Friday, June 27, 2014

Environmental Studies Syllabus (Osmania University)

Environmental studies: Definition, scope and importance, need for public awareness. Natural
resources: Water resources; use and over utilization of surface and ground water, floods,
drought, conflicts over water, dams - benefits and problems. Effects of modem agriculture,
fertilizer-pesticide problems, water logging salinity. Energy resources, growing energy needs,
renewable and nonrenewable energy sources. Land Resources, land as a resource, land
degradation, soil erosion and desertification.

Ecosystems: Concepts of an ecosystem, structure and functions of an ecosystem, producers,
consumers and decomposers, energy flow in ecosystem, food chains, ecological pyramids,
aquatic ecosystem (ponds, streams, lakes, rivers, oceans, estuaries).

Biodiversity: Genetic species and ecosystem diversity, bio-geographical classification of India.
Value of biodiversity, threats to biodiversity, endangered and endemic species of India,
conservation of biodiversity.

Environmental Pollution: Causes, effects and control measures of air pollution, water
pollution, soil pollution, noise pollution, thermal pollution and solid waste management.
Environment Protection Act: Air, water, forest and wild life acts, issues involved in
enforcement of environmental legislation.

Social Aspects and the Environment: Water conservation, watershed management, and
environmental ethics. Climate change, global warming, acid, rain, ozone layer depletion.
Environmental protection act, population explosion.
Disaster management: Types of disasters, impact of disasters on environment, infrastructure,
and development. Basic principles of disaster mitigation, disaster management, and
methodology, disaster management cycle, and disaster management in India.

Suggested Reading
1. A. K. De, Environmental Chemistry, New Age Publications, 2002.
2. E.P. Odom, Fundamentals of Ecology, W.B. Sunders Co., USA.
3. GL. Karia and R.A. Christian, West Water Treatment, Concepts and Design Approach, Prentice Hall of India, 2005.
4. Benny Joseph, Environmental Studies, Tata McGrawHill, 2005
5. V.K. Sharma, Disaster Management, National Centre for Disaster Management, IIPE, Delhi, 1999.

Thursday, June 26, 2014

Important questions and answers

Write about function of producers, consumers and decomposers in an ecosystem
The ecosystem can be divided, from the energetic view point into three types of organisms:
producers, consumers, and reducers. These can be explained as under:
(1) Producer
Photosynthetic algae, plants and bacteria are the producers of the ecosystem; all other
organisms depend upon them directly or indirectly for food.
(2) Consumers
Consumers are herbivorous, carnivorous, and omnivorous animals; they eat the organic
matter produced by other organisms.
(3) Decomposers
Decomposers are heterotrophic organisms like animals; they are fungi and bacterial that
decompose dead organic matter.

Describe the concept of an ecosystem
Every living organism has to depend and interact with different nonliving or abiotic and living or biotic components of the environment.
The abiotic environmental components include basic inorganic elements and compounds such as water and carbon dioxide, calcium and oxygen, carbonates and phosphates besides physical factors such as soil, rainfall, temperature, moisture, winds, currents and solar radiation.
The biotic environmental factors comprise plants, animals, and microbes.
The scientific study of the interactions of organisms with their physical environment and with each other, is called ecology.
The eco-system can be defined as any spatial or organizational unit including living organisms and non-living substances interacting to produce an exchange of materials between the living and non-living parts. The eco-system can be studied from either structural or functional aspects.
1. Structural Aspect
The structural aspects of ecosystem include a description of the arrangement, types and
numbers of species and their life histories, along with a description of the physical features
of the environment.
2. Functional
The functional aspects of the ecosystem include the flow of energy and the cycling of

Write brief notes about endangered and endemic species of India
Endangered species in comprise of a variety of rare species of wild animals, aquatic animals and insects. Some of the endangered species in India are Himalayan wolf, crocodile nico barica, red panda, etc. Endangered species are of four types:
Critically endangered (CR)
Endangered (EN)
Vulnerable (VU) and
Endemic species are those species that are specific to a specific locality. It may also relate to a disease or pathogen that is confined to one particular area. One particular species endemic to India is the black buck.

