Characterization of Heavy Metals in Vegetables

The heavy metals or trace elements play an important role in the metabolic pathways during the growth and development of plants, when available in required concentration. The heavy metal concentration of Cadmium (Cd), Cobalt (Co), Copper (Cu), Iron (Fe), Nickel (Ni), Lead (Pb) and Zinc (Zn) was analyzed using Inductive Coupled Plasma Analyzer (ICPA) (Perkin-Elmer ICP Optima 3300 RL, USA) in 21 vegetables collected from Vegetable Market of Anand town, Gujarat. The vegetables are Lady’s Finger (Abelmoschus esculentus), Onion (Alium sepa), Cauliflower (Brassica oleracea var. botrytis), Beat (Brassica oleracea), Chilli (Capsicum annum), Tindora (Coccinia indica), Pattarveli (Colocasia sp.), Coriander (Coriandrum sativum), Cucumber (Cucumis sativus), Turmeric (Curcuma longa), Vetches/Gavar (Cyamopsis soralioides), Bean Pods (Dolichos lablab), Carrot (Ductus carrotus), Ginger (Gingiber officinalis), Sweet Potato (Ipomoea batatas), Bottle Gourd (Lagernaria vulgaris), Tomato (Lycopersicum esculentum), Bitter Gourd (Momordica charantia), Drumstick (Moringa oleifera), Brinjal (Solanum melongena) and Parwar (Trichosanthes dioicea). The high concentration of Cd was found in Onion, Coriander and Cauliflower, while Co and Cu content was recorded high in Cauliflower and Bottle Gourd. On the other hand, high content of Fe was observed in Cauliflower and Cucumber. Vetches and Lady’s Finger had shown high concentration of Ni. Cauliflower and Onion showed high amount of Pb. On the other hand, Cucumber and Cauliflower registered maximum content of Zn. The heavy metal concentration in vegetables was within the prescribed safety limits except Fe owing to iron-rich soil of the area. The distribution and characterization of heavy metals in vegetables was studied in detail and discussed in this paper. @JASEM There are 35 metals that concerned us because of occupational or residential exposure; 23 of these are the heavy elements or "heavy metals". Distribution of heavy metals in plant body depends upon availability and concentration of heavy metals as well as particular plant species and its population (Punz and Seighardt 1973). Many researchers have shown that some common vegetables are capable of accumulating high levels of metals from the soil (Garcia et al. 1981, Khan and Frankland 1983, Xiong 1998, Cobb et al. 2000). Certain species of Brassica (Cabbage) are hyperaccumulators of heavy metals into the edible tissues of plant (Xiong 1998). Many people could be at risk of adverse health effects from consuming common market vegetables cultivated in contaminated soil. Often the condition of the soil is unknown or undocumented; therefore, exposure to toxic levels can occur. Xu and Thornton (1985) suggested that there are health risks from consuming vegetables with elevated heavy metal concentrations. The populations most affected by heavy metal toxicity are pregnant women or very young children (Boon and Soltanpour 1992). Neurological disorders, CNS destruction, and cancers of various body organs are some of the reported effects of heavy metal poisoning (ATSDR 1994a,b, ATSDR 1999a, ATSDR 1999b, ATSDR 2000). Low birth weight and severe mental retardation of newborn children have been reported in some cases where the pregnant mother ingested toxic amounts of a heavy metal through direct or indirect consumption of vegetables (Mahaffey et al. 1981). Studies on Cd, Cu and Ni levels in vegetables from industrial and residential areas of Lagos City, Nigeria was carried out by Yusuf et al. (2002) which revealed that the levels of Cd, Cu and Ni in different edible vegetables along with its soils on which they were grown were higher in industrial areas than those of the residential areas due to pollution. Trace element and heavy metal concentrations in fruits and vegetables of the Gediz River region was intensively studied by Delibacak et al. (2002). Also edible portions of five varieties of green vegetables, viz. Amaranth, Chinese Cabbage, Cowpea leaves, Leafy Cabbage and Pumpkin leaves collected from several areas in Dar Es Salaam, Africa, were analyzed for Pb, Cd, Cr, Zn, Ni and Cu. There was a direct positive correlation between Zn and Pb levels in soils with the levels in vegetables. The relation was absent for other heavy metals (Othman et al. 2002). Characterization of Heavy Metals in Vegetables... NIRMAL KUMAR, J I ; HIREN SONI; RITA N. KUMAR 76 In India, similar kind of study was undertaken by Somasundaram et al. (2003) on heavy metal content of plant samples of sewage-irrigated area of Coimbatore district. Leafy vegetables were found with very high levels of heavy metal contamination including Cd, Zn, Cu, Mn and Pb. A similar research was carried out in Delhi and its surrounding regions on `Vegetables eating up vegetarians' found the presence of deadly heavy metals in vegetable samples collected from across the capital (The Hindu 2003). Rana and Nirmal Kumar (1988) and Nirmal Kumar et al. (1989) have investigated elemental composition of certain aquatic plants by Energy Dispersive X-Ray Analysis (EDAX). Heavy metals like Al, Si, Mn, Fe were found accumulated in Vallisnaria spiralis, Hydrilla verticillata and Azolla pinnata. Nirmal Kumar and Rita N. Kumar (1997) also carried out elemental composition of certain economic important plants by EDAX. Some studies on distribution and characterization of heavy metals in vegetable plants and its parts collected from organic farms and village agriculture fields around Anand province, Gujarat, was also carried out by Nirmal Kumar et al. (2004). The present investigation aims to study the distribution and characterization of heavy metals in common vegetables sold in vegetable market of Anand town, Milk City of Asia, Gujarat. MATERIALS AND METHODS In the present study, 21 fresh vegetables sold in vegetable market of Anand town, Gujarat were collected and brought to the laboratory. The common vegetables available in market are Bean Pods, Beet, Bitter Gourd, Bottle Gourd, Brinjal, Carrot, Cauliflower, Coriander, Cucumber, Drumstick, Gavar, Tindora, Ginger, Chilli, Lady’s Finger, Onion, Parwar, Pattarveli, Sweet Potato, Tomato and Turmeric. The edible parts of these vegetables like roots, stems, leaves, flowers and fruits were collected. The samples were brought to the laboratory and washed under tape-water gently. The moisture and water droplets were removed with the help of blotting papers. 0.5 gm dry powder was weighed by electric monopan balance (Dhona 200D) and digested with Sulphuric acid (H2SO4), Nitric acid (HNO3) and Hydrogen Peroxide (H2O2) (2:6:6) as prescribed by Saison et al. (2004). The samples were analyzed in Inductive Coupled Plasma Analyzer (ICPA) (PerkinElmer ICP Optima 3300 Rl, USA) at Sophisticated Instrumentation Center for Applied Research and Testing (SICART), Vallabh Vidyanagar, Gujarat. The concentration of heavy metals such as Cadmium (Cd), Cobalt (Co), Copper (Cu), Iron (Fe), Nickel (Ni), Lead (Pb) and Zinc (Zn) were analyzed. The reading of each sample is calculated by taking the average readings of duplicate sets. All values are mentioned in mg/gr dry weight.