1c

Environ Geochem Health (2007) 29:1–10 DOI 10.1007/s10653-006-9067-8

REVIEW PAPER

Determination of metal accumulation in deposited street dusts in Amman, Jordan Omar Ali Al-Khashman

Received: 16 November 2005 / Accepted: 7 November 2006 / Published online: 4 January 2007
Springer Science+Business Media B.V. 2006

Abstract Street dust samples (120 in total) were collected under stable weather conditions during the hot, dry season (August and September) of 2004 from six different localities (industrial, heavy traffic, medium traffic, light traffic, low traffic and rural) in greater Amman, the capital of Jordan. The concentrations of Fe, Cu, Cd, Pb, Zn and Ni in the dusts were determined by atomic absorption spectrophotometry. The high concentrations of Pb, Fe and Zn in the street dust samples were related to both anthropogenic (industrial sources combined with traffic sources) and natural sources. Surprisingly, the concentrations of Cd in the dusts were low. Correlation coefficient analysis and principle component analysis identified three main sources of these elements and the corresponding distributions. The elements Pb, Zn, Cd, Fe, Cu and Ni were mainly derived from industrial sources, with Pb and Zn additionally derived from traffic sources. The street dusts were found to have highly elevated levels of Zn, particularly along the main trunk roads, indicating that the Zn in the street dusts may be derived from traffic sources, especially vehicle tyres. The concentrations of metals in the different street

O. A. Al-Khashman (&) Prince Faisal Center for Dead Sea, Environmental and Energy Research, Mutah University, Al-Karak 61710, Jordan e-mail: [email protected]

dust samples were found to vary depending on the density of traffic. Keywords Environmental pollution
Jordan
Metals
Statistical analysis
Street dust

Introduction Solid particles that accumulate on outdoor ground surfaces in urban areas are collectively referred to as ‘‘street dust’’. Street dusts are characterized by short residence times ‘‘...although they may contain substantial metal concentrations while street dusts represent only rather recent accumulate of pollutant’’ (Harrison, Laxen, & Wilson, 1981, p. 1379). The two main sources of street dust and, consequently, of the trace elements found therein are deposited airborne particles and displaced urban soil particles (Baptista & De Miguel, 2005). Of the unconsolidated materials (dust, sediment and soil) which originate primarily from the earth’s crust, dust material is the most pervasive and important factor affecting human health and well being (Banerjee, 2003; Yongming, Peixuan, Junji, & Posmentier, 2006). Street dusts that are the product of human activities originate from the interaction of solid, liquid and gaseous materials produced from different source of pollutants (Banerjee, 2003). The components and quantities

123

2

of dust in urban areas are environmental pollution indicators, especially in large cities (Yongming et al., 2006). In urban areas, the metals found in street dust may come from many different sources, including vehicle emissions, industrial discharges, weathered materials and various human activities (Al-Khashman, 2004; Gibson & Farmer, 1986; Harrison et al., 1981; Li, Poon, & Pui, 2001; Sezgin, Kurtulus, Demir, Nemlioglu, & Nayat, 2003; Thornton, 1991). Atmospheric pollution is one of the major sources of metal contamination. Metals can accumulate in the topsoil through atmospheric deposition by sedimentation, impaction and interception (Li et al., 2001). As such, topsoil and roadside dusts in industrial and urban area are indicators of metal contamination from atmospheric deposition. It has been noted that the roadside soils near locations of heavy traffic are polluted by metals (e.g., Charlesworth, Everett, McCarthy, Ordonez, & de Miguel, 2003; Li et al., 2001; Wong & Mak, 1997). Many studies throughout the world have identified the sources of metal contamination in urban dusts as being associated with vehicular traffic as well as with industrial and commercial operations (Al-Chalabi & Hawker, 1997; Charlesworth et al., 2003; Day, Hart, & Robinson, 1975; Jaradat & Momani, 1999; Yongming et al., 2006). In addition, the weathering material from building facades and street dust itself are recognized as significant pollution sources (Abdul-Wahab & Yaghi, 2004; Akhter & Madany, 1993). Soils represent another major source of metal contamination as they make up the dust that settles on urban and rural areas. Moreover, metal particles are emitted onto the road surface as brake dust, road paint, diesel exhaust particles (DEP), road construction materials and car catalyst materials (Adachi & Tainosho, 2004). In Jordan, the number of vehicles that mostly run on leaded fuel has greatly increased during recent years, leading to increasingly high level of metal pollution in both urban and rural areas. The objectives of this study were to determine the mean concentrations of six metals (Fe, Cu, Cd, Pb, Zn and Ni) in street dusts sampled from six different localities in Amman (2.5 million inhabitants), to define their natural or anthropo-

