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Soceanu et al.

Soceanu et al. /Environmental Engineering and Management Journal 6 (2007), 6, 593-596 2.2. Sample preparation The vegetables and fruits samples produced in the area of Constanta (Romania) were collected during one year. These samples were stored in Teflon vessels at the room temperature in a dark place for further analysis. A mineralization step is necessary to obtain a finally solution suitable for introduction in the spectrometer. This step is recommended even for liquid or water-soluble foodstuffs, the destruction of the organic matter preventing both spectral interferences and the accumulation of the residues in the burner head and spray chamber. In this context analyzed samples were submitted to digestion with 8 mL HNO 3 and 10 mL H 2 O 2 at 150 o C in a Digesdhal device provided by Hach Company. After the complete digestion, sample solutions were filtered made up to 50 mL with deionized water. Than Fe, Mn, Mg and Zn were determined by FAAS in air/acetylene flame using an aqueous standard calibration curve. Analyses were made in triplicates and the mean values are reported. A flame atomic absorption spectrometer Shimadzu AA6500 was used for the determination of five essential elements (Fe, Mn, Cd, Zn and Cu). An air-acetylene flame was used for all elements. Monoelement hollow cathode lamps were employed to measure the elements. The acetylene was of 99.999% purity at a flow rate 1.8-2.0 L/min. The characteristics of metal calibration are presented in Table 1. Table 1. Characteristics of metal calibration curves Metal λ, nm Concentration range (ppm) Correlation coefficient Fe 248.3 0.020-4.000 0.9976 Mn 279.5 0.008-1.600 0.9984 Cd 228.8 0.008–1.600 0.9999 Zn 213.9 0.016-0.510 0.9932 Cu 324.7 0.010–1.200 0.9990 The accuracy (expressed as standard deviation SD and coefficient of variance CV) of the results was determined from three replicates of homogenized samples, giving a good standard and precision for the analytical results of essential elements obtained by FAAS. 3. Result and discussion In Tables 2 and 3 the average values of Fe, Mn, Zn, Cd and Cu concentrations in vegetable samples (mg/kg) are presented. Concentrations of iron found in the bulb of carrot (825.51 mg/kg), in stem (506.03 mg/kg) and in leaves (1207.18 mg/kg) of cucumber were over the allowable maximum limit of iron in vegetables namely 425.5 mg/kg (Food Standards Programme, 2001). It can be observed that iron concentrations are higher in the leaves of bean and pea plant comparative to the others parts of these plants. Also, the content of iron is higher in the bean than in the pea. The plants absorb cadmium through their roots and leaves, which affect the plant metabolism and growth. The highest concentrations of cadmium in polluted plants are always reported for the leaves. The bean and pea leaves studied here indicate that levels of cadmium are lower than those measured by Angelova in bean, respectively pea leaves (6.4 mg/kg, respectively 1.13 mg/kg) (Angelova et al., 2003). They found that the movement and accumulation of the heavy metals (Cu, Cd and Zn) in the vegetative organs of different cultivated plants differed significantly. They also found that the content of heavy metals in the leaves was higher comparative to the root system. This situation is confirmed by the studies of Cobb et al., (2000) about the accumulation of cadmium, lead, zinc and copper in different vegetables, which indicate that each plant can accumulate differently heavy metal. Moraghan studied the accumulation of iron in beans (Moraghan et al, 2002). He determined the influence of lime, Fe chelates and type of soil on accumulation of iron in bean. In this context, he observed that iron chelates could drastically reduce Mn concentration. Table 2. Fe and Cd concentrations in vegetables Bean (Phaseolus vulgaris L) Sample Concentrations (mg/kg) Fe Cd Green pod 50.48±0.0032 1.97±0.0012 Leaves 217.77±0.0064 3.73±0.0012 Flower 188.93±0.004 10.71±0.0025 Bean 38.52±0.0025 3.3±0.0016 Pod 31.6±0.0011 2.81±0.0006 Leaves 153.55±0.0021 4.13±0.0025 Pea (Pisum sativum L) Pea 41.93±0.003 1.09±0.043 Carrot (Daucus carota L) Cucumber (Cucumis sativus L) Bulb 825.51±0.0278 3.391±0.0024 Leaves 249.3±0.0025 5.73±0.0017 Root 351.23±0.0027 47.03±0.0215 Stem 506.03±0.0001 61.32±0.0025 Leaves 1207.18±0.0022

Comparative study of some essential elements in different types of vegetables and fruits Tables 4 and 5 present the average values of Fe, Mn, Zn, Cd and Cu concentrations in fruit samples (mg/kg). It can be notice that, while Cu concentration was under detection limit in bulb of carrot, in leaves of carrot a high concentration of Cu (157.84 mg/kg) was detected of which is over the recommendable maximum limit (73.3 mg/kg). Peach (Prunus persica) Table 4. Fe and Cd concentrations in fruits Sample Nectarine (Prunus persica var.nucipersica) Concentrations (mg/kg) Fe Cd Stone 46.9565±0.0019 1.0543±0.0026 Green 49,28±0.0009 0.27±0.0042 Almost 73.94±0.0012 2.96±0.002 ripe Ripe 92.02±0.0048 5.43±0.0003 Leaves 193.74±0.0004 31.3±0.0027 Stone 67.0723±0.0043 0.8336±0.0019 Green 19.14±0.0001 2.76±0.0001 Almost 21.09±0.0015 4.72±0.0016 ripe Ripe 38.74±0.0003 5.98±0.0004 Leaves 180.32±0.0005 16.32±0.0009 Table 5. Mn, Zn and Cu concentrations in fruits Sample Concentrations (mg/kg) Mn Zn Cu Peach Stone

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