Scientific Registration No. 168 Number of Symposium: 1 Presentation: Oral Effect of effluent contaminated water on micro and potentially toxic elements in soils and potato plants Effets sur les sols et des cultures de pommes de terre de l épandage d effluents industriels contenant des oligoéléments et des éléments potentiellement toxiques BRAR M.S., SINGH A.P., C.L. ARORA Department of Soils, Punjab Agricultural University, Ludhiana - 11, India Abstract The effect of industrial effluent contaminated sewage water on the content of micro and potentially toxic elements in soils and potato plants was studied. The elemental composition of the sewage water changed after the addition of waste water of leather complex into it. Although the contents of all these elements in the sewage drain increased, a spectacular increase in the content of Cr, which increased from.7 to 1. mg kg -1 of soil was observed. As a result of irrigation by waste water there was a build up of these elements in the soils. The soils of the study area were generally light textured and there was a build up upto cm or lower depth. Application of waste water increased the concentrations of these elements in the potato plants. The concentrations of these elements were higher in leaves (Non edible part) as compared to tubers (edible part). Although the build up of Cu and Zn was more in soils these were not absorbed by the plants proportionally. The absorption of Cr and Ni by potato plants and its distribution in edible and non edible parts was proportional to its build up in soil (Key words: Sewage water, micronutrients, toxic elements, potato) Introduction Safe disposal of industrial effluents and municipal wastes constitute an important aspect of the environmental pollution. Some heavy metal pollutants can cause health hazard to soil-plant-animal/human system and their disposal is becoming a problem around cities, where a lot of pollutants are disposed off in the sewage system. Most of the industries, particularly leather industry of Jalandhar city in the Indian Punjab are throwing untreated waste water into the sewage drain which is being used by the farmers to irrigate crops. The objective was to study the effect of contaminated sewage water on nutrient and potentially toxic elements in soils and potato plants. 1
Materials and Methods Samples of waste water from the sewage drain were collected before and after the addition of water from the leather complex. After measuring the ph and electrical conductivity, about 5 ml of distilled HNO was added. For the elemental analysis 5 ml of water was dried in a beaker. About 1 ml of distilled HNO was added by washing the sides of the beaker. It was again heated till - ml material remain. About ml of HClO was added and digested on a hot plate till - ml material remained in beaker. The final volume was made to 1 ml and was analyzed on ICAP-AES. About sites growing potato were selected for soil and plant sampling. Fields at sites were irrigated with contaminated sewage water and at remaining sites with ground water. Elemental analysis of soil was done by extracting the soil with ammonium bicarbonate diethylene triamine penta acetic acid (AB-DTPA) described by Soltanpour (1985). Leaf and tuber samples of potato were collected, washed, dried, and prepared for analysis. Samples (.5g) was taken in a digestion tube, 5 ml of HNO was added to it and were kept over night. It was digested at a constant temperature, when - ml of material remained. It was cooled down and ml of H O was added and again digested till 1- ml of material remained. Total volume was made to 1 ml and analyzed on ICP-AES. Results and Discussion Composition of irrigation water Average values (locations and periods) of Cu, Fe, Mn, Zn, Al, As, Cr and Ni were.1,.1,.9,.5,.,., 8.7 and.6 µg ml -1 in waste water and.1,.1,.,.7,.8,.1,.6 and.5 µg ml -1, respectively in ground (tubewell) waters (Table 1). Due to disposal of industrial effluents, the waste waters have higher contents of Cu by times, Fe by 155, Mn by 98, Zn by 1, Al by 5, As by, Cr by 1 and Ni by 5 times over the tubewell waters. Although after the disposal of water from leather complex the contents of almost all the elements were increased, the spectacular increase was observed