Among many anthropogenic causes, rapid urbanization and industrialization are the two fundamental factors causing degradation of the environment [1,2]. Environmental pollution affects the quality of each of the spheres viz; pedosphere, hydrosphere, atmosphere, lithosphere and biosphere [3,4]. In recent era, environmental degradation and consequent problems of large cities and urbanindustrial agglomerations is a subject of fundamental concern and debate among planners and policy makers. The world is turning towards an urbanized world and more than half of the population is living in urban areas. This trend is getting momentous increase and more people are shifting to urban areas. This is one way, or the other effects the city environment and ultimately because of the human activities, the urban environment tend to be degraded. As the world urbanization prospects suggested the world urban population will reach from current to 8.3 billion in 2030 [5].

Contamination of urban soils with heavy metals has been studied and documented all over the world and in many disciplines including geography. This phenomenon followed by massive research has created a major apprehension at local, regional and global level due to their implication on human health [6,7]. Heavy metals can cause surface and ground water pollution and are taken up by plants, released as gases into atmosphere or bond semi enduringly by soil components such as organic matter and clay particles which later affects human health [8]. Natural sources of heavy metals are weathering of parent rocks. Furthermore there are several point and non-point sources of heavy metals frequently related to the urban land use, economic, industrial and transportation set up [9].

Moreover Xia et al. [4], excogitate the soil heavy metals pollution a major environmental dilemma while Maas et al. [10] considered the soil a sink as well as a source of pollution and most significant entity for risk evaluation. Vehicular emission commercial fertilizers, atmospheric deposition of contaminants through dust and aerosol’s, industrial and domestic waste, thermal power stations based on coal-fired and energy industry based on fossil fuel burning have also been sources of the huge amount of heavy metals contents in urban soil [10-12].

GIS is computer based information system which is a potent tool for the geochemical mapping of trace metals in the various compartment of the environment such as air, water and soil. Geographic Information System provides the techniques for measuring, modeling, manipulating, retrieval and analysis of spatial data. The interactions between the chemical contaminants such as trace metals and urban land features of the urban environment can be conducted with the help of overlaying analysis of the contaminants spatial distribution in the various urban landscapes [12-16]. Thus present research interrogates the spatial distribution of heavy metals in urban parks soil of the study area i.e.; Faisalabad city.

Aims and objectives of the study

The aim of study is to examine the spatial variation of the the heavy metals contents in surface soil of the study area by using GIS techniques.

a) To assess the environmental quality of urban parks by analyzing the pollution level of heavy metals in the urban soils of Faisalabad city.

b) To evaluate Spatial Risk of the heavy metals on human health.

The study area Faisalabad, “the Manchester of Pakistan” lies between longitude 73° to 74° east, latitude 30° to 31.5° north. The city’s elevation is 605 feet above mean sea level. Faisalabad is the third largest city in terms of population size and ranked third in the national hierarchy. Present population of the city is 25,53,000 souls. The districts surrounding Faisalabad have not been separated from the city by any natural and physiographical feature. Faisalabad is bordered by Sheikhupura, Okara and Sahiwal districts, towards the east and south east while on the west and south west has been bounded by district Jhang and Toba Tek Singh. In the north and northeast it is surrounded by Hafizabad and Sheikhupura districts. Because of population size as well as industrial concentration, all the compartments of the environment needs to be thoroughly examined and researched with the help of latest techniques currently used in geography.

Presently, City District Faisalabad consists of eight Towns, which are as follows: Lyallpur Town, Medina Town, Jinnah Town, Iqbal Town, Samundri Town, Tandlianwala Town, Jaranwala Town, and Chak Jhumra Town City Motorway are linked to city through M-3 section boundaries. The research work was conducted in four towns namely Lyallpur town, Iqbal town, Medina town and Jinnah town and the areal extent of sample sites was 213 sq Km (Figure 1). The soil in the Faisalabad city is calcareous in nature with alluvial deposition by two adjoining rivers viz; River Chenab, which flows 30 km northwest and river Ravi, 40km away from the city [17].

Figure 1: The study area.

