3.2. Improvement of phytoremediation using solubility-enhancing agents
The phytoremediation efficiency of P. major L. amended with liquid silicon dioxide (SiO2) was significantly greater than that of other solubility-enhancing agents with respect to the removal of cyanophos from contaminated soil within 3 days of treatment ( Fig. 1). Amending the soil with P. major plus SiO2 sharply decreased the level of cyanophos in the soil, and substantially increased cyanophos concentrations in plant leaves and roots. Plant leaves in soil planted with P. major and amended with liquid SiO2 extracted greater total amounts of cyanophos (32.99 µg/g) from the contaminated soil after 3 days than the roots (13.33 µg/g). The cyanophos concentrations in P. major leaves amended with SiO2, HPβCD, HA, and Tween 80 reached 32.99 µg/g, 15.84 µg/g, 15.18 µg/g, and 14.56 µg/g, respectively, within 3 days. Concentrations of cyanophos in P. major alone, autoclaved soil with P. major, and P. major amended with rice bran reached 11.86 µg/g, 7.78 µg/g, and 7.16 µg/g, respectively. This latter finding may be attributed, in part, to strong physical adsorption and binding of cyanophos to the adsorbent, rice bran ( Sera et al., 2005)