Environmental chemistry refers to the occurrence, movements, and transformations of chemicals in the environment. Environmental chemistry deals with naturally occurring chemicals such as metals, other elements, organic chemicals, and biochemicals that are the products of biological metabolism. Environmental chemistry also deals with synthetic chemicals that have been manufactured by humans and dispersed into the environment, such as pesticides, polychlorinated biphenyls (PCBs), dioxins, furans, and many others.

The occurrence of chemicals refers to their presence and quantities in various compartments of the environment and ecosystems. For example, in a terrestrial ecosystem such as a forest, the most important compartments to consider are the mineral soil, water and air present in spaces within the soil, the above-ground atmosphere, dead biomass within the soil and lying on the ground as logs and other organic debris, and living organisms, the most abundant of which are trees. Each of these components...