**2.6 Magnesium (mg)**

During the autumn and summer seasons, the average concentration for Mg accumulated in the plants was 18561.31 and 14976.21 μg/g respectively, as shown in **Figure 11**. A higher concentration of magnesium was accumulated by the plant during autumn. When the plants were measured for Mg, seasonal differences in the accumulation of Mg were not very pronounced.

*The Evaluation of the Macrophyte Species in the Accumulation of Selected Elements… DOI: http://dx.doi.org/10.5772/intechopen.105708*

**Figure 10.**

*Variation in the average Copper concentration accumulated by plant in summer and autumn.*

#### **2.7 Cobalt (Co)**

During the sampling periods, harvested plants were measured for the presence of Co. After the plant has been measured for the metals accumulated by the plant, it was observed that the plant harvested in summer has accumulated and stored in higher amounts of Co than in autumn, and this also follows the trends like that of Zn, Ni, Cu, and Mg. The average concentration for Co measured in summer was 58.13 μg/g, whilst the average concentration of Co in autumn was 43.24 μg/g as shown in **Figure 12**.

**Figure 12.** *Variation in the average Cobalt concentration accumulated by plant in summer and autumn.*