Write briefly about conservation of biodiversity
Biodiversity is the degree of variation of life forms within a given species, ecosystem, etc. Biodiversity generally tends to cluster in hotspots. Biodiversity is commonly used to replace the more clearly defined and long established terms. Biologists define biodiversity as the totality of genes, species or ecosystem of a region.
Biodiversity is not evenly distributed. It varies greatly across the globe as well as within regions. Biodiversity is directly and indirectly related to human health as it provides support for drug discovery and is a valuable medicinal resource.
It plays a part in regulating the chemistry of our atmosphere and water supply. It is directly involved in water supply, recycling nutrients and providing fertile soil.
Habitat destruction in the form of deforestation of tropical forests has led to extinction of wildlife.
Biodiversity can be conserved by the following techniques:
In-situ conservation and
Ex-situ conservation

Write briefly about the biogeographical zones in India
There are 10 biogeographical zones in India. They are briefly described below:
1. Trans-Himmalayas: The Trans-Himmalayas is an extension of the Tibetean plateau.
2. Himalayas: The Himalayas form the northern boundary of India. The Himalayas comprises a diverse               range of biotic provinces and biomes.
3. Desert: Three kinds of deserts are found in India. They are, Desert of western Rajasthan, Desert of               Gujarat and the high altitude cold desert of Jammu & Kashmir and Himachal Pradesh
4. Semi-arid: This zone lies in between the desert and the Deccan plateau.
5. Western Ghats: This is a mountain range that runs along the western coast of India. This ghat section             covers a diverse range of biotic provinces and biomes.
6. Deccan Plateau: It is a large triangular plateau south of Narmada valley. The Satpura mountains cover           the north side, western ghats and eastern ghats cover the west and east sides respectively. The plateau           slopes towards east. The plateau is covered with deciduous vegetation.
7. Gangetic plain: The Gangetic plains cover from south of the Himalayas to north of tropic of cancer.               These plains were formed by the Ganges river system and are relatively homogenous. The famous                 'sunderban' forests are located in these plains.
8. North-east India: The plains and non-himalayan hill ranges of northeastern India fall in this zone. This             zone is filled with a wide variety of vegetation.
9. Islands: The Andaman and Nicobar islands in the bay-of-bengal is a group of 300 small and large                 islands. Mostly tribes live in Nicobar islands. These islands have a highly diverse set of biomes.
10. Coasts: The Indian subcontinent is blessed with a long coastline on the east and west with distinct                   differences between the two.

Write notes on threats to biodiversity
Biodiversity has evolved simultaneously with human culture. Man has met the changing needs and pressures of increasing population by applying knowledge and skills. People have hunted, fished and gathered species for food, fuel, fiber and shelter thereby eliminating competing or threatening species.
Activities mentioned above destroys and depletes the basis of an ecosystem (genes and species). As a result, mankind loses food, medicine and industrial products in the present and future.
According to the World Conservation Union's Red List, the threat to biodiversity is due to human activity particularly, habitat destruction.
Few of the Major biodiversity threats are listed below:
i. Habitat destruction
ii. Extension of agriculture
iii. Filling-up of wetlands
iv. Conversion of rich biodiversity site for human settlement and industrial development
v. Destruction of coastal areas
vi. Uncontrolled commercial exploitation
One of the primary causes of loss of biodiversity is habitat destruction. The main causes for the same are listed below:
i. Agricultural activities
ii. Extraction including mining, fishing, logging and harvesting
iii. Developmental activities including human settlement, industry and associated infrastructure
Millions of hectares of forest area is lost due to illegal encroachment of forest land. Forest land is also lost due to construction of river valley projects, introduction of transmission lines and roads, etc. Change in forest composition and quality can lead to decline in primary food species for wildlife.
Fragmentation is the process of division of a population into several small groups. Habitat loss and fragmentation leads to formation of isolated, small and scattered populations which are susceptible to inbreeding, depression, high infant mortality and eventually possible extinction.
Introduced species are responsible for many recorded species extinctions, especially on islands. In these isolated ecosystems, a new predator, competitor or pathogen can rapidly endanger species that did not evolve simultaneously with the newcomer.
Several forest, fisheries and wildlife resources have been over-exploited to the point of extinction. A few cases are mentioned below as a point in case. Poaching of wild animals (The Tiger, Elephant, Rhinoceros) has resulted in their extinction. Population pressures adversely affect the forest resources on which the local communities depend while having a negative impact on biodiversity.
Pollutants strain ecosystems. Contamination affects the food chain. A point in case is marine pollution from non-point sources that ruins estuaries and coastal seas throughout the world. Pesticides used to control agricultural pests have shown to negatively impact birds due to severe air pollution in Spain.

