Received Date: June 06, 2017; Accepted Date: June 28, 2017; Published Date: July 06, 2017
Citation: Donyaei A, Pourkhabbaz A (2017) A Comparative Study of the Physico-Chemical Characteristics of Dust-Full Particles in Three Stations of Birjand City in Eastern Iran. J Climatol Weather Forecasting 5:207. doi: 10.4172/2332-2594.1000207
Copyright: © 2017 Donyaei A, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Dust storms happening frequently in arid and semiarid regions of the world carry huge amount of particulate matters; hence, these are recognized as one of the most important environmental issues at regional and international scales. This study aimed to evaluate heavy metals laden dustfall particles in Birjand, East Iran.
Sampling of dustfall particles was conducted once every 1 month from July 2016 for 6 month at three stations of Agriculture university, Aboozar avenue, and Shokat university simultaneously using Deposit Gauge Method. The concentration of Fe and Mn were measured using Flame Atomic.
Absorption Spectroscopy and Furnace Atomic Absorption Spectroscopy was used for analyzing Cd, Cr, Pb, As, Cu, and Zn. Then, pollution levels for the heavy metals were evaluated using Geo-Accumulation Index (Igeo) and Integrated Pollution Index (IPI). Mineralogy and morphology of the dustfall particles were inspected using X-ray diffraction and scanning electron microscopy.
Igeo index indicated that levels of pollution for Pb and Zn higher than other among the dustfall particles of the three stations whereas the concentrations of the other heavy metals were not evaluated as contaminant. Moreover, means of IPI values calculated for stations of Agriculture, Aboozar, and Shokat were 1.51, 1.99 and 1.66 respectively. X-ray diffraction revealed abundance of silicate (quartz) and carbonate (calcite) minerals in dustfall particles. Additionally, scanning electron microscopy emphasized on similarity of shape of dustfall particles in the three stations.
Mean of dustfall particles on area unit in Shokat station was less than Agriculture and Aboozar.
Dustfall phenomenon; Birjand; Heavy metals
The phenomenon of air pollution in urban regions is one of outcomes of the industrial revolution which has been embarked 300 years ago and is daily increased with the development of industry and urbanism. Whatever is interpreted as "world crisis of urban pollution” is in fact derived from disordering the balance between the main fundamental elements of natural environment?
The air pollution is one of the basic problems of modern societies. According to definition: the air pollution is predicated to the existence of one or several contaminants in the free air in an amount, time and features which is dangerous for the life of human, animal and plant and things and appurtenance of life, in a way that causes disorder in the relative welfare of human .
The phenomenon of dust is one of the air pollutions with which we were encounter in recent years. The dust is regarded to be the solid material composed of soil, metal anthropogenic mixtures and natural biogenic materials .
The phenomenon of dust is one of the serious bioenvironmental problems in the specific regions of the world. Whereas the most dust of atmosphere is occurred with the origin of fine aggregates and these aggregates enjoy high frequency in dried and semi-dried regions. In fact, the dust is a kind of reaction to change in the vegetation of environment that in this regard, the role of human activities should be attended beside the natural conditions of geographical environments. The effects of dust may be kept at a distance of 4000 km from the main source and cause the outbreak of unfavourable environmental effects and plenty damages in agricultural, industrial, transport and transmission systems. In addition to unstable climate, the existence or nonexistence of humidity is more effective in creating dust so that if the unstable climate consists of humidity, it would create rain, storm and thunder and if it has no humidity, it would cause dust storm .
The dust particles, with regard to their movement origin and path, enjoy high capacity in transporting the heavy metals. So, the study of amount of heavy metals contamination in dust is of much importance because of the dangers which threat the health of human beings. In general, the heavy metal contamination in the particles of dust is considered to be a serious problem because of toxicity, inseparability and concentration [4,5].
In general, two sources of human activities and detrital patterns of soil have been specified for the pollution of dust particles. This is expected from the human resources to cause the contamination of heavy metals because of further industrial activities in urban regions; whereas the existence of heavy metals with high concentration in the dust particles in non-industrial regions is generally related to the erosion of geology structures specially soil .
