M.Sc 2nd semster

1. BIOGEOCHEMICAL CYCLE
SUBMITTED BY
BHIMSEN
M.Sc 2nd Semester
ROLL NO. 11

2. The term biogeochemical tells us that Biological, Geological &
Chemical factors are involved.
In earth science, a biogeochemical cycle is a pathway by which a
chemical substances moves through both Biotic(Biosphere) &
Abiotic(Lithosphere, Atmosphere & Hydrosphere) compartments of earth.
A cycle is a series of change which comes back to the starting point &
which can be repeated.
INTRODUCTION

3. – “ More or less circular pathways, through which the
chemical elements, including all the essential elements of
the protoplasm, circulate in the biosphere from environment
to organisms and back to the environment, are known as the
Biogeochemical cycle”.
 Biogeochemical cycles always involve Hot equilibrium states:
A balance in the cycling of the elements between
compartments.
 As biogeochemical cycles describe the movements of
substances on the entire globe, the study of these is inherently
multidisciplinary.
DEFINATION

4. Macronutrients: required in relatively large
amounts
 “Big six": Carbon , Hydrogen , Oxygen , Nitrogen,
Phosphorous.
other Macronutrients:
 Sulfur, Potassium , Calcium , Iron , Magnesium
 Micronutrients: required in very small amounts,
(but still necessary)
 Boron
Copper
Molybdenum
CYCLING ELEMENTS

5. TYPE OF BIOGEOCHEMICAL CYCLE
Biogeochemical cycles can be
classed as;
GASEOUS CYCLE – The term
gaseous cycle refers to the
transformation of gases
between various biogeochemical
reservoirs; Hydrosphere,
Atmosphere & Biosphere
Important gaseous cycles are;
a) NITROGEN CYCLE
b) OXYGEN CYCLE
c) CARBON CYCLE
d) WATER CYCLE

6. Sedimentary cycles include the
leaching of minerals & salt’s from
the earth’s crust, which the settle as
sediment or rock before the cycle
repeats. Sedimentary cycle includes;
a) PHOSPHORUS CYCLE
b) SULFUR CYCLE
c) IRON CYCLE
d) CALCIUM CYCLE
 Sedimentary cycles vary from one
elements to another, but each cycle
consist fundamentally of a solution
phase & a sediment phase.
SEDIMENTARY CYCLE
LITHOSPHERE

7.  The majority of earth’s atmosphere is Nitrogen(78%).
However, Atmospheric N2 has limited availability for
biological use, and this form is relatively nonreactive and
unusable by plants.
Nitrogen availability can affect the rate of key ecosystem
processes including primary production and decomposition
 The Nitrogen(N2) cycle is the process by which N2 is
converted between its various chemical forms.
 This transformation can be carried out through both
biological & physical processes.
NITROGEN CYCLE

9. The nitrogen cycle processes
The processes involved in a complete nitrogen
cycle are:
Nitrogen fixation:
Atmospheric nitrogen is converted into the
usable form by lightning strikes or symbiotic
bacteria which are known as Diazotrophs. These
bacteria consist of a nitrogenase enzyme which
has the capability to combine gaseous nitrogen
with hydrogen to form ammonia.

11. Ammonification
When plants or animal die organic nitrogen is
again released back into the soil. Bacteria or fungi
present in the soil convert them back into
ammonium. This process is also called as
mineralization.
Assimilation
Primary producers take in this gas from the soil
with the help of their roots in the form of amino
acids, nitrite ions, nitrate ions or ammonium ions.
This way it enters the food cycle when the
consumers eat the plants.

12. Nitrification

13.  In this process, the ammonia is converted into
nitrate by the presence of bacteria in the soil.
Ammonia is oxidized to form nitrites by bacteria
such as Nitrosomonas species.
 Nitrates are converted into nitrates by Nitrobacter.
 This conversion is very important as ammonia gas
is toxic for plants.
Nitrification

14. Denitrification
In order to complete the nitrogen cycle, the nitrites
are reduced back to inert nitrogen gas in this process.
This is done by bacterial species such as Clostridium
and Pseudomonas in the absence of oxygen.
To learn more about the nitrogen cycle, visit BYJU’S.

15. The phosphorus cycle is the slowest Biogeochemical cycle
that describes the movements of phosphorus(P) through
the Lithosphere, Hydrosphere & Biosphere.
Unlike many other biogeochemical cycles, the atmosphere
does not play a significant role in the movements of
phosphorus.
It is an essential nutrient for plants and animals.
 It is a part of DNA-molecules and RNA-molecules,
molecules that store energy (ATP and ADP)
 It is also a building block of certain parts of the human
and animal body, such as the bones and teeth.
Phosphorus Cycle

17. Ecological Function
Phosphorus is an essential nutrient for
plants and animals.
Limiting nutrient for aquatic
organisms.
Forms parts of important lifesustaining
molecules that are very common in the
biosphere.

18. Biological Function
The primary biological importance of
phosphates is as a component of nucleotides,
which serve as energy storage within cells
(ATP) or when linked together, form the
nucleic acids DNA and RNA..

19.  Ecology and Environment – P. D. SHARMA
Biogeochemical cycle – Wikipedia, the free
encyclopedia.
REFERENCE