TY - JOUR
T1 - Evidence for phytodegradation of MTBE from coupled bench-scale and intermediate-scale tests
AU - Rubin, Ellen G.
AU - Ramaswami, Anu
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2007
Y1 - 2007
N2 - This paper presents methodologies and demonstrates the need to couple bench-scale and intermediate tree-scale experiments, to fully understand the transport and fate of organic contaminants, specifically methyl tert butyl ether (MTBE), in mature trees. Bench-scale experiments showed MTBE to be optimally taken up by small poplar saplings with a transpiration stream concentration factor of approximately 1, little or no degradation in soils and, nearly 100±20% recovery in the coupled water-plant-air system, indicating no measurable phytodegradation at the bench-scale. A large 14 ft tree chamber was designed to evaluate MTBE transport and fate through intermediate-scale (12 ft tall) poplar trees. Abiotic MTBE volatilization tests conducted in the tree chamber showed 100±20% MTBE mass recovery, thereby demonstrating the integrity of the large chamber and its air monitoring technique. In contrast, replicate intermediate-scale experiments conducted with large (12 ft) trees irrigated with a known mass of MTBE showed a deficit of MTBE mass recovery (65±20%) in replicate soil-tree-air systems monitored over a 2-week period. More significantly, tert butyl alcohol (TBA), a degradation product of MTBE, was detected in increasing concentrations in leaf biomass while MTBE concentrations in leaf biomass decreased as the experiment progressed. The MTBE mass recovery deficit, coupled with the detection of increasing TBA in leaf biomass, provides preliminary evidence of MTBE degradation in mature trees.
AB - This paper presents methodologies and demonstrates the need to couple bench-scale and intermediate tree-scale experiments, to fully understand the transport and fate of organic contaminants, specifically methyl tert butyl ether (MTBE), in mature trees. Bench-scale experiments showed MTBE to be optimally taken up by small poplar saplings with a transpiration stream concentration factor of approximately 1, little or no degradation in soils and, nearly 100±20% recovery in the coupled water-plant-air system, indicating no measurable phytodegradation at the bench-scale. A large 14 ft tree chamber was designed to evaluate MTBE transport and fate through intermediate-scale (12 ft tall) poplar trees. Abiotic MTBE volatilization tests conducted in the tree chamber showed 100±20% MTBE mass recovery, thereby demonstrating the integrity of the large chamber and its air monitoring technique. In contrast, replicate intermediate-scale experiments conducted with large (12 ft) trees irrigated with a known mass of MTBE showed a deficit of MTBE mass recovery (65±20%) in replicate soil-tree-air systems monitored over a 2-week period. More significantly, tert butyl alcohol (TBA), a degradation product of MTBE, was detected in increasing concentrations in leaf biomass while MTBE concentrations in leaf biomass decreased as the experiment progressed. The MTBE mass recovery deficit, coupled with the detection of increasing TBA in leaf biomass, provides preliminary evidence of MTBE degradation in mature trees.
KW - Organic compounds
KW - Scale effect
KW - Volatile organic chemicals
KW - Water pollution
KW - Water treatment
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U2 - 10.1061/(ASCE)0733-9372(2007)133:4(389)
DO - 10.1061/(ASCE)0733-9372(2007)133:4(389)
M3 - Article
AN - SCOPUS:34247596860
SN - 0733-9372
VL - 133
SP - 389
EP - 396
JO - Journal of Environmental Engineering
JF - Journal of Environmental Engineering
IS - 4
ER -