Write about energy flow in an ecosystem
Energy is an essential requirement for all living organisms. Solar energy is the only source of energy for the Earth. Solar energy is transformed to chemical energy by photosynthesis in plants (primary producers). Though lot of sunlight falls on plants, only 1% of this is utilized for photosynthesis.
Some amount of energy is used by the plant for growth and the remaining is transferred to consumers by the process of eating. Thus energy enters the ecosystem through photosynthesis and passes through different feeding levels (tropic levels)
The flow of energy through an ecosystem follows two laws of thermodynamics:
1. First law of thermodynamics states that “energy can neither be created nor destroyed, but can be converted from one form to another.” Ex: Energy for an ecosystem comes from the sun. It is absorbed by plants where it is converted and stored as chemical energy or solar energy is converted into chemical energy.
2. Second law of thermodynamics states that “whenever energy is transformed, there is a loss of energy through the release of heat.” Ex: Whenever energy is transferred between tropic levels, loss of energy takes place through respiration, running, hunting, etc.

Describe aquatic ecosystem
Aquatic ecosystem deals with water bodies. Types of organisms found in aquatic environment depend on salinity of water (salt content).
Types of aquatic life zones:
1. Fresh water life zones (Ponds, Streams, Rivers, Lakes)
2. Salt water life zones. (Oceans and Estuaries)
Pond ecosystems
i. Pond is temporary, only seasonal
ii. It is a stagnant freshwater body
iii. It is easily polluted due to limited amount of water.
Structure and function
Examples of abiotic components are temperature, light, water, organic and inorganic compounds.
Biotic components are comprised of 
i. Producers: These include green photosynthetic organisms. They are of two types:
a) Phytoplankton and
b) Microphytes
Phytoplankton are microscopic aquatic plants, which float freely on the surface of water. Examples of phytoplankton are Algae, Volvox, Pandorina, Anabena and Cosmarium.
Microphytes are large floating plants and submerged plants. Examples of microphytes are hydrilla, jussiaea, wolfia and demna.
ii. Consumers:
Primary consumers (Zooplanktons): These are microscopic animals that freely float on the surface of water. Zooplanktons are found along with phytoplanktons which they eat. Examples of zooplanktons are planktons, very small fish, ciliates, flagellates and protozoans.
Secondary consumers (Carnivores): They feed on zooplanktons. Examples of carnivores are insects like water beetles and small fish.
Tertiary consumers: They feed on smaller fish. Examples of tertiary consumers are large fish like game fish.
iii. Decomposers: They decompose dead plant and animal matter and their nutrients are released and reused by green plants. Examples of decomposers are fungi, bacteria and flagellates.
Lake ecosystems:
i. Lakes are natural shallow water bodies
ii. Lakes are supplied with water from rainfall, melting snow and streams.
iii. Lake is a permanent water body with large water resources.
iv. Lakes help in irrigation and supplying drinking water.

Structure and function of Lake Ecosystem: The abiotic components of lake ecosystems consist of temperature, light, proteins, lipids, turbidity, oxygen and carbon-dioxide.
The biotic components are classified into:
i. Producers: Green plants (Floating, Submerged and amphibious). Examples of producers are phytoplanktons, algae and flagellates.
ii. Consumers: Primary consumers are zooplanktons like ciliates, protozoans, etc that feed on phytoplanktons.
Secondary consumers  are carnivores like insects and smaller fishes that feed on zooplanktons
Tertiary consumers feed on smaller fish. Examples are large fish and game fish
iii.     Decomposers: Decomposers decompose dead plants and animals. Examples of decomposers are bacteria, fungi and actinomycetes.

