ИСТИНА

The city of Ulan-Ude with a population of more than 400 thousand belongs to a group of intermountain cities with a weak atmospheric dispersion of pollutants. Ulan-Ude is characterized by a significant concentration of industrial enterprises, a growing number of vehicles and a large area of private buildings with stove heating. The relevance of the research of this territory is caused by the lack of landscape-geochemical information available only for the central part of the city (Belogolovov, 1989) and the garden zone (Ubugunov & Kashin, 2004). The landscape-geochemical survey of the city in 2014 with sampling of snow cover, topsoils, bark and leaves of poplar hybrids was aimed at assessment of contemporary ecological and geochemical state of the components of urban landscapes and detection of long-term trends in heavy metal and metalloid (HMM) contamination of certain land-use zones of the city. Solid fraction in snow characterized the modern geochemical pressure on urban landscapes. It was enriched with wide spectrum of HMMs: Sb, Zn, Sn, W, Co, V, Cr, Ni, As, Cd, Mo, Cu, Bi (Kasimov et al., 2017). Geochemical anomalies in the snow cover were localized near highways, large industrial pollution sources and low-rise buildings with stove heating. The priority pollutants of the soil cover in Ulan-Ude were Sb, Pb, Cd, Sn. Soils of industrial zone were the most contaminated with Sb, Cd, Pb, Cu, Mo, W, Sn due to long and strong man-made impact, somewhere geochemical anomalies reached a very dangerous level (Kasimov et al., 2016; Kasimov et al., 2017). Soils of the traffic zone accumulated Sb, Pb, Cu, soils of residential zone – Sn, Sb, Cd, Pb. Leaves of poplar hybrids in the city contained more W, Ni, Sb, Mo and Zn compared to background values. Leaves in the traffic zone accumulated Ni, W, Sb, Sn, Zn, Cd, Cu, Mo and deconcentrated biophilic Mn. In the industrial zone bioaccumulation of W, Zn, Cd, Sb and dispersion of Cr occured. Analysis of the allocation of multi-elemental anomalies in snow, soils, bark, and poplar leaves made it possible to identify zones of stable, residual (relict) and modern pollution in the city. In Ulan-Ude, anomalies with residual pollution, predominating in the industrial and recreational zones, were identified by relatively high values of integral pollution indices for poplar bark and soil and low ones – for leaves of poplar and snow. This corresponded with the trend of reducing emissions from stationary sources in the last decade. In the traffic zone, relatively high values of integral pollution indices in poplar leaves and snow, weak geochemical transformation of poplar bark and soil indicated significant current flows of pollutants. This allowed us to forecast the increase of environmental pollution for this zone in the nearest future.