GIS is one of the key tools for soil, water, air and land pollution assessment widely used amongst researchers in various disciplines. Since, Faisalabad is an industrial city and more prone to contaminants therefore by considering, conducting and monitoring heavy metals contamination in surface soil of urban parks is as an important debt in academic circles. The current research work preceded with collection soil data from the selected sites in urban parks of Faisalabad city (Figure 2). Soil Samples were taken at 15 cm depth because top soil lies in this depth while hand held GPS was used to record the global coordinates of each selected site for spatial analysis. The selection of urban parks was based on maximum number of visitors per park and sixteen most popularly visited urban parks, playgrounds and green areas in the Faisalabad city were selected for heavy metals Zinc, Copper, Nickel and Lead analysis (Figure 3). The logic behind this was the greater exposure of human population in these parks meaning more the visitors more they will be prone to be affected by soil contamination. Analytical determinations of heavy metals contents were performed by Inductively Coupled Plasma (ICP), Optical Emission Spectroscopy, Perkin Elmer 2100 DV [15,18].

Figure 2: Location of soil sample sites urban parks, Faisalabad city.

Figure 3: Spatial analysis of Cu, Ni, Pb and Zn urban parks in Faisalabad city.

Heavy metals were analyzed by ICP spectroscopy in the Nuclear Institute of Agriculture and Biology (NIAB) laboratory for Ni, Zn, Pb, and Cu. Spatial maps of pollution assessment were designed with the help of Geographic Information System. Spatial distribution maps of heavy metals were created by using the quantities technique of graduated symbols method with help of ArcGIS 9.3 Software. Various statistical measures such as cluster analysis were performed in order to have an insight to the level of pollution of each parameter and their comparison with each other. The secondary data regarding the health condition prevalent in the study area was collected from the District Health Office, Faisalabad (DHO, 2011).

The concentration of Zn found in the soil of the urban park the study area range from 25 mg/Kg to 111 mg/Kg (Figure 3 and Table 1). The presence of Zn is strongly related to the uncontrolled solid and liquid waste from industrial, domestic and sewerage as well as other anthropogenic activities [11,19]. The maximum concentration of Zn (mg/Kg) 62-111 was recorded in Gol Park, Gousia Park and Plant pathology experimental area of UAF which has crossed the world average values Zn concentration (Table 2). Sheraz Park, Dhobi Ghat were reported to have 49-61 (mg/Kg) of Zn. Alfateh Ground, Jinnah Garden, Raja Park and Usman-e-Ghani Park have 38-48 mg/Kg of Zn contamination whereas, the 28-37 range were found in the urban parks Allama Iqbal, D-Ground, Hockey stadium, Foot Ball Ground, Iqbal Stadium. There were two places Madina Central Park and Kaleem Shaheed Park with minimum concentration of Zn i.e., 25-27 mg/Kg (Figure 3). Diarrhea is 2^nd most common disease in Faisalabad district in the month of January & February 2011 (Figure 4). Gastrointestinal infections are results of Zinc excessive exposure (Ghishan et al., 2006). Spatial variation of Cu contamination found in the soil of urban parks in the study area ranged from 14mg/Kg to 53mg/Kg and has been depicted through spatial map created by using the quantities technique of graduated symbols. The maximum quantity of Cu within the range 35- 53 (mg/Kg) and above the acceptable limit (Table 1) and far beyond the world average quantity of Cu (Table 2) was investigated and reported in Gol Park.

Table 1: Comparison of heavy metals values with the acceptable limits.

Table 2: heavy metals concentration in (mg/kg) in urban park soil of Faisalabad city (N=16).

Figure 4: Chronic diseases incidence in Faisalabad district during the month of March, 2011.

While, Cu in plant pathology experimental area of University of Agriculture Faisalabad and Jinnah Garden ranges from 25 mg/kg to 34 mg/kg above the world average (Table 1). Raja Park, Dhobi Ghat, Alfateh Ground, Gousia Park, Iqbal Stadium, Sheraz and Allama Iqbal Park have Cu contamination of 20-24 (mg/Kg). Hockey stadium and D-Ground have Cu contamination of 16-19 mg/kg. While the 28-37 range captured in the urban parks namely Allama Iqbal, D-Ground, Hockey stadium, Foot Ball Ground, Iqbal Stadium. There were two places viz; Foot Ball Ground and Madina Central Park, which have minimum quantity of Cu contamination i.e. 14 to 15 mg/Kg (Figure 3). Copper cause acute form of lungs diseases, hepatic and neurological diseases even liver failure and basal ganglia [20]. Lead causing the abdominal pain, developmental diseases and genes deregulation [21]. The Pb contamination in urban park’s soil of the study area ranged between 0 mg/Kg to 19 mg/Kg. Although Pb is related to human activities [22], but urban parks have least quantity of Pb because of minimum vehicular impact [6]. The maximum quantity of Pb with the one largest circle 15-19 (mg/Kg) was reported in the Gol Park.

