Level of atmospheric air pollution with heavy metals in the influence zone of coal industry enterprises (Berezovsky)

. The work presents the results of a study of atmospheric air pollution with heavy metals in a small mining town in the Kemerovo region. The assessment was carried out using the active biomonitoring method. The epiphytic moss Pylaisiella polyantha served as a bioindicator. The content of chemical elements was determined using the neutron activation method. Elements and areas of the city were identified for which high levels of concentrations values were obtained relative to background.


Introduction
The Kemerovo region is known as a coal basin, where numerous coal industry enterprises are located.As a result of the activities of such enterprises, a large amount of fine particles matter is released into the atmospheric air, posing a serious threat to human health [1].The increased danger of silty particles matter of Kuzbass coals is due to its geochemical specification -the particles contain large quantities of heavy metals (HM), which have carcinogenic effect [2][3][4].In this regard, it should be emphasized that the inhalation route of harmful substances entering the human body is the main one.This fact explains the high prevalence of respiratory diseases in the population of the Kuzbass cities [5].Currently used methods of atmospheric air pollution control are intended for determination of dust, soot, some organic compounds and gases.Data on the HM content in the atmospheric air is practically non-existent.The difficulty in assessing air pollution caused by fine particulate matter containing HM is due to their relatively low concentrations.In such cases, large observation periods are required to obtain reliable results, which can be achieved through bioindication methods [6][7][8][9].
The paper presents the results of determining the level of atmospheric air pollution by HM obtained by transplanting epiphytic mosses to the studied territories.The research was conducted in the influence zone of coal industry enterprises located in the Kemerovo region.

Materials and methods
The study area is located in the Kemerovo Oblast (the city of Berezovsky), Russia.The city is situated 30 km from the administrative center.According to publicly available network data, Berezovsky urban district has a sharply continental climate.The warmest month is July with an average temperature of 18.6 ° C, and the coldest is February, with an average temperature of -18.4 ° C. The average annual precipitation is 505 mm.The least precipitation falls in February, with an average of about 14 mm, and the most in July, with an average of 69 mm.Coal mining is the main industry in the region.In the study area there are concentrating plants "Berezovskaya", "Barzasskoe tovarishchestvo", "Chernigovskaya"; mines "Berezovskaya", "Yuzhnaya" and coal mine "Chernigovets" with the area of over 30 km2 (Figure 1).In total, 99 moss samples were placed in 33 points on the territory of Berezovsky and 3 samples on the background territory (village of Medynino, Kemerovo Oblast), similar in climatic conditions to the study area.During the collection of moss samples, the samples in point 1 were lost.
The active method of biomonitoring was used in the work.Samples of the moss species Pylaisiella polyantha (Hedw.)B. S. G. were collected in a clean territory of the Tomsk region.According to the methodology developed by the authors, the manufactured frameworks were placed for the summer period in the territory of Berezovsky and the E3S Web of Conferences 463, 02015 (2023) EESTE2023 https://doi.org/10.1051/e3sconf/202346302015background territory located far from large cities and enterprises.The frameworks were assembled in the fall of 2022, the exposure time was 4 months.
To determine the content of chemical elements in moss samples, the neutron activation method (NAA) was used.All moss samples were prepared for analysis according to the previously developed methodology for epiphytic moss [10].

Results
Concentrations of 26 elements were determined in the studied moss samples using NAA, the measurement error was 10-15%; average values were calculated for each sampling point.Table 1 presents the minimum, maximum and average values of concentrations for the studied and background areas.

Discussion
The content of all analyzed elements in the atmospheric air of Berezovsky is higher than background values.The exception is calcium, whose concentrations in moss samples do not significantly exceed background values.Concentrations of Sm, Ce, Th, Cr, Hf, Sr, Br, Cs, Sc, Rb, Fe, Zn, Co throughout the city exceed the background several times.High contents of Lu, U, Yb, Sb, higher than background by 5 and more times, were found on a large territory of the city, located in the southern part of the city (Figures 2-5).In some areas near mines, coal mines and concentrating plants, also located mainly in the southern part of the city, high concentrations of Ba, Nd, Na and Eu are observed, sometimes exceeding the background by tens of times.Atmospheric air of the northern part of the city is polluted with molybdenum, the content of which is 5-25 times higher than background level.This result can be explained by the influence of two enrichment plants (Figure 1).

Conclusion
The content of Sm, Ce, Th, Cr, Hf, Sr, Br, Cs, Sc, Rb, Fe, Zn, Co in the atmospheric air of Berezovsky is several times higher than the background values.The concentrations of Lu, U, Yb, Sb, Bs, Nd, Na, Mo and Eu in most samples exceed the background by tens of times.The most polluted air is in the southern part of the city, where mines, concentrating plants and coal mines are mainly concentrated.