INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 6, No 5, Copyright by the authors - Licensee IPA- Under Creative Commons license 3.

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1 INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 6, No 5, 2016 Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article ISSN Effect of wastewater irrigation on soil and some selected vegetables grown in Asansol, West Bengal Sumanta Roy 1, Srimanta Gupta 2 1- Research Scholar, Deptt. of Environmental Science, The University of Burdwan, Burdwan, West Bengal., Assistant Professor, Department of Environmental Science, The University of Burdwan, Burdwan, W.B., sumantaroyenvs@gmail.com doi: /ijes.6084 ABSTRACT This study was conducted in sub urban region of Asansol, where wastewater from that Nunia nala is widely being used by poor farmers for irrigating vegetable on long term basis. As a result elevated levels of heavy metals were found to accumulate in wastewater irrigated soil and vegetables, compared to well water irrigated soil and vegetables. The mean value of Pb, Mn and Zn content in both irrigation water showed the lower value in comparison to FAO/WHO standards, Cr and Cu value in wastewater and Cd value in both type of water exceeded the FAO/WHO standards. The trend of mean metal concentrations in well water and wastewater were Pb > Zn > Mn > Cr > Cd > Cu and Pb > Mn > Zn > Cr > Cd > Cu respectively.pollution load index (PLI) level in soils were in the order of Cu (2.40) > Cr (2.19) > Cd (2.00) > Mn (1.77) > Pb (1.25) > Zn (0.97). Higher enrichment factor of Cd was found in spinach, Cu in brinjal, Mn in cauliflower and Mn and Zn in carrot and pea respectively. Key words: Wastewater irrigation Heavy metals Vegetables Pollution Load Index. 1. Introduction The application of sewage and sometimes industrial effluent onto agricultural lands are common practices throughout the world. Globally, 2 million km 2 of land are irrigated with municipal wastewater (Hamilton et al., 2007). It is most evident in the peri- urban and suburban area in the developing countries. The long term irrigation with effluents are known to have significant contribution to trace elements such as Cd, Cu, Zn, Cr, Pb, and Mn in surface soil in the agricultural fields (Mapanda et al., 2005) as well as it improves the physicochemical properties in soil. Extent of toxic elements enrichment in irrigated soil depends on concentrations of heavy metals in irrigation water, period of application of wastewater and texture of soil. The availability of metals in vegetables depends on soil properties like ph, organic carbon, cation exchange capacity (Chaney, 1973; Chambers and Sliddle, 1991; Yassoglou et al., 1987). The accumulation of metals occurs in edible and non edible parts of vegetables. Consumption of high quantities metals in vegetables pose clinical problems both to animals and human beings consuming these metal-rich plants because there is no good mechanism for their elimination from the human body (Arora et al., 2008; Alam et al., 2003). Received on September 2015 Published on November

2 The present study was conducted to evaluate the suitability of irrigation water in respect to metals content, enrichment of metals in irrigated soil due long term irrigation practice and translocation of heavy metals from contaminated soil to vegetables. 2. Materials and methods 2.1 Study area Asansol, an industrial zone of Eastern India is located in the west side of the state of West Bengal. The study areas are located at Kalipahari (Latitude " N and Longitude " E) in Asansol. Control fields were chosen at Kalipahari considering the use of well water for irrigating vegetable and the fields situated half kilometer away from Kallipahari besides Nunia nala is considered as treated fields (Figure1) where wastewater from a natural channel, receiving effluents from different industrial wastewater and sewage are used for irrigating cultivated vegetables in this locality are consumed by poor farmers as per their needs and rest of the vegetables are sold to the nearby markets. Entire research work was conducted in winter season of Sampling and analysis Figure 1: Study area details Sampling was done in a regular interval in winter season. Wastewater used in irrigation was collected from different locations of Nunia nala and dug well water used in irrigation was also collected from a large abundant well. Sampling and physico chemical analysis of 895

