*3.3.4 As concentration*

In the root of E. hypnoides, the maximum concentration of As recorded was 2.8 mg/kg and the lowest was 0.2 mg/kg. The minimum concentration recorded in the


### **Table 11.**

*Concentration of lead in plant sample.*

*Toxic Heavy Metals in Soil and Plants from a Gold Mining Area, South Africa DOI: http://dx.doi.org/10.5772/intechopen.109639*


### **Table 12.**

*Concentration of arsenic in plant samples.*

plant's leaf was 0.2 mg/kg and 1.5 mg/kg as the maximum concentration (**Table 12**). Overall, the mean concentration of As in the soil is higher than the concentration recorded in the plant. This shows that the plant has a low potential of taking As from the soil.

The permissible limit of As in plant is 0.2 mg/kg [85]. With the recorded concentration of As in the studied plant all above 0.2 mg/kg, except the leaf concentration of the north within 500 m which is approximately 0.2 mg/kg. It means that the plant is contaminated therefore not suitable to feed cattle.

In order to determine the dependency of As, Cd, Pb and Zn concentration in the root and leaves of *E. hypnoides*, Chi-square test was used. Using SPSS to evaluate the result of heavy metal concentration in plant samples, it was revealed that the P-value, 0.05, is lower than the significance level of 0.213. This means that the null hypothesis can be rejected, and we can conclude that the concentration of As, Cd, Pb, and Zn in the roots and leaf of *E. hypnoides* are independent.

In conclusion, the results of all the evaluation are the same for all the metals. This means the studied heavy metals bioaccumulated in the plant by absorption through the roots and are translocated to the leaf. Hence, the reason for the consistency observed in all the studied heavy metals.

### **3.4 Heavy metal uptake by plants**

Importantly, it must be noted that plants have the potential and mechanism to uptake heavy metals by absorption from the soil through the roots [86]. To calculate the uptake of As, Cd, Pb and Zn by *E. hypnoides* eq. 3 was used and the result is in table **Figures 2**–**5** below.

### *3.4.1 Zinc uptake by plant*

The CF of Zn based on the recorded concentration of Zn in the plant and soil indicated that the plant is a good accumulator of Zn. The CF value of Zn is greater than 1 (**Figure 2**). This means that *E. hypnoides* can be useful to phyto-remediate a Zn polluted soil. Unfortunately, the consumption of plants with a high concentration of Zn is not healthy for both human and animals [87].

**Figure 2.**

*Zinc concentration factor in Eragrostis hypnoides. (north\* and east\* were taken at 1000 m while north and east were taken at 500 m).*

### **Figure 3.**

*Cadmium concentration factor in Eragrostis hypnoides. (north\* and east\* were taken at 1000 m while north and east were taken at 500 m).*
