BIOGEOCHEMICAL CYCLE CONCEPT
Everything on earth, both living and inanimate objects, is composed of matter.
This material is composed of, among others: carbon (C), oxygen (O), nitrogen (N),
hydrogen (H), sulfur or sulfur (S) and phosphorus (P). These chemical elements are
utilized by producers to form organic matter with the help of solar energy or energy
derived from chemical reactions. The organic matter produced is a source for organisms.
The process of eating or being eaten in the food chain results in the flow of matter from
other chains. Even though the beings in a chain of food are dead, the flow of matter
continues. Because the living thing that died was decomposed by the decomposer whose
death will enter the next food chain again. So that it continues so that it forms a flow of
energy and a mater cycle
A. DEFINITION OF BIOGEOCHEMICAL CYCLE
Biogeochemistry is a continuous exchange or change, between living and non-
living components of the biosphere. In an ecosystem, matter at every trophic point does
not disappear. Materials in the form of elements that make up organic matter are
recycled. These elements enter the biotic components through air, soil, and water. The
recycling of these materials involves living things and rocks (geophysical) so it is called
biogeochemical cycling
The function of the biogeochemical cycle is as a material silkus involving all
chemical elements that have been used by all those on earth, both biotic and abiotic
components, so that survival on earth is maintained
1. Water Cycle
Water in the atmosphere is in the form of water vapor. Water vapor comes
from water on land and sea that evaporates due to the heat of sunlight. Most of
the water vapor in the atmosphere comes from the ocean because the ocean
reaches 3/4 of the earth's surface area. Water vapor in the atmosphere condenses
into clouds that descend on land and sea in the form of rain. Rainwater on land
enters the soil to form surface water and groundwater.
Terrestrial plants absorb the water present in the soil. In the body of a
plant, water flows through a vessel. Then through transpiration water vapor is
released by plants into the atmosphere. Transpiration by plants covers 90% of
evaporation in terrestrial ecosystems. Animals get water directly from surface
water as well as from plants and animals they eat, while humans use about a
quarter of groundwater. Some of the water comes out of the bodies of animals
and humans as urine and sweat.
Groundwater and surface water partially flow into rivers, then into lakes
and into the sea. This cycle is called the Long Cycle. Meanwhile, the cycle that
begins with the process of Transpiration and Evapotranspiration of water found
on the earth's surface, then followed by precipitation or descent of water to the
earth's surface is called the Short Cycle
2. Round Nitrogen
In nature, Nitrogen is found in the form of organic compounds such as urea,
proteins, and nucleic acids or as inorganic compounds such as ammonia, nitrites,
and nitrates
➢ First stage
The nitrogen cycle is the transfer of nitrogen from the atmosphere
into the soil. In addition to rainwater carrying a certain amount of
nitrogen, the addition of nitrogen to the soil occurs through the process of
nitrogen fixation. Nitrogen fixation can biologically be carried out by
Rhizobium bacteria that symbiosis with legumes, Azotobacter and
Clostridium bacteria. In addition, green and blue algae in water also have
the ability to fix nitrogen
➢ Second stage
The nitrate produced by biological fixation used by producers
(plants) is converted into protein molecules. Furthermore, if a plant or
animal dies, decomposing creatures remodel it into ammonia gas (NH3)
and water-soluble ammonium salt (NH4+). This process is called
ammonification. Nitrosomonas bacteria convert ammonia and
ammonium compounds into nitrates by Nitrobacter. When oxygen in the
soil is limited, nitrates are quickly transformed into nitrogen gas or
nitrogen oxides by a process called denitrification
3. Sulfur Cycle
In this cycle there are oxidation (O2) and reduction (R) events, which are
key to the exchange of available SO4 reserves with iron sulfide reserves found
in the soil as reserves
The S and N cycles are heavily influenced by the population of factory
smoke and the burning of fossil fuels. SO2 will affect photosynthesis while NO2
will affect animal respiration. Also NO2 in the presence of ultraviolet light will
react with unburned hydrocarbons (from cars) and result in a painful
photochemical haze, this is the synergistic effect of NO2, with ultraviolet light.
Sulfur is found in the form of inorganic sulfate. Sulfur is reduced by bacteria to
sulfides and is sometimes found in the form of sulfur dioxide or hydrogen
sulfide. This hydrogen sulfide is often deadly to living things in the waters and
is generally produced from the decomposition of dead organic matter. Plants
absorb sulfur in the form of sulfate (SO4).
