Mangroves are the characteristic littoral plant formation of tropical and subtropical sheltered coastlines.

are trees and bushes growing below the high water level of spring tides which exhibits remarkable capacity for salt water tolerance.

basically evergreen land plants growing on sheltered shores, typically on tidal flats, deltas, estuaries, bays, creeks and the barrier islands. require high solar radiation and have the ability to absorb fresh water from saline/ brackish water. produces pneumatophores (blind roots) to overcome respiration problem in the anaerobic soil conditions

• Leaves are thick and contain salt secreting glands.
• exhibit viviparity mode of reproduction. i.e. SeedS germinate in the tree itself (before falling to the ground). This is an adaptative medianiSintoovercome the problem of germination in Saline water.
• crystals of salt on the back of the leaves; others block absorption of salt at their roots

The mangroves of Sundarbans are the largest single block of tidal holophytic mangroves of the world. famous for the Royal Bengal Tiger and crocodiles.

The mangroves of Bhitarkanika (Orissa), which is the second largest in the Indian sub continent, harbour high concentration of typical mangrove species and high genetic diversity have (additional) special roots such as prop roots, pneumatophores  which help to impede water flow and thereby enhance the deposition of sediment in areas (where it is already occurring), stabilize the coastal shores, provide breeding ground for fishes. protects coastal lands from tsunami, hurricanes:and floods release oxygen back to the atmosphere, along with a little methane gas

• Alternative Energy sources
  • Renewable energy
  • Nuclear Power
  • Reduce the carbon intensity of fossil fuels
• Energy efficiency and conservation
  • Transport and urban planning
  • Building design
  • Reforestation and avoid deforestation
  • Eliminating waste methane
• Geoengineering
  • Greenhouse gas remediation
    • Biomass
    • Carbon air capture
    • Carbon capture and storage
  • Societal control
    • Population
    • Sustainable life-style

Deserts are formed in regions with less than 25 cm of annual rainfall, .or sometimes in hot regions where there is more rainfall, but unevenly distributed in the annual cycle.

Lack’ of rain in the mid latitude is often due to stable high pressure zones; deserts in temperate regions often lie in “rain shadows”, that is where high mountains block off moisture from the seas.

The climate:of these biomes is modified by altitUde and latitude. At greater distance from the equator the deSerts are cold and hot near equator and tropics.

As the large volume of water passes through the irrigation system, salts may be left behind that will gradually accumulate over the years until they become limiting, unless means of avoiding this difficulty are devised

Adaptations

(i)  These plants conserve water by following methods:

They are mostly shrubs. Leaves are absent or reduced in size.

Leaves and stem are succulent and water storing.

In some plants even the stem contains chlorophyll for photosynthesis.

Root system is well developed and spread over large area.

The annuals wherever present germinate, bloom and reproduce only during the short rainy season, and not in summer and winter.

(ii) The animals are physiologically and behaviorally adapted to desert conditions.

They are fast runners.

They are nocturnal in habit to avoid the sun’s heat during day time.

They conserve water by excreting concentrated urine.

Animals and birds usually have long legs to keep the body away from the hot ground.

Lizards are mostly insectivorous and can live without drinking water for several days.

Herbivorous animals get sufficient water from the seeds which they eat.

Mammals as a group are poorly adapted to  deserts

Indian Desert — Thar desert (hot)

The climate of this region is characterised by excessive drought, the rainfall being scanty and , irregular.

The winter rains of northern India rarely penetrate into the region.

The proper desert plants may be divided into two main groups.

1. i) depending directly upon on rain and
2. ii) those depending on the presence of subterranean water.

The first group consists of two types:

the ‘ephemera’s’ and the rain perennials’.

The ephemera’s are delicate annuals, apparently free from any xerophilous adaptations, having slender stems and root-systems and often large Flowers.

They appear almost immediately after rain, develop flowers and fruits in an incredibly short   time, and die as soon as the surface layer of the soil dries up.

The rain perennials are visible above the ground only during the rainy season, but have a perennial underground stem.

The second group – depending on the presence of subterranean water

By far the largest number of indigenous plants are capable of absorbing water from deep below the surface of the ground by means of a well-developed root system, the main part of which generally consists of a slender, woody tap root of extraordinary length.

