A series of microcosm experiments were performed to determine the effectiveness of various gaseous electron donors (including hydrogen, 1-hexene, ethyl acetate, and liquefied petroleum gas [LPG]) for supporting biological perchlorate reduction under different electron donor concentrations and soil moistures. Under high soil moisture (16% w/w) conditions, complete or partial perchlorate degradat...

J O H N D . F O R T N E R , † C H U N L O N G Z H A N G , ‡ J I M C . S P A I N , § A N D J O S E P H B . H U G H E S * , † Department of Civil and Environmental Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, School of Natural and Applied Sciences, University of HoustonsClear Lake, Houston, Texas 77058, and Air Force Research Laboratory/MLQR, 139 Barnes Drive, Suite 2, Ty...

High concentrations of 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT) are present in vadose zone soils at many facilities where explosives manufacturing has taken place. Both DNT isomers can be biodegraded under aerobic conditions, but rates of intrinsic biodegradation observed in vadose zone soils are not appreciable. Studies presented herein demonstrate that nutrient limitation...

While ERT surveys are useful, Yeh et al. (2002) showed that uncertainties in tracking moisture movement in the Electrical resistivity tomography (ERT), during the past few years, vadose zone on the basis of ERT surveys alone can has emerged as a potentially cost-effective, noninvasive tool for imaging changes of moisture content in the vadose zone. The accuracy be quite significant. They report...

Sorption-desorption is one of the most important processes affecting the leaching of pesticides through soil because it controls the amount of pesticide available for transport. Subsurface soil properties can significantly affect pesticide transport and the potential for groundwater contamination. This research characterized the sorption-desorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-met...

Robust measurements of porous-medium tortuosity are one of the many components needed for accurate characterization and prediction of fluid flow and contaminant transport in the subsurface. A gasphase diffusive tracer-test method is evaluated for the in-situ measurement of tortuosity in the vadose zone. This technique presents an alternative to employing widely-used correlations to estimate tor...

Abstract. Slope stability is strongly influenced by soil hydraulic conditions. Considering rain-triggered shallow landslides, the can be markedly propagation of saturation front inside unsaturated zone. Soil shear strength varies in vadose zone depending on type and variations moisture. Monitoring done measuring volumetric water content using low-cost instrumentation, such as capacitive sensors...

ated with soil type, vadose zone flow and transport processes are also affected by such external factors as tillage Vadose zone flow and transport processes are known to be strongly practices. For example, Petersen et al. (1999, 2001) affected by both soil structure and soil texture. We conducted a field experiment to explore the impact of heterogeneity in soil structure showed that surface til...