Uptake of some toxic metals in spinach crop irrigated by Saggian drain water, Lahore

Transcription

1 BIOLOGIA (PAKISTAN) 2013, 59 (1), PK ISSN Uptake of some toxic metals in spinach crop irrigated by Saggian drain water, Lahore *Syed Tariq Rizwan 1, Sana Chaudhary 2 & Muhammad Ikram 3 1,2 Department of Botany, GC University, Lahore 3 Ex. Director, Soil Survey of Pakistan, Lahore ABSTRACT A comparative study to detect the uptake of toxic metals (Zn, Cr, Fe, Mn, Co, Ni, Cu, Pb and Cd) in spinach (Spinaceae oleraceae) irrigated by drain and tube well water was carried out along Saggian Drain, Lahore. The metal contents of drain water were fairly higher than those of the tube well water. Similar results are evident from the analytical data of root, shoot and leaves of spinach. It was observed that in root, irrigated with drain water, concentration of Zn was and that of Pb was while Zn was and Pb was 3.00 in roots irrigated with tube well water. In shoot the concentration of Cr was and Cu was being irrigated with drain water. While the concentration of these metals were lower in shoot irrigated with tube well water. In leaves irrigated with drain water the concentration of Pb was while it was 3.33 when irrigated with tube well water. However, the contamination level of edible parts is toxic to human health; its constant consumption may lead to various health disorders. Keywords: toxic metals, Spinach, Saggian drain INTRODUCTION Environment in its wider sense includes everything which is external to the human beings. Environmental pollution is attributed to the waste that cannot be dispersed off by natural recycling processes due to their excessive quantity and injurious quality or unique chemical composition. Environmental pollution, a worldwide problem resulted from industrial revolution and urbanization, is causing undesirable changes in the physical, chemical and biological characteristics of air, water, and soil ultimately affecting human, animal, and plant lives (Mishra & Dinesh, 1991). Agricultural fields throughout the world are receiving waste water, directly being dumped into the river channels, drains and water bodies from the industrial and municipal human settlements. This waste water enriches the soil as well as ground water with heavy metals which enter the food chain and pose a lethal threat to the life (WWF, 2001). The important segment of the pollution which effect the health via crops and soil is the indiscriminate use of sewage for the agricultural productions around the urban centers in arid and semi arid countries on account of increasing demand for the limited water supplies (Mishra & Dinesh, 1991) Heavy metals contamination of land is an increasingly important environmental, health and economic issue in Pakistan (Hussain, 1996). Pakistan is an agricultural country, and however in recent past the economy has started to * Corresponding author: tariq_rizwan@yahoo.com

2 184 S. T. RIZWAN ET AL BIOLOGIA (PAKISTAN) shift towards the industry. These industries are disposing off their effluents into open surface drains or nearby ponds which essentially end up to rivers and canals used for the irrigation. The rapid increase in the population together with the excessive use of fertilizers and chemicals in the agriculture and rapid industrialization combined with the unplanned disposal of industrial and domestic effluents have increased the threat of soil pollution (Khan & Scullion, 2000). In the city of Lahore it has been pointed out that most of the wastewater is collected by 12 pumping stations, located along the protection embankment. This water is discharged into sludge carriers which are open drains leading to the River Ravi. Along the sludge carriers seasonal food crops and vegetables are grown. These vegetables and food items are being utilized by the people and the animals. All the chemical contents thus come in the food chain of the human beings and animals (Qamar, 2004). Spinach is Spinacia oleracea. In Latin spina means spiny fruit and oleracea stands for herbaceous garden herb. It is a member of Chenopodiaceae (goosefoot) family. It is a low growing fleshy leafed annual that forms a heavy rosette of broad, crinkly tender leaves. The glabrous (non hairy) leaves which are edible vegetable portion, are ovate (oval but broader toward the base) to orbicular (round) in shape with the lower leaves being wider and the highest leaves being narrower. Leaf stems are also edible, but less preferred because of toughness. The Savoy leaved are usually preferred for fresh marketing; the smooth for processing (Sackett, 1975). Objectives Chemical analysis of Saggian Drain and Tube well water. Evaluation of the uptake of the toxic elements in Spinacia oleracea Comparison of uptake of toxic elements in Spinacia oleracea like Zn, Mn, Cr, Cu, Pb, Fe, Co, Cd and Ni irrigated with Saggian Drain and Tube well water. MATERIALS AND METHODS The site for experiment, collection of plants and water was SHAHDARA Soil series irrigated by the sewage along the drain area (Fig., 1). The collection of the waste water was done by dipping the sample bottles into the flowing water of Nullah with the help of thread and was taken out on filling, transferred to the polyethylene bottle. Similarly tube well water samples were taken directly from the outlet at least after half an hour tube well was running. ph and EC were measured with ph and EC meters. Heavy metal analysis of plant samples were made after digestion of plant samples in double acid (1:2) of perchloric and nitric acid. Heavy metals were analyzed using polarized Zeeman Atomic Absorption Spectrophotometer (Z- 5300). Data collected for various plants from both control and drain site were analyzed with Duncan s Multiple Range test (Steel & Torrie, 1980).