Generally, various other xerophilous adaptations are resorted to such as reduced leaves, thick hairy growth, succulence, coatings of wax, thick cuticle, protected stomata, etc., all having for  their object of reduction of transpiration.

 

Fauna

It is home to some of India’s most magnificent grasslands and sanctuary for a charismatic bird, the Great Indian Bustard. Among the mammal fauna, the blackbuck, wild ass, chinkara, caracal, Sandgrouse and desert fox inhabit the open plains, grasslands, and saline depressions.

The nesting ground of Flamingoes and the only known population of Asiatic wild Ass lies in the remote part of Great Rarm, Gujarat.

It is the migration flyway used by cranes and flamingos.

Some endemic flora species of Thar Desert includes Calligonum Polygonoides, Prosopis cineraria, Tecomella undulate, Cenchrus biflorus and Sueda fruticosa , etc

 

Eutrophication is a syndrome of ecosystem, response to the addition of artificial or natural substances such as nitrates and phosphates through fertilizer, sewage, etc that fertilize the aquatic ecosystem.

The growth of green algae which we see in the lake surface layer is the physical identification of an Eutrophication.

Some algae and blue-green bacteria thrive on the excess ions and a population explosion covers almost entire surface layer is known as algal bloom.  Nitrogen testing is a technique to find the optimum amount of fertilizer required for crop plants. It will reduce the amount of nitrogen lost to the surrounding area.

 

 

HARMFUL ALGAL BLOOMS

Algae or phytoplankton are microscopic organisms that can be found naturally in coastal waters. They are major producers of oxygen and food for many of the animals that live in these waters.

Algal blooms can be any color, but the most common ones are red or brown.

Most algal blooms are not harmful but some produce toxins and do affect fish, birds, marine mammals and humans.

Use of algae

Most species of algae or phytoplankton serve as the energy producers at the base of the food web, without which higher life on this planet would not exist.

Why Red Tide is a misnomer?

“Red Tide” is a common name for such a phenomenon where certain

phytoplankton species contain pigments and “bloom” such that the human eye perceives the water to be discoloured.

Blooms can appear greenish, brown, and even reddish orange depending upon the type of organism, the type of water, and the concentration of the organisms.

The term “red tide” is thus a misnomer because blooms are not always red, they are not associated with tides, they are usually not harmful, and some species can be harmful or dangerous at low cell concentrations that do not discolour the water.

What are the causes of these blooms?

Two common causes are nutrient enrichment and warm waters.

 

Any – body of standing water, generally large enough in area and depth, irrespective of its hydrology, ecology, and other characteristics is generally known as lake.

Ageing of Lakes

The nutrient enrichment of the lakes promotes the growth of algae, aquatic plants and various fauna. This process is known as natural eutrophication.

Similar nutrient enrichment of lakes at an accelerated rate is caused by human activities and the consequent ageing phenomenon is known as ‘cultural eutrophication’.

In India, natural lakes (relatively few) mostly ile in the Himalayan region, the floodplains of Indus, Ganga and Brahmaputra.

Lake ‘Sudarshan’ in Gujarat’s Girnar area was perhaps the oldest man-made lake in India, dating back to 300 BC.

Lakes are also classified on the basis of their water chemistry. Based-on the levels of salinity, they are known as Freshwater, Brackish or Saline lakes (similar to that of classification of aquatic ecosystem).

On the basis of their nutrient content, they are categorized as Oligotrophic (very low nutrients), Mesotrophic (moderate nutrients) and Eutrophic (highly nutrient rich).

Removal of the nutrients from a lake

• Flushing with nutrient-poor waters.
• Deep water abstraction.
• On-site P-elimination by flocculation/flotation with water backflow, or floating Plant
• NESSIE with adsorbents.
• On-site algae removal by filters and P-adsorbers.
• 0n-site algae skimming and separator thickening.
• Artificial mixing / Destratification (permanent or intermittent).
• Harvest of fishes and macrophytes.
• Sludge removal

The Kyoto Protocol has put in place three flexibility mechanisms to reduce emission of Green House Gases. Although the Protocol places maximum responsibility of reducing emissions on the developed countries by committing them to specific emission targets, the three mechanisms are based on the premise that reduction of emissions in any part of the globe will have the same desired effect on the atmosphere, and also that some developed countries might find it easier and more cost effective to support emissions reductions in other developed or developing countries rather than at home. These mechanisms thus provide flexibility to the Annexure I countries, helping them to meet their emission reduction obligations. Let us take a look at what these mechanisms are.