123

Environ Geochem Health (2007) 29:1–10

genic origin by principle component analysis (PCA) and to assess the levels of contamination. The city of greater Amman is suffering from serious air pollution problems from nearby industries, high population and high traffic density.

Materials and methods Study area Amman, the modern and ancient capital of Jordan, is one of the oldest continuously inhabited cities in the world. It covers an area of around 170 km2. The population of Amman has grown rapidly in the last 10 years and was approximately 2.5 million at the time of this study. Amman is the commercial, industrial and administrative center of Jordan. Most of the vehicles in Jordan are vintage 1990 or older and operate on leaded gasoline (0.11 g/l for regular gasoline and 0.17 g/l for super gasoline; Department of Statistics, 2001). The air quality in the Amman area is affected mainly by the level of road traffic and industrial activities. The study area, which is bounded by latitude 3157¢ North and longitude 3556¢ East (Fig. 1), is considered to be part of the highland region and is situated at an elevation of 1050 m a.s.l. The climate is typical of the eastern Mediterranean region, with a hot, dry summer and a rainy winter; the mean minimum temperature is 1.7C in January and 37.6C in July. Rainfall occurs only in the winter season, which is from November to April, and total annual precipitation is around 481 mm. There is the occasional snowfall between January and March, mainly in the highlands west of Amman; the mean number of days with snow is 5–7 days per year, and the maximum recorded annual snowfall is between 50 and 70 cm. The prevailing wind direction is from westerly to southwesterly (Department of Meteorology, 2004). The study area, and most of the country, is located in the northwest part of the Arabian plate. Upper cretaceous carbonaceous facies dominate the central part of the country, whereas ancient basement (pre-Cambrian) and Cambrian Nubian sandstone dominates in the southern part. The basalt desert in the northeast and the rift valley

Environ Geochem Health (2007) 29:1–10

3

Fig. 1 Location map of the sampling sites of Abdali (A1), Wahdat (A2), Wadi El-Seir (A3), Al-Madina (A4), Na’ur (A5) and Jordan University (A6)

form Jordan’s western borders. The sandy facies within the carbonate rock increases towards the south of the country (Banat, Howari, & Al-Hamad, 2005; Bender, 1974). Sampling sites were located in Amman city and involved four major roads, one medium road and one minor road (Fig. 1). They were located in predominantly residential, commercial, rural and industrial areas (Table 1). Background soil samples (n=4) were collected from a non-residential area 8 km west of the city atmosphere, a location not influenced by any source of pollution.

Table 1 Description of sampling locations

Sample collection

Al-Madina (A4) AL1–AL20 (n = 20)

A total of 120 samples of street dust were collected under stable weather conditions in the hot, dry season during the months of August and September 2004. The sampling was chosen at the end of the dry summer months following at least four rainless months, thereby removing any effect

Na’ur (A5) Na1–Na20 (n = 20)

Location/sampling point

Description

Abdali (A1) Ab1–Ab20 (n = 20)

Very high traffic, residential area, high population and commercial area Heavy traffic > 5000 vehicles per hour, high population and commercial area Industrial area, major workplace (mechanical, electrical and paints of vehicles), medium traffic area > 1000 vehicles per hour and residential area Medium traffic area < 1000 vehicles per hour and residential area Rural area, low traffic area (100 vehicles per hour), low population The biggest university in Jordan more than 40,000 people

Wahdat (A2) Wa1–Wa20 (n = 20) Wadi El-Seir (A3) W1–W20 (n = 20)

Jordan University (A6) Ju1–Ju20 (n = 20)

