Water is one of the key ingredient to life on Earth. It composed about 75% of the planet. Water cycle
describes the movement of water on, above and below the surface of the Earth-atmosphere system. It
starts with evaporation. Evaporation comes from the ocean storage or any other reservoir with liquid
water including oceans, rivers, lakes and streams, and transpiration from plants and its evaporation in its
parts such as leaves, stems and flowers. Water on the surface of oceans and freshwater bodies when
warmed by the sun will form vapor. Vapor and air when combined will eventually form into a cloud
wherein condensation takes place. Through the process of condensation, clouds will accumulate a
certain amount of water. As the clouds reach it capacity or when it cannot hold the water anymore, it
tends to give off. By condensation, water vapor in the atmosphere is released to form precipitation.
With the presence of gravity, it influences the rain clouds to give off its liquid water. Precipitation to the
land flows into rivers, streams and lakes. Surface runoff is precipitation runoff over the landscape.
Impervious areas cause excessive runoff, replenishing groundwater as well as surface water as it
percolates into an aquifer or moves to different freshwater bodies. Some of it will flow into the root
system of plants. When the soil is saturated and cannot hold the water anymore, it will flow according to
terrain then this is the time when runoff is formed. Most precipitation lands in the oceans while some of
it seeps into the soil where it is held underground and undergo in the process of infiltration and
percolation as groundwater which will move to the ocean storage. Then, the cycle repeats itself.
Human activities and interventions highly affect the water cycle. We tend to alter the cycle by
withdrawing large amounts of freshwater from the ground causing salt water to contaminate reservoir.
For example, there are various aquifers on a certain area and people will built a deep well in order to
pull out the water off the ground to use in their daily lives. In a matter of time the water in the aquifer
will be less than the surface it holds and will eventually affect the groundwater movement. Another
human intervention is the vegetation clearing which may cause soil erosion that may clogs streams. Due
to urbanization, we transform one place into subdivisions and establishments for economic growth.
Clearing vegetation that holds the soil can lead to soil erosion, Soil erosion can send soil-loaded water
down streams which may create heavy layers of sediments that prevent bodies of water from flowing
smoothly which will lead to flooding and destroying of houses. Human can also affect the water cycle
through cloud seeding. Cloud seeding may cause water to ultimately absorbed into soil, reducing water
vapor concentration on land. The most abundant human activity is polluting surface and underground
water. There are increased use of toxic chemicals in the agriculture, automotive and manufacturing as
well as the runoff from chemical fertilizers and pesticides pollutes our surface water and contaminate
ground soil.
Carbon is the foundation of all life on Earth. Carbon is a key ingredient in the food that we intake and
sustain us. It contributes in regulating the Earth's temperature and it also provides a major source of
energy to fuel our global economy. Plants consume energy from the sun in order to make food through
photosynthesis. Carbon dioxide in the atmosphere are being process by photosynthesis. Then, the plants
will produce products such as oxygen. Plants will be then consumed by the primary consumers which
are the animals and transform the energy into carbohydrates. Plants and animals use the carbohydrates
through a process called respiration, wherein it releases the energy contained and changes
carbohydrate back to the atmosphere. In a matter of time, the plant or animal will die and eventually
upon decomposing will become fossil fuels (with the help of decomposers). These fossil fuels are then
used for man-mad activities, which pumps more carbon back to the atmosphere.
The atmosphere is where the accumulation of carbon dioxide for it to be used by organisms in abiotic
community. In the hydrosphere phase, the carbon dioxide is being diffuse by plants and algae in the
oceans or other freshwater bodies. They consumed dissolved carbon dioxide that is available in the
atmosphere and will then consumed by the primary consumers underwater such as fishes and
predators. Even though they are underwater, they continue to respirate. Eventually, the consumers will
die and become carbonates in the sediment.
Human activities have greatly increased carbon dioxide levels in the atmosphere. Altered carbon cycle
combined with climate change increase vulnerability of human health. The amount of carbon dioxide in
the atmosphere is rapidly rising. Fossil fuel burning, clearing vegetation and even just breathing
contribute in the excess carbon dioxide in the atmosphere. Due to combustion, factories emit smoked
containing different kind of compounds such as sulfur dioxide and carbon dioxide. Trees and forests
balance the amount of carbon in the atmosphere. Changes in carbon cycle due to deforestation and
industrialization have contributed in causing air pollution, global warming and other greenhouse gases
problems.
