**2. Phytoremediation strategies**

Phytoremediation techniques include different modalities, depending on the chemical nature and properties of the contaminant (if it is inert, volatile or subject to degradation in the plant or in the soil) and the plant characteristics (Figure 1). Thus, phytoremediation essentially comprise six different strategies, though more than one may be used by the plant simultane‐ ously.

**Figure 1.** Schematic representation of phytoremediation strategies.

**1. Phytodegradation** (Phytotransformation): organic contaminants are degraded (metabo‐ lized) or mineralized inside plant cells by specific enzymes that include nitroreductases (degradation of nitroaromatic compounds), dehalogenases (degradation of chlorinated solvents and pesticides) and laccases (degradation of anilines). *Populus* species and *Myriophyllium spicatum* are examples of plants that have these enzymatic systems [9,10].

**2. Phytoremediation strategies**

486 Environmental Risk Assessment of Soil Contamination

**Figure 1.** Schematic representation of phytoremediation strategies.

ously.

Phytoremediation techniques include different modalities, depending on the chemical nature and properties of the contaminant (if it is inert, volatile or subject to degradation in the plant or in the soil) and the plant characteristics (Figure 1). Thus, phytoremediation essentially comprise six different strategies, though more than one may be used by the plant simultane‐


distribution of nutrients, however species of the genus *Pseudomonas* are the predominant organisms associated with roots [13,32,33].

There are other strategies, which are considered categories of phytoremediation by some authors, but actually, they are mixed techniques or variations of the above mentioned strat‐ egies. These include:

