Biogeochemical cycles are natural processes that involve the movement of essential elements through living organisms, the atmosphere, water, and soil. Here are five key characteristics of biogeochemical cycles:
Maintains a constant element amount in Earth’s closed system.
Involves exchange between living organisms and the geosphere, atmosphere, hydrosphere.
Elements move through the atmosphere, lithosphere, hydrosphere, and biosphere.
Often driven by solar energy, influencing processes like evaporation and photosynthesis.
Essential elements like carbon, nitrogen, and phosphorus cycle, sustaining life.
The carbon-oxygen cycle, also known as the carbon cycle, is a natural process that involves the exchange of carbon dioxide between living organisms, the atmosphere, and the Earth’s surface. It begins with photosynthesis in plants, where they absorb carbon dioxide and release oxygen. During respiration and combustion, organisms release carbon dioxide back into the atmosphere, completing the cycle.
The nitrogen cycle is a natural process that involves the conversion of nitrogen from the atmosphere into forms that living organisms can use and vice versa. It includes nitrogen fixation by bacteria, nitrification, denitrification, and assimilation by plants and animals.
Nitrogen fixation is the conversion of atmospheric nitrogen gas (N2) into ammonia (NH3). This process is essential for life on Earth, as all living organisms need nitrogen to build proteins and other essential molecules. Nitrogen fixation is carried out by a diverse group of microorganisms, including bacteria and archaea.
Nitrification is the conversion of ammonia into nitrates (NO3-). This process is carried out by two groups of bacteria: Nitrosomonas and Nitrobacter. Nitrosomonas convert ammonia to nitrites (NO2-), and Nitrobacter convert nitrites to nitrates. Nitrates are the most readily available form of nitrogen for plant uptake.
Denitrification is the conversion of nitrates back into nitrogen gas. This process is carried out by a diverse group of bacteria and archaea. Denitrification occurs in anaerobic environments, such as waterlogged soils and the deep ocean.