123

4

Environ Geochem Health (2007) 29:1–10

of rain on the trace metals that had accumulated. An area covering part of Amman city and the residential districts around it was classified into 2.5-km2 units. The dust samples were collected from pavement edges using a plastic dustpan and brushes, but they were not collected from sites adjacent to site-specific pollution sources (e.g. industrial sites and gasoline stations). Briefly, the dust samples were collected from both sides of the road on a dry day using a plastic dustpan and brush. A composite sample out of the two collected from both sides of the road was obtained after coning and quartering. About 100 g of dust was stored in small self-sealing plastic bags after being screened through a 2-mm plastic sieve to remove extraneous matter such as small pieces of brick, paving stone and other debris. The collected dust was transferred to self-sealing polyethylene bags for transport to the laboratory. Care was taken to reduce the disturbance to the fine particles to a minimum, as these were readily lost by resuspension. Recently soiled surfaces and areas where car or vehicles were parked or had been parked based on the presence of oil stains were avoided. Any obvious extraneous material, such as cigarette ends or other debris, was not collected with the sample. Between each sampling, the brushes were cleaned thoroughly (Banerjee, 2003). A more detailed description of the sampling locations is given in Table 1. The collected samples were left to dry at room temperature for 5 days (Banerjee, 2003; Baptista & De Miguel, 2005). The pH was measured in a 1:2.5 (sample:distilled water, w/v) mixture (Banerjee, 2003; Okalebo, Gathua, & Woomer, 1993). The percentage of organic matter in randomly chosen samples was determined by the chromic acid digestion method (Jackson, 1973). Organic carbon was evaluated by oxidation with hot K-dichromate and the titration of excess dichromate with ferrous ammonium (Baptista & De Miguel, 2005). Calcium carbonate was measured volumetrically using the Scheibler apparatus and Hg-manometer (Moller, Muller, Abdullah, Abdelgawad, & Utermann, 2005).

oven at 105C for about 4 h to a constant weight. The dried samples were passed through a 2-mm plastic sieve to remove large gravel-sized materials and then homogenized with a polypropylene mortar (Li et al., 2001). About 2 g of dried sample was accurately weighed and digested with 10 ml of concentrated HNO3 solution in a test tube and left overnight. The digested samples were then ultrasonicated for 1 h and heated in a test tube heater for 2 h at 90C. The solutions were cooled, filtered into 25-ml polyethylene volumetric flasks through 0.45-lm filters and then diluted to the mark with 1% HNO3 solution. Metals were determined using a Shimadzu atomic absorption spectrophotometer (model AA-6200). All of the standard solutions were prepared from analytical grade compounds. For the elements Fe, Cu, Cd, Pb, Zn and Ni, six standard solutions of different concentrations were prepared in 2 M HNO3; these standards fell within the linear concentration range for measuring metals. The calibration curves were prepared for each of the metals investigated using the least square fitting method. The accuracies of these methods have been evaluated by analysis of NBS standard reference materials and were better than ±10% (Jaradat & Momani, 1999). A quality control programme, including reagent blanks, replicate samples and standard reference material, was used to assess data precision and accuracy. Blanks were prepared in a procedure similar to that used for the street dust samples and routinely analysed before each measurement (Momani, 2006). All chemicals used for metal measurements were of analytical grade and high purity. All glassware, polyethylene labware and Teflon tubes used in the analyses of metals were washed with detergent, acid-soaked (10% HNO3) and then rinsed thoroughly with deionized water.

Sample preparation

The mean concentrations of metals in the street dust samples obtained at different locations in Amman are presented in Table 2. The concentrations of most of the metals in the majority of

The street dust samples were transferred from the collectors to quartz crucibles, then dried in the

123

Results and discussion Total metal concentrations

Environ Geochem Health (2007) 29:1–10

5

Table 2 The arithmetic mean, standard deviation of metal concentrations in street dust samples (n=20) (all values are expressed as microgram metal per gram street dust) Variables

Abdali (A1)

Wahdat (A2)

Wadi El Sir (A3)

Madina Ar Riadiya (A4)

Na’ur (A5)