3 irrigation water was done as per Standard methods, 1998 guidelines. Cultivated soils were collected from top soil zone throughout season with the help of steel dagger and were kept immediately into plastic bags. After that soil was dried in laboratory condition and then the sample volume was reduced with the help of coning and quartering method (IUPAC, 1990). Final volume of soil sample was crushed and sieved through 2 mm mesh for physico chemical analysis. Analysis of soil physico chemical parameter viz., ph, conductivity (Saxena, 1998), cation exchange capacity (Reeuwijk, 2002), soil organic carbon (Walkey and Black, 1934) and heavy metals (Ming and Ma, 2001) were carried out. Apart from soil commonly grown mature winter season vegetables like Tomato (Lycopersicon Esculatum L.), Family: Solanaceae, Brinjal (Solanum melongena), Family : Solanaceae, Spinach (Spinacia oleracea L.), Family:. Chenopodiaceae, Pea (Pisum sativuml.), Family: Fabaceae, Carrot (Daucus carota subsp. Sativus), Family: Apiaceae and Cauliflower (Brassica oleracea var botrytis), Family : Brassicaceae were collected randomly from the both fields (control and treated). Healthy and uninfected vegetables were also collected carefully. Vegetables samples were washed thoroughly with tap water followed by distilled water to get rid of dirt/soil. For estimation of metal content in vegetables, vegetables are cut into pieces with a stainless knife and dried at 80 0 C temperature for 24 hours and then powdered with mortar pestle. Metal concentration in different vegetables were analysed by microwave digestion method, 1 gm of dried powdered samples were treated with mixture of (4:1) of concentrated HNO3 and HClO4 (Buchaure, 1973) for 8 min at 600 W and in closed tephlon containers. After cooling the containers, double distilled water was added into the mixture. The suspension was filtered with Whatman 42 filter paper and the filtrate volume was making up to 50 ml. The clear solution obtained after digestion was analyzed for lead (Pb), manganese (Mn), chromium (Cr), cadmium (Cd), zinc (Zn) and cupper (Cu) by atomic absorption spectrophotometer (GBC, Avanta 932). Pb was estimated at λ = 217 nm at a silt width (SW) of 0.2nm and the detection range (DR) is μg ml 1 ; for Mn, λ = nm, SW = 0.2 nm, DR = 1 4 μg ml 1 ; for Cr, λ = nm, SW = 0.2 nm, DR = 2 15 μg ml 1 ; for Cd λ = nm at SW of 0.5 nm, DR = μg ml 1 ; for Zn, λ = nm, SW = 0.2 nm, DR = μg ml 1 ; for Cu, λ = nm, SW = 0.5 nm, DR = 1 5 μ g ml 1 (Gupta et al., 2008). The metal content in vegetables was expressed in terms of dry weight (DW) basis. All the experiment was performed in the research laboratory of the department of Environmental Science, B.U. 2.3 Data analysis The values of Pb, Mn, Cr, Cd, Zn and Cu were obtained from analysis of irrigation water, irrigated soil and cultivated vegetables are used to calculated for metal transfer factor, 2.4 Pollution load index The degree of soil pollution for each metal was measured using the pollution load index (PLI) technique depending on soil metal concentrations. The following modified equation was used to assess the PLI level in soils (Liu et al., 2005) 896

4 2.5 Enrichment factor Enrichment factor (Barman et al., 2000) has been calculated to determine the degree of soil pollution and heavy metal accumulation in plants growing in soil contaminated (wastewaterirrigated) with the effluent with respect to soil and plants growing at the uncontaminated (control) site. 2.6 Statistical analysis Descriptive statistics (mean, standard deviation, minimum and maximum) of the data (at least three) obtained were calculated. Correlation between the physico-chemical constituents and heavy metal in soil and metals content of the plants was done. All statistical analyses were done using the software XLSTAT version Quality assurance Appropriate quality assurance procedures and precautions were carried out to ensure reliability of the results. All chemicals used during analysis were of analytical grade (AR) reagents. All solutions were prepared with double distilled water. Calibration standards for each metal were prepared by making appropriate dilution of stock solution of 1,000 ppm of E. Merck standards. 3. Results and discussion 3.1 Physico-chemical signature of irrigation water used in both control and treated fields Results highlighted the significant differences in most of the estimated parameters of well water and wastewater used as irrigated water in control and treated fields respectively. Most of the parameters showed greater levels in wastewater as compared to the well water shown in Table 1. Mean values of ph, TDS and BOD of both irrigation water were within recommended IS 11624: The mean value of Pb, Mn and Zn content in both irrigation water showed the lower value compared to FAO/WHO standards, Cr and Cu value in waste water and Cd value in both type of water exceeded the FAO/WHO standards. The trend of mean metal concentrations in well water and wastewater were Pb > Zn > Mn > Cr > Cd > Cu and Pb > Mn > Zn > Cr > Cd > Cu respectively. Table 1: Physico-chemical characteristics of irrigation water used for irrigating peri-urban region of Asansol, West Bengal (n = 30) Tem BO CO M ph EC TDS Pb Cr Cd Zn Cu p. D D n Well Me water an Quality SD Mi n Ma

