Pak. J. Bot., 46(5): 1805-1810, 2014. ASSESSMENT OF HEAVY METAL AND METALLOID LEVELS IN SPINACH (SPINACIA OLERACEA L.) GROWN IN WASTEWATER IRRIGATED AGRICULTURAL SOIL OF SARGODHA, PAKISTAN KAFEEL AHMAD 1 , ZAFAR IQBAL KHAN 1 , ASMA ASHFAQ 1 , MUHAMMAD ASHRAF 2,3* AND SUMAIRA YASMIN 1 1 Department of Biological Sciences, University of Sargodha, Pakistan 2 Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan 3 Department of Botany and Microbiology, King Saud University, Riyadh, Saudi Arabia * Corresponding author’s e-mail: ashrafbot@yahoo.com Abstract Heavy metal-induced pollution causes an adverse effect on the agricultural production system. In the present study we studied the pattern of accumulation of different metals in spinach (Spinacia oleracea) irrigated with wastewater. Considerably elevated concentrations of metals were observed in the wastewater irrigated soil and vegetable. For example, the levels Mo, Cd and Pb in the vegetable exceeded the permissible limit suggested by the World Health Organization. A significant and positive correlation was observed between the soil and vegetable in terms of levels of different metals. Transfer coefficients for Cr, Zn and Cu were above 0.5 which indicated high level of metal contamination mainly due to anthropogenic activities in the study site. The pollution load index was also considerably high for the spinach plants growing on the metal contaminated soil suggesting that proper management of the study area is required to protect all vegetables being grown therein from the accumulation of high levels of different metals examined in the present study. Key words: Heavy metal, Metalloid, Spinacia oleracea, Wastewater, Soil. Introduction As compared with major commercial crops, vegetables are grown on a small scale, but the vegetable productivity entirely depends on the availability of good quality water. However, the area of vegetable cultivation in Pakistan is increasing consistently with time because of the reason that several vegetables are now being exported to other countries. For example, during 2007-08 vegetables were cultivated at about 253,800 ha (Perveen et al., 2010). However, most of the commonly used vegetables are grown in peri-urban areas wherein farmers use polluted water coming from sewage for irrigating all vegetables. Thus, it is naïve to expect that all vegetables from peri-urban areas accumulate considerable amount of different heavy metals the source of which being the sewage water (Tahir et al., 2011). Wastewater is believed to contain a variety of toxic metals, and accumulation of such metals in plants may take place due to extensive use of waste-water for irrigation of crops (Singh et al., 2004). Since the removal of metals from soils is very hard, so they easily move to the food cycle (Wilson and Pyatt, 2007). Spinach (Spinacia oleracea) is a potential leafy vegetable of many countries (Chopra et al., 1986). Compared with the root or stem vegetables, leafy vegetables including Brassica oleracea and Spinacia oleracea can accumulate considerably higher amounts of different metals in their leaves if grown on metal- contaminated soils (Al-Jassir et al., 2005). The present investigation was carried out to explore soil and vegetable metal pollution load, ascertain the suitability of wastewater for irrigating soils for the cultivation of spinach, a leafy vegetable grown round the year in most parts of Pakistan, and evaluate the pattern of accumulation of metals in this crop. Materials and Methods Study area: The present study was carried out at two different sites Phularwan and Chaba Purana, within District Sargodha. The experimental area is located at coordinates 32° 21' 20.52" N, 73° 00' 44.67" E. Site-I, Phularwan, is located at 50 km from Sargodha city, irrigated with canal water, whereas Site-II, Chaba Purana, is located at 67 km from Sargodha city, irrigated with wastewater. Sample collection: Ten samples each of soil and vegetable leaves were collected from each of the two selected sites. The vegetable samples were washed using distilled water and diluted HCl so as to remove air-born contaminants, if any. These samples were dried first in sunlight and then oven-dried at 65°C for 48 h. Thereafter, all samples were kept in clean plastic bags before their analysis. Sample preparation: Well ground vegetable and soil samples (each 2 g) were digested in H 2 O 2 and H 2 SO 4 in 2:1 on a hot plate for one hour, and then 2 ml of H 2 O 2 were added to each sample. The digestion process continued until the digestion mixture of each sample became transparent. The digested mixture, after filtration, was diluted to 50 ml using distilled water. Determination of metals and metalloids: For determining the concentrations of metals and metalloids in the digested soil and vegetable samples, an atomic absorption spectrophotometer was used. Particularly for the analysis of As and Se, a graphite furnace attached to an atomic absorption spectrophotometer (GFAA) was used. A standard calibration curve was drawn for each metal and metalloid. All standard quality assurance procedures were adopted to attain precise data for each metal.