What are the three flexibility mechanisms put in place of the Kyoto Protocol for reducing GHG emission?

• The three mechanisms are joint implementation. Emissions Trading and Clean Development

What is Joint Implementation?

• Through the Joint Implementation, any Annex I country can invest in emission reduction projects (referred to as joint Implementation Project) in any other Annex I country as an alternative to reducing emissions domestically.
• Two early examples are change from a wet to a dry process at a Ukraine cement works, reducing energy consumption by 53 percent by 2008-2012; and rehabilitation of a Bulgarian hydropower project, with a 267,000 ton reduction of C02 equivalent during 2008-2012.

What is Clean Development Mechanism?

• The Clean Development Mechanism (CDM) allows-‘l developed country with an emission reduction or emission-limitation commitment under the Kyoto Protocol to implement an emission reduction project in developing countries as an alternative to more expensive emission reductions in their own countries. In exchange for the amount of reduction In emission thus achieved, the investing gets carbon credits which it can offset against its Kyoto targets. The developing country gains a Step towards sustainable development.
• To get a CDM project registered and implemented, the investing country’ has to first take approval from the designated national authority in the host country, establish “Additionally”, define baselines and get the project validated by a third party agency, called a Designated Operational Entity (DOE). The Executive Body of CDM registers the project and issues credits, called Certified Emission Reductions (CERs), or carbon credits, where each unit is equivalent to the reduction of one metric tonne of. C02 or its equivalent. There are more than 4200 CDM projects in the pipeline as on 14.3.2010. The expected CERs till the end of2012 is 2,900,000,000

What is “Additionality” in a CDM project ?

• The feature of “additionality” is a crucial element of a CDM project it means that the industrialized country that is seeking to establish the CDM project in the developing country and earns carbon credits from it has to establish that the planned carbon reductions would not have occurred on its own, in the absence of the CDM project. They have to establish a baseline of the project. Which is the emission level that would have been there in the absence of the project. The difference between this baseline level and the (lower) emission level achieved as a result of the project is the carbon credit due to the investing country

What are some of the concerns regarding CDM ?

• The risk of “false Credits” is a cause for concern with regard to CDM projects. If a project does not actually offer an additionally and the reduction in emission would have happened anyway Even without the project.

 

 

defined as ‘an addition or excessive addition of certain materials to the physical environment (water, air and lands), making it less fit or unfit for life’.

Pollutants are the materials or factors, which cause adverse effect on the natural quality of any component of the environment.

Classifications

1. According to the form in which they persist after release into the environment.

• Primary pollutants: These persist in the form in which they are added to the environment e.g. DDT, plastic.
• Secondary Pollutants: These are formed by interaction among the primary pollutants. For example, peroxyacetyl nitrate (PAN) is formed by the interaction of nitrogen oxides and hydrocarbons.

2. According to their existence in nature.

• Quantitative Pollutants: These occur in nature and become pollutant when their concentration reaches beyond a threshold level. E.g. carbon dioxide, nitrogen oxide.
• Qualitative Pollutants: These do not occur in nature and are man-made. E.g. fungicides, herbicides, DDT etc.

3. According to their nature of disposal.

• Biodegradable Pollutants: Waste products, which are degraded by microbial action. E.g. sewage.
• Non-biodegradable Pollutants: Pollutants, which are not decomposed by microbial action. E.g. plastics, glass, DDT, salts of heavy metals, radioactive substances etc

4. According to origin

• Natural
• Anthropogenic

 

AIR POLLUTION

aggravated because of four developments:

Increasing traffic, growing cities, rapid economic development, and industrialization

contamination of air by the discharge of harmful substances

 

Major air pollutants and their sources

1. Carbon monoxide (CO)

• It is a colourless, odourless gas that is produced by the incomplete burning of carbon – based fuels including petrol, diesel, and wood.
• It is also produced from the combustion of natural and synthetic products such as cigarettes.
• It lowers the amount of oxygen that enters our blood. It can slow our reflexes and make us confused and sleepy.