The heavy metals which form in the fine and light mixtures stay in the environment in a suspended form and at the time of atmosphere rain, some of these contaminants are dissolved in the rain and return to the earth's surface and the metals which exist in the structure of macro and heavy particles, deposit during the time and reach the earth's surface. Generally, the existence of heavy metals in the atmosphere or dust causes the increase of these metals concentration in the body of citizenship of contaminated regions by swallowing, respiration and cutaneous absorption [7,8]. For example, it has been seen that the concentration of lead has been increased in the blood of children by its increase in the dust of atmosphere. If the children are exposed to more than 10 microgram of lead, the decrease of intelligence quotient would be tangible . The severe effects of cadmium such as lung and Prostate cancer, damaging Kidney, Emphysema and Osteoporosis have been reported in different resources. Also, it has been expressed that the respiration of air polluted with Chromium is resulted in Allergic rhinitis, attenuation of Immune system, severe respiratory problems such as Rhonchus and cough .
Of the previous studies about the constitutive mixtures of dust in Asia and Middle East, we can refer to the ones carried out by Krueger et al.; Jaradat et al. in Iran, Rajabi and Suri [6,11,12] carried out some studies about some heavy metals which exist in dust in Sanandaj, Khorramabad and Andimeshk.
The purpose of present research is the study of amount of heavy metals in dust particles of eastern half of Iran by the use of Geo- Accumulation Index and Integrated Pollution Index (IPI) . Also, in this study, the nature and form of sampled dust particles was evaluated by the use of X-ray Diffraction and Scanning Electron Microscope for the purpose of comparing dust particles in two studying seasons.
The Southern Khorasan province, with a land area of about 82864 square kilometer, covers 5/7 percent of total area of country. This province has been located in east of Iran beside eastern north of Lut Desert (Figure 1).
Birjand, county town of province, has a land area of 14265 square kilometer and with regard to the mathematic location it locates in the coordinates of 3253 north latitude and 5913 east longitude and has been risen 1470 m above sea level. This town has been located at the gradient of Bagheran mountain range and nearly in the center of Birjand Desert and has been surrounded by the mountain range .
The climate of Birjand city is of semi-desert kind and has cold winters and dry and hot summers. According to its climate, the rain level of this city is low and the most level of raining is occurred from 21 November to 21 May that this rain is often falls in form of snow in winter. The air of Birjand has severe storm and dust in average in 12 days of year.
Sample preparation and analysis
In present research, the atmosphere dust sampling traps were fitted on rooftops of three builds with 5 m heights and proper locative dispersion for the purpose of sampling atmosphere dust and studying the heavy metals in the atmosphere of Birjand.
The sampling regions are including: Amirabad region, rooftop of Agriculture faculty of Birjand University with the coordinates of 32° 51' 57N latitude and 59° 52' 20E longitude; the second station, the urban region of Aboozar avenue, rooftop of boyish dormitory with the coordinates of 32° 51' 57N latitude and 59° 8' 48E longitude; and the third station, Shokatabad region, rooftop of central build of Birjand University with the coordinates of 50° 37' 32N latitude and 59° 17' 21E longitude (Figure 2).
The atmosphere dust sampling traps (Figure 3) consist of one leg, bottle for collecting dust, one funnel put conversely on the bottle and one glass for collecting particles.
Figure 3: A: Barrier for birds, B: Glass for collecting particles, C: Plastic pipe fixed with tape, D: Backward funnel, E: Collecting bottle, F: Leg .
The dust samples were collected monthly during 6 months (21 June to 21 December). Six samples at each station and totally 18 samples were collected during these six months. The samples were weighed after transferring to the laboratory.
After transferring the samples to the laboratory, the sampled dust particles were washed with the twice distilled water and were heated for 2 h at the temperature of 105°C for the purpose of decreasing the mass of solution and were refined after being cool by Whatman filter No. 42 and were weighed for determining the amount of dust rained on the area. Then, 100 mg of dissolved containments remained on Whatman filter was digested with 5 ml of 0/01% Nitric Acid and was heated for 2 h at 95°C by the use of Block digest system. In next step, the samples were put in Ultrasonic washroom for 30 min at 50°C and then were again refined by Whatman filter No. 42 and the solution reached the mass of 25 ml [15,16].
