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Hamid Raza HM*, Sidra Khawer, Umar Farooq, Makshoof Athar and Saima Atif
Institute of Chemistry, University of the Punjab, Lahore, Pakistan
Received date: August 16, 2013; Accepted date: October 14, 2013; Published date: October 20, 2013
Citation: Hamid Raza HM, Khawer S, Farooq U, Athar M, Atif S (2013) Assessment of Soil Contamination near Samanabad Sewage Drain and its Nutritional Potential for Aesthetic Beauty. J Earth Sci Clim Change 5: 167. doi:10.4172/2157-7617.1000167
Copyright: © 2013 Hamid Raza HM, 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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Soils are the primary component of urban ecosystems. Pollution of soil caused usually due to xenobiotic materials and alteration in the environment natural soils, which is due to improper waste disposal, agriculture chemicals and industrial activities. The present study is to monitor the soil pollution and the suitability of contaminated soil to be used to enhance floral beauty of land adjacent to Samanabad Sewage Drain, Lahore. Total 6 km of land was divided into 8 sites, 4 on each side of the drain. A total of 32 samples were collected from four different depths: 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm. Soil quality parameters: Saturation percentage, electrical conductivity, moisture content, organic content, potassium, phosphorus and heavy metals in soil samples were analyzed and compared with different available standards statistically. Results showed that the soil electrical conductivity, potassium, phosphorus, organic contents and heavy metals were relatively higher than standards. Due to high nutritional value, soil can be used as compost or fertilizer to enhance floral beauty through selective planting of salts and metal tolerant ornamental plants.
Soil analysis; Aesthetic beauty; Plantation; Samanabad sewage drain; Compost
Rapid and drastic urbanization have not only resulted in amplified soil pollution but also a worsening hazard of contaminants up taken by organisms. Soil in urban areas is the recipient of diverse physical and chemical contaminants that are frequently used as indicators of environmental quality [1,2]. These contaminants are related to a number of anthropogenic sources of pollution, such as emissions from industrial plants, vehicle exhausts, thermal power stations and dumping of different wastes in soil [3-5].
Soils are the primary component supporting plants in urban ecosystems. Plants render their valuable services such as offsetting emission of carbon, removing pollutants in air, regulation of microclimate, sustainable urban structure as well as aesthetic beauty of urban areas. For example, in China tree plantation has been proposed by the government as a mean to alleviate air pollutants in Beijing . Earlier study conducted on soil around Hudiara drain near River Ravi, Lahore has shown that the contaminants present in drain water not only cause soil pollution but also affects plant’s growth of that area .
The present study is to evaluate the soil contamination and the soil’s ability to support plants, which enhance aesthetic value of the urban environment. To achieve the main objective of this study different physical parameters (soil texture, saturated percentage and moisture content), chemical parameters (phosphorus, potassium, organic content, pH, electrical conductivity) and heavy metals (Cd, Pb, Zn, Fe, Cu, Ni, Cr) of soil samples collected from land adjacent to Samanabad sewage Drain, Lahore were analyzed. The results were compared statistically with different available standards.
The sampling plan was prepared based on a map of Samanabad Sewage drain, Lahore obtained from Google Earth® (Figure 1). The Latitude and Longitude of Samanabad Sewage Drain is 31°32´40.44´´ North and 74°18´01.91´´ East respectively. Sampling was done in the month of March with average temperature 25°C, average precipitation was 2mm, average wind was 7 Km/h and average sea level pressure was 1011hPa. Total six square kilometre area of land was divided into 8 sites that is 4 on each side of drain and categorized as SITE 1, SITE 2 and so on up to SITE 8. Each site is of 1.5 kilometres approximately in length (Figure 1). Initially, soil samples were collected at four randomly selected subsites of each site. To obtain a composite soil sample, subsamples of each soil depth were mixed separately for each site. Four samples (1, 2, 3, and 4) were excavated from 0-15cm, 15-30cm, 30-60cm and 60- 91cm respectively from each site with Auger and measuring tape. Total 32 samples were taken to determine concentration of contaminants separately at different depths by the stainless steel soil Auger (STIHL BT 121). Samples were placed in airtight plastic containers, brought to the laboratory for the purpose of analyses. Each container contained about 1.5 kilograms of soil. For the physical and chemical analysis, representative sample from each soil sample was air-dried and ground to get powder form then stored in labelled airtight plastic containers. All the sample collection and analytical work was done according to the standard protocols given in ‘Diagnosis and Improvement of Saline and Alkali Soils’ . All dilutions were done by using doubly distilled water and chemicals used were of analytic grades directly obtained from Merck, (Germany).