River Ecosystem: 
i. It is fresh water and freely flowing water system
ii. Flowing water allows mixing of water resulting in higher dissolved oxygen
iii. River deposits large amount of nutrients.
Structure and function of River Ecosystem: The abiotic components of river ecosystems are temperature, light, pH, nutrients, organic and inorganic compounds.
Biotic components are classified into:
i. Producers: Phytoplankton, Algae, water grasses, aquatic grasses and other amphibious plants.
ii. Consumers: Primary consumers feed on phytoplanktons. Examples are water insects, snails and fishes.
Secondary consumers are feed on primary consumers.
iii.     Decomposers: Decomposers decompose dead plants and animals. Examples of decomposers are bacteria, fungi and actinomycetes.
Ocean ecosystems:
i. Oceans occupy a large surface area and made up of saline water.
ii. Commercial activities are carried out in oceans.
iii. Oceans are rich in biodiversity
iv. Oceans moderate the temperature of the earth.
Structure and function of Ocean Ecosystems:
The abiotic components of ocean ecosystems are temperature, light, NaCl, K, Calcium and Magnesium salts and alkalinity.
The biotic components comprise of 
i. Producers: Phytoplanktons (diatoms, unicellular algae, etc) and marine plants (sea weeds, chlorophyceal, phaeophyceae)
ii. Consumers: They are heterotrophic macroconsumers which depend upon producers for their nutrition.
a. Primary consumers or herbivores feed on producers (Ex: Crustaceans, Mollusks, Fish
b. Secondary consumers or carnivores feed on herbivores (Ex: Herring, Mackerel, etc)
c. Tertiary consumers are the top consumers and feed on small fishes. (Ex: Cod, Haddock, etc)
iii. Decomposers decompose dead organic matter. (Ex: Bacteria and fungi)

Estuarine ecosystem:
i. Estuaries are transition zones that are strongly affected by tides of the sea.
ii. Water in estuaries change periodically
iii. The organisms in estuaries have a wide tolerance
iv. Salinity remains highest in summer and lowest in winter.
Structure and function of Estuarine Ecosystems:
Abiotic components of estuarine ecosystems are temperature, pH, sodium and potassium salts and nutrients.
Biotic components consist of
i. Producers: Examples are marsh grasses, seaweeds, seagrasses and phytoplankton.
ii. Consumers: Examples are Oysters, Crabs, Seabirds, and small fishes
iii. Decomposers: Examples are Bacteria, fungi and actinomycetes.

Write in detail about structure and function of an ecosystem.
Ecology is the study of ecosystems and ecosystem is the basic functional unit of ecology. A group of organisms interacting amongst themselves and with the environment is called ecosystem. An ecosystem is a community of different species interacting with each other and their non-living environment thereby exchanging energy and matter.
Structure of an ecosystem shows the relationship between abiotic and biotic components. 
All the living members of an ecosystem form the biotic community. Ex: Plants (producers), animals (consumers) and microorganisms (decomposers).
The non-living components (physical and chemical) of an ecosystem collectively form the abiotic community. Ex: Climate, Soil, Energy, Nutrients, Water and Air.
Physical components are necessary for the growth and maintenance of living components of the ecosystem.
Chemical components are the source for essential nutrients. They consist of organic substances (protein, lipids, carbohydrate) and inorganic substances (Al, Co, Zn, Cu-micro elements C, H, O, P, N, P, K-macro elements)
Function of an ecosystem is of three types:
Primary function: The primary function of all ecosystems is to manufacture starch (photosynthesis)
Secondary function: The secondary function of all ecosystems is to distribute energy to all the           consumers in the form of food.
Tertiary function: All living organisms die and these dead systems are decomposed to initiate the third system of ecosystems called “cycling”.

Define and differentiate between food chain and food web with a diagram
A food chain is a model that shows the flow of energy from autotrophs to a series of organisms in an environment. The energy that flows can be different for each food chain. The food chain describes the flow of food from one organism to the next thereby giving energy to the organism digesting the food. The number of steps involved in a food chain is restricted to four or five. The energy available decreases with each step. The energy loss takes place in the form of heat. The three types of food chains are: 
Grazing food chain,
Detritus food chain and 
Parasitic food chain. 
All food chains start with the sun.
The interlocking pattern of various food chains in an ecosystem is known as food web. In a food web many food chains are interconnected. In a food web different types of organisms are connected at different tropic levels resulting in several opportunities of eating and being eaten at each tropic level.
An important difference between food chain and food web is that food chain is linear and this implies that if one species becomes extinct, the species in the subsequent tropic levels are also affected. However, in a food web, if one species is affected, there is no serious effect on other tropic levels as there are several options available at each tropic level.