3 VOL. 59 (1) UPTAKE OF SOME TOXIC METALS IN SPINACH 185 Fig., 1: Existing sewerage infrastructure in Lahore (Source WASA 2008) RESULTS AND DISCUSSION The major objectives of wastewater irrigation are that it provides a reliable source of water supply to farmers and has the beneficial aspects of adding valuable plant nutrients and organic matter to soil (Liu et al., 2004). With careful planning and management, the positive aspects of wastewater irrigation can be achieved (WHO, 2006). Hence, continual use of wastewater over extended periods can exert adverse impacts on quality of soil and plants grown on it (Sinha et al., 2006). It is evident from the Table 1 that the values of ph and EC are greater for Drain water as compared to Tube well water. ph of tube well water was within the permissible limits. ph provides adequate information about the behavior of soils and water. Deficiency of Co, Cu, Mn, Fe and Zn increases with the increase in soil ph beyond 7.0. The preferred range for most crops is ( ). EC of tube well water was within the permissible limits while EC of Saggian Drain water was higher than the permissible limits i.e.,1.33ds/m. Higher values of EC reflect build up of salinity. Many studies also showed that continuously irrigating the soils with waste waters inhibit the soil fauna and flora due to the change in ph, EC, soil aggregates and accumulation of toxic levels of salts (Leiu & Feng, 2005). Table 1 also shows that the concentration of iron is also within the permissible limits and same behavior was observed for other heavy metals. However the concentrations are greater than the tube well water. Same is the case with Co, Cr and Ni where greater ratio of heavy metals was observed towards drain water.

4 186 S. T. RIZWAN ET AL BIOLOGIA (PAKISTAN) Table 1: Chemical analysis of Saggian drain and Tube well water and comparison with NEQS, 1997 by Govt. of Punjab. Parameter s Saggian Drain water mg/l Tube well water mg/l NEQS* ph EC(dS/m) <1.25 Zn mg/l Co Cr mg/l Cd mg/l Ni mg/l Cu mg/l Fe mg/l Mn mg/L NEQS = National Environmental Quality Standards It is clear from the Table 2 that all the metals were more concentrated in roots except Fe and Mn which were more concentrated in leaves (2265 & ) irrigated with Saggian Drain water. It is also evident from the Table that in all the cases there was more uptake of metals in various parts of plants irrigated with drain water as compared to plant parts irrigated with Tube well water. Tables 2 shows the comparison and concentration of these heavy metals in various parts of spinach irrigated with Saggian drain and Tube well water. Metals like Cu and Ni are more concentrated in shoots and leaves respectively. Most of the metals are concentrated in leaves which is edible portion of plant by humans while exceptions were observed for Co and Zn which were more concentrated in roots i.e., and 3.00 respectively as compared to leaves i.e., 1.00 and irrigated with drain water. Comparison between drain water and tube well water root is statistically significant. This was observed for Cr, Fe, Mn, Co, Ni, Cu and Pb whereas statistically non-significant difference was observed for Zn and Cd in roots irrigated with drain water and tube well water. Coming to shoots the results are non-significant for Fe, Mn, Pd and Cd while for others these are significant. Coming to leaves the values which were significant are Zn, Cr, Pb, Fe, Mn, Co Ni, Cu while for Cd these were nonsignificant as there is no sharp difference in their means. The different heavy metal levels in plants grown on unpolluted soil are: Fe = 140, Cu=4-15, Zn=8-100, Ni=1, Cr=0.2-10, Pb=0.1-10, Cd= μg/g dry weight as suggested by Allaway (1968). Interestingly the concentrations of heavy metals in almost all the plant parts growing on polluted soil are higher than the plants grown on unpolluted soils. According to these standards Cd in spinach falls in the permissible limits i.e., 0.33 in roots, while Cu and Cr fall in the non permissible range. Similarly Pb is also in non-permissible range in roots (12.00) and leaves (11.00) of Spinach irrigated with Drain water. Alloway, (1995) showed that spinach and

