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Carbon Cycle/Oxygen Cycle/Phosphorus Cycle


Carbon Cycle Oxygen Cycle Phosphorus Cycle

Carbon Cycle

This cycle contains any of the natural pathways by which essential elements of living matter are circulated. Biogeochemical cycles are named for the cycling of biological, geological and chemical elements through Earth and its atmosphere.
• The cycles move substances through the biosphere, lithosphere, atmosphere and hydrosphere. Cycles are gaseous and sedimentary.
• Gaseous cycles include nitrogen, oxygen, carbon, phosphorous, sulfur and water.
• These elements cycle through evaporation, absorption by plants and dispersion by wind. Sedimentary cycles include the leeching of minerals and salts from the Earth’s crust, which then settle as sediment or rock before the cycle repeats.

Energy flows through an ecosystem and is dissipated as heat, but chemical elements are recycled.
• For the living components of a major ecosystem (e.g., a lake or a forest) to survive, all the chemical elements that make up living cells must be recycled continuously.
• Energy flows directionally through Earth’s ecosystems, typically entering in the form of sunlight and exiting in the form of heat. However, the chemical components that make up living organisms are different (they get recycled).
• Elements within biogeochemical cycles flow in various forms from the nonliving (a biotic) components of the biosphere to the living (biotic) components and back.
• Repetition of the cycles is important. Plants absorb carbon dioxide and release oxygen, making the air breathable. Plants also acquire nutrients from sediment. Animals acquire nutrients from plants and other animals, and the death of plants and animals returns these nutrients to the sediment as they decay. The cycle then repeats and allows other living things to benefit.
• The simplest example of biogeochemical cycles at work includes water. Water evaporates from the oceans, condenses as clouds and precipitates as rain, which returns the water back to the earth in a cycle.
Many elements cycle through ecosystems, organisms, air, water, and soil. Many of these are trace elements. Other elements, including carbon, nitrogen, oxygen, hydrogen, sulfur, and phosphorus is critical components of all biological life.
Each biogeochemical cycle can be considered as having a reservoir (nutrient) pool a larger, slow-moving, usually abiotic portion and an exchange (cycling) pool a smaller but more-active portion concerned with the rapid exchange between the biotic and abiotic aspects of an ecosystem.
Types of Bio-geochemical Cycles:
From the viewpoint of the ecosphere as a whole, biogeochemical cycles fall into two basic groups:
Gaseous Types, in which the reservoir is in the atmosphere or the hydrosphere (ocean); and
Sedimentary Types, in which the reservoir is in the crust of earth.
CARBON CYCLE
Carbon is a constituent of all organic compounds, many of which are essential to life on Earth. The source of the carbon found in living matter is carbon dioxide (CO2) in the air or dissolved in water. Carbon is found in all organic macromolecules and is also a key component of fossil fuels.
Steps in the carbon cycle
1. Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
2. Carbon dioxide is absorbed by producers to make carbohydrates in photosynthesis.
3. Animals feed on the plant passing the carbon compounds along the food chain. Most of the carbon they consume is exhaled as carbon dioxide formed during respiration. The animals and plants eventually die.
4. The dead organisms are eaten by decomposers and the carbon in their bodies is returned to the atmosphere as carbon dioxide. In some conditions decomposition is blocked. The plant and animal material may then be available as fossil fuel in the future for combustion.
The cycle has four major reservoirs of carbon interconnected by pathways of exchange. The reservoirs are:
1. the atmosphere
2. the terrestrial biosphere (which usually includes freshwater systems and non-living organic material, such as soil carbon)
3. the oceans (which includes dissolved inorganic carbon and living and non-living marine biota
4. the sediments (which includes fossil fuels).
The annual movements of carbon, the carbon exchanges between reservoirs, occur because of various chemical, physical, geological, and biological processes.
Other facts:
Algae and terrestrial green plants (producers) are the chief agents of carbon dioxide fixation through the process of photosynthesis, through which carbon dioxide and water are converted into simple carbohydrates.
These compounds are used by the producers to carry on metabolism, the excess being stored as fats and polysaccharides. The stored products are then eaten by consumer organisms, from protozoans to man, which convert them into other forms.
CO2 is added directly to the atmosphere by animals and some other organisms as a by-product of respiration. The carbon present in animal wastes and in the bodies of all organisms is released as CO2 by decay, or decomposer, organisms (chiefly bacteria and fungi) in a series of microbial transformations.
Part of the organic carbon the remains of organisms has accumulated in Earth’s crust as fossil fuels (e.g., coal, gas, and petroleum), limestone, and coral. The carbon of fossil fuels, removed from the cycle in prehistoric time, is now being released in vast amounts as CO2 through industrial and agricultural processes, much of it quickly passing into the oceans and there being “fixed” as carbonates. If oxygen is scarce (as in sewage, marshes, and swamps), some carbon is released as methane gas.
Human Impact on the Carbon Cycle:
Felling of forests, coal-burning power plants, automobile exhausts, factory smokestacks, and other waste vents of the human environment contribute about 22 billion tons of carbon dioxide (corresponding to 6 billion tons of pure carbon) and other greenhouse gases into the earth’s atmosphere each year. This alters the Carbon Cycle drastically.
Carbon dioxide emissions are now around 12 times higher than in 1900 because of increased quantities of coal, oil and gas consumption for energy. This serious imbalance in the Carbon cycle is responsible behind the phenomena like Green House Effect, Global Warming and Climate Change. It is now an established fact that this environmental impact will have disastrous consequences for the entire biosphere and humanity.

