Biogeochemical Cycle in environment. Various Forms of Nitrogen in our ecosystem. Microbes plays important role in nitrogen cycle.

1. GOVT.SCIENCE (AUTO.) COLLEGE
JABALPUR
SESSION : - 2018 - 19
SUBJECT:- ENVIRONMENTAL CHEMISTRY
SUBMITTED TO : -
DR.
SHIKHA SAXENA
SUBMITTED BY : -
HIMANSHU ASATI
M.Sc. - 4th SEM
Sr. No. - 11
TOPIC - NITROGEN CYCLE

2. INTRODUCTION
• The nitrogen cycle is a biogeochemical cycle.
• N itrogen is converted into multiple chemical forms as it
c i r c u l a t e s among the atmosphere, terrestrial and marine
environment.
• Nitrogen availability can effect rate of key ecosystem
process, primary production and decomposition.
• Alteration in global nitrogen cycle has been observed
• Fossil fuel combustion, use of artificial nitrogen
fertilizers and release of nitrogen in waste water.

3. STEPS OF NITROGEN CYCLE
1) Nitrogen fixation
3) Ammonification
2) Assimilation
4) Nitrification
5) Denitrification

5. • Conversion of nitrogen to nitrates and nitrites
through atmosphere, industrial and biological
Process is called as nitrogen fixation.
• But most fixation is done by free-living or
symbiotic bacteria known as Diazotrophs.
• These bacteria have the nitrogenase enzyme.
N2
Nitrogen
3H2
2NH3
1 NITROGEN FIXATION
Ammonia

6. Atmospheric Industrial

7. • the incorporation of inorganic nitrogen
compounds into organic molecules.
• Nitrates and ammonia are assimilated
or Incorporated into specific tissue.
Nitrogen is assimilated in the f o rm
ammonium ions directly from roots.
2 ASSIMILATION

9. • The remains of all living thing and their waste products
are decomposed by microorganisms in the process of
ammonification which yields ammonia from organic nitrogen.
• Ammonia can leave the soil or be converted into other
nitrogen compounds depending on part of soil condition.
CH3CHNH2COOH +1/2O2
Alanine
Alanine
CH3COCOOH + NH3Deaminase
Pyruvic acid Ammonia
3 AMMONIFICATION
NH3 NH4+
Ammonia Ammonium

11. • The conversion of ammonium to nitrate is performed
mainly by the Nitrifying bacteria.
• In the primary stage of nitrification, the oxidation of
ammonium to nitrite is performed by Nitrosomonas sps.
which further converts in to nitrates.
• Other bacterial species such as Nitrobacter are
responsible for the oxidation of the nitrities to nitrates.
• Ammonia gas is toxic to plants.
4 NITRIFICATION

12. NH NO2
NO33

13. • Denitrification is the reduction of nitrates back
into nitrogen gas (N2), completing the nitrogen cycle.
• This process is performed by bacterial species
such as Pseudomonas and Clostridium in anaerobic
conditions.
• They use the nitrate as an electron acceptor in
the place of oxygen during respiration.
• Denitrification occurs in anaerobic conditions.
5 DENITRIFICATION

15. FORMS OF NITROGEN
• It is in the form of dinitrogen(N2) gas.
• Organic form of nitrogen make up a very h i g h
percentage of the total nitrogen.
• Plants are able to use only very specific
inorganic forms of nitrogen.
• It is present in the form of organic nitrogen,
ammonia, a m monium, nitrite, nitrate,
nitrous oxide, nitric oxide or inorganic nitrogen.

16. MICROBES IN NITROGEN CYCLE
1) Nitrogen fixation through Nitrogenase
symbiotic relationship.
2) bacteria (Deaminase) break down proteins
through t h e process by decay.
3) Nitrosomonas and Nitrobacter help in
nitrification.
4) Pseudomonas/clostridium help in
denitrification.

17. THANK YOU