Air Pollution Effects in Some Plant Leaves Morphological and Anatomical Characteristics within Baghdad City. Iraq

The present study examined the air pollutants effects in seven plant species leaves, Olea europea L., Zizphus spina-christi L. Desf., Conocarpus lancifolius Engl., Albizia lebbeck L. Benth., Eucalyptus camaldulensis Dehnh., Clerodendron inermis L. Graeth and Dodonaea viscasa Jacq., distribute within Baghdad city. The leaves sample were collected from May (2016) to April (2017) in five regions within Baghdad city, which are Karrada, Sadr City, Shoula and Mansur, as well as Baghdad tourist island as a control region. The Sulfur dioxide (SO2), Nitrogen dioxide (NO2), Carbone monoxide (CO), Volatile organic compounds (VOCs) and Suspended particulate matter (PM) were measured in all study regions. The present study results showed an increase in concentration of all air pollutants in the four study regions compared to Baghdad tourist island, (SO2) average was (0.56) ppm, while (NO2) average was (0.80) ppm, (CO) average was (27.69) ppm, (VOCs) average was (5.99) ppm, while (PM) average was (480.80) μg /m3. The morphological and anatomical characteristics include length, width, area, number of stomata; the number of epidermis cells, and stomatal index were measured in plant leaves. E. camaldulensis leaves were recorded highest length rate (11.03) cm, while highest width rate (5.51) cm and leaf area rate (49.63) cm2 were recorded in A. lebbeck leaves. The highest number of stomata and epidermal cells were also recorded in A. lebbeck leaves (101.25 and 738.85) in respectively. But highest stomatal index value was recorded in D. viscasa leaves (14.21). KeywordsAir pollution, Plant leaves, Morphological characteristics, Anatomical characteristics. How to cite this article: A.H.M.J. Al-Obaidy, I.M. Jasim and A.R.A. Al-kubaisi, “Air Pollution Effects in Some Plant Leave Morphological and Anatomical Characteristics within Baghdad City, Iraq,” Engineering and Technology Journal, Vol. 37, Part C, No. 1, pp. 84-89, 2019.


Introduction
Air pollution is a major problem in modern society. It is also a bigger problem in cities, as air pollutants spread everywhere. These pollutants include different gases and particulate matter that can harm human health and the environment. The relationship between plants and different types of contaminants has been investigated by many researchers [1][2][3][4][5][6]. Emissions from cars, buses, minibusses, wagons, motorcycles, and trucks may be a major source of urban air pollution. These sources produce different types of pollutants in the environment such as (nitrogen oxides, sulfur oxides, hydrocarbons, ozone, particulate matter, etc.). These pollutants not only affect human and animal health but also threaten plant life in any areas [7]. Emissions from automobiles can directly affect the plant by entering the leaf, destroying its cells, and thereby limiting the ability of the plant to produce food. Urban air pollution is a major environmental problem, especially in developing countries [8]. The leaf is the most sensitive part of the plant that is affected by air pollutants compared to other parts such as stem and roots. This sensitivity is due to the fact that the most important physiological processes of the plant occur in leaves [9]. Pollutants from automobile have long-term effects on plants by affecting the content of carbon dioxide, light intensity, temperature and precipitation. Therefore, plants need special protection because they are not only a source of food but also play a role in purifying and softening environment [10,11]. The air pollutants effects in plants are studied in many types of research as one of plant environmental interference. This may be due to fact that plants are most living organisms that suffer from the effect of air pollution due to their stability within their environments and their long exposure to air pollutants when compared with other organisms [12]. The basic plants role in research related to air pollution was in several directions, including giving early pollution presence signal or warning in a given area and thus help in assessing air quality, and through the plants diversity can determine geographical distribution of air pollutants, and helps to concentrations estimate of those contaminants, if accumulated in plant tissues, and facilitate direct diagnosis of different pollutants depending on plant response types to contaminants [13].

I. Air pollutants concentration
Air pollutants were measured and plant's samples were collected for five regions within Baghdad City Karada, Sadr City, Shula and Mansour as well as the control region (Baghdad tourist island), during one year from May 2016 to April 2017. The air pollutants were measured by using specialized digital devices GFG -Quality control G460MICROTECTOR II Germany for gaseous pollutants (SO 2 and NO 2 ) and Particle mass counter Met One Instrument. USA for particulate pollutants.

II. Plants indicators
The plant samples included O. europea L., Z. spina-christi L. Desf., C. lancifolius Engl., A. lebbeck L. Benth., E. camaldulensis Dehnh., C. inermis L. Graeth and D. viscasa Jacq., were selected due to their abundance and dispersal in all study regions within Baghdad City and also exposed to air pollutants continually. In addition, plant leaf morphological characteristics, which included length, width and area, were measured according to [14], [15]. While plant leaf anatomical characteristics, which included epidermal cells number, stomata number and stomatal index were measured and calculated according to [16].

