Persistence of methyl tertiary butyl ether (MTBE) against metabolism by Danish vegetation.
BACKGROUND
Methyl tertiary butyl ether (MTBE) is the second most highly produced industrial chemical in the US and a frequent groundwater pollutant. At the same time, MTBE is quite persistent to biotic and abiotic decomposition. The goal of this study was to find plant species that could degrade MTBE and might be used in phytoremediation.


METHODS
Excised roots and leaves (0.3 g) from more than 24 Danish plant species out of 15 families were kept in glass vessels with 25 ml spiked aqueous solution for 2 to 4 days. MTBE concentrations were 1 to 5 mg/L. Samples were taken directly from the solution with a needle and injected to a purge and trap unit. MTBE and the main metabolite, TBA, were measured by GC/FID.


CONCLUSIONS
Solutions with roots of poplar (Populus robusta) and a willow hybrid (Salix viminalis x schwerinii) produced TBA in trace amounts, probably stemming from bacteria. Significant MTBE reduction (> 10%) was not observed in any of the tests. Leaves from none of the species (trees, grasses and herbs) reduced the concentration of MTBE in the solution and no TBA, nor any other known metabolite of MTBE, was detected.


CONCLUSIONS
It was not possible to find plants capable of efficiently degrading MTBE. This gives rise to the conclusion that plants probably cannot degrade MTBE at all, or only very slowly.


CONCLUSIONS
For phytoremediation projects, this has, as consequence, that the volatilization by plants (except with genetically engineered plants) is the only relevant removal process for MTBE. For risk assessment of MTBE, degradation by the plant empire is not a relevant sink process.
Trapp
Stefan
S
Environment & Resources DTU, Technical University of Denmark, Bygningstorvet 115, DK-2800 Kgs. Lyngby, Denmark. stt@er.dtu.dk
Yu
Xiaozhang
X
Mosbaek
Hans
H
D001673:Biodegradation, Environmental; D002273:Carcinogens / Q000378:metabolism*; D003718:Denmark; D008738:Methyl Ethers / Q000378:metabolism*; D018517:Plant Roots; D032107:Populus / Q000502:physiology*; D032108:Salix / Q000502:physiology*; D014835:Volatilization
D002273:Carcinogens; D008738:Methyl Ethers; C043243:methyl tert-butyl ether