Enumerate the value of biodiversity
The value of biodiversity is classified into:
Direct values and
Indirect Values
Direct value of biodiversity: Biodiversity has direct value in the form of consumption in agriculture, medicine and industry. Among all plant species identified as fit for human consumption, only 150 have been cultivated on a large scale. Two types of direct values are:

  Consumptive use value and 
Productive use value
Consumptive use value is the value placed on nature's products that are consumed directly without passing through a market. Consumptive use value is not included in national income accounts. Consumptive use value benefits the communities closest to the resource if harvested sustainably with proper management. Product examples of consumptive use value are firewood, food and game meat.
Productive use value refers to products that are commercially harvested and sold in a market. Its value is estimated at production end after addition of cost and value. The productive use value has a major impact on national economy. Product examples of productive use value are timber, fish, honey, mushrooms, game meat sold in markets and medicinal plants.
Biodiversity has indirect value since it provides economic benefits without being harvested. Direct value of biodiversity is derived from its indirect value. Indirect value of biodiversity is listed below:
Non consumptive use value
Optional value
Existence value and
Information value
Non consumptive use value refers to nature's functions and services. Examples of this are photosynthesis by plants that provides support system for other species, maintenance of water cycle, regulating climate, production and protection of soil, absorption and breakdown of pollutants, recreational, aesthetic, socio-cultural, scientific, educational, spiritual and historic values of natural environments.
Option value refers to the indirect value of a species potential to produce economic benefits to the society in the future.
Existence value is the value gained from continuous knowledge of existence. An example in this context is the expense incurred by the administration of various countries to develop techniques in order to prevent a species from becoming extinct (Giant Panda, Blue whale, White tiger, etc).
Information value refers to the educational, scientific, aesthetic and tourism values of biodiversity in an ecosystem.

What are the types of  biodiversity conservation
With the rapid increase of human population and resulting expansion of man's needs coupled with scientific knowledge led to over-exploitation of natural resources. Eventually, conservation of biological diversity became a global concern. This involves influencing behaviour of people at local level through education, at the national level through policy work and awareness programs. International corporations should ensure that their business do not contribute to further loss of biodiversity.
The two main types of biodiversity conservation are:
In-situ conservation and
Ex-situ conservation
In-situ conservation is defined as the conservation of genetic resources through their maintenance within natural or man-made ecosystems in which they occur.
In-situ conservation effort is setting-up of protection areas. This technique is the best conservation strategy. However, its implementation is sometimes unfeasible. National Parks, Sanctuaries and Biosphere reserves are some types of in-situ conservation.
Ex-situ conservation is defined as conservation made outside the habitat of an ecosystem. In case the habitat of rare or endangered species is destroyed, ex-situ conservation is the only means of conserving  a species. It also provides a back-up solution to in-situ conservation projects. A few examples of ex-situ conservation are seed banks, botanical gardens, pollen storage, tissue culture and genetic engineering

Biogeochemical cycles: Phosphorus cycle

Form taken up by plant:                                    H2PO4-, HPO4=
Mobility in soil:                                            None; roots must come in direct contact with                                                                                                orthophosphate P
Mobility in plant:                                    Yes
Deficiency symptoms:                                    Lower leaves with purple leaf margins
Deficiency pH range:                                           <5.5 and >7.0
Toxicity symptoms:                                      None
Toxicity pH range:                                   Non toxic (optimum availability pH 6.0-6.5)
Role in plant growth:                                   Important component of phospholipids and nucleic acids                                                                               (DNA and RNA)
Role in microbial growth:                                     Accumulation and release of energy during cellular                                                                                       metabolism
Concentration in plants:                                   1,000 – 5,000 ppm (0.1 –0.5%)
Effect of pH on availability:                           H2PO4- at pH < 7.2
                                          HPO4= at pH > 7.2
P fertilizer sources:                                           Rock phosphate, phosphoric acid, Ca orthophosphates,                                                                               ammoniumphosphates, ammonium poly-phosphates, nitric                                                                             phosphates, K phosphates, microbial fertilizers                                                                                            (phosphobacterins) increase P uptake

The Water Cycle

The Water Cycle

Water is constantly being cycled through the atmosphere, ocean, and land. This process, known as the water cycle, is driven by energy from the sun. The water cycle is crucial to the existence of life on our planet. 

