Figure 2.

Tube system for introducing pollutants inside the box. (a) For the treatments with H₂SO₄ or NaCl, a syringe placed outside of the Faraday cage and connected to a silicone tube inserted into the plant soil was used to inject the solution at various concentrations. (b) Ozone was injected into the box through a silicone tube, while a second outlet tube withdrew the ozone from the box to the chemical hood. (Online version in colour.)