A Statistical Analysis of Traffic-Related Pollution and City Center Dynamics in Ankara: The Cases of Ulus and Kızılay

Urban pollution, which reduces the quality of life of residents and poses a vital threat to human health, can be reduced by effective city planning. Pollution due to heavy metals is increasing in today’s cities, and these heavy metals are of particular concern because as they do not naturally decompose on earth, they can bioaccumulate in the human body and cause serious diseases. It is, however, possible to reduce exposure to pollutants through making spatial decisions


Introduction
The United Nations estimates that by 2050, 32% of people will live in rural areas, and 68% in urban (United Nations, 2019). Clearly this growth in population will affect urban development (Chen et al., 2021), in which correct site selection for urban uses, as well as careful planning of usage decisions, are essential to ensure the quality of life of a city's residents (Işınkaralar ve Varol, 2021). One important area of concern when managing the needs of the increasing population in urban areas (Öztürk and Işınkaralar, 2019) is the subsequent high density of motor vehicles in cities. An intensive use of fossil fuels, as well as dealing with unplanned and uncontrolled urbanization, causes various, and often very complex, problems (Isinkaralar, Varol and Yilmaz, 2022). Factors such as construction, the application of inappropriate and insufficient energy generation techniques, and a reduction in forests and other forms of open and green areas, can all be a cause of environmental problems (Eguiluz-Gracia et al., 2020;Umar et al., 2021;Roelich, 2019). Furthermore, environmental problems do not remain at the local and regional scale, they also contribute to national and global problems such as climate change and global warming (Ren et al., 2022;Pee and Pan, 2022). Air pollution is therefore a priority environmental problem in developing and transitioning economies in urban areas (Amiraslani, 2022;Lillio et al., 2022;Cassita and de Oliveira David, 2022;Pal et al., 2022), and poses a danger and risk to not only people, but all living things (Pajewska-Szmyt, 2019; Saravanan et al., 2021).
Heavy metals are one of the most dangerous pollutants for humans (Liu et  • Analysis of the suitability of possible species for use in biomonitoring, • Determination of the accumulation levels in different organs of the species.
In line with the determined purposes, air quality was measured in the city of Ankara through biomonitoring. It was determined whether these woods could be used effectively or not by analyzing the Mn accumulation in the leaves, bark, and wood of different species.

Sampling Area
Urbanization is the most fundamental cause of air pollution in developing countries (Wu et al., 2020). Due to the rapid disintegration of rural areas in the post-republican period, population growth in urban areas, and unplanned construction, the spatial structure of Ankara has changed (Hosanlı and Resta, 2021). The city of Ankara is located in the middle latitude region between latitudes 38°33'N and 40°47'N and longitudes 30°52'E and 34°06'E, as depicted in Figure 1 (Atıcı et al., 2020).
Ankara became the capital of Türkiye in 1923, and is one of the country's most populated cities. The choice of Ankara for the capital was not due to the city's internal dynamics, but because of political reasons. However, being chosen as the capital activated a process of socio-spatial change, in addition to economic and political dimensions (Demiröz and Güçhan, 2021;Gökçe and Chen, 2019).
The rapidly increasing number of public buildings and the settlement of these government employees in the city, as possible bioindicators ( Figure 3). As heavy metals accumulate in plants as well as in all living things, it is very difficult to identify the exact sources of pollution. However, the usability of woods in monitoring for comparison purposes and providing quantitative information on environmental quality in areas where externalities are similar has been demonstrated by many studies (Markert et al., 2003;Madejón et al., 2006).

