Accumulation of metals by vegetation in a small drainage area exposed to aerotechnogenic pollution

Abstract

Changes in the rate and direction of geochemical processes are among the consequences of anthropogenic impact on the environment. Sharp changes in the balance of metals occur in areas affected by the mining and metallurgical industries. The spread of gaseous and dust emissions enriched with ore elements leads to the formation of multielement technogenic anomalies that encompass all components of an ecosystem, including the ground air layer, soil, biota, and natural waters. Forest vegetation plays an important role in the control of this process: it forms a physical barrier to the migration of airborne metal compounds, accumulates metals in long-lived phytomass components (the stem, branches, bark, and roots), involves them in the minor biological cycle of matter, and has an effect on the input of metals in the global cycle with surface waters.The biological accumulation of metals in forest biogeocenoses is a major component of their turnover within the ecosystems of river drainage areas. The mechanisms of metal intake through roots, leaves, and bark are known (Kabata-Pendias and Pendias, 1989;Sudachkova et al. , 1990;Fokin et al. , 1996;Davydova, 2001), and the role of forests as physical barriers restricting the spread of metals over the area is being investigated (Geifel'buim and Boyaryshnikov, 2001). However, there are insufficient data on the accumulative function of forest phytocenoses as a whole with respect to metals coming to the biogeocenosis from the air. The amount of metals transported by river waters and, hence, their concentration in water objects and bottom sediments largely depend on this function. Studies on the quantitative parameters characterizing the involvement of metals in the production process (without disturbing the functioning of the phytocenosis) are important both for setting safety norms of technogenic impact on ecosystems and for constructing models of metal migration in the industrial plant-atmosphere-biogeocenosis-hydrosphere system. MATERIAL AND METHODSStudies were performed in the ecosystem of a small river drainage area (15.8 km 2 ) affected by emissions from a copper-smelting plant and located 10-12 km northwest of their source. The terrain is flat, gently sloping to the main watercourse; the amount of woodland is 100%.The plant cover in the river valley is represented by a bird cherry-alder tall-grass group of associations; the remaining area is under secondary mixed birch-pine communities, with a mixed herb-bilberry association prevailing in the ground vegetation layer. In the tree stand (8P2B), two layers are distinguished. The upper layer (22-25 m high) consists of Scotch pine ( Pinus sylvestris ) with an admixture of weeping birch ( Betula pendula ); its density is low (0.4-0.5) because of felling. The lower tree layer (tree height 8-12 m, stand density 0.5-0.6) consists of weeping birch. The understory is poorly developed, with a dominance of Sorbus aucuparia, Rosa cinnamomea, R. acicularis , and Chamaecytisus ruthenicus. Site conditions are of quality classes 2-3. In th...

Effect of boric acid on the ability of plants to accumulate heavy metals

“…It is notewor thy that the content of Zn in the aboveground phyto mass of all three species significantly exceeded those of all other HMs. This is apparently explained by very high mobility and biological absorption level charac teristic of this element (Fedorova and Odintseva, 2005).…”