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MA2 Exposure to POPs Through Terrestrial Vegetation
() Differential uptake of persistent organic pollutants (POPs) by agricultural species.
White, J.1, Incorvia Mattina, M.1, Eitzer, B.1, Kelsey, J.2, 1 Connecticut Agricultural Experiment Station, New Haven, CT, USA2 Muhlenberg College, Allentown, PA, USA
ABSTRACT- Research conducted over the last 5 years has indicated that the bioavailability of two weathered persistent organic pollutants (POPs), chlordane and p,p-DDE, to vegetation is highly species specific. The bioconcentration factor (BCF, concentration ratio of p,p-DDE or chlordane in the roots to that in the soil) ranges from 0.5-4 for many plant species but approaches 16 for certain cucurbits (Cucurbita pepo; squash and pumpkin). Similarly, stem BCFs(contaminant ratio in the stems to soil) ranged from 0.08-0.52 for many plant species but up to 22 for certain varieties of squash and pumpkin. Current investigations are focused on elucidating the mechanism by which cucurbits accumulate these highly weathered hydrophobic contaminants. Data suggests that unique modes of nutrient acquisition, potentially mediated through the exudation of low molecular weight organic acids and partial soil matrix deconstruction at the molecular scale, may partially explain the unexpectedly large degree of contaminant bioavailability to these plants. A full characterization of the uptake mechanism will permit an assessment of the exposure risk to other organisms of interest, as well as the ability to predict those interactions without obtaining in situ measurements. For example, preliminary data suggests that plant-induced alteration of the soil matrix by C. pepo may significantly reduce the availability of weathered POPs to worm species present in the soil with the vegetation. Lastly, the hypothesized mechanism of contaminant uptake for C. pepo is likely non-specific with regard to contaminant type, raising the potential that this species may provide a major entry point for a range of POPs into terrestrial food chains. Preliminary investigations assessing the uptake and translocation of weathered polycyclic aromatic hydrocarbons (PAHs) indicates that C. pepo accumulates significantly greater levels of total PAH, including a preferential uptake recalcitrant 5 and 6 ring constituents. Similar findings with weathered polychlorinated biphenyls (PCBs) will be presented.
Key words: POPs, Bioavailability, Bioaccumulation, Cucurbits
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