In March, 1983 a workshop on Pollutants in Porous Media was hosted by the Institute of Soils and Water of the Agricultural Research Organi- zation in Bet Dagan, Israel. At this workshop, the unsaturated zone be- tween the soil surface and groundwater was the focal point of discus- sions for scientists from various disciplines such as soil chemists, physicists, biologists and environmental engineers. Since then, the prob- lem of soil and water pollution has only worsened as more and more cases of pollution caused by human activities including agriculture and industry have been revealed. A...