  • During part of the water cycle, the sun heats up liquid water and changes it to a gas by the process of evaporation.   Water that  evaporates from Earth’s oceans, lakes, rivers, and moist soil rises up into the atmosphere.
  • The process of evaporation from plants is called transpiration. 
  • As water (in the form of gas) rises higher in the atmosphere, it starts to cool and become a liquid again.  This process is called condensation.   When a large amount of water vapor condenses, it results in the formation of clouds.
  • When the water in the clouds gets too heavy, the water falls back to the earth.  This is called precipitation.
  • When rain falls on the land, some of the water is absorbed into the ground forming pockets of water called groundwater.  Most groundwater eventually returns to the ocean.  Other precipitation runs directly into streams or rivers.  Water that collects in rivers, streams, and oceans is called runoff.

Biogeochemical cycles: Sulphur cycle

Biogeochemical cycles: Sulphur cycle

  • Sulfur- S, it is an element
  • Naturally found in earth
  • At room temperature it is a solid
  • Present in proteins, amino acids, vitamins, and enzymes, necessary for plants and animals
  • Often reacts with hydrogen creating hydrogen sulfide (H2S)
  • Can dissolve in water
  • With metals in water, forms metal sulfides and sulfates in air

  • In ground: most found in rocks, or salt in earth, or as sediment at bottom of ocean
  • Found as S, H2S, SO4-2, (NH4)2SO4
  • Underground: Plants absorb, or left by acid deposition (fog or precipitation)
  • Found as SO4-2, (NH4)2SO4, converted to H2S by bacteria, decay, and plant use
  • Stored: Ground, rock, ocean, some quantities in air

  • Sulfur is transferred into biosphere then back into ground, or from ground to atmosphere
  • Microorganisms turn it into H2S (gas) 
  • Oxidized in atmosphere to SO2, and then to H2SO4 (an acid) with water contact
  • Mined ores released to atmosphere in factories as H2S and SO2
  • Volcanoes and hot springs
  • Deposited next in water
  • Through precipitation, dry deposition, leaching
  • SO4-2 leaches from soil into ocean as sediment
  • H2SO4 falls into ocean
  • Dimethyl Sulfide, carbonyl sulfide (biogenic gases), released by plankton returns back into atmosphere (turns into SO2)
  • Either re-evaporated, left as sediment for long time, or deposited on land 
  • When back on land, cycle repeats
Sulphur cycle driven by:
  • constant addition of sulfur to environment by earths interior (Geosphere)
  • Human disturbance, addition of sulfur to atmosphere, (also dug up from environment)
  • Natural processes (Biological, Hydrological and due to Sun’s energy)
  • Plant uptake, microbes (Desulfovibrio sp. or Desulfotomaculum sp.)
  • Most sulfur in particulate form
  • Therefore it is a sedimentary cycle
  • Very short residence time in atmosphere (1-2 days)
  • Even in atmosphere, found as aerosols (<1 micrometer), not gas usually
  • In atmosphere, very much less than 1%
  • 90-95% SO2 from power plants and factories
  • In the process of mining ores, sulfur/sulfides released into soil
  • Combustion of fossil fuels
  • Release of SO2, causes acid rain, increases amount already present
  • Almost 30% of sulfur in rivers from pollution, mining, erosion, etc.
  • Sulfur cycle but also upset balance- too much Sulfur induces acid rain
  • Hydrodesulphurization (refining hydrocarbons)
Sulfur Cycle is important to biological and natural processes although human’s role impacts nature in a negative way
Driving force for life

Biogeochemical cycles - Oxygen cycle

  • Oxygen, one of the main components of the Earth’s atmosphere
  • Two oxygen atoms make up one oxygen molecule, and three oxygen atoms together make up the molecule called ozone.
  • As a gas, oxygen is odorless, colorless, and highly reactive. 
  • Oxygen is essential for the survival of many organisms, and, in the ozone, provides protection to life by filtering out the sun’s ultraviolet rays.
  • In the oxygen cycle, oxygen atoms present in the earth circulate through a series of processes.  
  • Like the nitrogen, carbon, and water cycles, the oxygen cycle is a biogeochemical cycle.
  • A biogeochemical cycle is the movement of matter through the biotic and the abiotic spheres of the ecosystem.

