ABSTRACT
Molecules, ions, and solid particles in the environment undergo physical and chemical transfer processes which distribute mass within or among phases; for example, the volatilisation of a chemical from water to air, or the dissolution of calcite (CaCO3). Knowledge of the basic principles of chemistry is essential to be able to quantify these transfer processes and to assess the distribution of concentrations of chemicals in space and time and their chemical speciation . Speciation refers to the occurrence of different forms, whether chemical or physical, of an element. The speciation of an element determines its bioavailability and toxicity and controls its transport and fate in soil and water.