Persian and Alexander


Persian and Alexander

Persian and Alexander

Persian Invantion
Cyrus (558 – 530 B.C)
• Cyrus the Great was the greatest conqueror of the Achaemenian Empire.
• He was the first conqueror who led an expedition and entered into India.
• He captured the Gandhara region.
• All Indian tribes to the west of the Indus river submitted to him and paid tribute.
• His son Cambyses had no time to pay attention towards India.
Darius I (522 – 486 B.C.)
• Darius I, the grandson of Cyrus, conquered the Indus valley in 518 B.C. and annexed the Punjab and Sindh.
• This region became the 20th Satrapy of his empire.
• It was the most fertile and populous province of the Achaemenian Empire.
• Darius sent a naval expedition under Skylas to explore the Indus.
Xerxes (465-456 B.C.)
• Xerxes utilized his Indian province to strengthen his position.
• He deployed Indian infantry and cavalry to Greece to fight his opponents. But they retreated after Xerxes faced a defeat in Greece.
• After this failure, the Achaemenians could not follow a forward policy in India.
• However, the Indian province was still under their control.
• Darius III enlisted Indian soldiers to fight against Alexander in 330 B.C.
Effects of the Persian Invasion
• The Persian invasion provided an impetus to the growth of Indo-Iranian commerce.
• It also prepared the ground for Alexander’s invasion.
• The use of the Kharoshti script, a form of Iranian writing became popular in north-western India and some of Asoka’s edicts were written in that script.
• The influence of Persian art can be seen on the art of the Mauryas, particularly the monolithic pillars of Asoka and the sculptures found on them. The very idea of issuing edicts by Asoka and the wording used in the edicts are traced to Iranian influence.
Alexander’s Invasion of India (327-325 B.C.)
Political Condition on the eve of Alexander’s Invasion
• On the eve of Alexander’s invasion, there were a number of small kingdoms in northwestern India.
• The leading kings were Ambhi of Taxila, the ruler of Abhisara and Porus who ruled the region between the rivers of Jhelum and Chenab.
• There were many republican states like Nysa.
• The northwestern India remained the most disunited part of India and the rulers were fighting with one another.
• They never came together against common enemy.
Causes of the Invasion
• Alexander ascended the throne of Macedonia after the death of his father Philip in 334 B.C.
• He conquered the whole of Persia by defeating Darius III in the battle of Arbela in 330 B.C.
• He also aimed at further conquest eastwards and wanted to recover the lost Persian Satrapy of India.
• The writings of Greek authors like Herodotus about the fabulous wealth of India attracted Alexander.
• Moreover, his interest in geographical enquiry and love of natural history urged him to undertake an invasion of India.
• He believed that on the eastern side of India there was the continuation of the sea, according the geographical knowledge of his period. So, he thought that by conquering India, he would also conquer the eastern boundary of the world.
Battle of Hydaspes
• In 327 B.C. Alexander crossed the Hindukush Mountains and spent nearly ten months in fighting with the tribes.
• He crossed the Indus in February 326 B.C. with the help of the bridge of boats.
• He was warmly received by Ambhi, the ruler of Taxila.
• From there Alexander sent a message to Porus to submit, but Porus refused and decided to fight against Alexander.
• Alexander marched from Taxila to the banks of the river Hydaspes (Jhelum).
• As there were heavy floods in the river, Alexander was not able to cross it.
• After a few days, he crossed the river and the famous battle of Hydaspes was fought on the plains of Karri.
• Although Porus had a strong army, he lost the battle.
• Alexander was impressed by the courage and heroism of this Indian prince, treated him generously and reinstated him on his throne.
• Alexander continued his march as far as the river Beas encountering opposition from the local tribes.
• He wanted to proceed still further eastwards towards the Gangetic valley, but he could not do so because his soldiers refused to fight.
• Hardships of prolonged warfare made them tired and they wanted to return home and Alexander could not persuade them and therefore decided to return.
• Alexander made arrangements to look after his conquered territories in India and divided the whole territory from the Indus to the Beas into three provinces and put them under his governors. H
• is retreat began in October 326 B.C. Many republican tribes attacked his army.
• On his way he reached Babylon where he fell seriously ill and died in 323 B.C.
Effects of Alexander’s invasion
• The immediate effect of Alexander’s invasion was that it encouraged political unification of north India under the Mauryas.
• The system of small independent states came to an end.
• Alexander’s invasion had also paved the way for direct contact between India and Greece.
• The routes opened by him and his naval explorations increased the existing facilities for trade between India and West Asia.
• His authority in the Indus valley was a short-lived one because of the expansion of Mauryan Empire under Chandragupta Maurya.


