Applied Microbiology

Biogeochemical Cycles

Biogeochemical cycles involve the fluxes of chemical elements among different parts of the Earth: from living to non-living, from atmosphere to land to sea, and from soils to plants. They are called “cycles” because matter is always conserved and because elements move to and from major pools via a variety of two-way fluxes, although some elements are stored in locations or in forms that are differentially accessible to living things. Human activities have mobilized Earth elements and accelerated their cycles – for example, more than doubling the amount of reactive nitrogen that has been added to the biosphere since pre-industrial times., Reactive nitrogen is any nitrogen compound that is biologically, chemically, or radioactively active, like nitrous oxide and ammonia, but not nitrogen gas (N2).