for cleaning of contaminated air is not less important. Plants absorb contaminants primarily through their roots and leaves. Contaminants enter leaves as a result of the direct spraying of plants with agrochemicals and by absorption of gaseous contaminants in the air. Lead is a widely used heavy metal and its world production is several million tons annually. The most important anthropogenic sources of lead are processes in metallurgy, metal working, engineering, chemical, petrochemical and the exhaust gases of internal combustion engines using lead-containing petrol. Lead compounds are emitted as solid particles from internal combustion engines together with the exhaust gases. The cultivation of agricultural plants, especially fast growing vegetables near roads is, therefore, not recommended. Twelve plant species were chosen to study the accumulation of lead in two different points of Tirana city, one with very heavy traffic density and the other in an unpolluted area. Determination of lead content in soils in the three stations was evaluated as well. The level of accumulated Pb was higher for Citrus medica L. and Tilia tomentosa Monech plant species, with about 0.41 mg.kg -1 and 0.38 mg.kg -1 , respectively. The content of lead in plant species grown in the polluted area resulted to be more than four times of the content in plants grown in the unpolluted area. Almost all plant species of the unpolluted area resulted to accumulate less than 0.05mg.kg -1 even though the content in soil was approximately the same. Key words: lead accumulation, high plant species, air pollution Introduction. Most air pollution arises from the burning of coal and other fossil fuels and from smelting of iron and nonferrous metals. Some trace pollutants, most likely Se, Au, Pb, Sn, Cd, Br, and Te, can exceed 1000 times their normal concentration in air. In general, elements that form volatile compounds, or are present at a lower particle radius, may be readily released into the atmosphere from the burning of coal and other industrial processes (Kabata-Pendias, 2000). The atmospheric deposition of trace elements, mainly of heavy metals, contributes to contamination of all other components of the biosphere (e.g., waters, soils, and vegetation). Heavy metals are also dangerous because they tend to bioaccumulate. Lead is one of the most dangerous and toxic heavy metals. Levels of lead in the environment are not stable and vary according to industrial production, urbanization, climate changes and many other factors (Singh et al., 1997). The levels of lead in the environment vary between 4 and 20 mg/g of dust. Commonly, quality of air is evaluated by using only chemical parameters related to air composition. However, the results obtained do not allow direct conclusions on the impacts of environmental concentrations of pollutants on living organisms. The use of bioindicators has proved to be an effective methodology to detect the effect of atmospheric pollutants on the organisms and identify potential environmental hazards (Divan Junior et al., 2007, 2008). The great variation of Pb content in plants is influenced by several environmental factors, such as the presence of geochemical anomalies, pollution, seasonal variation, and genotype ability to accumulate Pb. Nevertheless, natural Pb in plants grown in uncontaminated and unmineralized areas appears to be quite constant, ranging from 0.1 to 10 ppm (DW) and averaging 2 ppm (DW) (Allaway, 1968). Of great environmental significance is the ability of plants to absorb Pb from two sources, soil and air, even although Pb is believed to be the metal of least bioavailability and the most highly accumulated metal in root tissues. Several plant species and genotypes are adapted to grow in high Pb concentrations in the growth media; this is reflected by anomalous amounts of this metal in the plants. The highest bioaccumulation of Pb generally is reported for leafy vegetables (mainly lettuce) grown in surroundings of nonferrous metal smelters where plants are exposed to Pb sources of both soil and air. In these locations, highly contaminated lettuce may contain as much as 0.15% Pb (DW) (Roberts et al., 1974).