Elevated Atmospheric CO₂ Enhances Copper Uptake in Crops and Pasture Species Grown in Copper‐Contaminated Soils in a Micro‐Plot Study

Abstract

The biomass of plants for the purpose of phytoremediation is often small. Carbon dioxide (CO2) can enhance plant biomass and so, it is reasonable to draw such an assumption that CO2 can be used to help plants to phytoremediate heavy metal contaminated soils through enhancing the biomass of remediating plants. To identify this assumption, a micro‐plot study in six separate growth chambers was conducted to investigate the effect of high CO2 levels (approximately 1000 ± 50 µL L−1) on Cu accumulation and the remediation potential of three rape varieties and another five crop and pasture species grown in soils contaminated with Cu (485 mg Cu kg−1, denoted as soil‐L, and 1200 mg Cu kg−1, denoted as soil‐H). The results showed that independently of the CO2 treatment, the shoot biomass and Cu concentration in the eight plants varied with the species and soil Cu levels. The plants grown in soil‐L produced a higher aboveground biomass than those grown in the more heavily contaminated soil‐H, but the Cu levels were high in all the plants grown in soil‐H. Regardless of the CO2 treatment, the shoot biomass and Cu concentration in the plant parts also varied with the species and soil Cu levels. Overall, the exposure of all the plants to elevated CO2 resulted in a biomass increase of 6–136% and a significantly higher remediation capacity. The results indicate that the ever‐increasing atmospheric CO2 may enhance the phytoremediation efficiency of Cu contaminated soils; however it also suggests a risk of food safety under the future scenario of elevated atmospheric CO2.

A reduced fraction of plant N derived from atmospheric N (%Ndfa) and reduced rhizobial nifH gene numbers indicate a lower capacity for nitrogen fixation in nodules of white clover exposed to long-term CO<sub>2</sub> enrichment

“…Plants growing under eCO 2 had a higher concentration of Cu, a response that has been observed previously (Tian et al, 2013), higher B and S content and the eCO 2 soil a higher B content. The values for these elements were in the "adequate" range recommended for pastures (Fleming 2003).…”

Concurrent elevation of CO2, O3and temperature severely affects oil quality and quantity in rapeseed

“…When it comes to the quality of oil crops, the limited research available indicates that elevated [CO 2 ] may have a positive effect, but certainly there are also negative impacts on oil quality by changing the composition of FAs on a dry weight basis. Illustrated by the handful of studies available on a very limited number of cultivars in sunflower ( Pal et al , 2014 ), castor bean ( Vanaja et al , 2008 ) and rapeseed ( Högy et al , 2010 ; Tian et al , 2014 ), the crop quality response to elevated [CO 2 ] is not unequivocal. A growth chamber study of the rapeseed cultivar ‘Mozart’ – likely the same cultivar also analysed in the present study – demonstrated decreased seed oil% as well as seed yield, while vegetative biomass increased ( Franzaring et al , 2011 ; [CO 2 ] 550ppm).…”

Physiological Response at Different Plant Development Stages in Glycine max Exposed to Elevated CO2 Concentrations and Fly Ash-Amended Soils

“…Considering that in the future further increases in global CO 2 levels and contamination with heavy metals are likely, it is important to do more studies on the physiological response of crops. Although recently a few studies have assessed this problem, they were based on the accumulation of metals in plants without consideration of the physiological response in plants [9,16,17,23,26,34,41,42,45].…”