Jordan University (A6)

pH EC (ls/cm) %OM %OC %CaCO3 Fe Cu Cd Pb Zn Ni

8.3 632 3.9 2.3 1.4 7132 350 11.2 1131 410 88

8.1 520 3.7 1.8 2.1 5890 320 9.6 1012 377 77

7.8 710 4.9 1.9 1.5 5230 325 6.8 962 267 57

8.2 581 3.8 2.1 1.6 623 285 7.3 787 314 71

7.9 258 5.1 3.3 1.2 2316 66.5 3.1 210 166 43

8.0 389 4.8 3.1 1.9 3816 123 3.5 321 221 67

± ± ± ± ± ± ± ± ± ± ±

0.2 121 0.2 0.8 0.2 91.2 23.5 1.4 21.3 9.2 7.5

± ± ± ± ± ± ± ± ± ± ±

0.1 86.2 0.1 0.2 0.3 78.1 28.2 0.3 25.6 3.2 9.6

the samples analysed were relatively high, and a wide range of values was observed between the different locations that is most likely indicative of the effect of motor vehicles, industrialization and urbanization. The concentrations of these metals in the street dust can also vary greatly according to the strength and direction of wind, composition and pH values. The pH values were relatively similar across the area, ranging from 7.8 (Wadi El-Seir, A3 location) to 8.3 (Al-Madina, A4 location), with dust samples collected nearer to the industrial area in the A3 location being more acidic (Table 1). The percentage of organic matter in the street samples ranged from 3.7 (Wahdat location, A2) to 5.1 (Na’ur location, A5). However, the distribution pattern of organic matter likely reflects the variable distribution of plant, grass and vegetation in the study area. Also, high electrical conductivity values were found at the Wadi El-Sir location (710 ± 131 ls cm–1), while the lowest value of conductivity was found at the Na’ur location (258 ± 57 ls cm–1). The percentages of CaCO3 contents in the street dusts were 2.1% for the major road location (Wahdat) to 1.2% for the minor road location (Na’ur) (Table 2). It would therefore appear that the street dust of Wahdat and the major roads are calcareous and that the CaCO3 content of dust collected from the major roads of Amman city (2.1%) is higher than that reported (1.2%) by AlChalabi and Hawker (1997). In Jordan, which is considered to have a semi-arid climate, the soil and lithology of rocks are predominantly com-

± ± ± ± ± ± ± ± ± ± ±

0.4 131 0.3 0.2 0.7 94.4 52.1 0.1 17.1 9.2 8.5

± ± ± ± ± ± ± ± ± ± ±

0.3 95 0.4 0.2 0.5 77.6 23.1 1.2 1.8 1.9 2.3

± ± ± ± ± ± ± ± ± ± ±

0.3 57 0.1 0.4 0.6 86.5 12.5 0.8 6.3 1.2 6.6

± ± ± ± ± ± ± ± ± ± ±

0.4 55 1.2 1.8 1.4 75.3 13.5 0.5 16.5 1.6 7.3

posed of silicates, clay minerals and carbonate materials such as calcite and dolomite. Street dust is composed mainly of soil materials. The highest values of organic carbon were found at the Na’ur location, and the lowest values at the Wahdat location. As can be seen in Table 2, the mean metal concentrations in the street dust samples were in the order Fe > Zn > Pb > Cu > Ni > Cd. The mean concentrations of metals are lower at site A5 (Na’ur) than at the other sites. Leaded gasoline is the major fuel used in Jordan for cars, small pick-ups and minibuses, and it has been estimated that 89% of Jordan’s vehicles run on the leaded gasoline. In order to reduce air pollution from Pb, gasoline oil in Jordan will meet international standards by 2008 (Momani, 2006). The lowest value of Pb was measured at site A5 (Na’ur; 210 lg g–1), and the highest values at site A1 (Abdali; 1131 lg g–1). The higher concentrations of Pb in the surface sediments may have resulted from the use of leaded gasoline and the increased number of vehicles. Only one sample (Ab9) from the Abdali site had a very high concentration of Pb (1256 lg g–1), and the only possible explanation for this was that it originated from the exhausts of motor vehicles in traffic. Lead is added to gasoline as organic tetraalkyl lead additives in the form of tetra-methyl lead, tetraethyl lead and mixed alkyls triethylmethyl lead, diethyl-dimethyl lead and ethyltrimethyl lead (Arslan, 2001). In general, most of the locations in Amman showed a significant correlation between airborne Pb and vehicular