Analysis of physico-chemical parameters
A 250 g of soil was taken in plastic beaker and doubly distilled water was added to get saturated soil paste till soil paste glisten reflect light from the surface and slide freely from the spatula. Saturation percentage of soil sample was calculated by the amount of water used. This paste was further used for determination of Electrical conductivity by using a conductivity meter (CD-2002 VIS 05, SELECTA).
For pH measurement, soil-water suspension was prepared by (1:2.5 by weight-volume soil to water ratio). The contents were allowed to equilibrate for half an hour by stirring and pH was measured by pH meter (HANNA 212 Microprocessor, USA). Soil texture of all the soil samples was calculated by their silt, clay and sand percentages and then classes of texture were measured by using ‘Soil Texture Triangle’. For moisture content determination, soil (25 g) were transferred into Petri dish of known weight and kept in oven at 105°C till constant mass. Samples were re-weighed and moisture content was measured by the difference method.
Available phosphorus was analyzed by Olsen method. A measured quantity (2.5 g) of air dried and ground soils were mixed with extracting solution (50 ml) i.e. NaHCO3 (0.5M) at pH 8.5 and taken on Spectrophotometer (APEL-PD-303S, JAPAN). Available Potassium (K) was analyzed by ammonium acetate extraction method . A measured quantity (5.0 g) of air-dried soil sample and 25 ml of ammonium acetate extracting reagent was added into 250 ml Erlenmeyer flask. After shaking at 150 rpm for 30 minutes at 298 K on rotary shaking (9007400-IKA, GERMANY) samples were filtered and filtrates were analyzed by using flame photometer (JENWAY PFP-7).
Organic content in soil was determined by Walkly-Black acid digestion method . Ammonium Bicarbonate Diethylene Triamine Penta Acetic Acid (AB-DTPA) extractable heavy metals (Zn, Cd, Cr, Pb, Fe, Ni and Cu) in soil were determined as done by Soltanpour . Digested samples solutions were analyzed using Atomic Absorption Spectrophotometer (Perkin Elmer 800, USA). All chemicals and metal salts were used of analytical grades of Sigma-Aldrich followed by dilutions with doubly distilled water.
Data and statistical analysis
Statistical study of mean values and standard deviation were done on statistical Minitab® (version 15). The Results were compared with the standard value by Agriculture Department Punjab (ADP), European Community Commission (ECC) and Indian Allowable Limits (IAL).
Samanabad sewage drain is one of the major open drains of Lahore which originates from Muridkay near Lahore while carrying different types of commercial, industrial and residential solids and liquid wastes. Solid waste was dumped on the sites particularly at site 2, which also have many inlets of wastewater coming from residential areas. There was no proper waste disposal management system in this area surrounded by Samanabad sewage drain.
The result showed that all the soil samples were of sandy clay loam category of soil texture triangle. Loam soils contain silt, sand and clay in a proportions that non-adhesiveness and stickiness is in balance. Hence, it can be mouldable but not sticky and "friendliest" soil to cultivate . The saturation Percentages (SP) of all the samples are in the range from 32 to 44%. The mean of saturation percentage at different soil depths 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm are 37.75 ± 1.44%, 37.25 ± 4.33%, 38.5 ± 1.24% and 37.25 ± 1.19% respectively (Figures 2a and 2b). All values were within the ADP permissible limits i.e. 30 to 45%, which consider as cultivation friendly soil. The pH values of all sampling sites of study area range from 7.5 to 8.3. Mean pH values at 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm depths are 7.9 ± 0.07, 7.9 ± 0.06, 8.0 ± 0.07 and 8.0 ± 0.08 respectively (Figures 3a and 3b). All sampling sites have pH within ADP standard i.e. 8.0, except SITE 1 and 2. The low and high pH value in particular area may be due to the constant decomposition of surface litter and high concentration of acidic or basic salts. Soils with higher pH generally have reduced capacity for regaining its nutrients.
Electrical Conductivity (EC) of all collected soil samples is ranged from 1.35 to 23 mS/cm. The Mean value of electrical conductivity of soil at 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm depths are 4.0 ± 1.40 mS/cm, 4.2 ± 2.24 mS/cm, 4.1 ± 2.27 mS/cm and 4.5 ± 2.68 mS/cm respectively (Figures 4a and 4b). Mean values of soil depths were higher than that of the ADP standard value i.e. 4 mS/cm. Other sampling sites have less or equal values except SITE 2, which have highest value that is 19.18 ± 2.05 mS/cm. Higher EC at site 2 is because there were inlets of wastewater coming from residential and commercial areas and dumping of heavy amount of wastes at this site followed by addition of salts. It may also be due to the upward movement of water and high rate of evaporation from the soil surface.