Aquaculture


Aquaculture

Aquaculture or aqua farming is the cultivation of aquatic organisms – fish, shellfish and aquatic plants.Farming implies some form of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc.
It includes both marine water and freshwater species and can range from land based to open ocean production.
Particular kinds of aquaculture include the production of kelp, seaweed, and other algae, fish farming, and shrimp farming, shellfish farming, and growing of cultured pearls.
Types of Aquaculture
a) Algaculture
• Algaculture involving the farming of species of algae.
• The majority of algae cultivated fall into the category of microalgae referred to as phytoplankton microphytes, or plankton, algae Microalgae, commonly known as seaweed.
• Due to their size and the specific requirements of the environment in which they grow, they are not cultivated on a large scale ,more often harvested wild from the ocean.
b) Fish farming:
• It is the principal form of aquaculture.
• It involves raising fish commercially in tanks or enclosures, usually for food.
• Fish species raised by fish farms include salmon, catfish, tilapia, cod, carp, trout, etc.
• Increasing demands of wild fisheries by commercial fishing operations have caused Widespread Over fishing.
• Fish farming offers an alternative solution to the increasing market demand for fish and fish protein.
c) Fresh water prawn farming:
• It is an aquaculture business designed to raise and produce fresh water prawn or shrimp for human consumption.
d) Integrated multi-trophic aquaculture (IMTA):
• It is a practice in which the byproducts (wastes) from one species are recycled to become inputs (fertilizers, food) for another.
• Food aquaculture (e.g. fish, shrimp) is combined with inorganic extractive (e.g. sea weed) and organic extractive (e.g. shell fish) aquaculture to create balanced systems.
• It helps in maintaining environmental sustainability, economic stability (product diversification and risk reduction), and social acceptability (better Management practice).
e) Mariculture:
• It is a specialized branch of aquaculture involving the cultivation of marine organism for food and other products in the open ocean, an enclosed section of the ocean.
• Example is the farming of marine fish, prawns, or oysters in salt water ponds.
• Non-food products produced by mariculture include fish meal, nutrient agar, jewelleries (e.g. cultured pearls), and cosmetics.
f) Shrimp farming:
• It is the form of aquaculture for the cultivation of marine shrimp for human consumption.
• About 75% of farmed shrimp is produced in Asia in particular China and Thailand.
• The other 25% is produced mainly in Latin America, where Brazil is the largest producer. The largest exporting destination is Thailand.
g) Whaling:
• Whale is, in fact, a sea mammal and not strictly fish. However, it makes significant contribution to the economy of large fishing nations.
• Two thirds of the whales are caught in the southern oceans, south of latitude 50 degree, the other one third coming mainly from the north Pacific and north Atlantic.
• South Africa, South America and Australia account for nearly 10%.