Nitrogen is the most abundant element in our atmosphere. In fact, nitrogen makes up about 75% of the
air. It is an essential to life since it is a building block of DNA and is vital to plant growth. Since there are
a lot of nitrogen in the atmosphere, nitrogen-fixing bacteria through the process of nitrogen fixation
takes nitrogen from the air and fixes it into a usable form. Then, a host of soil bacteria participate in
turning ammonia into nitrate which can be used by animal and plants. Through the process of
assimilation, plants absorb the nitrogen through their roots. Animals that will consume the plants are
then able to use these nutrients in their own. Eventually, animals and plants will die. A process called
ammonification will take place. During the process, these decomposers break down nutrients into
nitrates and ammonia and then release those compounds back to the soil. Alternatively, the ammonium
may be converted back into the atmosphere through the process of denitrification.
Human interventions greatly affect the nitrogen cycle by adding gases to atmosphere that contribute to
acid rain. The exhaust from cars, trucks and buses as well as the burning of fossil fuels releases nitrogen
oxides into the air which can cause acid rain. Another human intervention that influences the cycle is the
adding of nitrous oxide to the atmosphere through farming practices which can warm the atmosphere
and deplete ozone. Foe example: in agricultural system, the use of fertilizers is crucial in production but
increasing use is leaking nitrous oxide, an ozone-deteriorating gas into the atmosphere. Nitrogen oxide
emissions would be the largest ozone depleting gas emission.
Contaminating groundwater from nitrate ions in inorganic fertilizers also alter the nitrogen cycle. The
process of making synthetic fertilizers for agriculture are used extensively to increase plant production
but unused nitrogen in the form of nitrate can leach out of the soil and enter streams and rivers and
ultimately make its way to our potable water.
Phosphorus which cycle primarily through the terrestrial and aquatic environments, is one of the most
important elements that influence the growth of plants. It is in the rocks where the phosphorus cycle
begins. As it rains, phosphates are removed from the rocks through the process of weathering and
distributed to both soils and water. It is then taken up by autotrophs and passed through the food web
(both land and marine). Dissolved phosphate can runoff directly into streams and then become part of
the ocean floor and lake bottoms. They form new sedimentary layers. After some time, the excretion by
animals (both land or ocean) and the decomposition of both animals and plants release phosphates on
land or in water. Conversion of sediments into phosphate rocks is a very slow process. Then, the cycle
repeats.
Humans have greatly influenced the phosphorus cycle. It has been mined, converted into fertilizers and
transported around the world. Humans alter the phosphorus cycle by removing amounts of phosphate
from the earth to make fertilizers. Fertilizers carried in runoff may cause excessive growth of algae or
other microbes that were limited by nitrogen or phosphorus (eutrophication). Eutrophication in
waterways make water take or smell bad or produce toxic compounds and elements. Another human
intervention is the reduction of phosphorus in tropical soils by clearing forests. When trees are
removed, soil levels of phosphorus are diminished greatly and this nutrient is vital for plant growth.
People also add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.
Human activities serve to harm aquatic systems, whenever excess amounts of phosphorus are leached
into the water. Runoff from agricultural fields and animal feces extends to the surface of water which
can lead to a decrease in the available oxygen, resulting in suffocation of fish and other animals.
Sulfur cycle is the collection of processes by which sulfur moves between rocks, waterways and other
living systems. Sulfur is a vital component in various proteins and other biochemical. It has a significant
presence in soil, water and the atmosphere.
There are a variety of sources that emits sulfur directly into the atmosphere including volcanic eruptions
and burning of coals from power plants and industries. Volcanic eruptions releases hydrogen sulfide and
then combined with oxygen which resulted to sulfur dioxide, a gas that is toxic to the environment.
Then, the sulfur dioxide when contaminates with water will be converted into sulfuric acid. The sulfuric
acid made contact with ammonia will form ammonium sulfate will by then transform acidic fog and
precipitation. Sulfur settles back to into the Earth or comes down through precipitation or acid rain.
Then, the sulfate is taken up by plants and other organisms and is converted into organic forms by then
is consumed by animals through foods they eat which transfer the sulfur into a food chain. Eventually,
the animals and plants will die and upon decomposing through the help of decomposers the decaying
matter will give off metallic sulfide deposits. A continuous loss of sulfur from terrestrial ecosystem
runoff occurs through drainage into water bodies. Within the ocean, a portion of sulfur is release in the
environment through dimethyl sulfide then when combined with the atmosphere will turn into sulfur
dioxide and the cycle repeats itself.
Human activities have played a major role in altering the balance of global sulfur cycle. This is cause by
burning of coal, oil and fossil fuels, processing of metals by power plants and mining which leads to
erosion. Human intervention such as burning coal and oil have greatly influence the sulfur cycle.
Emissions from industries resulted in a reaction of chemicals in the atmosphere that turns the sulfate
salts into acid rains which is corrosive and will the damage the natural and man-made environment.
Also, the refining sulfur containing petroleum and the conversion of sulfur-containing metallic ores into
free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment affect the cycle.