Moisture Content Percentage (MC%) of all soil samples is ranged from 4.20 to 20.80%. The mean values of moisture content at soil depths of 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm are 14 ± 10%, 13.3 ± 1.67%, 12.5 ± 1.75% and 13.5 ± 1.80% respectively. Sampling sites have less Moisture Content percentage except SITE 1, which has 19.9 ± 0.49% (Figures 5a and 5b). Rise in temperature causes evaporation of moisture from soil, which may be the reason of decrease in soil moisture in sampling site. Shaded areas have higher moisture Content while areas where sunlight is directly incident have lesser moisture content.
Organic content values of soil samples ranged from 0.84 to 2.23% in all sampling sites of study area. The mean values of organic content at 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm depths are 1.4 ± 0.31%, 1.2 ± 0.49%, 1.2 ± 0.31% and 1.2 ± 0.23% respectively. The comparison showed that 0-6˝ depth in particular has higher value of organic content (Figures 6a and 6b). The mean values of all samples of SITE 7 and SITE 8 have higher organic content than that of ADP standard, which is 1.29 %. The climate of study area was warm so this may be a probable reason for low organic content. It has been observed that organic content is available more generally in cooler climates than warmer climates . The higher concentrations of organic matter in some sites may be due to the dumping of organic waste in specific areas.
The Potassium concentration of soil samples collected is in the range from 82 mg/kg to 606 mg/kg. The mean potassium concentrations at soil depths 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm are 200.25 ± 58.80 mg/kg, 196.62 ± 45.30 mg/kg, 176.50 ± 45.00 mg/kg and 161.87 ± 36.70 mg/kg respectively. The comparison with ADP standards showed that average conc. of potassium at 0-15 cm and 15-30 cm depths is higher but lower at 30-60 cm and 60-90 cm than that of the standards i.e. 180 mg/kg. The potassium concentration at all sampling sites are within permissible limits given by ADP standard i.e. 180 mg/kg except SITE 1 and 2 (Figures 7a and 7b). Soils had comparatively elevated clay and silt fractions, signifying their capability to retain K. There is a positive association between soil pH and exchangeable cations like potassium as already reported by Evangelou . Moreover, another study showed that release of non-exchangeable K could have increased the available K. Since Mica being one of the component of silt and contributing total K that can be positively correlate to clay content in soil texture .
Phosphorus concentration in all samples is in the range from 4.36 to 103 mg/kg. The mean concentration value of phosphorus at depth of 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm are 33.3 ± 10.50 mg/kg, 21.4 ± 6.95 mg/kg, 15.8 ± 4.60 mg/kg and 16.1 ± 3.46 mg/kg respectively. The comparison with ADP standard showed that mean values of phosphorus in all soil depths are much higher than that of the standard value i.e. 14 mg/kg. Concentration of phosphorus is 9.4 ± 1.19 mg/kg and 11.6 ± 3.71 mg/kg at SITE 4 and SITE 5 respectively while other sites have higher values except SITE 6 (Figures 8a and 8b). Their comparison with ADP standard shows that the mean phosphorus concentration at SITES 1, 2, 3, 7 and 8 are higher than standard i.e. 14.0 mg/kg while at SITE 4, 5 and 6 are within the permissible limits. It is stated that manure dissolves rock phosphate and may lead to high soil phosphorous concentration. Actually, manure itself is a source of phosphorous that can elevate soil phosphorous level significantly. Manure and human waste from drain water could be a possible reason for these alleviated values as drain is receiving wastewater from residential area. This also has been found in previous studies that manure have a strong dynamic force for the dissolution of phosphate rock in a manner which increase the available phosphate in soil (Table 1) .
