The reverse of sorption is desorption. The process is the opposite of sorption (that is, either adsorption or absorption). A more general term is "sorption", which covers absorption, adsorption, and ion exchange. In deep or turbid water processes, sorption and biodegradation take place. These types are a function of the shape of the desiccant's moisture sorption isotherm. The term "sorption" encompasses both processes, while "desorption" is the reverse of it. Known degradation pathways are through&colon; photolysis, chemical dissociation, sorption, bioaccumulation and plant or animal metabolism. Liming of soils also frequently induces zinc deficiency by increasing zinc sorption. Organic compounds tend to be undergo sorption due to hydrophobic expulsion from the surrounding water. For water sorption isotherms, water relative vapor pressure is more commonly expressed as relative humidity. Chromium(III) phosphate is also used to catalyze cation exchange in sorption reactions. This enables the determination of sorption selectivities in gaseous and liquid phase. This is done by using sorption where suspended solids are removed by sedimentation. Liming of soils frequently relieves Mo deficiency by decreasing Mo sorption. Degradation and sorption are both factors which influence the persistence of pesticides in soil.