Analysis of chlorophyll “a”, “b”, and carotenoids in leaves of oriental maple, biota, common oak, and chestnut trees resistant to harmful substances emitted by motor vehicles in Tashkent city

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Analysis of chlorophyll "a", "b", and 
carotenoids in leaves of oriental maple, biota, 
common oak, and chestnut trees resistant to 
harmful substances emitted by motor vehicles 
in Tashkent city
 
Husan
Khodjibabayev
1*
, 
Bahadir
Ismailkhodjaev
2
, 
Malokhat
Abdukodirova
2
, 
Dildora
Mavlyanova
2
, 
Ibrokhim
Israilov
2
, and 
T.
Samandarov
3 
1
Research Institute of Environment and Nature Conservation Technologies, Tashkent, Uzbekistan 
2
"Tashkent Institute of Irrigation and Agricultural Mechanization Engineers" National Research 
University, Tashkent, Uzbekistan
3
Tashkent State Pedagogical University, Tashkent, Uzbekistan 
Abstract
.
The work is devoted to the composition of the atmospheric air 
on the main streets, the level of traffic on these streets, the selection of 
resistant species of phenol trees for growing ornamental trees, and the laws 
of changing the number of pigments in these trees depending on the streets 
and season in the Republic of Uzbekistan. At the same time, the types of 
ornamental trees and their resistance to pollution from the pollution of 
carbon dioxide, nitrogen oxides, and sulfur dioxide are mainly represented 
by atmospheric air pollution.
1 Introduction
Nowadays, the growth rate of large cities depends on the growth of industrial enterprises 
and motor transport, which requires many environmental issues. Air pollution is mainly 
caused by large-scale enterprises and motor vehicle emissions, especially on roads along 
major highways, with motor vehicle emissions. In this case, pollutants are mainly exposed 
to tree leaves. This is because photosynthesis and many other processes that allow the 
growth of the leaves to take place in these leaves. Therefore, it is important to study the 
degree of contamination of tree leaves with various contaminants and to evaluate the 
resistance of these toxic compounds to the green and yellow pigments involved in the 
photosynthesis process in the leaves and their resistance to heavy metals. The volumes of 
carbon dioxide absorption and oxygen production in different species of trees and leaves 
vary. The air purification efficiency of ordinary juniper trees is 100 %, pine 
–
164%, large 
deciduous 
–
254 %, oak 
–
450 %, and Berlin poplar 
–
691 % [1]. Decorative trees play an 
aesthetic and social role in the environment and affect the quality of atmospheric air [2]. 
Trees in urban areas were planted to create favorable environmental conditions close to 
optimal parameters corresponding to the so-called comfort zone. When the wind speed in 
*Corresponding author: 
[e-mail]
  
E3S Web of Conferences 
401
, 02032 (2023)
CONMECHYDRO - 2023
https://doi.org/10.1051/e3sconf/202340102032
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative
Commons Attribution License 4.0 (https://creativecommons.org/licenses/by/4.0/). 

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the comfort zone is 2-6 m/s, and the relative speed is 30-70%, then the average temperature 
is about 18-28°C. Under favorable conditions, the noise should not exceed 45 dB (in the 
evening) and 65 dB (in the afternoon). Remember that some factors determine comfort 
conditions and depend on the degree of air pollution with gases and other particles [3]. In 
nature, there are also artificial forests, parks, and even single trees, which significantly 
improve the climate, creating a high level of comfort and hygiene. The green massif has its 
own microclimate [4]. According to Roberta Baroni Fornasiero, fluoride and many 
fluorides are vital to humans and plants. Fluoride flora is found in highly industrial areas: 
characteristic leaves are present on the leaves, the tip separating them from burns and 
healthy, undamaged tissues. As a result of pollution, it is observed that the leaves of the 
trees fall, the ends and edges of the leaves change, and they turn red and brown [5]. Air 
pollutants are any gases or solid particles that can harm human health and the environment 
at a sufficiently high concentration. It is known that air pollution occurs mainly from two 
sources: natural factors and a human product 
–
from anthropogenic sources or both. 
Pollutants are found in most parts of the troposphere; nevertheless, surface pollution in the 
boundary layer is the most alarming since the concentrations caused by surface sources are 
relatively high [6]. An increase in population, a reduction in natural resources, and an 
increase in pollutants enhances climate change. It was previously believed that the climate 
does not affect the surface of the Earth or living organisms in the Earth's crust. It plays an 
important role in determining climate change on Earth [7]. Global warming associated with 
climate change is one of the most discussed topics. There are also natural causes and the 
various anthropogenic effects of air pollution worldwide. Many factors play a decisive role 
in climate change and global warming, leading to changes in global temperatures and the 
nature of precipitation [8]. Anthropogenic pollution occurs mainly due to pollutants 
entering the air from industrial enterprises, automobiles, air, rail, and water transport, and 
the use of various types of fuel. In the era of science and technology, air pollution is 
becoming more intense [9]. Currently, there are more than 40,000 sources of air pollution in 
Uzbekistan, and almost half of them are not equipped with filters, which leads to more than 
2 million pollutants in the country with more than 150 pollutants per year, tons of waste are 
released into the atmosphere [10]. As a result of the effect of polluted air on the 
environment, many health problems arise both for the environment and for humans and 
cause diseases such as asthma, bronchitis, cardiovascular diseases, heart attack, and 
hypertension [11]. The largest industrial cities of the country are Tashkent, Andijan, 
Fergana, Navoi, and others, which are among the largest cities in Europe in terms of air 
pollution [12]. Atmospheric air is mainly contaminated with carbon monoxide, nitrogen 
oxides, and sulfur oxides. From a scientific point of view, the choice of decorative trees and 
their durability is important for cleaning and protecting the air from pollution. In this 
situation, it is necessary to conduct phenological observations of growing trees under these 
conditions and study the quantity and quality of substances in their various organs. It is also 
known that most of the toxins are primarily affected by the leaves of the trees due to 
photosynthesis and many processes that occur in them. From this, we can conclude that the 
amount of photosynthetic pigments in trees is a measure of resistance to harmful gases in 
trees. Given the above, we plan to study the formation of green and yellow dyes on the 
leaves in the example of the city of Tashkent. Purpose of the study. Study of drought 
tolerance of decorative trees, determination of atmospheric air pollution, seasonal studies of 
dyes in tree leaves along the main highways of the city of Tashkent.