Biological cycles really helpful for all students specially for botany

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BIOGEOCHEMICAL
CYCLES
ALI HASSAN VIRK

2. INTRODUCTION:
A biogeochemical cycle is defined as the movement of elements, like those
mentioned just a moment ago, through organisms and the environment. A way to
remember this is to break apart the word 'biogeochemical' into pieces. The first
part of the word, bio, involves biological organisms, like bacteria, plants, and
animals. The next part of the word, geo, involves geological processes, like
weathering of rocks. The last part of the word indicates chemical processes, such
as the formation of molecules.
Not all elements have the same biogeochemical cycle. Some biogeochemical
cycles are simple, while others are quite complex. Let's take a look at the simple
biogeochemical cycle phosphorus takes. Phosphorus is trapped in sedimentary
rocks. When exposed to water, phosphorus can be released in the form of
phosphate ions. When phosphate ions wash away, they soak into the soil. Plants
are starving for phosphate, so their roots gobble it up and incorporate it into their
tissues.
When an animal eats the plant, the phosphate transfers to the animal's tissue.
When the animal dies, decomposing bacteria cycle the phosphate back into the
soil. The phosphate can either be gobbled up by plants again or stay in the soil. If
the soil conditions are right, any phosphate remaining in the soil can slowly
reform back into rocks. You help recycle phosphorus, too! For example, a plant
like spinach is full of elements like phosphorus. When you eat it, your body
incorporates this element to form strong bones and teeth.
MAJOR BIOLOGICAL CYCLES:
Some of the major biogeochemical cycles are as follows: (1) Water
Cycle or Hydrologic Cycle (2) Carbon-Cycle (3) Nitrogen Cycle (4)
Oxygen Cycle.
The producers of an ecosystem take up several basic inorganic nutrients
from their non-living environment. These materials get transformed into
the bio mass of the producers. Then they are utilised by the consumer
population and are ultimately returned to the environment with the help
of the reducers or decomposers

3. Common Biogeochemical Cycles are:
In this cycle, Water from the transpiring plants, oceans, rivers and
lakes evaporates into the atmosphere. These water vapors
subsequently cool and condense to form clouds and water. Water
returns to the earth as rain and snow.

4. (2) Carbon-Cycle:
Most of the carbon dioxide enters the living world through
photosynthesis. The organic compounds synthesized are passed from
the producers (green plants) to the consumers (herbivores and
carnivores). During respiration, plants and animals release carbon
back to the surrounding medium as carbon-dioxide. The dead bodies
of plants and animals as well as the body wastes, which accumulate
carbon compounds, are decomposed by micro-organisms to release
carbon dioxide. Carbon is also recycled during burning of fossil fuels.

5. (3) Nitrogen Cycle:
Nitrogen of the atmosphere is in the elemental form and cannot be
used as such by living organisms. It has to be “fixed” i.e. combined
with other elements such as hydrogen, carbon or oxygen to become
usable for the green plants.
Nitrogen is continuously entering into the air by the action of
denitrifying bacteria and returning to the cycle through the action of
lightening and electrification.
(4) Oxygen Cycle:
Oxygen required for respiration in plants and animals enters the body
directly from the surrounding medium (air or water).
Oxygen returns to the surroundings in the form of Carbon-dioxide or
water. It also enters the plant body as carbon dioxide and water during
photosynthesis and is released in the form of molecular oxygen as a
by-product in the same process for use in respiration. Thus, the cycle
is completed.

6. Ecosystem is a functional system which in a balanced condition, is
self-sufficient and self-regulating. A balanced ecosystem is essential
for the survival of all living organisms. Organisms at each trophic level
in a food chain are preyed upon by an organism at the next higher
trophic level, for example, herbivores feed on the plants and are in
turn eaten by the predator.If the numbers of herbivores increase in a
specific area, there will be a rapid destruction of the vegetation, which
in turn will eventually destroy the herbivores (due to lack of food). So,
the population of herbivores is kept in check by predators such as lions
and tigers.
IMPORTANT CYCLES AND DIAGRAMS:

9. Biogeochemical cycles can be classed as gaseous, in which the reservoir is the air
or the oceans (via evaporation), and sedimentary, in which the reservoir is Earth’s
crust. Gaseous cycles include those of nitrogen, oxygen, carbon, and water;
sedimentary cycles include those of iron, calcium, phosphorus, sulfur, and other
more-earthbound elements.
Gaseous cycles tend to move more rapidly than do sedimentary ones and to
adjust more readily to changes in the biosphere because of the large atmospheric
reservoir. Local accumulations of carbon dioxide (CO2), for example, are soon
dissipated by winds or taken up by plants. Extraordinary disturbances (such as
global warming) and more-frequent local disturbances (such as wildfires and
storm-driven events) can, however, seriously affect the capacity for self-
adjustment.

10. Impacts on human health: nitrate accumulation in drinking water
Leakage of Nr (reactive nitrogen) from human activities can cause nitrate
accumulation in the natural water environment, which can create harmful
impacts on human health. Excessive use of N-fertilizer in agriculture has been one
of the major sources of nitrate pollution in groundwater and surface water. Due
to its high solubility and low retention by soil, nitrate can easily escape from the
subsoil layer to the groundwater, causing nitrate pollution. Some other non-point
sources for nitrate pollution in groundwater are originated from livestock feeding,
animal and human contamination and municipal and industrial waste. Since
groundwater often serves as the primary domestic water supply, nitrate pollution
can be extended from groundwater to surface and drinking water in the process
of potable water production, especially for small community water supplies,
where poorly regulated and unsanitary waters are used.

11. Conclusion:
AT the end with this knowledge, the words “biogeochemical cycle” can be easily
broken down. “Bio-” is the biotic system, “geo-” is the geological component, and
“chemical” is the elements which are moved through a “cycle”. At particular
stages of their cycling, any of the elements may be stored and accumulated within
a particular place for a long period time (e.g. within a rocky substrate, or in the
atmosphere). These places are called “sinks” or “reservoirs”. A “source” is
anything from which an element is output, for example volcanoes give off large
amounts of carbon in the form of CO2, while human waste is a source for
nitrogen, sulfur and phosphorous. The biosphere is a term which can be used to
describe the system that contains all living organisms, including plants, animals
and bacteria, as well as their interactions among and between each other, and
their interactions with the Earth’s abiotic systems. The biosphere is sometimes
called the ecosphere, and can be defined as the sum of all ecosystems. In other
words, the Earth only receives energy from the sun, which is given off as heat,
whilst all other chemical elements remain within a closed system. The main
chemical elements that are cycled are: carbon (C), hydrogen (H), nitrogen (N),
oxygen (O), phosphorous (P) and sulfur (S). These are the building blocks of life,
and are used for essential processes, such as metabolism, the formation of amino
acids, cell respiration and the building of tissues. These fundamental elements can
be easily remembered with the acronym CHNOPS.