Changes in the Phytoremediation Potential of Indoor Plants with Exposure to Toluene

Abstract

Changes in phytoremediation efficiency after repeated exposures (three) to toluene (1.3 ppm) were assessed in 26 species and two additional cultivars of indoor plants. There was a rapid increase in toluene removal efficiency in 27 of the 28 crops with the greatest increase between the first and second exposure (i.e., after 3 days). The increase in efficiency between the first and third exposure ranged from 378 μg·m −3 ·h −1 ·m −2 leaf area in Pinus densiflora to –16.6 in Salvia elegans with a mean of 156 for all crops. Percent change ranged from 614 ( Pittosporum tobira ) to –8 ( Salvia elegans ) but was not necessarily indicative of phytoremediation value of a species. Rapid changes in phytoremediation efficiency in response to exposure to toluene appear to be widespread in plants and may be the result of an effect on gene expression in the plant and/or certain soil microbes or changes in the population density of toluene-metabolizing microbes. Increasing toluene removal efficiency is advantageous and as a consequence, a better understanding of the mechanism(s) operative may improve use of the response for practical applications.