The oxygen cycle begins with plants and photosynthesis.
  • Through photosynthesis, plants convert the energy from the sun and water into carbohydrates and oxygen. 
  • During the day: plants convert carbon dioxide into oxygen.
  • During the night: plants convert oxygen into carbon dioxide to maintain their metabolism.
Oxygen in water
Oxygen in water is known as dissolved oxygen. When water runs over rocks, oxygen enters and creates a lot of high surface area which allows oxygen to transfer from the air into the water very quickly. 

Animals contribution to the oxygen cycle
Animals breathe in oxygen and breathe out carbon dioxide through their processes of metabolism, sparking the process of photosynthesis, once again linking back to the plants’ contribution to the oxygen cycle. 

The Three Main Reservoirs of Oxygen
  • Biosphere (living things)
  • Lithosphere (Earth’s crust)
  • Atmosphere (air)
Within the biosphere and atmosphere, plants begin the oxygen cycle and animals continue it.
Photolysis also donates to a large portion of the oxygen in the atmosphere, where high energy ultraviolet radiation breaks down the atmospheric water and nitrate. 

Figure depicting the interrelationship of Atmosphere, Hydrosphere, Biosphere, Ecosphere and Oxygen

Much of the oxygen present in the atmosphere is used during respiration and decay mechanisms, where animal life and bacteria consume oxygen and release carbon dioxide.
Oxygen is also cycled between the biosphere and lithosphere.

Ecologists fear that there may come a time when the amount of carbon dioxide is very large and there are too few plants to covert it into Oxygen. 
Hence, it is essential that we reduce pollution and protect our environment in order to maintain a well functioning oxygen cycle.

Biogeochemical cycles - Nitrogen cycle

Nitrogen Cycle

Sources of Nitrogen

  • Lightning
  • Inorganic fertilizers
  • Nitrogen Fixation
  • Animal Residues
  • Crop residues
  • Organic fertilizers

Forms of Nitrogen
Urea = CO(NH2)2
Ammonia = NH3 (gaseous)
Ammonium = NH4
Nitrate = NO3
Nitrite = NO2
Atmospheric Dinitrogen = N2
Organic Nitrogen

Role/Importance of Nitrogen

  • Plants and bacteria use nitrogen in the form of NH4+ or NO3-
  • It serves as an electron acceptor in anaerobic environment
  • Nitrogen is often the most limiting nutrient in soil and water.
  • Nitrogen is a key element for:
    • amino acids
    •  nucleic acids (purine, pyrimidine) 
    • cell wall components of bacteria
Nitrogen Cycles
  • Ammonification/mineralization
  • Immobilization
  • Nitrogen Fixation 
  • Nitrification
  • Denitrification

Ammonification or Mineralization or Nitrogen fixation

  • Decomposers: earthworms, termites, slugs, snails, bacteria, and fungi
  • Uses extracellular enzymes  initiate degradation of plant polymers
  • Microorganisms uses:
  • Proteases, lysozymes, nucleases to degrade nitrogen containing molecules

When plants or bacterial cells die, they release of organic nitrogen 
Organic nitrogen is converted to inorganic nitrogen (NH3)
When pH is less than 7.5, NH3 is converted rapidly to NH4

  • It is the opposite of mineralization
  • Takes place when nitrogen is limiting in the environment
  • Nitrogen limitation is governed by C/N ratio
  • C/N typical for soil microbial biomass is 20
  • C/N < 20 Mineralization takes place
  • C/N > 20 Immobilization takes place
Nitrogen Fixation is
  • Energy intensive process
  • Performed only by selected bacteria and actinomycetes
  • Performed in nitrogen fixing crops (ex: soybeans)
Microorganisms responsible for fixing nitrogen are:
  • Azobacter
  • Azospirillum
  • Clostridium
  • Cyanobacteria
  • Require the enzyme nitrogenase
  • Inhibited by oxygen and ammonia (end product)
Two step reactions that occur together :

