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MA2 Exposure to POPs Through Terrestrial Vegetation
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() Trichloroethylene in edible fruit growing above shallow groundwater plumes: greenhouse results.

Chard, B1, Doucette, W1, Chard, J1, Bugbee, B1, Gorder, K2, 1 Utah State University, Logan, Utah, USA2 Hill Air Force Base, Layton, Utah, USA

ABSTRACT- A greenhouse study was conducted to quantify the uptake of trichloroethylene (TCE) by fruit trees and determine if TCE was transferred into edible fruit. Dwarf peach and apple trees were sub-surface irrigated with solutions of 14C-TCE at concentrations of approximately 5 and 500 g/L. These concentrations bracketed groundwater levels observed during a field survey conducted in the fall of 2001 where trace levels of TCE were detected in several fruit samples collected from residential areas surrounding Hill Air Force Base, Utah. Control trees were grown within the canopy of the dosed trees and in a separate greenhouse. Tissue samples (leaves, stems, fruit, trunk, roots) were analyzed for TCE and 14C using headspace gas chromatography mass spectrometry (HS/GC/MS) and combustion/liquid scintillation counting (LSC). All non-control plant tissue contained measurable levels of 14C that were proportional to the exposure concentration and amount of water transpired. Concentrations of 14C were greatest in the roots, followed by the leaves, stems, and fruit. Fruit concentrations of 14C were generally tens times lower than leaves or stems. No parent TCE was detected in any tissue samples, including fruit, except in the lower portion of the trunk and the roots. This implies that the 14C detected in the leaves and fruit is associated with non-volatile TCE transformation products and/or TCE strongly bound to the plant tissue. The identification of the TCE metabolites trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA) in leaves from a high dose apple tree support this hypothesis. However, metabolites have not been identified thus far in the fruit. Fruit were regularly sampled throughout the study and 14C concentrations appeared to reach a maximum midway through the season. This may indicate that a majority of the 14C moves into fruit early in the season when the xylem concentration to the fruit is greatest.

Key words: Fruit, Trichloroethylene, Uptake, Translocation


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