Integrated Pest Management (IPM)


Integrated Pest Management (IPM)

Integrated Pest Management (IPM) is a program that should be based on prevention, monitoring, and control which offers the opportunity to eliminate or drastically reduce the use of pesticides, and to minimize the toxicity of and exposure to any products which are used. IPM does this by utilizing a variety of methods and techniques, including cultural, biological and structural strategies to control a multitude of pest problems.
IPM is the answer or an amicable alternative to chemical pesticides.
As per United Nation’s Food’ and Agriculture Organization (FAO), IPM is defined as:
“The careful consideration of all available pest control technique’s and subsequent integration of appropriate measures that discourage the development of pest populations and keep pesticides and other interventions to levels that are economically justified and reduce or minimize risks to human health and the environment. 1PM emphasizes the growth of a healthy crop with the’ least possible disruption to agro-ecosystems and encourages natural pest control mechanism”.
Methods used under IPM
1. Acceptable pest levels: It aims on controlling and not eradicating pests: Allowing a pest population to survive at a reasonable threshold reduces selection pressure. This lowers the rate at which a pest develops resistance to a control and maintains homeostasis by maintaining the normal food web around the pest.
2. Regulatory or Legislative Control: It is mainly done through quarantine control.
3. Cultural Control: It involves crop sanitation or clean culture. Cleaning of pruning shears to prevent spread of infection is an important method. Other methods include: tillage, irrigation, use of balanced fertilizers, use of clean certified seed (removal of undesired or diseased plants and Want debris), proper crop spacing, crop rotation, intercropping, trap crops, companion cropping etc.
4. Mechanical and Physical Controls: Hand-picking, barriers, traps for insect pests, manual weed control, cultivation and temperature modifications (heat or cold), and manipulation of moisture (as in stored grains).
5. Biological Control: By using natural pest enemies like predators, parasites, parasitoids, pathogens (fungi, bacteria, viruses) and bio-pesticides.
6. Genetic Control: It involves traditional selective breeding and newer biotechnology to produce robust varieties.
Pests are virtually never eradicated. Thus record-keeping system is essential to establish trends and patterns in pest outbreaks. Further a regular evaluation program is essential to determine the success of the pest management strategies.
National Centre for Integrated Pest Management (NCIPM) of Indian Council of Agricultural Research.
(ICAR), India develop and promote IPM technologies for major crops so as to sustain higher crop yields with minimum ecological implications and develop information base on all aspects of pest management and to advise on related national priorities and pest management policies.


Generations of Biofuels


Generations of Biofuels

Biofuels are energy sources made from recently grown biomass (plant or animal matter). Biofuels are a renewable resource because they are continually replenished.
The generations of biofuels are discussed below:
• First Generation biofuels are produced directly from food crops by abstracting the oils for use in biodiesel or producing bioethanol through fermentation. Crops such as wheat and sugar are the most widely used feedstock for bioethanol while oil seed rape has proved a very effective crop for use in biodiesel.
Pros: Stable, known technology that, depending on feedstock cost, can be cost competitive with fossil fuels.
Cons: Open to food vs fuel criticisms, and generally have feedstock commodity price volatility, as well as geographic limitations that do not always match up well with fuel demand.
• Second Generation biofuels: They are produced from non-food crops such as wood, organic waste, food crop waste and specific biomass crops. Cellulosic ethanol technology fits in here, as do non-food crop technologies such as jatropha-based biofuels.
Pros: A wider selection of geographies; more available biomass; less controversial.
Cons: Early days for the technology; high capital costs; domestication issues with some feedstocks such as jatropha.
• Third Generation of biofuels is based on improvements in the production of biomass. It takes advantage of specially engineered energy crops such as algae as its energy source. The algae are cultured to act as a low-cost, high-energy and entirely renewable feedstock. It is predicted that algae will have the potential to produce more energy per acre than conventional crops.
Pros: Can be made anywhere where CO2 and water is found in sufficient concentration; less controversial.
Cons: Early days for the technology; domestication issues with the feedstock platforms such as algae, cyanobacteria; high capital costs.
• Fourth Generation Biofuels are aimed at not only producing sustainable energy but also a way of capturing and storing co2.
Pros: Can be made anywhere where CO2 and water is found in sufficient concentration; less controversial for biodiversity, environment advocates. Generally, the processes produce drop-in fuels.
Cons: Early days for the technology; can de dependent on a source for low-cost sugars, or CO2; high capital costs; generally speaking, use microbial organisms to do the fuel conversion and processing times generally need to be improved to make fuels cost-competitive.

Sai Praveen

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