Finally, in the obtained solution, the metals (Cd, Cr, Zn, Cu, Pb and As) were measured by Furnace Atomic Absorption Spectroscopy and the metals (Fe and Mn) were measured by Flame Atomic Absorption Spectroscopy.
The heavy metals measured in the sample were evaluated by the use of following indexes:
1) Geo-Accumulation Index (Igeo): The index Igeo, according to equation 1, calculates the contamination into heavy metals with regard to the ratio of concentration of each heavy metal in the studied sample into the background concentration of that metal in the earth crust .
2) Integrated Pollution Index (IPI): The index IPI provides an average of ratio of concentration of several heavy metals into the background concentration of same metals in the sample that is calculated according to equation 2 .
Finally, the quantity of IPI is calculated for all metals in the form of average of PI amounts.
The categorization of levels of contamination has been shown according to the amount of Igeo and IPI indexes in Tables 1 and 2 [3,17]. Also, the study of nature and form of dust particles was done by x-ray diffraction and electron microscope imaging.
|Igeo||Igeo class||Contamination level|
|4-5||5||Strongly to extremely strongly contaminated|
|2-3||3||Moderately to strongly contaminated|
|0-1||1||Uncontaminated to moderately contaminated|
Table 1: Pollution levels classified based on Igeo values .
|IPI||IPI class||Contamination level|
Table 2: Pollution levels classified based on IPI values.
The Figure 4 shows the procedure of change among dust particles rained on the area at three stations in Birjand city during the sampling period. As is observed, the changes of dust amount at three stations follow similar procedure so that the least and most amount of dust at all three stations has been occurred at the end of autumn and middle of summer, respectively. Also, the average of amount of dust particles rained on the area for agriculture faculty, Aboozar Square and Shokat University was measured 5/33, 3/29 and 2/24 g/m2 in a period of 30 days.
The amounts of maximum, minimum, standard deviation and mean of concentration of measured heavy metals in dust particles of three stations (agriculture faculty, Aboozar Square and Shokat university) have been shown in Table 3 and as is observed, the most and least amounts at all three stations are related to Zn and Cd, respectively.
Table 3: Values min, max, average and standard deviation of heavy metals in the dust Agriculture University, Abooza Avenue, Shokat University.
The Figures 5-7 and also Tables 4-6 show a little amount of Igeo index for the measured heavy metals at three stations during the sampling period.
|Igeo||Uncont||Uncont||Uncont||Uncont||Moderately Contaminated||Uncont||Moderately Contaminated||Uncont|
|IPI||Moderately Contaminated||Uncont||Uncont||Moderately Contaminated||Strongly contaminated||Uncont||Strongly contaminated||Uncont|
Table 4: Comparison of heavy metals quality values based on Igeo and IPI indices at Agriculture Station.
|Igeo||Uncont||Uncont||Uncont||Uncont||Moderately Contaminated||Uncont||Moderately to Strongly Contaminated||Uncont|
|IPI||Moderately Contaminated||Uncont||Uncont||Uncont||Extremely contaminated||Moderately Contaminated||Moderately to Strongly Contaminated||Uncont|
Table 5: Comparison of heavy metals quality values based on Igeo and IPI indices at Aboozar Station.
|Igeo||Uncont||Uncont||Uncont||Uncont||Moderately Contaminated||Uncont||Moderately Contaminated||Uncont|
|IPI||Moderately Contaminated||Uncont||Uncont||Uncont||Strongly contaminated||Uncont||Extremely Contaminated||Uncont|
Table 6: Comparison of heavy metals quality values based on Igeo and IPI indices at Shokat Station.
As is observed, the amounts of Igeo index for Zn and Pb have secured the most level of contamination to themselves at all three stations and after them, Cd and Cu show the lower level of contamination, whereas the amounts of Igeo index for the other heavy metals were not evaluated contaminating (Igeo<0). Also, the comparison of Figures 5-7 shows the more amounts of Igeo index, especially for Zn and Pb in Aboozar Square than the other two stations during the summer (20 July to 20 August).
The procedure of changes in IPI index for the studied heavy metals at each station has been shown in Figure 8 that confirms tangibly the higher levels of contamination of dust particles with heavy metals at Aboozar station specially in summer (20 July to 20 August); so that the average of amounts of this index for agriculture faculty, Aboozar Square and Shokat university were calculated 1/51, 1/99 and 1/66, respectively.