2. Carbon dioxide (CO2)

principle greenhouse gas

3. Chloroflorocarbons (CFC)

• gases that are released mainly fromair-conditioning systems and refrigeration.
• When released into the air, CFCs rise to the stratosphere, where they come in contact with few other gases, which lead to a reduction of the ozone layer that protects the earth from the harmful ultraviolet rays of the sun.

 

4. Lead

present in petrol, diesel, lead batteries, paints, hair dye products, etc.

affects children in particular. cause nervous system damage and digestive problems and, in some cases, cause cancer.

 

5. Ozone

• occurs naturally in the upper layers of the atmosphere.
• at-the ground level, it is a pollutant with highly toxic effects.
• Vehicles and industries are the major source of ground-level ozone emissions.
• Ozone makes our eyes itch, burn, and water. It lowers our resistance to cold and pneumonia.

 

6. Nitrogen oxide (Nox)

• causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal.
• Nitrogen oxide can make children susceptible to respiratory diseases in winters.

 

7. Suspended particulate matter (SPM)

• consists of solids in the air in the form of smoke, dust, and vapour that can remain suspended for extended periods
• The finer of these particles when breathed in can lodge in our lungs and cause lung damage and respiratory problems.

 

8. Sulphur dioxide (S02)

• a gas produced from burning coal, mainly in thermal power plants.
• Some industrial processes, such as production of paper and smelting of metals, produce sulphur dioxide.
• a major contributor to smog and acid rain.
• Sulphur dioxide can lead to lung diseases

 

9. Smog

• a combination of the words fog and smoke. Smog is a condition of fog that had soot or smoke in it.
• interaction of sunlight with certain chemicals in the atmosphere.
• primary components of photochemical smog is ozone.
• Ozone is formed through a complex reaction involving hydrocarbons, nitrogen oxides, and sunlight. It is formed when pollutants released from gasoline, diesel- powered vehicles and oil-based solvents react with heat and sunlight from biofuels, the four most serious pollutants are particulates, carbon monoxide, polycyclic organic matter, and formaldehyde

 

Pollutants

1. i) Volatile organic compounds

The main indoor sources are perfumes, hair sprays, furniture polish, glues, air

fresheners, moth repellents, wood preservatives, and other products.

 

1. ii) Biological pollutants

It includes pollen from plants, mite, and hair from pets, fungi, parasites, and some bacteria.

iii) Formaldehyde

Mainly from carpets, particle boards, and insulation foam. It causes irritation to the eyes and nose and allergies.

1. iv) Radon

It is a gas that is emitted naturally by the soil. Due to modern houses having poor ventilation, it is confined inside the house and causes lung cancers.

 

Fly Ash

Ash is produced whenever combustion of solid material takes place.

Composition

1. Aluminium silicate (in.large amounts)
2. silicon dioxide (Si02) and
3. Calcium oxide (Ca0).

Fly ash particles are oxide rich and consist of silica, alumina, oxides of iron, calcium, and magnesium and toxic heavy metals like lead, arsenic, cobalt, and coppers

 

Policy measures of MoEF:

• The Ministry of Environment and Forests vide its notification in 2009, has made it mandatory to use Fly Ash based products in all construction projects, road embankment works and low lying land filling works within 100 kms radius of Thermal Power Station.
• To use Fly Ash in mine filling activities within 50 kms radius of Thermal Power Stations.
• Arresters: These are used to separate particulate matters from contaminated air.
• Scrubbers: These are used to clean air for both dusts and gases by passing it through a dry or wet packing material.

Government Initiatives

(1) National Air Quality Monitoring Programme

In India, the Central Pollution Control Board (CPCB) has been executing a nationwide programme of ambient air quality monitoring known as National Air Quality Monitoring

Programme (NAMP).

The National Air Quality Monitoring Programme (NAMP) is undertaken in India

(i) to determine status and trends of ambient air quality;

(ii) to ascertain the compliance of NAAQS;

(iii) to identify non-attainment cities;

(iv) to understand the natural process of cleaning in the atmosphere; and

(v) to undertake preventive and corrective measures.

Annual average concentration of SOx levels are within the prescribed National Ambient

Air Quality Standards (NAAQS).

National Ambient Air Quality Standards (NAAQS) were notified in the year 1982, duly revised in 1994 based on health criteria and land uses .