123

6

traffic density (Jaradat & Momani, 1999), indicating that automobile exhaust emissions could be the source of atmospheric lead in the city. Lead is used in the manufacture of pesticides and fertilizers, in paints and dyes, and in batteries and explosives (Ahmed & Ishiga, 2006). Therefore, by-products of industrial activities are a major source of atmospheric Pb contamination, as is the leaded gasoline used by the increasing number of vehicles in Amman city. The accumulation of metals in Amman roadside soils was also observed by Jaradat and Momani (1999), who reported that it was most likely due to high volumes of vehicle traffic in Amman city and the surrounding areas (Fig. 2). Higher levels of Zn and Cd in high traffic zones indicate that the fragmentation of car tyres is a likely source of these metals (Elik, 2003). The street dust samples generally contained lower levels of Cd than the other metals analysed. The mean concentration of Cd in street dusts collected from areas with heavy, medium, light and low traffic density were 11.2, 9.6, 1.32 and 3.1 lg g–1, respectively. While the highest mean value of Cd was found to be in the

Environ Geochem Health (2007) 29:1–10

street samples from the industrial area (Wadi ElSeir, A3): samples wa12, wa15 and wa18 from the workplace of Wadi El-Seir. The Cd in the street dust is likely to have been produced as a combustion product in the accumulators of motor vehicles or in carburetors (Divrikli, Soylak, Elci, & Dogan, 2003). The range for median values of Cd in street dust samples worldwide has been reported to be 0.5–4.0 lg g–1 (Fergusson & Kim, 1991). The maximum concentration of Zn was found in street dust samples from locations of heavy traffic and industry (Al-Khashman, 2004; Al-Khashman & Shawabkeh, 2006; Elik, 2003). According to Charlesworth et al. (2003), Zn and Cu may be derived from the mechanical abrasion of vehicles, and the location of high values of these elements in Amman may therefore be related to high volumes of traffic. The maximum Zn content was found at site 1 (Abdali, A1), while the lowest values of Zn were found at the Na’ur location (Fig. 2, Table 2). Elevated Zn values in high traffic density areas may have originated from traffic sources, such as from the wear and tear of vulcanized vehicle tyres and the corrosion

Fig. 2 The distribution of Pb and Zn contents in street dust samples collected from various sampling sites in Amman city

123

Environ Geochem Health (2007) 29:1–10

of galvanized automobile parts (Ahmed & Ishiga, 2006; Li et al., 2001). Adriano (2001) also reported that the corrosion of galvanized steel is a major source of Zn emission in the surface environment. The range of median concentrations of Ni and Cu in street dust samples throughout the world is 50–100 lg g–1 and 100– 300 lg g–1, respectively (Fergusson & Kim, 1991). The source of Cu in the street dust in the environment is thought to be due to the corrosion of metallic parts of cars and derived from engine wear and bearing metals (Jaradat & Momani, 1999). In the present study, the mean levels of Ni and Cu in dust samples from Amman were 88 and 350 lg g–1, respectively. The minimum and maximum values of Cu in the street dust were found to be 66.5 lg g–1 (sample 9, Jordan University, A6) and 782 lg g–1 (sample 5, Wadi El-Seir industrial estate, A3). The mean Cu concentration in the Amman dust samples was higher than the mean world dust concentration given by Fergusson and Kim (1991). Li et al. (2001) found higher concentrations of Zn in the street dust of Hong Kong than those reported in a similar study in London (Thornton, 1991). These researchers stated that, based on the high temperatures in the tropical environment, the abrasion of car tyres would be increased (Zn is used as a vulcanization agent in vehicle tyres). On the other hand, Cu is used in car lubricants, while leaded gasoline is the major source of Pb in the urban environment (Moller et al., 2005). Minimum and maximum values of Ni in the street dust samples were found to be 43 lg g–1 (A5) and 88 lg g–1 (A1), respectively. The concentration of Ni in the dust samples from Amman city were agreement with the average world dust concentration given by Fergusson and Kim (1991). Iron is the most abundant metal element in street dust (Hopke, Lamb, & Natusch, 1980), and in the present study it was present at higher concentrations than any of the other metals measured. The high concentration of Fe in the street dust samples may be attributed to the soil of the study area, which has a high Fe content. In addition, Fe may be derived from anthropogenic processes, such as industrial activities, the wear of brake lining material (brake dust) and the corrosion and wear of vehicles (Adachi and Tainosho, 2004; Garg et al., 2000;

