Measurement of organic vapor isotherms on wet soils and aquifer materials

A technique for measuring organic vapor sorption onto water coated soils and aquifer materials is presented. The method has several advantages over other techniques such as microbalance, extraction, and headspace method. The solids used are coated with a surface layer of water and are in equilibrium with a gas phase at 100% relative humidity, simulating conditions in the unsaturated zone. Advantages of the method include the ability to measure isotherms over at least 5 orders of magnitude in organic vapor concentration, the ability to measure sorption onto very low sorbing solids, and the ability to allow an indefinite time for equilibrium to be reached.