The NAAQS have been revisited and revised in November 2009 for 12 pollutants, which include. sulphur dioxide (S02), nitrogen dioxide (NO2), particulate matter having size less than 10 micron

(PM10),particulate matter having size less than 2.5micron (PM2.5), ozone, lead, carbon monoxide (CO), arsenic, nickel, benzene, ammonia, and. Benzopyrene.

WATER POLLUTION

Addition of certain substances to the water such as organic, inorganic,

biological, radiological, heat, which degrades the quality of water so that it

becomes unfit for use.

Putrescibility is the process of decomposition of organic matter present in water by microorganisms using oxygen.

Water having DO (dissolved oxygen)  content below 8.0 mg/L may be

considered as contaminated.  Water having DO content below. 4.0 mg/L is

considered to be highly polluted.

Water pollution by organic wastes is measured in terms of Biochemical Oxygen Demand-(BOD). BOD is the amount of dissolved oxygen needed by bacteria in decomposing the organic wastes present in water.

Chemical oxygen demand (COD) is a slightly better mode used to measure pollution load in water. It is the measure of oxygen equivalent of the requirement of oxidation of total organic matter (i.e. biodegradable and non- biodegradable) present in water.

A cripling deformity called Minamata disease due to consumption of fish captured from mercury contaminated Minamata Bay.

Water contaminated with cadmium can cause itai itai disease also called ouch-ouch disease (a painful disease of bones and joints) and cancer of lungs and liver.

The compounds of lead cause anaemia, headache, loss of muscle power and bluish line around the gum

Excess nitrate in drinking water reacts with hemoglobin to form non -functional met haemoglobin, and impairs oxygen transport.  This condition  is  called methaemoglobinemia or blue baby syndrome.

Over exploitation of ground water may lead to leaching of arsenic from soil and rock sources and contaminate ground water.  Chronic exposure to arsenic causes black foot disease. It also causes diarrhoea,-peripheral neuritis, hyperkerotosis and also   lung and skin cancer.

SOIL POLLUTION

Industrial waste includes chemicals such as mercury, lead, copper, zinc, cadmium, cynides, thiocynates, chromates, acids, alkalies, organic substances etc

Four R’s: Refuse, Reduce, Reuse, and Recycle

NOISE POLLUTION

Sound is measured in decibels (dB). An increase of about 10 dB is approximately double the increase in loudness.

A person’s hearing can be damaged if exposed to noise levels over 75 dB over a prolonged period of time.

The World Health Organization recommends that the sound level indoors should be less than 30 dB.

Ambient Noise Level Monitoring –   Noise Pollution (Control and Regulation) Rules, 2000 define ambient noise levels for various areas as follows-

1. Industrial Area—75DB to 70Db (Day time-6am to 10pm and night time 10pm to 6am ..75 is day time and 70 is night time)
2. Commercial Area–65 to 55
3. Residential Area–55 to 45
4. Silence Zone– 50  to 40

• The Government of India on Mar 2011 launched a Real time Ambient Noise Monitoring Network.
• Under this network, in phase- I, five Remote Noise Monitoring Terminals each have been installed in different noise zones in seven metros (Delhi, Hyderabad, Kolkata, Mumbai, Bangalore, Chennai and Lucknow).

In Phase II another 35 monitoring stations will be installed in the same seven cities.

Phase III will cover installing 90 stations in 18 other cities.

Phase-III cities are Kanpur, Pune, Surat, Ahmedabad,  Nagpur, Jaipur,  Indore,

Bhopal, Ludhiana, Guwahati, Dehradun, Thiruvananthpuram, Bhubaneswar,

Patna, Gandhinagar, Ranchi, Amritsar and Raipur.

Silence Zone is an area comprising not less than 100 metres around hospitals, educational institutions, courts, religious places or any other t area declared as such by a competent authority.

 

 

RADIO ACTIVE POLLUTION

Non-ionising radiations affect only those components which absorb them and have low penetrability.   They include short-wave radiations such as ultraviolet rays, which forms a part of solar radiation. Sunburns is due to these radiation Ionising radiations have high penetration power & cause breakage of macro molecules

They include X-rays, cosmic rays and atomic radiations -(radiations emitted by radioactive elements

Alpha particles, can be blocked by a piece of paper and human skin.

