| Title: | Vapor-phase transport of trichloroethene in an intermediate-scale vadose-zone system: retention processes and tracer-based prediction |
| Author(s): | Costanza-Robinson MS; Carlson TD; Brusseau ML; |
| Address: | "Department of Soil, Water, & Environmental Science, School of Earth and Environmental Sciences, The University of Arizona, 429 Shantz, Building #38, Tucson, AZ 85721, USA" |
| DOI: | 10.1016/j.jconhyd.2012.12.004 |
| ISSN/ISBN: | 1873-6009 (Electronic) 0169-7722 (Print) 0169-7722 (Linking) |
| Abstract: | "Gas-phase transport experiments were conducted using a large weighing lysimeter to evaluate retention processes for volatile organic compounds (VOCs) in water-unsaturated (vadose-zone) systems, and to test the utility of gas-phase tracers for predicting VOC retardation. Trichloroethene (TCE) served as a model VOC, while trichlorofluoromethane (CFM) and heptane were used as partitioning tracers to independently characterize retention by water and the air-water interface, respectively. Retardation factors for TCE ranged between 1.9 and 3.5, depending on water content. The results indicate that dissolution into the bulk water was the primary retention mechanism for TCE under all conditions studied, contributing approximately two-thirds of the total measured retention. Accumulation at the air-water interface comprised a significant fraction of the observed retention for all experiments, with an average contribution of approximately 24%. Sorption to the solid phase contributed approximately 10% to retention. Water contents and air-water interfacial areas estimated based on the CFM and heptane tracer data, respectively, were similar to independently measured values. Retardation factors for TCE predicted using the partitioning-tracer data were in reasonable agreement with the measured values. These results suggest that gas-phase tracer tests hold promise for characterizing the retention and transport of VOCs in the vadose-zone" |
| Keywords: | "Air Groundwater Models, Theoretical *Trichloroethylene/chemistry Volatile Organic Compounds/chemistry *Water Pollutants, Chemical/chemistry;" |
| Notes: | "MedlineCostanza-Robinson, Molly S Carlson, Tyson D Brusseau, Mark L eng P42 ES004940/ES/NIEHS NIH HHS/ ES 04940/ES/NIEHS NIH HHS/ Research Support, N.I.H., Extramural Research Support, U.S. Gov't, Non-P.H.S. Netherlands 2013/01/22 J Contam Hydrol. 2013 Feb; 145:82-9. doi: 10.1016/j.jconhyd.2012.12.004. Epub 2012 Dec 22" |