Analysis Procedure
The research consists of five primary stages that are depicted in Figure 4: collecting the woods, drying, decomposition, calibrating the values, and reading the measurements. Approximately 25-30 cm of branch samples were taken during the collection stage. Care was taken to collect the branch samples at the end of the growing season. The samples were placed in sealed bags to reduce contact with the air as much as possible, and then taken to the laboratory for research. Depending on the purpose of the study, the leaves, bark, and other parts of the tree, were separated for examination. All experiments were greatly complicated the process of urban planning (Ozlu-Diniz and Kasapoglu, 2021). The traditional city center has been exposed to population, construction, and traffic pressure due to the housing problem caused by migration. In the study, samples were first taken from Ulus and Kızılay to represent the accumulation levels. The research area is concave due to its topographic structure ( Figure  2), with high-rise buildings reducing the effect of the prevailing wind.
Samples were collected from Kızılay, the post-Republican center of the city, which connects Ulus and Atatürk Boulevard, which is the historical center of the town, and Çankaya, which is located on the outskirts of Ankara Castle. It can therefore be stated that the examples were taken from the axis and its surroundings, which constitute the traditional and modern centers of a metropolitan city. The main materials of the study are Robinia pseudoacacia (RP), Platanus orientalis (PO), Acer negundo (AN), Fraxinus excelsior (FE), Ailanthus altissima (AA), Aesculus hippocastanum (AH) and Tilia tomentosa (TT). These species were selected to investigate their usability used at concentrations of 0.02-200 µg/mL. Distilled water was added until the levels of the samples were 50 mL before being placed in the instrument. Before initiating the calibration process, the plasma of the ICP-OES device was first matched. For the device to again reach equilibrium, ultrapure water was passed through it for 15 minutes. Calibration curves were drawn with a value of R 2 :0.99 standard solutions of Mn concentration. Since this is widely preferred as an indicator in traffic-based studies (Karacocuk et al., 2022), it was chosen to measure Mn concentrations. After the calibration lines were created, the samples were placed in the device, and the values were obtained three times to validate the result. Measurements with high deviation were renewed. Since the mass value (0.5 g) used at the beginning was completed to calculate the result concentration, the results obtained were multiplied by 100 to achieve normalization was achieved. Analysis of variance was applied to the obtained data with the help of the SPSS package program.
validated using the limit of detection (LOD), the limit of quantification (LOQ), and the relative standard deviation (RSD). The blank method was used to specify the LOD and LOQ values of 0.00 -0.02 ppb.
The samples were placed into glass tubes for preparation analysis. They were first put into a heat controller oven at a temperature of 60 o C for 15 days without any contamination until it was certain that all humidity had been removed from the samples. 0.5-g portions were separated for the acid digestion process and impregnated by pouring 6 mL of 65% and 2 mL of 65% HNO 3 . As stated in the USEPA 3052 Method, the samples were stabilized at 200 °C at a heating rate of 15 o C/min for 15 minutes while using a microwave (Millstone Ethos One) oven, and then a microwave-based digestion system step was applied (Method 3052, 1996). The dissolved samples were then placed into volumetric flask. Mn values of the samples were determined with the GBC Integra XL-SDS-270 ICP-OES device and a five-point calibration curve was Mn concentration based on species and organs according to samples taken from locations close to the Ulus region is given in Table 2.
As a result of the analysis of the variance of the samples taken from the area close to the Kızılay region, it was determined that the change in Mn concentration in all species and all organs was statistically significant (***p<0.001 Homogeneous groups were obtained using the Duncan test for the factors in which statistically significant differences existed to achieve at least a 95% confidence level (*p<0.05). The data was then simplified and interpreted by being added to the tables.

Results
Results are given below in Table 1. The mean values of the Mn concentration selected in the study are based on species and organs, while the F value is obtained from the analysis of variance, the error rate, and the groups formed as a result of the Duncan test.
As a result of the analysis of variance, it was determined that the change in Mn concentration in all species and all organs based on species was statistically significant (***p<0.001). When the data is examined, it is seen that the lowest values in organs were obtained in wood in all species except P. orientalis and A. altissima. The highest values were obtained in the leaves in A. negundo and A. altissima and the bark in other species. When the changes based on species are examined, the lowest value in the leaves is P. orientalis; the highest value is in A. altissima, the lowest value in T. tomentosa, the highest value in A. hippocastanum, the lowest value in R. pseudoacacia, and the highest value in A. altissima in wood. The variation of tion habits changed, and public spaces and commercial activities shifted to the periphery. It is now accepted that the functions in the city center have become decentralized. However, while low-carbon city centers are targeted in developed countries , the main arteries that have been enlarged over the years for the flow of vehicular traffic in Kızılay have fragmented the pedestrian zones and encouraged the use of private vehicles. As a result, open spaces have emerged that have moved away from their role as a square, and Kızılay has lost its former significance and turned away from being a socio-political center and turned into a traffic intersection (Sarıkahya and Tuğral, 2022;Topal et al., 2019). There is no doubt