The transfer of sulfate occurs through the process of the food chain, then
all living things die and will be decomposed of their organic components by
bacteria. Several types of bacteria are involved in the sulfur cycle, including
Desulfomaculum and Desulfibrio which will reduce sulfate to sulfide in the form
of hydrogen sulfide (H2S). Then H2S is used anaerobic photoautotrophic
bacteria such as Chromatium and releases sulfur and oxygen. Sulfur is oxidized
to sulfate by chemolithotrophic bacteria such as Thiobacillus.
4. Posfor Cycle
Phosphorus is a rare element compared to nitrogen.in waters P:N2 = 1:23,
tillage in the USA for 50 years reduced the phosphorus content in the form of P2
O5 by 36%
Phosphorus is an important element in life because all living things need
phosphorus in the form of ATP (Adenosine Triphosphate), as an energy source
for cell metabolism. Phosphorus is found in nature in the form of phosphate ions
(PO43-). Phosphate ions are found in rocks. The existence of erosion and
weathering events causes phosphate to be carried to rivers and the sea to form
sediments. The movement of the earth's bottom causes phosphate-containing
sediment to appear to the surface. On land plants take phosphate dissolved in
groundwater
Herbivores get phosphate from the plants they eat and carnivores get
phosphate from the herbivores they eat. All animals excrete phosphate through
urine and feces. Bacteria and fungi decompose inorganic materials in the soil and
then release phosphorus that is then taken up by plants
B. BASIC TYPES AND PATTERNS OF BIOGEOCHEMICAL CYCLES
Chemical elements including protoplasmic elements tend to form cycles
in nature with a special pattern: environment =>organism=> environment, and
this cycle is known as the biogeochemical cycle. The flow of elements and
compounds necessary for life is simply called the food cycle
For each cycle, a compartment (pool) will be found, namely:
a. Reserve pool: large and slow-moving, generally composed of non-biological
components
b. The exchange pool or circulation pool is a smaller, but more active part that
moves back and forth quickly between organisms and the environment
In terms of the biosphere as a whole, biogeochemical cycles consist of two
basic groups:
a. type of gas in which the reserve is diathmospheric or hydrosphere
b. The type of sediment where the reserves are in the earth's crust
The gaseous type cycle is more perfect than the sediment type because the
elements P and Fe tend to be disturbed, both elements are abundant in the pool.
Humans can affect the elemental cycle because it can change the perfect cycle
(cyclic) to an imperfect cycle (acyclic), for example, the mining of element P
will interfere with the cycle of unwise use of fertilizer will result in
eutrophication and can reduce water quality.
The purpose of protecting natural resources is to make the acyclic process
into a cyclic. Water recycling is a good place to start the improvement of the
elemental cycle because water recycling will be able to control the nutrients in
the water
C. QUANTITATIVE ASSESSMENT OF BIOGEOCHEMICAL CYCLES
The speed of exchange or transfer of elements from one place to another
is more important in determining the structure and function of the ecosystem
from the amount that exists in a place at a time To understand the role of the
material cycle, the speed of the circulation of substances must be quantitative.
The cycle speed of the substance can be determined by using tracers and
monitoring and remote sensing techniques.
The use of isotopes for tracers, for example, using P32 and Ca45,
generally P does not move smoothly and evenly from the organism. Some P will
be bound to organisms or rocks, the speed of P uptake by organisms is influenced
by temperature, season and activity of organisms, for example during the growth
period P uptake will be fast
Fertilization of ponds with P fertilizer irregularly can affect this productivity
because certain organisms have been adapted to the needs of P in a typical way.
Continuous overfertilization can result in a change in the type of Botryococcus
braunii thrives at a concentration of P 89 mg/m3 while Nitzchia palae thrives at
a concentration of P 18 mg/m3.An increase in P from 18 mg/m3 to 89 mg/m3
means the replacement of Botryococcus with Nitzchia.
1. Recycling Pathway
The two nutrient recycling pathways in the food chain are as follows:
a. Return through the animal excretory route.
b. Return through the decomposition pathway of microorganisms and
detritus.
Both pathways function within the ecosystem. Recycling pathway 1 is
expected to be dominant on plankton and other communities where the main
energy flow through the grassland food chain. In contrast, the 2nd circulation
pathway is dominant in grasslands, temperate climate forests and other
communities, where energy flow pathways pass through the detritus food
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chain. Pathway 3 involves direct plant-to-plant circulation through symbiotic
microorganisms.