5 x Wastewat Me er an Quality SD Mi n Ma x Safe limit* *Source: Pescod (1992), ph, TDS, BOD (IS : 1986) n: No of samples ** Values represented in mg l -1, except Temp. ph and EC Similar kind of heavy metals enrichment in wastewater agreeing with many workers (Jayadev and Puttaih.,2013; Chopra and Pathak.,2012; Singh et al., 2012; Ahmad and Goni, 2010; Gupta et al., 2010; Mushtaq and Khan., 2010; Singh et al., 2010; Arora et al.,2008; Farooq et al., 2008; Gupta et al., 2008; Khan et al., 2008; Mishra and Tripathi., 2008 and others) but, the concentration of metals differ widely with concerned sources. 3.2 Physico-chemical characteristics of irrigated soil Except ph, all the parameters including heavy metals showed higher level in wastewater irrigated soil (treated soil) with compare to well water irrigated soil (control soil) Table 2. The mean values of ph were 7.97 ±0.10 (alkaline) and 6.79 ±0.19 (acidic) in control and treated soil respectively. This may be due to production of CO2 and organic acid by soil microorganisms. This observation is corroborated with Tiwari, Saraswat, and Agrawal., 2003, Singh et al., 2004 and Waly et al., The nutrients and organic matter added by sewage irrigation may enhance the activities of soil microorganisms and also increment of organic carbon (OC) level in soil with wastewater irrigation (Singh et al, 2010). Rattan et al. (2005) reported an increment of 59% in OC content of soil having long-term use of sewage irrigation of peri-urban agricultural land under the Keshopur effluents irrigation scheme (KEIS) of the Delhi government, India. Similarly, Bansal, Nayyar, and Takkar.,1992 have reported a 47.9% increase in OC content of topsoil (0 15 cm) receiving industrial wastewater for irrigation as compared to the soil irrigated with tube well water at a site situated in Jamalpur, a village near the industrial town of Ludhiana, Punjab. Higher OC content increase organic matter in soil with in turn increases the cation exchange capacity (CEC) in soil. The mean levels of Pb, Zn and Cu content in both type of irrigated soil were within the recommended limit, but Cd level exceeded in case treated soil (Awasthi, 2000). According to the criteria of heavy metal concentration in uncontaminated soil, it was found that only Cd level in soil exceeded limit (Bowen, 1966). Pollution load index (PLI) level in soils were in the order of Cu (2.40) > Cr (2.19) > Cd (2.00) > Mn (1.77) > Pb (1.25) > Zn (0.97). Heavy metals loading in soil through irrigation were reported by many researchers. Gupta et al., 2008; Ahmad and Goni, 2010 showed Pb, Zn, Cd, Cr and Cu levels in irrigated soil, which were quite high level with respect to this study. High level of metals in wastewater irrigated soils were also reflected in the study of Jayadev and Puttaih,2013; Chopra and Pathak, 2012; Perveen et al, 2012; Gupta et al.,2010; Farooq et al, 2008; Mishra and Tripathi, 2008 and others. 898