in Cr which was higher by times as compared to ground water. Therefore, the contents of Cr is a matter of concern and could become a potential hazard for crops irrigated with this water and it may also pollute the shallow underground waters. Since the water consumed by villagers is drawn from the shallow depth hand pumps, there is a need to monitor the chromium status of hand pump waters installed along the drain to prevent the human/animal health hazards. Bhagat (199) reported that tannery waste in Tamil Nadu state of India, which contained 9. to 1.8 µg ml -1 of hexavalent chromium, deteriorated the quality of surface water. The sewage drain water of Jalandhar which contained 1. µg ml -1 of AB-DTPA extractable Cr may also become a potential hazard for crops irrigated with this water. Effect of sewage irrigation on ph, EC, O.C and different elements in soils: On an average the ph of the soils irrigated by sewage water of drain deceased from 6.9 to 6.6. E.C. and O.C. increased from.8 to.6 dsm -1 and. to.1%, respectively. The average contents of Cu, Fe, Mn, Zn, Al, As, Cr and Ni in soils receiving tubewell water were.99, 1.8, 1.,.9,.6, 1.9,.81 and.56 mg kg -1, respectively which were found to increase to., 9.7, 18.9, 1.7, 6.5,.9, 1.7 and 1.7 mg kg -1 in
soils receiving sewage water which showed accumulation to the extent of.,.9, 1., 5.1, 1.8, 1.1,.1 and. times, respectively over the adjoining fields irrigated with tubewell waters. Vertical distribution of micronutrients in soils (Fig. 1) showed that Cu was generally retained in surface layer where the differences between sewage irrigated and tubewell irrigated soils were more than times. However, the difference decreased at lower depths. The Fe content of the soils irrigated with sewage water was higher than those irrigated with tubewell water throughout the depth of the profile studied upto 6 cm. It indicated that in addition to surface layer the Fe is also accumulated in sub-surface layers of the coarse textured soils. The extent of accumulation depended upon the use of industrial waste water. While Bansal (198) observed the accumulation upto cm, Jayabaskaran & Sree Ramula (1996) observed that continuous application of sewage water lead to the accumulation of Fe in surface soils but vertical movement was higher in light textured soils. Manganese content in sewage irrigated soils was higher than tubewell irrigated soils at all the depths. The zinc content in upper to 15 cm soils was 5 times and in lower depths to times higher in sewage irrigated soils. Higher content in upper to 15 cm soils was also due to use of ZnSO as fertilizer. The content of Al was higher in sewage irrigated soils, however, there was no differences in As content of the soils. The differences in the contents of Cr and Ni were more predominant upto cm soil depth. The build up of Cr (Singh et al. 1991) and Ni (Anderson 1997) were also observed upto cm depth with the application of sewage water. As no external application of any element except zinc was done by the farmers, the differences were mainly due to the application of sewage water. Since most of the elements are mainly retained upto cm depth(the rooting zone of most of the crops) it is likely that plants may absorb excessive amounts of these elements. Effect of sewage irrigation on element concentrations in potato plants: Average copper concentrations in leaves and tubers were 5.9 and. mg kg -1 in ground water irrigated fields and increased to 9. and 5.6 mg kg -1 in sewage water irrigated fields. Against. fold increase in soils the increase in leaves and tubers were 1.6 and 1. folds respectively with the application of sewage water. The copper concentrations were higher in leaves than in tubers. Average iron concentration increased from 51 to 555 mg kg -1 in leaves and from 91 to 15 mg kg -1 in tubers with the application of sewage water over the adjoining fields irrigated with ground water. The concentrations were 5 folds higher in leaves than in tubers. Manganese concentrations in leaves and tubers increased from 89 to mg kg -1 and 16.9 to.9 mg kg -1, respectively with the application of sewage water. The pattern of build up was almost similar in soils and plants. However, the concentration was spectacularly