Discussion
Urban processes occur through interaction within a multidimensional, complex, and dynamic structure (Isinkaralar and Varol, 2023). It is impossible to make inferences about the dependent variable by preparing the urban internal and external dynamics under similar conditions, as in an experimental setup. The analysis of urban pollutants is complicated, especially since weather studies are extremely vulnerable to external factors, such as forms of urban settlement and natural elements.
All processes affecting cities also influence air quality. After 1980, due to the effect of neoliberal policies, consump- lation of heavy metals in the plant (Aricak et al., 2020;Sevik et al., 2020). However, the information about the structural change and displacement of heavy metals after they enter an area is minimal (Shahid et al., 2017).

Conclusion
This paper aims to increase understanding of urban air pollution in city centers and bioindicators. It also helps in the extremely complex subject, which includes many dynamics, to identify land-use selection decisions in urban planning. According to the values obtained from the plant samples taken from the area, the average values of plants brought from Kızılay are higher than Ulus. Therefore, it has been determined that using motor vehicles is an influential factor in heavy metal accumulation. While the values in the bark of the same plant were high in Kızılay, even higher values were obtained in the leaves in Ulus. This finding reflects the possibility of introduction of heavy metals from the soil or air. Research results reveal poor traffic-induced air quality in a capital's central areas that have become dilapidated and transformed into transit areas.
Monitoring heavy metals regularly in cities is of critical value in terms of spatial location selection. Determination of the pollution values in the planning of uses such as nurseries, hospitals, and rehabilitation centers used by disadvantaged groups, such as the elderly and children, is a compassionate issue in terms of health. However, it is not considered to be a criterion in planning analysis for future land use. that air quality has been adversely affected due to the increase in the use of motor vehicles, the limitation of the city's air corridor, which can be said to be in the form of a bowl, as well as adjacent-order construction due to the topographic structure of the town.
Past studies have demonstrated that the air pollution level of Ankara varies significantly due to the large area of the city (Yildiz et al., 2008). For this reason, centers that are thought to have similar external conditions, but differ relatively in terms of traffic, were selected for analysis. Many studies have determined that different heavy metals are more concentrated in other plants and species (K. Isinkaralar, O. Isinkaralar and Sevik, 2022;Isinkaralar, 2022a;Mahapatra et al., 2019), and in the related literature, traffic is one of the essential heavy metal sources (Çetin et al., 2020;Shahid et al., 2017) Turkyilmaz et al. (2018 investigated the usability of T. tomentosa, E. angustifolia, P. cerasifera, and A. altissima as traffic-dependent bioindicators. The amount of Pb measured in other species grown in areas with heavy traffic was found to be high. Using Abies ' Needles, Cetin et al. (2021) investigated the relationship of Ba concentration with organ, organ age, and traffic density and found a significant correlation. Past trends of Pb and Cd concentrations, Cedrus atlantica (Endl.) Manetti ex Carrière have followed the wet and dry accumulation of emissions of their levels (Isinkaralar, 2022b). It was determined, using the chosen type as a bioindicator, that the amount of lead decreased in parallel with the widespread use of unleaded gasoline in the tree ring over the years.
This paper investigation of Mn accumulation in plants, contributes to the many studies about heavy metals (Yildiz et al., 2011;Isinkaralar, 2022c). Savas et al. (2021) investigated the potential of using C. atlantica at Cr and Mn concentrations. The research results showed that their concentrations are relatively high in the east and north directions, where the traffic is heavy. This paper measured the Mn values of C. atlantica between 1929 and 29531.7 ppb. Igwe et al. (2022) revealed the Mn concentration in the mining area. In this research, A. negundo and F. excelsior were determined as being the most suitable species that can be used to reduce the concentrations of Mn elements in the air. In addition to plant structure and environmental factors such as plant species, the amount of rainfall and moisture, plant habitus, organ structure, heavy metal species, and interaction with the plant are also significant factors which affect the accumu-