The response of lichens to the environmental pollution under the bauxite mining in the taiga zone
The activity of the mineral complex enterprises resulted in the pollution of the biosphere by the products of mining and processing of minerals. The open method of mining is the most vulnerable for the landscapes. Northern ecosystems have relatively low capacity of self-purification and self-healing, which increases their vulnerability to anthropogenic impact. The functional status of the three lichen species (Hypogimnia physodes, Lobaria pulmonaria and Peltigera aphthosa) from the areas with different degree of pollution in the zone of influence of the largest in Eurasia Middle Timan bauxite mine was studied. It is shown that the bauxite dust pollution led to the accumulation of metal compounds in the thalli, especially aluminum and iron. Their content in the lichen samples collected on the plot located near the concentrating mill, reached 16000-20000 μg/g of dry weight (DW). It is 40 times more compared to relatively clean (background) site. The significant part of the metal compounds was localized in the surface fraction. In the intracellular fraction it was detected from 3-10% (Mn, Fe, Al, Cr, Pb) to 40% (Cu) of their total amount. The content of organogenic elements (carbon, hydrogen and oxygen) was lower by 10-15% in the thalli from impact areas. These thalli showed a high level of lipid peroxidation and increased activity of antioxidant enzymes that indicate the development of oxidative stress. The lipid peroxidation, and superoxide dismutase, and peroxidase activities were increased by 1.5-2 times. Judging by these parameter values, the reaction of three-component cyano-lichens L. pulmonaria and P. aphthosa to pollution were expressed more strongly in comparison with chloro-lichen H. physodes. It was concluded that the application of physiological approaches increases the efficiency of lichenoindication and allows us to identify the first signs of defects long before significant reduction in vitality and taxonomic diversity of lichens will become apparent.