7

Hildemann, Markowski, & Cass, 1991; Thomson, Mcbean, Snodgrass, & Monstrenko, 1997). In this study, the highest Fe concentration was found at the Abdali location A1, sample Ab7), which is proximal to the workplace of a car service operation (132 lg g–1). Based on the results of this study, industrial activities, fuel combustion, and traffic emissions are principally responsible for enhanced concentrations of the metals analysed. Statistical analyses and data treatment Correlation coefficient analysis Pearson’s correlation coefficients for metal elements in street dusts in Amman city are summarized in Table 3. Inter-element relationships provide interesting information on the sources and pathways of the metals. A very significant correlation was found between the element pairs Pb-Zn (0.824), Fe-Ni (0.695), Zn-Ni (0.676) and Pb-Ni (0.658). No other metals were significantly correlated with any other metal. Cu is also positively correlated to Fe, Pb and Cd, indicating that it is derived in part from a natural source (soil dust), although it may also be influenced by traffic, industrial and agricultural activities. Significant positive correlations exist for the six metals (Cu, Pb, Zn, Fe, Cd and Ni), suggesting a possible common origin for these metals. The metal concentrations do not correlate with pH, CaCO3, organic matter and organic carbon Table 3 Correlation matrix between metals in the street dust samples. Cells show the Pearson correlation coefficient and the corresponding P value

Fe Cu Cd Pb Zn Ni

Fe

Cu

Cd

Pb

Zn

0.554 0.001 0.252 0.001 0.531 0.000 0.619 0.000 0.695 0.001

0.765 0.001 0.543 0.005 0.314 0.001 0.366 0.000

0.533 0.001 0.35 0.003 0.408 0.000

0.824 0.000 0.658 0.000

0.676 0.005

Ni

123

8

Environ Geochem Health (2007) 29:1–10

Table 4 Rotated component matrix for data of Amman street dusts (PCA loadings > 0.50 were shown in bold) Parameters

Factor 1

Factor 2

Factor 3

pH Organic material Fe Cu Cd Pb Zn Ni Eigenvalue % Variance % Cumulative

0.138 0.118 –0.25 –0.368 0.584 0.864 0.817 0.857 3.464 43.296 43.296

–0.375 0.297 0.802 0.586 0.376 0.156 –1.59 –6.22 1.073 13.418 56.714

0.785 0.913 0.157 0.108 –0.016 –5.16 3.54 –2.79 1.016 12.698 69.421

contents. Owing to the narrow range of pH (7.1– 8.3) measured in the street dust samples, this parameter has limited importance on metal distribution. Principle component analysis PCA was carried out to ascertain the contribution of various factors on the concentrations of metals in the street dust samples and thereby determine the sources of pollution (Banerjee, 2003). The rotation of the principle component was carried out by the varimax method. The factor loadings obtained by PCA with varimax for various metals are given in Table 4. The loadings with a value greater than 0.50 are marked in bold in the table. Two principle components were extracted from the variable dataset; these explained a total variance of approximately 56.71% (Table 4). The first factor, which accounted for 43.30% of the total variance, has high loadings on the element Cd, Pb, Zn and Ni. This factor (source) should be air-borne emissions from various sources and industrial activities (Banerjee, 2003). Pb and Zn were significantly correlated, as can be shown from their correlation coefficient, and have a common traffic source, coupled with industrial sources. Cd and Ni may originate mainly from traffic and industrial sources. High levels of Pb in street dust samples have long been recognized to be linked mainly to traffic activities due to the utilization of leaded gasoline (Day et al., 1975; Yongming et al., 2006). The second factor explains about 13.4% of the variance, with Fe and Cu providing the highest loadings. These

