Peshawar basin is an intra mountain basin (>5500 km2) situated at the southern margin of the Himalayas and northwest of the Indus plain in the North West Frontier Province (NWFP) of Pakistan. It is bounded by the mountain ranges of Khyber in the west and northwest, Attock Cherat in the south and Swat in the north and northeast while the Indus river borders its southeastern side where it is open for discharge of water. Peshawar, the capital city of NWFP, Nowshera, Charsadda and Mardan are the major cities of this basin. It is mainly irrigated by the Kabul and Swat rivers and their tributaries. The Peshawar basin has Quaternary flanglomerates along the margins of the basin while the central part of the basin is generally covered with fluvial micaceous sand, gravels and lacustrine deposits. On the basis of varying lithologies, the Quaternary sediments, covered soils and hosting aquifers of the Peshawar basin are classified as Peshawar piedmont, Peshawar floodplain and Peshawar lacustrine sediments, soils and aquifers respectively.
For the last two decades, the high rate of industrialization resulted in drastic and unplanned urbanization with heavy load of transportation together with a retarded rate of awareness / education in mainly poor masses have contributed much in creating pollution of all sorts including those of air, water and soil within the Peshawar basin in general and in the Peshawar metropolis in special. The present study is, therefore, based on the monitoring of the environmental degradation of the Peshawar basin, one of the largest basin of Pakistan, during the years 2003 and 2004 by considering mainly the physico-chemical parameters of waters and soils. In order to evaluate the increase and decrease of these parameters with the passage of time. the results of this research were also compared with the previous studies. Physical parameters such as pH, temperature (T), electrical conductivity (EC) and total dissolved solids (TDS) and the anions such as sulfate (SO4), bicarbonate (HCO) and chloride were determined in both surface and ground water while cations such as calcium (Ca), magnesium (Mg), sodium (Na), potassium (K) and the heavy and trace elements such as iron (Fe), copper (Cu), lead (Pb), chromium (Cr), nickel (Ni), cadmium (Cd) and cobalt (Co) were determined in the waters and soils of the Peshawar basin. The physical as well as chemical parameters of the waters were compared with the permissible limits set by US-EP A and WHO and the chemical parameters of the soils were compared with that of the normal agricultural soils.
The aquifers of the Peshawar basin are generally categorized as alkaline earth fresh water with high contents of alkalis but in certain areas small input of alkaline freshwater has also been noticed. Among the physical parameters, pH of the waters of the Peshawar basin varies from acidic (pH = 4.5) to alkaline (pH = 10.1) while the EC and TDS are generally within the permissible limit with elevation in certain areas of the basin. In most parts of the basin both surface and ground waters have cations (Ca, Mg, Na, K) and anions (i.e, SO4, Cl, HCO3) within the permissible limit. However, in certain areas of the basin these cations and anions have high concentrations and could be considered hazardous. The high concentration of these cations and anions can be attributed to the percolation of these waters through the limestone, dolomite, gypsum and seams of sui fides, salts and coals within the Quaternary sediments. The heavy and trace elements (i.e., Fe, Cu, Pb, Cr, Ni, Cd, Co) in the waters of most of the areas of Peshawar basin are within the permissible limit but in certain areas of the basin the concentrations of Fe, Pb, Cr and Ni are too high and may pose a threat to the health of the people. Both anthropogenic and geogenic sources could be responsible for this contamination. The anthropogenic sources include the waste from the industrial Estates and many tannery industries in the Peshawar city and the corrosion of underground pipes while the geogenic sources include the sulfide seams and the mafic and ultramafic rocks in the northwest and northeast of the Peshawar basin. The physico-chemical studies of the surface and ground waters of the Peshawar basin further suggest that there is no significant change in the chemical concentration in these waters with the passage of time.
The chemical characteristics of the soils of Peshawar basin have been evaluated by comparing these with the normal agricultural soil values during this study. This study shows that among the major and minor element oxides, the SiO2, TiO2 and Fe2O3 in majority of the soils of the basin are within the permissible limit for normal agricultural soil but Al2O3, CaO, Na2O and K2O in majority of the soils exceed the limit for normal agricultural soil. The geogenic sources such as the weathering of limestone, dolomite, mafic and ultramfic rocks and K-bearing clays in the surrounding mountains and water logging and salinity are considered to be the main cause of enrichment of AI, Na, Ca and Mg in certain areas of the basin. Among the heavy and trace elements in the soils of the Peshawar basin, relatively high concentrations of Cu, Pb, Ni and Cr have been found in the majority of the Peshawar floodplain soils while Zn is relatively high in the Peshawar piedmont soil. This concentration reached to a high toxicity level in the soils of certain areas, which may have drastic environmental impact on the ecosystem of the region. The high concentration of these elements in the soils of the basin can be attributed to the weathering and erosion of the sulfides, and mafic and ultramafic rocks in the surrounding mountainous regions with greater input from the rocks of the Kohistan island arc in northern regions of the Peshawar basin. This study further suggests that there is no significant change in the concentration of these metals in the soils of the basin with the increase or decrease of the depth and also with the passage of time.
The heavy metal concentrations in the aerosol / dustfall in the traffic congested areas of the Peshawar metropolitan have been investigated with the passage of time. It has been noticed that due to the greater influx of the vehicles in Peshawar, there is an increase in the air pollution in regard to the heavy metals. The multi-fold increase of Pb during the last several years in the ambient air aerosol samples at various places of Peshawar suggests that the vehicular emission is the main cause of the Pb pollution in the air.
The earlier studies suggest that the aquifers in the basin are generally replenished both by rain water and water from Kabul and Swat rivers. This suggests that the contamination in these rivers may have direct effect on the underground water, especially the shallow water (dug wells). As a major portion of the aquifer system of the basin has various cations and anions within permissible limit, it is indicative of the fact that no significant contamination from the surface source has occurred so far. This clearly indicates that if the rivers and adjacent streams and canals of the basin got polluted due to anthropogenic sources in future, there are greater chances of pollution in the major aquifers, even at deeper level, especially in the vicinity of these rivers. Like other metropolitan cities of the world, Peshawar also has most of the environmental problems. The air, water and soil pollution in Peshawar city and cantonment areas have already been reported in previous studies. These studies indicate that the air and sewerage system of the Peshawar metropolis is highly polluted by the heavy metals and are mainly drained in the Budni canal, which ultimately falls in the Kabul river. If the disposal of municipal and industrial waste is continuously falling in the Kabul and Swat rivers, which are irrigating most of the basin, there are greater chances that in future with the establishment of industrial zones, as proposed, in Peshawar, Swat and Nowshera, the aquifer system of the basin would be polluted to a greater extent.