Paper Reviewed
Zhang, M., Liu, J., Wang, W. and Bao, Y. 2019. Responses of Bougainvillea spectabilis to elevated atmospheric CO2 under galaxolide (HHCB) pollution and the mechanisms of its rhizosphere metabolism. Journal of Soils and Sediments 19: 159-170.

Soils in a number of locations throughout the world are contaminated with higher quantities of heavy metals (such as lead) or persistent organic pollutants. Recognizing that elevated levels of atmospheric CO2 have a stimulatory effect of plants, scientists have begun to search for plants suitable to grow on contaminated lands that can extract pollutants and help remediate soils to uncontaminated conditions. The latest study to address this topic comes from the four-member research team of Zhang et al. (2019).

Working in a controlled-environment, the scientists grew Bougainvillea (Bougainvillea spectabilis) under different treatment levels of CO2 and soil contamination (galaxolide, a persistent organic pollutant hereafter abbreviated as HHCB). The CO2 treatments included values of 400, 750 or 950 ppm, corresponding to control (400 ppm) and elevated (750 or 950 ppm) conditions. However, the elevated CO2 levels were only applied between the hours of 0800 and 1800 each day. Soil contamination was achieved by applying 3 levels of HHCB: control (0 mg kg^-1) and elevated (50 or 100 mg kg^-1). The full experiment lasted 40 days.

In summing up their findings, Zhang et al. report that the presence of HHCB had a negative effect on B. spectabilis, reducing its chlorophyll content and/or altering photosynthetic pigments. Elevated CO2, not surprisingly, increased plant biomass improved the ability of the roots to absorb HHCB. Consequently, the authors conclude that "B. spectabilis may be well suited for use as a phytoremediation material to remove HHCB from contaminated soil under elevated CO2."