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An alternative to ocean fishing is aquaculture , a method in which fish and shellfish are deliberately raised for food. There are two types of aquaculture: fish farming and fish ranching. With fish farming , the fish or shellfish (e.g. carp, catfish, oysters) are raised in closed ponds or tanks with a controlled environment. When they reach maturity they are harvested. Fish ranching is used with species such as salmon that live one part of their lives in freshwater and the other part in salt water ( anadromous species ). Salmon are raised in captivity for a few years and then released. They are harvested when they return to spawn. Some of the disadvantages of aquaculture include the need for supplying large amounts of food and water, and disposal of the large amounts of waste that are produced.

Algae into oil, bones into stones

Scientists and textbooks tend to separate biological and geological entities and processes, but the complex cycling of matter on Earth actually blurs those categories. Indeed, some of our most important energy and mineral resources have biological origins. As a consequence, the location and size of these resources depends upon the distribution and productivity of ancient habitats.


Petroleum is a generic term for oil and natural gas, and their products. Petroleum doesn’t look organic, but it is derived from the remains of countless marine organisms. It begins with blooms of microscopic algae and other plankton in oceans and large lakes. These organisms sink when they die, and if the seafloor or lakebed they land on has low oxygen and high sedimentation, they can be buried in mud before they decompose. At depth and over time, heat and pressure begin to convert the organic molecules into hydrocarbons. The hydrocarbons begin to liquefy into oil at 50-60° C, and vaporize into methane at 100° C. If the temperature exceeds 200° C, they break down and disappear.

Where petroleum is abundant, it can be pumped from below ground and refined into fuels such as gasoline, propane, jet fuel, and heating oil, and into tar and asphalt. Petroleum is also a component of plastics, dyes, synthetic fibers, fertilizers, compact discs, cosmetics, and explosives.

Petroleum is extremely useful, but it is unevenly distributed around the world, and reserves are being depleted rapidly. Petroleum formation is a complex process that requires just the right biological conditions to produce sufficient plankton, and just the right geologic conditions to preserve and cook the organic matter. The entire sequence takes a million years or more. Because many countries, like the United States, have very limited deposits, and because all petroleum reserves are being drained rapidly, conservation and alternatives are gaining importance. For instance, worn highway asphalt is now being reprocessed and replaced rather than discarded. Plastic recycling is becoming more widespread. Wind, solar, nuclear, geothermal, and hydroelectric power is increasing.


Limestone is a type of rock made of calcium carbonate. Although few things seem less life-like than rocks, most limestone is actually biogenic, formed from the shells and skeletons and excretions of marine invertebrates. In the shallows around tropical islands and continents, warm clear water, strong sunlight, and abundant nutrients allow mollusks, crustaceans, and plankton to flourish. When these creatures die or molt, their hard parts fall to the sea floor. As the remains pile up, the weight of the overlying debris compacts the deepest layers. Cements precipitate out of groundwater, fusing the individual fragments into solid rock. Some limestone goes no further, so that the component shells remain distinct and clearly visible. In other limestone, subject to more intense heat and pressure, the organic material is recrystallized into a featureless mass.

Limestone is widely used in industrial processes. Crushed limestone is a component of cement, paper, plastic, and paint, and is used to adjust the pH of soil and water. Whole limestone that retains visible shell material is used for decorative stonework. Common blackboard chalk is a limestone made from microscopic skeletons.

Limestone is extremely abundant, making up about 10-15% of all sedimentary rocks on Earth, so that even though it is heavily used, its reserve are not being significantly depleted.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Ap environmental science. OpenStax CNX. Sep 25, 2009 Download for free at http://cnx.org/content/col10548/1.2
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