123

metals may be from a source of mixed origin, including industrial and vehicular emissions and metals that were independent of the source of pollution. The third factor accounts for 12.70% of the total variance and was composed of characteristics of street dust pH and organic matter. This factor represents the physicochemical source of the variability and, in the present analysis, is nonsignificant. The first factor represents the contribution of metals from local anthropogenic activities. The second factor represents the contribution of metals from lithogenic and anthropogenic sources. This factor’s high loadings on the elements Fe and Cu suggests the influence of natural sources and some anthropogenic input. Relatively high levels of Cu and Fe in the investigated dusts are interpreted here to be the result of natural enrichment by weathering and pedogenic processes. The results of the statistical analysis and data treatment of the pollutant metals suggests that industrial activities and vehicular emissions represent the most important pollutant sources in Amman city. Conclusion The aim of this study was to define the essential characteristics of metal levels and the sources of metal pollution in street dust samples from Amman city, Jordan. This study demonstrates that the content of street dust in Amman city is primarily the result of local atmospheric deposition. In various cities, the extent of metal pollution in street dust is influenced more by heavy traffic and industrial activities than by population size, with the highest metal concentrations generally being found at locations with industrial emissions and at sites of heavy traffic. On the other hand, the lowest levels of metals in street dust samples are often found at sites with a low population density and low vehicular traffic (e.g., in rural areas). In the present study, the mean concentrations of the metals studied were in order Fe > Zn > Pb > Cu > Ni > Cd. The results of the statistical analysis suggested that vehicular traffic represents the most important contamination source in the studied urban environment of Amman. The current level of metals in the street

Environ Geochem Health (2007) 29:1–10

dust samples of Amman city are within acceptable limits. In the study area, motor vehicles that run on leaded gasoline are, through the emission of particulates, the primary source of the high levels of metals found in the street dust. The trend of increasing anthropogenic activities, such as industrialization and traffic activity, in the city of Amman suggests the need for atmospheric pollution to be controlled. Further study is needed not only to assess the spatial distribution of metals in street dust and roadside soil, but also to examine variations on a small scale. More intensive sampling will be needed, and studies will be required to monitor and measure any change or increase of metals in street dust samples in urban Amman.

References Abdul-Wahab, S. A., & Yaghi, B. (2004). Total suspended dust and heavy metal levels emitted from a workplace compared with nearby residential houses. Atmospheric Environment, 38, 745–750. Adachi, K., & Tainosho, Y. (2004). Characterization of heavy metal particles embedded in tire dust. Environment International, 30, 1009–1017. Adriano, D. C. (2001). Trace elements in terrestrial environments: Biogeochemistry, bioavailability, and risks of metals (2nd ed.). Springer, New York, p. 867. Ahmed, F., & Ishiga, H. (2006). Trace metal concentrations in street dusts of Dhaka city, Bangladesh. Atmospheric Environment, 40, 3835–3844. Akhter, M. S., & Madany, I.M. (1993). Heavy metals in street dust and house dust in Bahrain. Water, Air, and Soil pollution, 66, 111–119. Al-Chalabi, A. S., & Hawker, D. (1997). Response of vehicular lead to the presence of street dust in the atmospheric environment of major roads. The Science of the Total Environment, 206, 195–202. Al-Khashman, O.A. (2004). Heavy metal distribution in dust, street dust and soil from the work place in Karak Industrial Estate, Jordan. Atmospheric Environment, 38, 6803–6812. Al-Khashman, O., & Shawabkeh, R. (2006). Metal distribution in soils around the cement factory in southern Jordan. Environmental Pollution, 140, 387–394. Arslan, H. (2001). Heavy metals in street dust in Bursa, Turkey. Journal of Trace and Microprobe Techniques, 19(3), 439–445. Banat, K.M., Howari, F.M., & Al-Hamad, A.A. (2005). Heavy metals in urban soils of central Jordan: Should we worry about their environmental risks. Environmental Research, 97, 258–273.