III. Statistical analysis
Statistical Analysis System (SAS) was used to analyze data and study location and plant type effect on studied plant characteristics [17]. Table 1 shows the concentrations average of examined air pollutants, namely (SO 2 ), (NO 2 ) and (TSP). The seasonal differences in these pollutants values were observed in all studied regions, sulfur dioxide highest concentrations were recorded in spring in p 2 region and reached (1.23) ppm, but lowest concentration was recorded in C region in autumn (0.03) ppm, while sulfur dioxide value in proposal Central Pollution Control Board, Baghdad, Iraq is (0.1) ppm, but nitrogen dioxide highest concentration recorded in winter and reached (1.47) ppm in p 1 and p 4 regions, while C region recorded low concentration in spring and autumn reached (0.04) ppm, nitrogen dioxide value in proposal Central Pollution Control Board, Baghdad, Iraq is (0.25) ppm. The highest suspended particulate matter concentration recorded in autumn was (235.3) μgm-3 in p 2 region, but C region had lowest value in autumn (45) μgm-3.     Table 7 shows the highest stomatal index rate of O. europea leaf recorded in p 3 region (11.71) and lowest (11.47) in p 1 . And highest rate reached in Z. spini-christi leaf (14.21) in p 1 and lowest record rate (13.34) in p 3 , While highest rate of C. lancifolius recorded in p 2 (6.82) and lowest (5.63) in C region. A. lebbeck recorded highest rate in p 4 (12.59) and lowest (12.15) in p 1 , but the highest rate of E. camaldulensis (14.19) in p 4 and the lowest rate (12.69) recorded in C region, while C. inermis reached highest rate (6.81) in p 2 and the lowest rate (5.78) in C region. The D. viscasa reached the highest rate (14.61) in p 4 and the lowest rate (13.52) in C region.

Discussion
Plants are exposed in their environments to many external stress factors. These stresses may occur either simultaneously or sequentially within varying intensity and frequencies. The leaves are first parts of the plant that exhibit usually symptoms of these stresses including air pollution, so the evaluation of morphological characteristics such as length, width and area are the most important steps in monitoring programs [18], [19]. The present study results show variation in length, width and area studied plant leaves values through comparing polluted regions with less polluted region. These results have been interpreted as one of the plants morphological characteristics response form to exhaust pollution as external stress [18]. And also explained the reduction of plant leaves characteristics length, width and area as one of plant adaptation mechanisms to survive under severe environmental stress as exhausts air pollution [20]. As well as this reduction in leaf size may be due to the air pollution effect on leaf growth and elongation [21]. This decrease in morphological properties is explained as one of plant leaves resistance ways to air pollutants and maintain the water balance of plant leaf tissues by reducing leaf area; plant leaves area decreases with more plant leaves the stress and little water leaves loss and increases plant resistance [22]. Leaves area, length and width reducing may lead to reduced contact between air pollutants and plant leaves and thus protect the plant from pollution [23]. In another study, the reason for leaf area reducing in Albizia lebbeck growing in high-polluted industrial areas in Khuzestan, Iran, was attributed to plant's suffering from some physiological disturbances resulting from its exposure to pollution, so plant leaf area is described as an important feature that reflects of plant response degree to external stresses [24]. This effect was attributed to the level of dust rising from the intensity of traffic in city streets [25]. The present study results show a decrease in the number of stomata and epidermal cells in most plant leaves when compared between polluted and less polluted regions. While stomatal index values of majority plant leaves showed an increase in polluted regions compared with less polluted region. This variation in results may be due to plant response degree to air pollutants and also their differences between studied species. The decrease in stomata and epidermal cells number in plant leaves may be due to reduced leaf area [26]. These changes explained that urban environmental conditions have an effect on plant leaf morphological and anatomical characteristics. And also considered as a plant resisting means to drought or air pollutants because of low leaf area low stomata number and low water loss rate by transpiration and low plant leaf gas exchange rate and thus reduced polluting gases penetration rate into leaf [21]. Stomatal index can be considered as one of good anatomical adaptations shown by the plant to air pollution [27]. Low stomata number has been considered to be a sign of plant adaptation to air pollution, because of lower stomata number, lower of gaseous pollutants absorption from the air [28].

Conclusion
From current study can conclude the important effect of air pollutants on morphological and anatomical characteristics of leaves more than physiological characteristics. Thus, the study of leaves morphological and anatomical characteristics gives a more credible description of environmental effects on the plant. The plant's response to air pollution is different, so it is possible to count plants as quantitative and qualitative indices for air pollution.