higher in leaves than in tubers. Zinc concentration increased from. to 7.6 mg kg -1 in leaves and from 8.6 to.7 mg kg -1 in tubers with the application of sewage water. The build up was. folds in leaves and 1. folds in tubers against the 5.1 fold increase in zinc content of soils. This indicated that zinc is not being absorbed proportionally to its content in soils by the plants. The Al content in leaves increased from 7 to 6 mg kg -1 and in tubers from 8 to 97 mg kg -1 with the application of sewage water. Al concentration in leaves were more than times higher than in tubers indicating that most of it is retained in the non-edible (leaves) part of the plant. The As content increased from 1.1 to 16.5 mg kg -1 in leaves and from 8.5 to 8.6 mg kg -1 in tubers with the irrigation of sewage water. The increase in As
content with the application of sewage water was more in leaves than in tubers. The Cr content increased from 7.6 to 1.8 mg kg -1 in leaves and from.8 to 8.5 mg kg -1 in tubers. Hence concentration in sewage irrigated field were nearly double than those in irrigated by ground water. The content of Cr was almost double in soils as well. This indicated that application of sewage water is building up the Cr content in soils and it is being absorbed by the plants proportionally. The build up was similar both in edible and non-edible parts of the plant. Similar is the situation in case of Ni where its concentration in leaves increased from.8 to 7. mg kg -1 and from 1.1 to.5 mg kg -1 in tubers. The build up was. fold in soil,.6 fold in leaves and.1 folds in tubers. The data indicated that irrigation with sewage water mixed with effluents of the leather complex resulted in the maximum build up of zinc and copper. However, their absorption by the plants were not proportional to the build up in soils. But in case of Cr and Ni the absorption by plants and their distribution in edible and non edible portions was proportional to their build up in soils. Hence Cr and Ni seem to be the element polluting the fields irrigated by sewage water and may become health hazards for consumers of crops grown on the fields irrigated by sewage water contaminated with effluent of leather complex. References Anderson, A. 1977. Some aspects on the significance of heavy metals in sewage sludge and related products used as fertilizer. Swedish J. Agri. Res. 7: 1-5. Bansal, R.L., Nayyar, V.K. and Takkar, P.N. 199. Accumulation and bio-availability of Zn, Cu, Mn and Fe in soils polluted with industrial waste water. J. Indian Soc. Soil Sci. : 796-799. Bhagat, R. 199. Water in tannery polluted areas. Indian Express. May 7, 199. Chandigarh. Jayabaskaran, K.J and Sree Ramulu U.S. 1996. Distribution of heavy metals in soils of various sewage farms in Tamil Nadu. J. India Soc. Soil Sci. : 1-. Singh, R.R., Singh, V. and Shukla, A.K. 1991. Yield and heavy metal contents of berseem as influenced by sewage water and refinery effluents. J. Indian Soc. Soil Sci. 9: -. Soltanpour, P.N. 1985. Use of ammonium bicarbonate- DTPA soil test to evaluate elemental availability and toxicity - Commun. Soil Sci. Pl. Anal. 16: -8. Keywords: Sewage water, industrial effluents, micronutrients, toxic elements. Mots clés : eaux usées, effluents industriels, oligo-éléments, élément toxique
Table 1. Composition of irrigation water (µg ml -1 ) Elements Ground Sewage water Before LCW * After LCW * Average Cu.1...1 Fe.1 16...1 Mn..5..9 Zn.7 1.99.51.5 Al.8..8. As.1... Cr.6.7 1. 8.7 Ni.5 * LCW = Leather Complex Water.19.5.6 Table. Average content of elements in surface soils and potato plants irrigated by sewage and ground waters Elements Soils (mg kg -1 ) Plants (mg kg -1 ) IGW * ISW ** Leaves Tubers IGW * ISW ** IGW * ISW ** Cu.99. 5.9 9.. 5.6 Fe 1.8 9.7 51. 555. 91. 15. Mn 1. 18.9 89.. 16.9.9 Zn.9 1.7. 7.6 8.6.7 Al.6 6.5 7. 6. 8. 97. As 1.87.1 1.1 16.5 8.5 8.6 Cr.81 1.7 7.6 1.8.8 8.5 Ni.56 1.7.8 7. 1..5 * IGW - Irrigated with Ground Water ** ISW - Irrigated with Sewage Water 5
Fig 1. Depthwise distribution of elements in soils(mg/kg) 16 Zn & Cu Zn-SW Zn-TW Cu-SW Cu-TW 5 Fe & Mn Fe-SW Fe-TW Mn-SW Mn-TW 1 1 1 8 6 1-15 15- -5 5-6 -15 15- -5 5-6 7 Al & As Al-SW Al-TW As-SW As-TW Cr & Ni Cr-SW Cr-TW Ni-SW Ni-TW 6 5 1.5 1.5 1-15 15- -5 5-6 -15 15- -5 5-6 6