BIOGEOCHEMICAL
CYCLE

Biogeochemical Cycle
Whenever some nutrient are transfer in living organism as well as
in their non-living environment that is called biogeochemical
cycle.
Bio is related to living organism geo is related to earth. Chemical
news chemical compound we can say some nutrient which are
use for plants as well as for animals which may be nitrogen,
carbon , sulpher , oxygen. And cycle is related to circulation.
Biogeochemical cycle can be present in two ways :-

I. Gaseous cycle
In gaseous cycle we will discuss about nitrogen cycle , carbon
cycle
II. Sedimentary cycle
Phosphorus cycle
Sulphur cycle

Carbon Cycle
 The carbon cycle is the process is which carbon travels from
the atmosphere into organism and the earth and then back into
the atmosphere.
 The Biological Carbon Cycle
Carbon enters all food webs, both terrestrial and aquatic through
autotrophic .
 Autorophs
captures co2 from the air water and use to wake organic
compound such as glucose.
 Heterotrophs
Humans , consume the organic molecules and the organic
carbon is passed through food chain and webs.

The geological carbon cycle
 It is longer pathway takes millions of year , carbon returned
through geological pathway.
Carbon are strode is ocean sediments soil ,rocks , fossil
fuels

What is the carbon ?
 An element : 6 protons , 6 neutrons.
 The basic of life of earth .
 Found in all earth system .
Carbon Cycle :-
The same carbon atoms are used repeatedly on earth. The cycle
between the atmosphere , hydrosphere , geosphere and biosphere.

Process that transfer carbon.
• photosynthesis
• Respiration
• Consumption
• Decomposition
• Combustion
• Weathering of rock
• Vaporization

Animal consume and release carbon
• When organism eat plants or other organism .They take in the
carbon and source of it becomes part of their own bodies.
• When they berth , They release carbon

Plants And Animals Die
• When plants and animals die , most of their bodies are decomposed
and carbon atoms are returned to the atmosphere.
• Some are not decomposed fully and end up in geosphere deposits
underground or at the bottom of ocean.

Natural Combustion
• Forest and grass fires are a natural and release carbon into
atmosphere .
• Fire return carbon to the soil.

Carbon in ocean
• Oceans store large amount of carbon
• Largest amount of carbon is exchange by carbon cycle
through the process of vaporization.
• Many animals pull carbon from water to use in the shells
etc.When these animals die, The carbon substances are
deposited at the bottom of ocean.

Carbon Cycle
Carbon in
ocean water
Carbon in
atmosphere
Carbon in
rock
Evaporation
Dissolution
Weathering
Tectonics
Plants
Soil marine
sediment
Fossil fuels
Consumption Lithification
Decomposition
Respiration

• Photosynthesis‘ gain carbon in the form of CO2 for making food .
• Cellular respiration , Combustion and erosion of limestone return.
• Carbon to the water and atmosphere of the biotic environment.

Why carbon cycle is important ?
• Through Photosynthesis and respiration , it is the way the earth
produces food and other renewable resources.
• Carbon plays central role in combustion.
• Through decomposition ,it serves as the earth’s waste disposal
system.

Why carbon is bad for humans
?
Carbon dioxide becomes a poisonous gas when there is too much of
it in the air you breath. Besides the effects it can have on the planet
and the atmosphere, carbon dioxide poisoning can lead to central
nervous system damage and respiratory deterioration in humans and
other breathing creatures.

Human impacts on the carbon cycle
 When fossils fuels are burned , co2 is released into the air ,
increasing use of fossils fuels has led to elevated levels of
atmospheric co2 .
Deforestation
 The cutting down of contributor to increasing co2 . Levels
trees and other parts of a forest ecosystem sequester
carbon and much of the carbon is release as co2. if the forest
is cleared.
 Some of the extra co2 is produced by human activities is
taken up by plants or absorbed by the ocean , but this
process is not enough . So atmospheric co2 is risen day by
day.

Nitrogen Cycle
The nitrogen cycle is the process by which nitrogen is converted
between its various chemical forms . This transformation can be carried
out through both biological and physical process.

Forms of Nitrogen
a) Organic nitrogen as -
• Ammonium (NH4-)
• Nitrite (NO2-)
• Nitrate ( NO3-)
• Nitrous Oxide (N2O)
• Nitric Oxide (NO)
b) Inorganic nitrogen as -
• Nitrogen gas (N2)

Steps
1) Nitrogen Fixation
2) Nitrogen assimilation
3) Ammonification
4) Nitrification
5) Denitrification
6) Sedimentation

1) Nitrogen fixation
Conversion of free nitrogen into nitrogenous compounds.
a) Biological nitrogen fixation
Symbiotic bacteria , blue – green algae can fix nitrogen to the soil.
E.g. – Rhizobium .
b) Non-biological nitrogen fixation
Atmospheric nitrogen combines with oxygen during lighting and
produce nitrogen oxides.
N2 + 2(O)
2NO + 2(O)
2NO
2NO2

c) Industrial nitrogen fixation
Under high pressure and temp. , hydrogen and atmospheric
nitrogen combine is the form of ammonia (NH3).

2) Nitrogen assimilation
Inorganic nitrogen in the form of nitrates , nitrites and ammonia is
absorbed by the green plants , it is converted into nitrogenous organic
compounds.
3) Ammonification
It is the process of releasing ammonium by certain micro organism
utilizing organic compounds derived from dead organic plants and
animals.

4) Nitrification
Nitrification is a process of enzymatic oxidation of a
ammonia to nitrate by certain micro organisms in soil and
ocean.
5) Denitrification
Denitrification is the reduction of nitrates back into the largely inert
nitrogen gas (N2).

6) Sedimentation
Nitrates of soil are locked up in the rock while they are washed down
to the sea or leached deeply into the earth along with water.

Nitrogen Cycle
Atmospheric
Nitrogen
Nitrogen fixing
bacteria and blue
green algae fix
nitrogen
Bactria turn
compounds of
nitrogen into
gaseous nitrogen
Lighting
fixes
Nitrogen
Bactria turn fix
nitrogen into
nitrogenous
compounds
Compounds of
nitrogen in the soil
Nitrogenous
Waste
Uptake
by
plants
Animals
eat
plants

Human impact on the
nitrogen cycle
Excessive use of fertilizers has added lots of nitrates (NO3
-1 ) to
the soil, leading to:
Eutrophication :-
 Nitrates travel in the spring runoff and cause algae to grow
rapidly in lakes and ponds.
 Bactria that decompose dead algae consume oxygen , causing
less oxygen to be available for aquatic organisms death