Also, the pictures provided by the use of Electron Microscope (SEM) show that the similar particles with irregular forms are more effective in creating dust in both seasons (Figure 9).
The study of x-ray diffraction related to the samples of two seasons (Figure 10) confirms the high frequency of Carbonate Minerals (Calcite) and Cilicate (Quartz), although shows the existence of few amounts of the other minerals, too.
The precedence of entrance of dust and heavy dirt from the Arabian countries adjacent with the west of Iran is not so new matter. With regard to the capacity of these dusts in transporting the metals and the importance of matter of continuous encountering of human with the metals which has harmful effects on the health of all living creatures; the study and more attention to the matter of analysing the harmful metals as a new and important matter, in addition to studying dusts and measuring the amount of particles, is of special importance . Being adjacent with Iraq as main center of development of dust, besides this fact that the dry and semi-dried regions cover more than two-thirds of Iran area; justifies the occurrence and exacerbation of this phenomenon in the country . Of three studied station in present research, Aboozar Square is the one in which more amounts of particles is seen because of locating at lower latitude and also lower raining average and higher monthly temperature and being near to the main center of production of dust. The amount of these particles decreases by moving toward the more latitudes and running away from the recourse of production of dust particles . So, the amount of dust particles rained on agriculture faculty and then Shokat university show a reducing procedure in comparison to Aboozar Square. The similarity of changes pattern of amount of dust rained on three stations (Figure 4) can be the indicative of a similar recourse of dust particles in these three stations.
The comparison of amounts of studied metals (Table 3) demonstrates the absolute prominence of Zinc in the studied samples that corresponds to the study done by Bheravesh et al. about the traffic dusts of Mashhad city in 2013 .
As is observable in Figures 5-7 the similarity of changes pattern of Igeo index at the studied stations confirms the identic resource of dust particles reached to the agriculture, Aboozar and Shokat stations with regard to the heavy metals. Also, the Igeo index shows a high level of contamination of dust particles with Zn and Pb at three stations that corresponds to the study carried out by Salmanzadeh et al. . The levels of contamination evaluated by this index for the studied metals demonstrate a relative reduction in autumn in comparison with summer [25,26]. It seems that the prevalence of Breast cancer in women with more than 30 years old  and also increasing Lead in milk tooth of children among the citizens of Birjand city can be related to the toxicity of this heavy metal in dust of eastern hemisphere of country. The Igeo index also shows amounts of low to middle contamination of Cd in the sampled dust particles in all stations (agriculture faculty, Aboozar Square and Shokat University) that the results are similar to the ones obtained from the study done by Javidaneh et al. . This index demonstrates a relative reduction for Zn, Pb and Cd in autumn. Furthermore, the application of Igeo index didn’t evaluate the measured amounts of As, Cr, Mn, Fe and Cu in the dust of three stations contaminating.
The amounts of IPI index show lower oscillation in agriculture faculty and Shokat University during 6 months, whilst follow a similar procedure at these two station (Figure 8); whereas the amounts of this index increase in Aboozar Square in the middle of summer and then descend in autumn. The descending procedure of average of IPI index amounts for the agriculture faculty, Aboozar Square and Shokat university stations is evaluated (1/99, 1/66 and 1/51) respectively and the level of contamination of dust particles with the heavy metals at three stations is evaluated intermediate (Table 2). Kouhzad  consider the four main regions including Sudan, some parts of Saudi Arabia, Iraq and Pakistan and some parts of Iran and Afghanistan that enjoy high level of frequency in Sudan, the main resources of dust storms in Middle West that the frequency of its occurrence from 21 May to 21 July is more than the other months and the level of contamination into heavy metals increases by increasing these dust storms that corresponds to the results obtained of this study.
SEM images review show more dust particle in the summer and fall mainly have a spherical and irregular shapes that associated with its natural origin. Also, it can be said in decreasing process of diameter size of the relative distribution of the particle size, initially larger particles come out of suspension during the transportation of dust particles. In other words, the distance from the source of dust particles tend to be thin (smaller) . It seems the smaller dust particles relate with the order of source distance with the mineral sepiolite. Because sepiolite mineral density of dust particles is reduced toward the equator . Also from the minerals observed in the dust, sepiolite mineral having the smallest size .