6 Table 2: Physico-chemical characteristics of irrigating soil in peri-urban region of Asansol, West Bengal (n = 36) ph EC CEC OC Pb Mn Cr Cd Zn Cu Control soil Quality Treated soil Quality Safe limit* Mean S D Min Max Mean S D Min Max * Awasthi,2000 ** EC value in ds m -1, CEC in meq100gm -1, OC in % and all metals are in mg kg Heavy metals enrichment in vegetables The results of the heavy metal content in edible part of studied vegetables grown with well water and wastewater are presented in Table 3 and 4. Table 3: Heavy metals accumulation in vegetables winter (Control area) mg kg -1 dry weight basis Name of vegetables Pb Mn Cr Cd Zn Cu Tomato Bringal Spinach Pea Carrot Cauliflower Table 4: Heavy metals accumulation in vegetables winter (Treated area) mg kg -1 dry weight basis Name of vegetables Pb Mn Cr Cd Zn Cu Tomato Bringal Spinach Pea Carrot Cauliflower * Safe value * Awashthi,

7 It is well known the plant uptake the soluble metals through roots naturally considering as essential elements and stores them in their biomass. Absorption and accumulation of heavy metals in plant tissues depends on several factors viz., ph, EC, CEC, OC and nutrients level in soil, plant species, metal transfer factor and degree of maturity etc (Sharma et al., 2007; Chaney, 1973). The greater enrichment of wastewater irrigated vegetables and in the vegetables of control site soil agreeing with many workers (Gupta et al., 2007; Sharma et al., 2007; Sinha et al., 2006; Godson et al., 2002). With compare the recommended safe limit (Awashthi, 2000) it was found that Pb content in tomato in control and treated site and carrot in control site exceeded limit but heavy metals content in cultivated vegetables is within the safe limit Table 3. The order of heavy metal accumulation in vegetables of control and treated soil showed different trend Table 5 and 6. Higher enrichment factor were found Cd in spinach, Cu in brinjal, Mn in cauliflower, Mn and Zn in carrot and pea respectively Table 7. The sequence of enrichment factor of heavy metals in vegetables is shown in Table 8. Table 5: Order of metal accumulation in vegetables of control soil Vegetable Order of metal accumulation Tomato Pb > Zn > Mn > Cr > Cd > Cu Brinjal Pb > Zn > Mn > Cr > Cd > Cu Spinach Pb > Zn > Cr > Mn > Cd > Cu Pea Pb > Mn > Cr > Zn > Cd > Cu Carrot Pb > Zn > Mn > Cr > Cd > Cu Cauliflower Pb > Zn > Cd > Mn > Cr > Cu Table 6: Order of metal accumulation in vegetables of treated soil Vegetable Order of metal accumulation Tomato Pb > Mn > Zn > Cr > Cd > Cu Brinjal Zn > Pb > Mn > Cr > Cd > Cu Spinach Mn > Pb > Zn > Cd > Cr > Cu Pea Pb > Mn > Zn > Cr > Cd > Cu Carrot Mn > Pb > Zn > Cr > Cd > Cu Cauliflower Mn > Pb > Zn > Cr > Cd > Cu Table 7: Enrichment Factor Name of vegetables Pb Mn Cr Cd Zn Cu Tomato Brinjal Spinach Pea Carrot Cauliflower Heavy metals enrichment in vegetables through irrigation water also highlighted by other researchers (Chopra and Pathak. 2012; Ahmad and Goni. 2010; Gupta et al., 2010; Singh et al. 2010; Arora et al., 2008; Mishra and Tripathi. 2008; Gupta et al., 2008 and many other researcher, but all the vegetables considered in this study were not applicable to their study. 900