5 LSD Tw c ± c ± ab ± b ± bc d 7.00c ± c ±3.21 Leaves Dw b ± b ± a ± a ± ab ± a ± bc ± ab ±7.00 Tw c ± d ± ab ± b ± c 8.00d ± bc ± bc ± a Shoot Dw ab ± c ± ab ± b ± ab ± c ± a ± bc ±1.00 Tw 25.66ab ± b ± a b ± b ± c 16.33b ± bc ± c ±1, a Root Dw a ± a b ± a ± a ± a 21.50b ± a ±8.00 Plant parts sample Zn Cr Fe Mn Co Ni Cu Pb Cd VOL. 59 (1) UPTAKE OF SOME TOXIC METALS IN SPINACH 187 Lettuce can accumulate high level of Cd in their leaves. Cieslinski et al., (1996) also reported that spinach accumulate elevated levels of heavy metals including Cd, Pb and Ni in its leaves and accumulation trend was similar as observed in this study. Table 2: Comparison and concentration of Heavy Metals in Spinaceae oleraceae irrigated with Saggian Drain and Tube well water Mean followed by different letters in the same column are significantly different at P < According to Duncan s new multiple range test, ±: standard deviation, LSD: Least Significant difference. *Dw = Drain water, # TW = Tube well water

6 188 S. T. RIZWAN ET AL BIOLOGIA (PAKISTAN) Conclusion It is evident from the study that sewage of Main Outfall Drain to irrigate crops is saline and sodic. Irrigation with this water results in high concentration of Zn (223), Cr (47.67 ), Fe ( ) and Cu (21.5 ) in plants. The concentrations of other metals (Cd, Co, Mn, Ni and Pb) though in permissible limits, yet are higher than those of Tube well water used for irrigation. These metals with the continuous irrigations accumulate and reach harmful limits deteriorating the soil. Plants may uptake these metallic ions and cause serious problems among human beings and animals. The economic impacts of the use of waste water on crop production depend on the degree of treatment and composition of waste water, type and nature of crops grown and the overall farm level water management practices. Given the agronomic and water management practices, it can be used as supplementary water for irrigation,reduce fertilizers cost and can increase/decrease the yield depending on the plant nutrient content of waste water, which has the implication for profitability of crop production. REFERENCES Allaway, W. H., Agronomic controls over environmental cycling of trace elements. Adv. Agron., 20: Alloway, B.J., Heavy metals in soils.london: Blackie Academic & Professional.UK. Cieslinski, G., K. VanRees, C.J., Huang, P. M. Kozak, L. M. Rostad, H. P.W.& Knott, D.R., Cadmium uptake and bioaccumulation in selected cultivars of durum wheat and flax as affected by soil type. Plant soil.182: Hussain, Contaminants and the soil environment in the Australia Pacific Region (R. Naidu, R.S. Kookana). Khan, M. & Scullion, J., Effect of soil on microbial responces to metal contamination. Environmental pollution, 110: 115. Leiu, M. H. & Feng, J. C., Wastewaters of soap industry and growth of cereal crops in China. Env. Sci., 15: Liu,D.,W.Jiang and X.Gao.2004.Effects of Cadmium on root growth,cell division and nucleoli in root tips of garlic, Physiologia Plantarum.,47:79-83 Mishra, S. G. & Dinesh, D., Soil Pollution, Ashing Publishing House, New Delhi, pp Qamar, M. K., Impact of sewage irrigation on ground water quality of Lahore, Proceedings of the WSSD Workshop on Human Settlement and Environment Islamabad, pp: 5-8. Sackett, C., United Fresh Fruit and Vegetable Assn. 727 N. Washington, Alexandria, VA Sinha, S., Gupta, A,. Bhatt, K., Pandey, K., Rai, U. N. & Singh. K. P., Distribution of metals in the edible plants grown at Jammu,Khanpur(India) receiving treated tannery wastewater: Relation with physic-chemical properties of the soil. Env. Mon. Assessment.115: Steel, R. G. D. & Torrie, J.H., Principles and procedures of statistics. A Biometrical Approach, 2 nd Edition. McGraw- Hill, New York. 144pp.

7 VOL. 59 (1) UPTAKE OF SOME TOXIC METALS IN SPINACH 189 WASA, Water and sanitization agency. WASA master plan for bulk water supply and sewerages system. Presentation on Faisalabad city. WHO, Guidelines for safe use of wastewater,excreta and grey water: Waste water use in agriculture (volume II). WWF, Water quality monitering of Hudiara Drain. Environmental Pollution unit. Worldwide Fund for Nature, Lahore- Pakistan.