Effect of nitrate and ammonium fertilization on Zn, Pb, and Cd phytostabilization by Populus euramericana Dorskamp in contaminated technosol

This study aimed at assessing the effect of nitrogen addition under two forms, nitrate and ammonium, on the stabilization of Zn, Pb, and Cd by Populus euramericana Dorskamp grown in contaminated soils for 35 days under controlled conditions. Temporal changes in the soil pore water (SPW) were monitored for pH, dissolved organic carbon (DOC), and total dissolved concentrations of metals in the soils rhizosphere. Rhizospheric SPW pH decreased gradually with NH₄ ⁺ addition and increased with NO₃ ⁻ addition up to one unit, while it slightly decreased initially then increased for the untreated control soil DOC increased with time up to six times, the highest increase occurring with NH₄ ⁺ fertilization. An increase in the metal concentrations in the rhizospheric SPW was observed for NH₄ ⁺ addition associated with the lowest rhizospheric SPW pH, whereas the opposite was observed for the control soil and NO₃ ⁻ fertilization. Fertilization did not affect plant shoots or roots biomass development compared to the untreated control (without N addition). Metals were mostly accumulated in the rhizosphere and N fertilization increased the accumulation for Zn and Pb while Cd accumulation was enhanced for NH₄ ⁺ addition. Collectively, our results suggest metal stabilization by P. euramericana Dorskamp rhizosphere with nitrogen fertilization and are potential for phytostabilization of contaminated technosol.