**2. Experimentation of impact of soil contamination on vegetables and fruits**

### **2.1 General principles of experimentation**

It has been shown that when environmental conditions allow heavy metals to infiltrate the soil and, implicitly, groundwater, whole food chain is degraded and there is a direct risk of pollution. The dissemination of metals in food chains place as follows: contaminated soil with toxic metals - plants that absorb metals from the soil in the root, stem, leaves and fruit- humans and animals who eating plants contaminated with dangerous toxic metals and drinking water that can circulate through groundwater and surface water that has metals drains in them.

The danger of contamination of soil and plants with heavy metals depends primarily on the species of the plant and the properties of the soil, and second, the amount and concentration of the metal in the soil. But on the other hand the existence of chemical elements that can change the effect of metals and other substances, can reduce or amplify the absorption or adsorption processes in the soil. The adverse effect depends on the mobility and solubility of heavy metals in the soil. As control measures, there must be optimal conditions for passing metals from the soil solution into stable forms.

In plants, the concentration of metals varies depending on the species of the plant, its period of development, the vegetative organs (roots, stems, leaves, shoots, etc. branches, buds, flowers, fruits). There are plant species that can preferentially

accumulate heavy metals according to their vegetative organs, as well as varying amounts. Therefore, in polluted areas, especially mining areas, it is not recommended, to ingest especially green vegetables, because toxic metals quickly get into the leaves due to foliar absorption.

Therefore, for areas at risk of soil pollution and implicitly of plants, the population must selectively consume the plants that grow on those contaminated soils. The selection of plants for consumption is based on the following criteria:


In this study, the following vegetables and fruits were used in a controlled environmental experimentation:


These vegetables and fruits have been chosen because they are frequently eaten, and grown by the inhabitants of suburban areas of Romania, being essential and rich in micromacronutrients, proteins, antioxidants and vitamins beneficial to the human body.

The selected vegetables also have a high capacity of accumulating metals without the phytotoxicity of the plants being observable by consumers. The vegetables studied had a relatively short life cycle (about 60 days) and developed well in pots, in the greenhouse, where a controlled environment was created.

### **2.2 Actual development of experiments**

The heavy metals studied were copper, lead and zinc introduced into potted soils in four different concentrations for the solution of each metal, namely: 1.5%, 3.0%, 4.5% si 6.0%. The solutions were prepared individually, using distilled water, as a solvent and copper sulfate, lead acetate and zinc sulphate, as reagents. 250 ml solution of each metal (Cu, Pb, Zn) with the concentrations for each metal was placed, at 1 kg of soil.

Soil contamination with metal solutions and their concentrations was carried out by homogenizing them evenly in the soil prior to planting in pots, no additional until harvest.

*Evaluate the Impact of Soil Contamination on Vegetables and Fruits DOI: http://dx.doi.org/10.5772/intechopen.110445*

In pots, carrot seeds, parsley, cucumber and salad seedlings, raspberry bushes and strawberry stems were planted, which were 1 year old at the time of planting.

At the same time, the reference samples were also made, which consisted of planting seeds, seedlings, bushes and stems in fertile, uncontaminated soil.

The basic properties of the soil used in the experiments were: PH 6.2, moisture 15.4%, particle elements <18 mm 85–95%, total phosphorus 0.8%, total potassium 1%, total nitrogen 2%.

The analysis of the metal content for samples from soils and plants was made on ash resulting from the samples. The methods and techniques used were consistent with the recommendations developed by [46, 47] using an atomic absorption spectrophotometer [48]. The method used was the spectrophotometric method (atomic absorption in flame) [48, 49].

### **2.3 Experimental results**

**Table 1** presents the content of metals in soil uncontaminated and in soli contamination with Cu, Pb and Zn separated concentrations.

The experimental data obtained for vegetables are presented in the **Table 2** and for fruits in the **Table 3**. Based on them, the mathematical modeling was done.

Also, aspects with the plants during the experimental research are shown in the **Figure 3**.


### **Table 1.**

*The content of metals in soil function of four concentrations.*



### **Table 2.**

*The experimental data from vegetables.*


### **Table 3.**

*The experimental data from fruits.*

### **3. Development of mathematical models**

### **3.1 Study of the transfer coefficient of plants studied**

The transfer coefficient reflects the heavy metal uptake ability from the soil by the plant as a function of the heavy metal concentration in the soil.

The definition formula is (Eq. (13)):

$$\mathbf{C}\_{t} = \frac{\mathbf{C}\_{fp}}{\mathbf{C}\_{\text{is}}} \tag{13}$$

For vegetables and fruits, the variation of the transfer coefficient (Ct) depending on the initial concentration of heavy metal in the plants (Cfp) and on the initial concentration of heavy metal in the soil (Cis,) is represented in the following tables (**Table 4** for vegetables and **Table 5** for fruits).

*Evaluate the Impact of Soil Contamination on Vegetables and Fruits DOI: http://dx.doi.org/10.5772/intechopen.110445*

**Figure 3.** *Aspects with the plants during the experimental research.*
