The potential for phytoremediation of MTBE

This paper examines the potential for phytoremediation of MTBE, a gasoline additive that has become a prevalent and persistent groundwater pollutant, due to its' non-sorbing and non-reactive nature in water. A novel experimen tal design is developed to measure plant uptake and transpiration of MTBE f rom hydroponic systems, separating these processes from passive volatilizat ion of the chemical. Plant uptake experiments indicate 30% reduction in MTB E mass in water over a 1-week period by small poplar saplings, at both high (1600 ppb) and low (300 ppb) MTBE concentrations. Active plant uptake of M TBE was approximately double that achieved by passive volatilization throug h a balsa wood control. MTBE was detected in biomass at the 100-ppb level, confirming passage of MTBE through the plant. A mass balance indicated that MTBE was largely untransformed during transport through the small poplar s aplings to air. The high degree of MTBE removal achieved by small plants ov er a short period of time indicates great potential for successful phytorem ediation of subsurface MTBE plumes using poplar trees. The fraction of MTBE removed from the hydroponic systems correlated well with volume of water t ranspired by the plants; the correlation enabled computation of the MTBE tr anspiration stream concentration factor of approximately 1, an important pa rameter for the design of engineered MTBE phytoremediation systems. (C) 200 1 Published by Elsevier Science Ltd.