Responses of Bougainvillea spectabilis to elevated atmospheric CO2 under galaxolide (HHCB) pollution and the mechanisms of its rhizosphere metabolism

Due to the discovery of synthetic musks in soil and the gradual increase in atmospheric carbon dioxide (CO 2 ), it is important to reveal the potential implications of these compounds for bioremediation systems. Hence, this study was conducted to investigate the combined influence of galaxolide (HHCB) and elevated CO 2 on an ornamental remediation plant. We conducted pot experiments with Bougainvillea spectabilis , an ornamental remediation plant, in which the biomass, HHCB and chlorophyll contents, and rhizosphere metabolism of the plants were analyzed. We showed that B. spectabilis exhibited high tolerance under combined HHCB and elevated CO 2 stresses. The addition of HHCB alone to the soil did not significantly reduce the biomass components of B. spectabilis , whereas the presence of elevated CO 2 (750 μL L −1 ) alone showed a relatively strong ability to increase plant biomass, especially that of the leaves. An elevated CO 2 concentration stimulated the absorption of low doses of HHCB by the roots. Regarding the root metabolites of B. spectabilis , carbohydrates and organic acids were highly correlated with HHCB concentration, and amino acids were well correlated with CO 2 concentration. Our study indicates that B. spectabilis may be well suited to remove HHCB from contaminated soil under elevated CO 2 levels, and the root metabolism of this plant provides information about HHCB contamination and elevated CO 2 conditions.