8 Table 8: Sequence of enrichment factor in different vegetables Vegetable Sequence of enrichment factor in vegetables Tomato Cr (1.45) > Cd (1.44) > Mn (1.43) > Pb (1.25) > Cu (1.14) > Zn (1.12) Brinjal Cu (2.44) > Zn (1.52) > Mn (1.38) > Pb (1.27) > Cr (0.95) > Cd (0.78) Spinach Cd (3.34) > Mn (1.32) > Cu (1.28) > Cr (0.85) > Pb (0.67) > Zn (0.63) Pea Zn (1.70) > Pb (1.24) > Mn (1.20) > Cu (1.19) > Cd (1.16) > Cr (0.95) Carrot Mn (1.70) > Cd (1.66) > Zn (1.54) > Cr (1.32) > Cu (0.91) > Pb (0.49) Cauliflower Cr (2.19) > Mn (2.00) > Cu (1.25) > Zn (1.22) > Cd (0.67) > Pb (0.65) 4. Conclusion From the present study it may conclude that wastewater irrigation practice is not suitable for cultivating edible vegetables specially those are consumed regularly. Because excess heavy metals are considered as toxic elements due to accumulation in the biological systems and subsequently interfere in metabolic activity of organ specific. In this study vegetables cultivated in both sites are safe for consumption except tomato and carrot in control fields. So, emphasis is given in selecting cultivated vegetables which have less accumulation potential. 5. References 1. Ahmad J.U. and Goni M.A., (2010), Heavy metal contamination in water, soil and vegetables of the industrial areas in Dhaka, Bangladesh, Environmental Monitoring Assessment, 166, pp Alam M.G.M., Snow E. T. and Tanaka A., (2003), Arsenic and heavy metal concentration of vegetables grown in Samta village, Bangladesh, The Science of the Total Environment, 111, pp APHA (American Public Health Association) (1998), Standard methods for the examination of water and waste water (20th ed.), Washington: APHA. 4. Arora M., Kiran B., Rani A., Rani S., Kaur B. and Mittal M., (2008), Heavy metal accumulation in vegetables irrigated with water from different sources, Food Chemistry, 111, pp Awashthi S.K., (2000), Prevention of food adulteration act 37 of 1954, In Central and state rules as amended for 1999, 3rd ed, New Delhi: Ashoka Law House. 6. Bansal R.L., Nayyar V.K. and Takkar P.N., (1992), Accumulation and bioavailability of Zn, Cu, Mn, and Fe in soil polluted with industrial waste water, Journal of Indian Society of Soil Science, 40, pp

9 7. Barman S.C., Sahu R.K., Bhargava S.K. and Chatterjee C., (2000), Distribution of heavy metals in wheat, mustard and weed grown in fields irrigated with industrial effluents, Bulletin of Environmental Contamination and Toxicology, 64, pp Bowen H.J.M., (1966), Trace Elements in Biochemistry, New York: Academic Press. 9. Buchaure M.J., (1973), Contamination of soil and vegetation near zinc smelter by Zn, Cd, Cu and Pb, Environmental Science and Technology, 7 (2), pp Chambers J.C. and Siddle R.C., (1991), Fate of heavy metals in abandoned lead zinc tailing ponds: I Vegetation, Journal of Environmental Quality, 20, pp Chaney R.L., (1973), Crop and food chain effects of toxic elements in sludge and effluents: Recycling municipal sludges and effects on land. U.S. EPA, Washington, D.C., pp Chopra A.K. and Pathak C., (2012), Bioaccumulation and translocation efficiency of heavy metals in vegetables grown on long term wastewater irrigated soil near Bindal river, Dehradun, Agricultural Research, 1(2), pp Farooq M., Anwar F. and Rasid U., (2008), Appraisal of heavy metal contents in different vegetables grown in the vicinity of an industrial area, Pakistan Journal of Botany, 40(5), pp Godson R. E., Ana E. and Sridhar M. K. C., (2002), Soil quality near a chemical fertilizer industry at Port Harcourt, Nigeria, AJEAM/RAGEE, 4(2), pp Gupta N., Khan D. K. and Santra S. C., (2008), An assessment of heavy metal contamination in vegetables grown in wastewater irrigated areas of Titagarh, West Bengal, India, Bulletin of Environmental Contamination and Toxicology, 80, pp Gupta S., Satpati S., Nayek S. and Garai D., (2010), Effect of wastewater irrigation on vegetables in relation to bioaccumulation of heavy metals and biochemical changes, Environmental Monitoring Assessment, 165, pp Hamilton A. J., Stagnitti F., Xiong X., Kreidl S. L., Benke K. K. and Maher P., (2007) Wastewater irrigation: The state of play, Vadose Zone Journal, 6, pp IUPAC (1990), Analytical Chemistry Division, Commission on Analytical Nomenclature. Nomenclature for sampling in analytical chemistry (Recommendations 1990), Pure and Applied Chemistry, 62, Jayadev and Puttaih E.T., (2013), Assessment of heavy metals uptake in leafy vegetables grown on long term wastewater irrigated soil across, Vrishabhavahti river, Bangalore, Karnataka, Journal of Environmental Science, Toxicology and Food technology, 7 (6), pp

