BROMINE IN THE POPLAR LEAVES OF URBAN AREAS: NATURAL AND ANTHROPOGENIC SOURCES OF SCATTERING

Abstract

Relevance of the work. Bromine is a tolassophilic, organophilic and essential element. The combination of natural and anthropogenic sources of dispersion of this element determines the complexity and multifactorial nature of its entry into the environment, affects the characteristics of halogen accumulation and distribution in natural environments. The main attention in the work is focused on urbanized areas of the local and regional levels of the study with sources of Br emission. The migration routes and biogeochemical accumulation of bromine remain poorly studied issues. The main aim of the research is to determine the quantitative content of Br in the leaves of woody plants of the genus poplar (Populus L.), growing in urbanized areas of South-East Eurasia, and based on the principles of biogeochemical zoning to identify the halos of Br load, determine the main factors of their formation. Methods. Poplar leaves (Populus L.) served as the object of the study. Sampling was carried out in August 2015–2018 on the territory of more than 50 cities along a uniform network with a step of 1×1 and 2×2 km. The average sample size in cities was 30 samples. In total, about 1700 samples of poplar leaves were taken. Leaf ash was carried out by dry mineralization in a muffle furnace at 450 °C for 5 hours. The authors have taken into account the literature data that Br loss in the ash obtained at 400 °C was no more than 20 % of the calculated value. Content of Br and other chemical elements in the ash of poplar leaves was determined by the method of instrumental neutron activation analysis in the nuclear geochemical laboratory at the educational research nuclear reactor (IRT-T) at Tomsk Polytechnic University. The analysis results were processed using descriptive statistics, cluster and discriminant analyzes. Results. The average Br content in the ash of poplar leaves in urbanized areas was 56,5±2,1 mg/kg, with a range from 0,3 to 1730,1 mg/kg. The median is 30,6 mg/kg. The lower anomalous Br content was 103,4 mg/kg. Two conjugated anomalous bromine biogeochemical regions were revealed: Kulunda – natural genesis and North Kazakhstan – natural and technogenic genesis. Areas are depleted in area in bromine biogeochemical subprovince, first described in this work.

Keywords

• biogeochemical indication
• poplar leaves
• bromine
• instrumental neutron activation analysis
• urban areas