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By the end of this section, you will be able to:
  • Discuss the biogeochemical cycles of water, carbon, nitrogen, phosphorus, and sulfur
  • Explain how human activities have impacted these cycles and the resulting potential consequences for Earth

Energy flows directionally through ecosystems, entering as sunlight (or inorganic molecules for chemoautotrophs) and leaving as heat during the transfers between trophic levels. Rather than flowing through an ecosystem, the matter that makes up living organisms is conserved and recycled. The six most common elements associated with organic molecules—carbon, nitrogen, hydrogen, oxygen, phosphorus, and sulfur—take a variety of chemical forms and may exist for long periods in the atmosphere, on land, in water, or beneath Earth’s surface. Geologic processes, such as weathering, erosion, water drainage, and the subduction of the continental plates, all play a role in the cycling of elements on Earth. Because geology and chemistry have major roles in the study of this process, the recycling of inorganic matter between living organisms and their nonliving environment is called a biogeochemical cycle    .

Water, which contains hydrogen and oxygen, is essential to all living processes. The hydrosphere    is the area of Earth where water movement and storage occurs: as liquid water on the surface (rivers, lakes, oceans) and beneath the surface (groundwater) or ice, (polar ice caps and glaciers), and as water vapor in the atmosphere. Carbon is found in all organic macromolecules and is an important constituent of fossil fuels. Nitrogen is a major component of our nucleic acids and proteins and is critical to human agriculture. Phosphorus, a major component of nucleic acids, is one of the main ingredients (along with nitrogen) in artificial fertilizers used in agriculture, which has environmental impacts on our surface water. Sulfur, critical to the three-dimensional folding of proteins (as in disulfide binding), is released into the atmosphere by the burning of fossil fuels.

The cycling of these elements is interconnected. For example, the movement of water is critical for the leaching of nitrogen and phosphate into rivers, lakes, and oceans. The ocean is also a major reservoir for carbon. Thus, mineral nutrients are cycled, either rapidly or slowly, through the entire biosphere between the biotic and abiotic world and from one living organism to another.

Concept in action

Head to this website to learn more about biogeochemical cycles.

The water cycle

Water is essential for all living processes. The human body is more than one-half water and human cells are more than 70 percent water. Thus, most land animals need a supply of fresh water to survive. Of the stores of water on Earth, 97.5 percent is salt water ( [link] ). Of the remaining water, 99 percent is locked as underground water or ice. Thus, less than one percent of fresh water is present in lakes and rivers. Many living things are dependent on this small amount of surface fresh water supply, a lack of which can have important effects on ecosystem dynamics. Humans, of course, have developed technologies to increase water availability, such as digging wells to harvest groundwater, storing rainwater, and using desalination to obtain drinkable water from the ocean. Although this pursuit of drinkable water has been ongoing throughout human history, the supply of fresh water continues to be a major issue in modern times.

Questions & Answers

what is demand and supply
Lansana Reply
what is liquidity
VICTOR Reply
the ability to easily turn asset or investment to cash
Johnson
liquidity is refers to the ease with which an asset or security, can be converted into ready cash without affecting it's market price. example is milk and checking a account in the bank.
Gyamfua
the meaning PPP is public _private partnership and PPP in economic is purchasing power_parity.
Gyamfua
what is economy production
Miracle Reply
what is Monopoly
Miracle
what is monopoly
Aina Reply
what is the full meaning of gpa?
Eedris Reply
why the firm will be happy to make normal profit?
Anold Reply
1.to make further increase 2.to established the firm 3. to draw and attract more customers 4. to foresee the future of the firm. 5. to get goods in galore
Castino
when marginal utility is zero? what is the total utility?
Scott Reply
definition of choice?
Anick Reply
it refers to the act of selecting one alternative from the other
Donfack
State and explain three advantages and two disadvantages of capitalist economic system
Ghislain Reply
What is cross elasticity of demand
Justice Reply
Is a demand in which the of goods change over time.
Shadrick
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Shadrick
join what?
Castino
it measure the extend in which the quantity demanded of a good respond to change in price of other good.
Donfack
refers to sensitivity of quantity demanded in change of price of commodity
Daniel
meaning of PPP
OBANYI
What is balance of payments
Bah Reply
what are free good
Maillot Reply
how do you determine price change
Matri Reply
what is economics?
Yaya Reply
what is economic
Nana Reply
Economics is the study of how Individual consumer, institution and society as a whole uses its available finite resources to satisfy infinite needs and wants
Richard
Explain the following concepts using suitable exemple. 1) National budget. 2) National debt
Rosalie
Difference between extinct and extici spicies
Amanpreet Reply
While the American heart association suggests that meditation might be used in conjunction with more traditional treatments as a way to manage hypertension
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Source:  OpenStax, Environmental biology. OpenStax CNX. Aug 10, 2015 Download for free at https://legacy.cnx.org/content/col11863/1.1
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