Chlorinated ethenes from groundwater in tree trunks

The purpose of this investigation was to determine whether tree-core analys is could be used to delineate shallow groundwater contamination by chlorina ted ethenes. Analysis of tree cores from bald cypress [Taxodium distichum ( L.) Rich], tupelo (Nyssa aquatica L.), sweet gum (Liquidambar stryaciflua L .), oak (Quercus spp.), sycamore (Platanus occidentalis L.), and loblolly p ine (Pinus taeda L.) growing over shallow groundwater contaminated with cis -1,2-dichloroethene (cDCE) and trichloroethene (TCE) showed that those comp ounds also were present in the trees. The cotes were collected and analyzed by headspace gas chromatography. Bald cypress, tupelo, and loblolly pine c ontained the highest concentrations of TCE, with lesser amounts in nearby o ak and sweet gum. The concentrations of cDCE and TCE in various trees appea red to reflect the configuration of the chlorinated-solvent groundwater con tamination plume. Bald cypress cores collected along 18.6-m vertical transe cts of the same trunks showed that TCE concentrations decline by 30-70% wit h trunk height. The ability of the tested trees to take up cDCE and TCE mak e tree coring a potentially cost-effective and simple approach to optimizin g well placement at this site.