There are two sites with second largest range of 10-14 while four sites have Pb in the range of 3-9. There were five places where Pb ranged from 1-2 mg/kg while minimum quantity of Pb contamination with value less than 1 mg/kg was found in four of the samples sites (Figure 3).

The spatial distribution of Ni contamination found in urban parks’ soil of the study area ranges from 9.3 mg/Kg to 25.75 mg/Kg (Table 1). In soils, Ni naturally occurs in rocks and is usually present in the organically bound form which can increase its mobility and bioavailability [6,23]. It has been delineated through spatial analysis that the level of Ni contamination in the study area is highest from 26 mg/Kg to 23 mg/ Kg for plant pathology experimental area, University of Agriculture Faisalabad, Jinnah Garden, Allama Iqbal Park Gousia Park, Raja Park and Gol Park. Comparatively lower quantity was observed in Iqbal Stadium, Kaleem Shaheed Park, and Hockey stadium, D-Ground, Dhobi Ghat, Alfateh Ground and Madina Central Park ranging from 15-22 mg/kg. The minimum value for Ni was found in the Foot Ball Ground (Figure 3). Excessive exposure to Ni through inhaling, ingestion and dermatitis can cause the cardiovascular, kidney and lungs disorders (Alessio, 2011). Pulmonary infection is the most commonly prevalent diseases in sample areas with maximum percentage in Faisalabad district (Figure 4). The mean concentration of Zn, Cu, Pb and Ni in mg/Kg in urban parks soil of the study area was found to be 48.4, 24, 5.46 and 21.4 respectively (Table 2).

Box-Whisker Plot diagrammatically provides the statistical calculation of Q1, median, Q3, inter quartile range (Figure 5). The clusters 1 (Zn mg/kg) and 3 (Pb mg/kg) joined with 95.78% of similarity level while Cluster 1 (Zn mg/kg) joined with cluster 2 (Cu mg/Kg) with the similarity level 92.19%. Moreover Cluster 1 also joined with cluster 4 with 76.8% similarity level (Figure 6 and Table 3).

Figure 5: Boxplot of Zn, Pb, Cu, Ni (mg/kg) in urban parks soil of Faisalabad city.

Figure 6: Dendrogram.

Table 3: Cluster Analysis of Variables: Zn, Pb, Cu, Ni (mg/Kg).

During the last few decades industrial development and momentous urbanization are the two significant factors in Pakistan as well as many large cities of the country which are considered to be the potent causes of environmental degradation. Since all the major cities are suffering from various environmental problems and Faisalabad is by no means an exception. As the city of Faisalabad is 2^nd largest industrial city of the country and shares all the environmental issues of such cities in Pakistan as well as in the world. Faisalabad has long been a source of influx of several pollutants, particularly heavy metals into its urban environment. Undeniably, there is a rising concern and apprehension among the people of Faisalabad over the prospects of pollution of urban soils with heavy metals. Hence, an extensive soil survey was conducted in urban parks of Faisalabad city, Pakistan, to assess the existing status of heavy metal contamination. Urban and industrial influences triggered the heavy metals pollution in the study area with the mean concentration ranging from 25.02-111.15, 13.83-53.23, 9.30-26.00 and 0.00-18.93 mg/ Kg for the Zn, Cu, Ni and Pb respectively. The decreasing order for the calculated variance about the analyzed parameters is Zn>Cu>Ni>Pb. Gol Park and plant pathology experimental area University of Agriculture Faisalabad urban parks reported to have crossed the acceptable limits for the Cu contamination in the soil which is pertinent to hepatic and basal ganglia degeneration among the people living nearby. It is recommended that there should be appropriate legislations to make certain effectiveness in the disposal method which is crucial to the sustainable development of urban environments. In order to reduce the rate and extent of future pollution problems in the city regular monitoring of heavy metal pollution in soil is essential.