A pollutant released at the surface infiltrates the soil through pore spaces in the soil matrix and moves downward through the unsaturated zone under the force of gravity until the top of the saturated zone (the water table) is reached.
地表释放的污染物透过土壤基质中的孔隙渗入土壤，在重力作用下，向下移动，穿过非饱水带，一直到达饱和层顶部（潜水面）。