10 20. Khan S., Cao Q., Zheng Y. M., Huang Y. Z. and Zhu Y. G., (2008), Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China, Environmental Pollution, 152, pp Khan S., Rehman S., Khan A.Z., Khan M.A. and Shah M.T., (2010), Soil and vegetables enrichment with heavy metals from geological sources in Gilgit, northern Pakistan, Ecotoxicology and Environmental Safety, 73, pp Liu W. H., Zhao J. Z., Ouyang Z. Y., Soderlund L. and Liu G. H., (2005), Impacts of sewage irrigation on heavy metals distribution and contamination, Environment International, 31, pp Mapanda F., Mangwayana E. N., Nyamangara J. and Giller K. E., (2005), The effects of long term irrigation using water on heavy metal contents of soils under vegetables, Agriculture, Ecosystem and Environment, 107, pp Ming C. and Ma L.Q., (2001), Soil Science Society of America Journal 65, pp Mishra A. and Tripathi B.D., (2008), Heavy metal contamination of soil, and bioaccumulation in vegetables irrigated with treated wastewater in the tropical city of Varanasi, India, Toxicological & Environmental Chemistry, 90(5), pp Mushtaq N. and Khan S., (2010), Heavy metals contamination of soils in response to wastewater irrigation in Rawalpindi region, Pakistan Journal of Agricultural Science, 47(3), pp Pescod M. B., (1992), Wastewater treatment and use in agriculture: Irrigation and drainage (FAO Paper 47) Rome: Food and Agriculture Organization of the United Nations (FAO). 28. Rattan R. K., Dutta S.P., Chhonkar P.K., Suribabu K. and Singh A.K., (2005), Long-term impact of irrigation with sewage effluents on heavy metal content in soil crops and ground water A case study, Agriculture Ecosystem and Environment, 109, pp Reeuwijk L.P.Van., (2002), Procedure for soil analysis (Sixth edition), International Soil Reference and Information Centre., FAO, United Nations, pp Saxena M.M.,(1998), Environmental analysis water, soil and air. Agro. Botanica, Vyas Nagar, Bikaner, India. 31. Sharma R.K., Agrawal M. and Marshall F., (2007), Heavy metal contamination of soil and vegetables in suburban areas of Varanasi, India, Ecotoxicology and Environment Safety, 66, pp Singh S., Zacharias M., Kalpana S. and Mishra S., (2012), Heavy metals accumulation and distribution pattern in different vegetable crops, Journal of Environmental Chemistry and Ecotoxicology,4, pp

11 33. Singh A., Sharma R.K., Agrawal M. and Marshall F. M., (2010), Health risk assessment of heavy metals via dietary intake of foodstuffs from the wastewater irrigated site of a dry tropical area of India, Food and Chemical Toxicology, 48, pp Singh K. P., Mohan D., Sinha S. and Dalwani R., (2004), Impact assessment of treated/untreated waste water toxicants discharge by sewage treatment plant on health agricultural and environmental quality in waste water disposal area, Chemosphere, 55, pp Sinha P., Dube B. K., Srivastava P. and Chatterjee C.,(2006), Alteration in uptake and translocation of essential nutrients in cabbage by excess lead, Chemosphere, 65, pp Tiwari R. C., Saraswat P. K. and Agrawal H. P., (2003), Changes in macronutrient status of soils irrigated with treated sewage water and tube well water, Journal of Indian Society of Soil Science, 51 (2), pp Walkley A. and Black I.A.,(1934), An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method, Soil Science, 37, pp Waly T. M., Abd Elnaim E.M., Omran M. S. and El Nashar M.B., (1987), Effect of sewage water on chemical properties and heavy metals content of El Gabal El Asfar sandy soils, Biological Wastes, 22, pp WHO (2007), Joint FAO/WHO Expert standards program codex Alimentation Commission, Geneva, Switzerland. 40. Yassoglou N., Kosmas C., Asimakopoulos J. and Kallinou C., (1987), Heavy metal contamination of roadside soils in the greater Athens area, Environmental Pollution, 47, pp