First step catalyzed by Nitrosomonas
Second step catalyzed by Nitrobacter
Optimal pH is between 6.6-8.0

Removes a limiting nutrient from the environment
Inhibited by O2
Not inhibited by ammonia
Microbial reaction
Nitrate is the terminal electron acceptor

Monday, June 23, 2014

Multidisciplinary nature of environmental science

Multidisciplinary nature of environmental science

The word environment is derived from the French verb ‘environner’ which means to ‘encircle or surround’. Thus our environment can be defined as the physical, chemical and biological world that surround us as well as the complex of social and cultural conditions affecting an individual or community. This broad definition includes the natural world and the technological environment as well as the cultural and social contexts that shape human lives. It includes all factors living and nonliving that affect an individual organism or population at any point in the life cycle; set of circumstances surrounding a particular occurrence and all the things that surrounds us.

There are three reasons for studying the state of the environment.

  1. Need for information that clarifies modern environmental concepts like equitable use of natural resources, more sustainable life styles etc. 
  2. Need to change the way in which we view our own environment, using practical approach based on observation and self learning. 
  3. Need to create a concern for our environment that will trigger pro-environmental action, including simple activities we can do in our daily life to protect it.

Environmental science is essentially the application of scientific methods and principles to the study of environmental issues.

Scope of environmental studies
Since the environment is complex and actually made up of many different environments, including natural, constructed and cultural environments, environmental studies is the inter disciplinary examination of how biology, geology, politics policy studies, law, geology, religion engineering, chemistry and economics combine to inform the consideration of humanity’s effects on the natural world. This subject educates the
students to appreciate the complexity of environmental issues and citizens and experts in many fields. By studying environmental science, students may develop a breadth of the interdisciplinary and methodological knowledge in the environmental fields that enables them to facilitate the definition and solution of environmental problems.

The scope of environmental studies is that, the current trend of environmental degradation can be reversed if people of educated communities are organized and empowered; experts are involved in sustainable development.

Environmental factors greatly influence every organism and their activities. The major areas in which the role of environmental scientists are of vital importance are natural resources, ecosystems, biodiversity and its conservation, environmental pollution, social issues and environment human population and environment.
It is essentially a multidisciplinary approach and its components include Biology, Geology, Chemistry, Physics, Engineering, Sociology, Health Sciences, Anthropology, Economics, Statistics and Philosophy It is essentially a multidisciplinary approach. An Understanding of the working of the environment requires the knowledge from wide ranging fields.

Biogeochemical cycles - Carbon cycle in brief

Carbon exists in the nonliving environment as:
Carbon dioxide (CO2)
Carbonic acid ( HCO3−)
Carbonate rocks (limestone and coral = CaCO3)
Deposits of Fossil fuels
Dead organic matter

Organic Carbon
Hydrocarbons:  CH4
Carbohydrate: CH2O

Inorganic carbon
Carbon Dioxide: CO2
Calcium Carbonate: CaCO3 

Carbon is released into the atmosphere in several ways
Respiration by plants and animals. 
Decay of animal and plant matter. 
Combustion of organic material
Production of cement. 
The ocean releases CO2 into the atmosphere.
Volcanic eruptions and metamorphism

Carbon is taken from the atmosphere in several ways
The oceans when the  seawater becomes cooler, more CO2  dissolve and become carbonic acid.
In the upper ocean areas organisms convert reduced carbon to tissues, or carbonates.

CO2   + H2O  + sunlight   =>  CH2O  + O2

CH2O  + O2   =>  CO2   + H2O  + energy

Human Impacts on the Carbon Cycle => Combustion or Oxidization of hydrocarbon
86% of global primary energy consumption is fossil fuels.

Fossil Fuels
Natural Gas

CO2 Concentration
Pre-Industrial value => 280 ppm  (600 billion tons)
Current value => 380 ppm (800 billion tons)
Critical value => 560 ppm (1200 billion tons)