PARENT SESSION
PT6 - Biomonitoring
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P648) The Correlation between Sapwood Tree Cores and Groundwater Samples Obtained from a Shallow Alluvial Aquifer.
Harvey, G*,1, Vroblesky, D2, Jones, S2, Braun, C2, Nzengung, V3, 1 Wright-Patterson AFB, Wright Patterson AFB, OH2 USGS3 University of Georgia-Athens
ABSTRACT- Plants explore and exploit subsurface heterogeneity to obtain water and nutrients. The ability of plants to derive water from the subsurface has provided investigators a means to obtain an indication of the presence of subsurface contamination by means of tree-core analysis. Sapwood cores obtained from phreatophytic trees have repeatedly shown utility detecting volatile organic compounds (VOCs) such as trichloroethylene (TCE) in historically contaminated shallow aquifers under a variety of different conditions. To test how closely VOCs levels in sapwood cores and cut stems from a eastern cottonwood phytoremediation plantation located above a shallow TCE contaminated aquier in Fort Worth, TX we obtained. These vegetative samples were then placed in glass vials and allowed to degas. Vial headspace vapor samples were a analyzed by GC-PID and compared with groundwater samples obtained in real time from wells less than 6 feet away from the respective tree samples. Preliminary results show that the relative vapor concentrations in headspace analysis of sapwood cores show a general correspondence to aqueous concentrations from groundwater. The TCE concentrations in stems tend to be lower than concentrations in the core from the trunk. Additional work will be necessary to employ cut stems as surrogates for sapwood cores.
Key words: dendrochemistry, VOCs, shallow groundwater