Simultaneous counter-flow of chlorinated volatile organic compounds across the saturated–unsaturated interface region of an aquifer

Concentrations of chlorinated volatile organic compounds (Cl-VOCs) at the saturated–unsaturated interface region (SUIR; depth of ∼18 m) of a sandy phreatic aquifer were measured in two monitoring wells located 25 m apart. The concentrations of the Cl-VOCs obtained above and below the water table along a 413-day period are interpreted to depict variable, simultaneous and independent movement of trichlorothene, tetrachloroethene, 1,1-dichloroethene, cis-1,2-dichloroethene, 1,1,1-trichloroethane, chloroform and 1,1-dichloroethane vapors in opposite directions across the SUIR.