biogeochemical cycle
The cycling of a chemical element through the biosphere; its pathways, storage locations, and chemical forms in living things, the atmosphere, hydrosphere, and geosphere
carbon-silicate cycle
a complex biogeochemical cycle over time scales as long as one half billion years. Included in this cycle are major geologic processes, such as weathering, transport by ground and surface waters, erosion, and deposition of crustal rocks. It is believed to
carbon cycle
cyclic movement of carbon in different chemical forms from the nonliving environment to the living environment and then back to the nonliving environment
chemical reaction
a change in which one or more substances are converted into different substances
denitrification
conversion of nitrates in the soil by bacteria into nitrogen gas
drainage basin
the area that contributes to surface runoff to a stream or river
geologic cycle
the formation and destruction of earth materials and the processes responsible for these events. The geologic cycle includes the following substances: hydrologic, tectonic, rock, and geochemical
hydrological cycle
the circulation of water from the oceans to the atmosphere and back to the oceans by way of evaporation, runoff from streams and rivers, and groundwater flow; also called the "water cycle
limiting factors
any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms
macronutrients
chemical elements that organisms need in large amounts to live, grow, or reproduce. Examples are carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, potassium, calcium, magnesium, and iron
micronutrients
chemical elements that organisms need in small or even trace amounts to live, grow, or reproduce. Examples are sodium, zinc, copper, chlorine, and iodine
missing carbon sink
substantial amounts of carbon dioxide released into the atmosphere but apparently not reabsorbed and thus remaining unaccounted for
nitrogen cycle
the transfer of nitrogen from the atmosphere to the soil, to living organisms, and back to the atmosphere
nitrogen fixation
process in which bacteria convert atmospheric nitrogen gas into nitrogen compounds plants can use to make proteins
phosphorus cycle
the movement of phosphorus atoms from rocks through the biosphere and hydrosphere and back to rocks
plate tectonics
the theory that explains how large pieces of the lithosphere, called plates, move and change shape
rock cycle
the series of processes in which a rock forms, changes from one type to another, is destroyed, and forms again by geological processes
tectonic cycle
the processes that change Earth's crust, producing external forms such as ocean basins, continents, and mountains