As the main product of erosion in sedimentary environment, the presence of minerals calcite and quartz in dust samples represents the natural and probably sedimentary origin of this phenomenon [32,33].
Relationship of mineral particles contained in dust particles with the particle diameter size can be evaluated. Spherical particles with approximate sizes of 5 μm are more than clay (sepiolite) that create dense cluster . Regular crystal structures with 10-20 μm dimensions are more than Calcite crystals. Coarse crystals in sizes 20-40 μm are with prismatic structure of minerals of the albite. Particles close to spherical or have irregular shapes that are approximately 10-20 μm, are also seen as a single mineral [22,24].
But the presence of clay minerals in the soil sepiolite and particulate matter has always been considered as the most important factors of absorb and transmission. The specific chemical structure of this mineral such that contains van der Waals weak links which the meteorological parameters such as temperature changes and moisture breaks down the links and increase production and stimulate of mineral as dust particles . From types of clay minerals, sepiolite minerals due to its specific morphological structure have special importance. Small size, wide and thin shape and presence of large amounts metal oxides shows its role in attracting, retaining and transport of heavy metals in dust.
Concerning the heavy metals, it can be referred to the role of clay in transferring them. The abundance of Calcite and Quartz in both seasons as main products of Sedimentary Clastic environments is the indicative of totally sedimentary derivation for the dust particles of Birjand. The existence of claying minerals as miner mineral phase plays the absorbent role of some heavy metals. The non- ability of most of metals in transmission and reaction with Quartz and Calcite indicates that these minerals play no effective role in the concentration of heavy metals and as the special heavy metals existed, they were more thrown from the environment around themselves in the structure of dust particles and have unnatural derivation .
Also, the study of main oxides which comprise the dust particles in deserts and different regions indicate that Felsic and Tectosilicates mineralogy mixtures are the most essential geochemical structures of these particles  that the existence of Albite, which is of Tectosilicates family, corresponds to the foresaid studies. Also, the existence of Pitromerite in two seasons that are of Potassium minerals and the existence of Potassium is one of important factors in the production of dust particles in the world corresponds to the foresaid studies.
The Pearson Correlation of Cr, Cu, Mn, As, Cd, Zn, Pb and Fe was evaluated and has been shown in Table 4. All metals except Mn have positive correlation with each other. The high positive correlation of metals with each other indicates the similar source of these metals in the dust that can be the same nature and Mn has a different source because of non-correlation with these metals. For instance, Pb and Zn exist more in Carbonate phases and Iron (III) Oxide phases that the main minerals of carbonate phase is produced of the dusts derived from the materials of city.
With regard to the present study, it was specified that the level of contamination of heavy metals in the dust is related to the traffic mass and speeds of cars, because the increase of speed of vehicles can be resulted in the increase of fuel consumption and also the erosion of road surface and tires. The Plumbum existed in the urban dust is derived from the leaded fuel, vehicle oil and erosion and scrappiness of tires. Also, the erosion of cars tires causes the existence of much Zinc in the environment. The highest level of concentration of Copper is related to Aboozar station because of frequent putting on the brakes. There is a high concentration of Cu and Pb in the places in which there exists traffic light because of exorbitant stopping of waiting cars. The existence of industries and industrial wastewaters and also the treatment plant existing in Amirabad region is of main resources of entering Arsenic into the atmosphere.
Also, according to the study done by the use of Igeo and IPI indexes about the amounts of heavy metals in dust particles, there exists rather high level of contamination at the station of Aboozar Square in summer in comparison with the agriculture faculty and Shokat University in summer. These results reveal that the diffusion of heavy metals at first rate is related to the traffic resources and its features such as number of vehicles, kind and speed. With regard to the biological conditions of region, the public approaches of controlling the contaminants can be considered for the purpose of improving the air quality of Birjand city as following: Optimizing the urban traffic or executing methods for controlling traffic and exerting technical and municipal terms and conditions for accelerating the urban traffic, developing the urban greenbelt and regional parks and general education and attracting the attention and cooperation of managers and industrial owners for controlling the air pollution.