Effects of elevated CO₂ on the phytoremediation efficiency of Noccaea caerulescens

Concentrations of atmospheric carbon dioxide have been continuously increasing, and more investigations are needed in regard to the responses of various plants to the corresponding climatic conditions. In particular, potential variations in phytoremediation efficiency induced by global warming have rarely been investigated. Objective of this research was to evaluate the changes in phytoremediation efficiency of Noccaea caerulescens exposed to different concentrations of CO₂. The concentrations of CO₂ in the elevated CO₂ treatments were adjusted to 550 ± 50 ppm to match the level of atmospheric CO₂ predicted in 2050–2070. Compared to ambient controls (400 ppm), biomass yields and metal concentrations of N. caerulescens increased under elevated CO₂ conditions, thus indicating that the phytoremediation efficiency of the species could increase in higher CO₂ environment. In addition, water soluble and exchangeable Pb and Cu concentrations in soils decreased under elevated CO₂ conditions, which reduced the leaching risks of the metals. The concentrations of malondialdehyde (MDA) of N. caerulescens decreased to different degrees with the increased CO₂ concentrations. The overall findings suggested that elevations in CO₂ can reduce the oxidative damage caused by metals in this species. The phytoremediation efficiency of N. caerulescens grown in multiple metal-enriched soils could be enhanced with global warming.