Skip to main content

Nitrogen Cycle

 Nitrogen occurs prominently in all the spheres of the environment. The atmosphere is 78% elemental nitrogen, N2, by volume and comprises an inexhaustible reservoir of this essential element. Nitrogen, although constituting much less of biomass than carbon or oxygenoxygen, is an essential constituent of proteins. The N2 molecule is very stable so that breaking it down into atoms that can be incorporated with inorganic and organic chemical forms of nitrogen is the limit- ing step in the nitrogen cycle. This does occur by highly energetic processes in lightning discharges that produce nitrogen oxides. Elemental nitrogen is also incorporated into chemically bound forms. or fixed by biochemical processes mediated by microorganisms. The biological nitrogen is mineral- ized to the inorganic form during the decay of biomass. Large quantities of nitrogen are fixed synthetically under high-temperature and high-pressure conditions according to the following over- all reaction:


             N2+3H2         2NH3

The production of gaseous N2 and N2O by microorganisms and the evolution of these gases to the atmosphere complete the nitrogen cycle through a process called denitrification. The nitrogen cycle is discussed from the viewpoint of microbial processes. 



Comments

Popular posts from this blog

Carbon Cycle

CARBON CYCLE: Carbon circulates through the carbon cycle. It shows that carbon may be pres- ent as gaseous atmospheric CO2 constituting a relatively small but highly significant portion of global carbon. Some of the carbon is dissolved in surface water and groundwater as HCO-3 or molecular CO2 (aq). A very large amount of carbon is present in minerals, particularly magnesium and calcium carbonates such as CaCO3. Photosynthesis fixes inorganic C as biological carbon. represented as (CH2O), which is a constituent of all life molecules. Another fraction of carbon is fixed as petroleum and natural gas, with a much larger amount as hydrocarbonaceous kerogen (the organic matter in oil shale), coal, and lignite. Manufacturing processes are used to convert hydro- carbons to xenobiotic compounds with functional groups containing halogens, oxygen, nitrogen, phosphorus, or sulfur. Although a very small amount of total environmental carbon, these com- pounds are particularly significant because of...

Chemical species

  Hello! Welcome to my blog. Today we will discuss about chemical species. lets start. If one  molecule  is identical to another, we can say they are the same chemical species. Ion: It is an atom or group of atoms having a charge on it. The charge may be positive or negative.  There are two types of ions:       Cations: An atom or group of atoms having positive charge on it is called cation. They are formed when atoms lose electron from their valance shells. Examples:   Ca 2+   Ag +    Al 3+     H 3 O +     NH 4 +     Hg 2 +2      Fe +2     Fe  +3        Anions: An atom or group of atoms having negative charge on it is called anion. They are formed by gain or addition of electron to an atom. Examples: Cl –    OH –      I –     Cr 2 O 7 -2     O -2      SO ...

Cycles of Matter

 Very much connected with environmental chemistry, cycles of matter, often based on elemental cycles, are of utmost importance in the environment. Global geochemical cycles can be regarded from the viewpoint of various reservoirs, such as oceans, sediments, and the atmosphere, connected by conduits through which matter moves continuously among the hydrosphere, atmosphere, geo- sphere, biosphere, and, increasingly, the anthrosphere. The movement of a specific kind of matter between two particular reservoirs may be reversible or irreversible. The fluxes of movement for particular kinds of matter vary greatly as do the contents of such matter in a specified reservoir. Most cycles of matter have a strong biotic component, especially through the biochemical processesof plants and microorganisms. The cycles in which organisms participate are called biogeochemical cycles, which describe the circulation of matter, particularly plant and animal nutrients, through ecosystems. Most biogeoche...