Sorption of Trichloroethylene (tce) and Other Halogenated Aliphatics on Plant Materials

Common chlorinated solvents have octanol:water partition coefficients in the range of 100-300. This significantly alters their movement through soil and plant tissues. Sorption coefficients on wood were estimated, by static equilibration techniques, for trichloroethylene (TCE), trichloroethane (TCA), chloroform and dichloromethane (DCM). For TCE and TCA the sorption to ground alfalfa and low organic sandy soil was also measured. Estimates of sorption coefficient were also determined by passsing water carrying the contaminant through an intact stem section and then sectioning the stem to determine the concentration that accumulated. In the static experiments a wood:water accumulation ratio of about 7 was observed for TCE while for TCA it was only 2. For alfalfa the ratios were about 10 for TCE and 5 for alfalfa. Based on 1% organic matter the sorption of TCE in soil was about 100. Coefficients for chloroform, and DCM with wood were less than for TCA. Estimates for TCE in intact stem sections were 25 30 while for TCA a value of 18 was obtained. Sorption must be included in any model of contaminant movement through plants, as an important addition to exclusion from the transpiration stream.