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The nitrogen cycle is an important process in the ocean as well. While the overall cycle is similar, there are different players [42] and modes of transfer for nitrogen in the ocean. Nitrogen enters the water through the precipitation, runoff, or as N 2 from the atmosphere. Nitrogen cannot be utilized by phytoplankton as N
Without supplies of fixed nitrogen entering the marine cycle, the fixed nitrogen would be used up in about 2000 years. [83] Phytoplankton need nitrogen in biologically available forms for the initial synthesis of organic matter. Ammonia and urea are released into the water by excretion from plankton.
A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle, the nitrogen cycle and the water cycle. In each cycle, the chemical element or molecule is ...
The preferred nitrogen electron acceptors in order of most to least thermodynamically favorable include nitrate (NO 3 −), nitrite (NO 2 −), nitric oxide (NO), nitrous oxide (N 2 O) finally resulting in the production of dinitrogen (N 2) completing the nitrogen cycle.
The most common denitrification process is outlined below, with the nitrogen oxides being converted back to gaseous nitrogen: 2 NO 3 − + 10 e − + 12 H + → N 2 + 6 H 2 O. The result is one molecule of nitrogen and six molecules of water. Denitrifying bacteria are a part of the N cycle, and consists of sending the N back into the atmosphere.
Reactive nitrogen can contaminate drinking water through runoff into streams, lakes, rivers, and groundwater. In the United States alone, as much as 20% of groundwater sources exceed the World Health Organization's limit of nitrate concentration in potable water.
The nitrogen cycle is one of the Earth's biogeochemical cycles. It involves the conversion of nitrogen into different chemical forms. The main processes of the nitrogen cycle are the fixation, ammonification, nitrification, and denitrification. As one of the macronutrients, nitrogen plays an important role in plant growth.
When nitrogen in the form of nitrate is in excess, it can lead to a dead zone. A dead zone is a body of water that has a depleted oxygen concentration that is low and can lead to the suffocation of animals. [4] An example of this is the dead zone located off the coast of the Mississippi River.