9 Banerjee, A.D.K. (2003). Heavy metal levels and solid phase speciation in street dusts of Delhi, India. Environmental Pollution, 123, 95–105. Baptista, L.F., & De Miguel, E. (2005). Geochemistry and risk assessment of street dust in Luanda, Angola. A tropical urban environment. Atmospheric Environment, 39(25), 4501–4512. Bender, F. (1974). Geology of Jordan. Berlin, Germany: Gerbruder Borntraeger. Charlesworth, S., Everett, M., McCarthy, R., Ordonez, A., & de Miguel, E. (2003). A comparative study of heavy metal concentration and distribution in deposited street dusts in a large and a small urban area: Birmingham and Coventry, West Midlands, UK. Environment International, 29, 563–573. Day, J. P., Hart, M., & Robinson, M. S. (1975). Lead in urban street dust. Nature, 253, 343–345. Department of Meteorology (2004). Internal report ‘‘data and files of the department of meteorology’’. Amman, Jordan. Department of Statistics (2001). Annual report. Amman, Jordan. Divrikli, U., Soylak, M., Elci, L., & Dogan, M. (2003). The investigation of trace metal concentrations in the street dust samples collected from Kayseri, Turkey. Journal of Trace and Microprobe Techniques, 21, 713–720. Elik, A. (2003). Heavy metal accumulation in street dust samples in Sivas. Communications in Soil Science and Plant Analysis, 34, 145–156. Fergusson, J. E., & Kim, N. D. (1991). Trace elements in street and house dusts: sources and speciation. The Science and the Total Environment, 100, 125–150. Garg, B. D., Cadle, S. H., Mulaua, P. A., Groblicki, P. J., Laroo, C, & Parr, G. A. (2000). Brake wear particulate matter emissions. Environmental Science Technology, 34, 4463–4469. Gibson, M. G., & Farmer, J. G. (1986). Multi-step chemical extraction of heavy metals from urban soils. Environmental Pollution, B11, 117–135. Harrison, R. M., Laxen, D. P. H., & Wilson, S. J. (1981). Chemical association of lead, cadmium, copper and zinc in street dust and roadside soil. Environmental Science Technology, 15, 1378–1383. Hildemann, L. M., Markowski, G. R., & Cass, G. R. (1991). Chemical composition of emissions from urban sources of fine organic aerosol. Environmental Science Technology, 25, 744–759. Hopke, P. K., Lamb, R. E., & Natusch. D. F. S. (1980). Multi elemental characterization of urban roadway dust. Environmental Science Technology, 14, 164–172. Jackson, M. L. (1973). Soil chemical analysis. New Delhi: Prentice Hall of India Private Ltd. Jaradat, Q., & Momani, K. (1999). Contamination of roadside soil, plants and air with heavy metals in Jordan, A comparative study. Turkish Journal of Chemistry, 23, 209–220. Li, X. D., Poon, C. S., & Pui, S. L. (2001). Heavy metal contamination of urban soils and street dusts in Hong Kong. Applied Geochemistry, 16, 1361–1368.

123

10 Moller, A., Muller, H. W., Abdullah, A., Abdelgawad, G., & Utermann, J. (2005). Urban soil pollution in Damascus, Syria: Concentrations and patterns of heavy metals in the soils of the Damascus Ghouta. Geoderma, 124, 63–71. Momani, K. A. (2006). Partitioning of lead in urban street dust based on the particle size distribution and chemical environments. Soil & Sediment Contamination, 15, 131–146. Okalebo, J. R., Gathua, W., & Woomer, P.L. (1993). Laboratory methods of soil and plant analysis. A working manual. TSBF program, Nairobi, Kenya. Sezgin, N., Kurtulus, H., Demir, G., Nemlioglu, S., & Bayat, C. (2003). Determination of heavy metal concentrations in street dust in Istanbul E-5 highway. Environment International, 29, 979–985.

123

Environ Geochem Health (2007) 29:1–10 Thomson, N. R., Mcbean, E. A., Snodgrass, W., & Monstrenko, I. B. (1997). Highway storm water runoff quality: Development of surrogate parameter relationships. Water, Air and Soil pollution, 94, 307–347. Thornton, I. (1991). Metal contamination of soils in urban area. In: P. Bullock, & P.J. Gregory (Eds.), Soil in the urban environment (pp. 47–75). Blackwell. Wong, J. W. C., & Mak, N. K. (1997). Heavy metal pollution in children playgrounds in Hong Kong and its health implications. Environmental Technology, 18, 109–115. Yongming, H., Peixuan, D., Junji, C., & Posmentier, E. (2006). Multivariate analysis of heavy metal contamination in urban dusts in Xian, central China. The Science of the Total Environment, 355, 176–186.