|Mean||36.5 ± 1.91||7.8 ± 0.14||2.1 ± 0.30||19.9 ± 0.99||1.0 ± 0.31||186.5 ± 16.98||20.7 ± 4.37|
|Mean||32.5 ± 1.00||7.5 ± 0.05||19.1 ± 4.10||7.8 ± 3.29||1.1 ± 0.40||501.5 ± 80.3||63.2 ± 29.10|
|Mean||37 ± 2.00||8.1 ± 0.08||1.8 ± 0.35||11.8 ± 1.05||0.9 ± 0.13||141.7 ± 9.98||16.3 ± 9.70|
|Mean||42 ± 2.31||8.1 ± 0.05||2.1 ± 0.29||17.3 ± 1.15||1.1 ± 0.25||129.5 ± 11.85||9.4 ± 2.38|
|Mean||40.5 ± 3.42||8.0 ± 0.12||2.1 ± 0.44||14.8 ± 1.9||1.2 ± 0.22||144.5 ± 30.8||11.6 ± 7.42|
|Mean||41 ± 1.15||8.1 ± 0.17||1.6 ± 0.34||13.0 ± 1.92||1.3 ± 0.16||136.8 ± 29.7||9.9 ± 6.83|
|Mean||37 ± 1.15||8.1 ± 0.05||2.1 ± 0.07||7.9 ± 1.84||1.5 ± 0.16||98.7 ± 13.96||20.4 ± 5.28|
|Mean||35 ± 1.15||8.0 ± 0.05||2.1 ± 0.16||14.2 ± 1.29||1.9 ± 0.40||131.2 ± 14.38||21.7 ± 12.18|
|Average of Sites||37.6 ± 3.25||7.9 ± 0.20||4.1 ± 6.06||13.3 ± 4.19||1.2 ± 0.29||183.8 ± 13.06||21.6 ± 17.50|
Table 1: The physico-chemical values of soil samples collected from land adjacent to Samanabad sewage drain, Lahore.
The concentration of heavy metals zinc, cadmium, chromium, lead, iron, nickel and copper in soil samples are 102 mg/Kg to 153 mg/Kg with mean 128.8 ± 16.75 mg/Kg, 2.7 to 7.3 mg/Kg with mean 4.6 ± 1.68 mg/Kg, 104 to 135 mg/Kg with mean 118.8 ± 11.22 mg/Kg, 543 to 780 mg/Kg with mean 672.1 ± 85.8 mg/Kg, 21.80 to 40.60 mg/ Kg with mean 31.8 ± 7.87 mg/Kg, 155 to 440 mg/Kg with mean 305 ± 127.1 mg/Kg and 180 to 350 mg/Kg with mean 276.6 ± 62.8 mg/ Kg respectively (Figure 9 and Table 2). The reason of having ECC (European Community Commission) standards and Indian allowable standards for comparison is that they are mostly adapted all over the world and India has almost similar climatic and weather conditions as in Pakistan. According to European Community Commission (ECC) and Indian allowable standards Zn concentration is less than standards, Cd concentrations on sampling sites are a little higher or near to standard values, the chromium values are higher than ECC standard, lead contamination are very higher than both the standards, nickel and copper are also higher than ECC and Indian Standards. Possible explanations for the obtained data of heavy metals can be the growing density of the traffic in the past few years or the fact that samplings have been done on area having roads on their sides. Another significant reason is dumping of industrial and household wastes outflows. Some Previous studies showed that extremely high lead contamination can be due to the use of leaded gasoline that is more often in use. Cadmium, cobalt, copper, lead, manganese, and zinc are good quality indicators of contagion in soil because they appear in gasoline, vehicle exhausts and car components . This soil can be used as compost and fertilizer for the plantation of salts and heavy metals tolerant ornamental species like Psilostrophe bakerii (Paper-flower), Stanley pinnata (Prince's-Plume), Gleditsia triacanthos (Honey locust) etc. Only those plants should be planted that would not become part of food chain as it contain high concentration of heavy metals. There should be the planned and detailed research conducted on the possibility to extraction and utilization of drain water as well as soil nutrient components as fertilizers in a manageable way.
|AVERAGE of||128.8 ± 16.7||4.6 ± 1.6||118.8 ± 11.2||672.1 ± 85.8||31.8 ± 7.8||313.3 ± 114.2||276.6 ± 62.8|
Table 2: The heavy metals values of soil samples collected from land adjacent to Samanabad Sewage drain, Lahore.
From the above mentioned results conclusion can be drawn that the soil electrical conductivity, potassium, phosphorus, organic matter and heavy metals were found above the standards limits. The main reason of these concentrations is waste dumping and continuous contact of drain water with the sampling sites. The data presented in this study present a baseline for the planners to increase public awareness about soil contamination. The following recommendations can be verbalized from the present investigation:
• Planners may formulate their decision towards more sustainable urban structure and design to use the urban soil near drains by controlling the toxicity in soil. Laws should be effectively enforced followed by suitable educative measures in order to avoid illegal waste dumping on soil that has negative impact on soil nutrients and biotic.
• Due to high nutritional value, the soil under study may be used as compost or fertilizer. However, it can be used for selective plantation of salt and metal tolerant ornamental plants to enhance the aesthetic beauty of vicinity.
• Laws should be effectively enforced in order to avoid illegal waste dumping on soil that has negative impact on soil nutrients.
• If the addition of industrial, municipal and sewage sludge continues, it will raise, in the end, the concentration of heavy metals and salts to toxic level. Hence, safe ways should be used for their disposal.
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