Beta particles can penetrate through skin, while can be blocked by some pieces of glass and metal.

Gamma rays can penetrate easily to human skin and damage cells on its way through, reaching far, and can only be blocked by a very thick, strong, massive piece of concrete radium-224, uranium-238, thorium-232, potassium-40, carbon-14, etc.

The nuclear arms use uranium-235 and plutonium-239 for fission and hydrogen or lithium as fusion material

The radio nuclides with long half-time are the chief source of environmental radioactive pollution.

Biosphere is a part of the earth where life can exist.

represents a highly integrated and interacting zone comprising of atmosphere (air), hydrosphere (water) and lithosphere (land) Life in the biosphere is abundant between 200 metres (660 feet) below the surface of the ocean and about 6,000 metres (20,000 feet) above sea level. absent at extremes of the North and South poles. Living organisms are not uniformly distributed  throughout the biosphere

The elements or mineral nutrients are always in circulation moving from non-living to living and then back to the non-living components of the ecosystem in a more or less circular fashion. This circular fashion is known as biogeochemical cycling (bio for living; geo for atmosphere).

1. Nutrient Cycling:

The nutrient cycle is a concept that describes how nutrients move from the physical environment to the living organisms, and subsequently recycled back to the physical environment.

It is essential for life and it is the vital function of the ecology of any region. In any particular environment, to maintain its organism in a sustained manner, the nutrient cycle must be kept balanced and stable.

 

Types of Nutrient Cycle

Based on the replacement period a nutrient cycle is referred to as Perfect or Imperfect cycle.

A perfect nutrient cycle is one in which nutrients are replaced as fast as they are utilised.

Most gaseous cycles are generally considered as perfect cycles.

In contrast sedimentary cycles are considered relatively imperfect, as some nutrients are lost from the cycle and get locked into sediments and so become unavailable for immediate cycling.

Based on the nature of the reservoir, there are two types of cycles namely Gaseous and sedimentary cycle

Gaseous Cycle — where the reservoir is the atmosphere or the hydrosphere, and

Sedimentary Cycle — where the reservoir is the earth’s crust.

 

2. Gaseous Cycles:

Water Cycle (Hydrologic)

The hydrologic cycle is the continuous circulation of water in the Earth-atmosphere system which is driven by solar energy.

Water moves from one reservoir to another by the processes of evaporation,

transpiration, condensation, precipitation, deposition, runoff,

infiltration, and groundwater flow.

 

3. The Carbon Cycle

without carbon dioxide life could not exist, because it is vital for the production of carbohydrates through photosynthesis by plants. It is the element that anchors all organic substances from coal and oil to DNA(deoxyribonudeic acid: the compound that caries genetic information) Carbon cycle involves a continuous exchange of carbon between the atmosphere and organisms. Carbon from the atmosphere moves to green plants by the process   of photosynthesis, and then to animals. By process of respiration and decomposition of dead organic matter it returns back to atmosphere.

 

4. The Nitrogen Cycle

an essential constituent of protein and is a basic building block of all living tissue. It constitutes nearly 16% by weight of all the proteins.

There is an inexhaustible supply of nitrogen in the atmosphere but the elemental form cannot be used directly by most of the living organisms needs to be ‘fixed’, that is, converted to ammonia, nitrites or nitrates, before it can be taken up by plants. on earth it is accomplished in three different ways:

(i) By microorganisms (bacteria and blue-green algae)

 

(ii) By man using industrial processes (fertilizerfactories) and

(iii) To a limited extent by atmospheric phenomenon such as thunder and lighting

The amount of Nitrogen fixed by man through industrial process has far

exceeded the amount fixed by the Natural Cycle.

As a result Nitrogen has become a pollutant which can disrupt the balance of

nitrogen. It may lead to Acid rain, Eutrophication and Harmful Algal Blooms.

Certain microorganisms are capable of fixing atmospheric nitrogen into

ammonium ions. These include free living nitrifying bacteria (e.g. aerobic

Azotobacter and anaerobic Clostridium) and symbiotic nitrifying bacteria living in  association with leguminous plants(pulse etc) and symbiotic bacteria    living in non leguminous root nodule plants (e.g. Rhizobium) as well as blue green algae (e.g. Anabaena, Spirulina).

Ammonium ions can be directly taken up as a source of nitrogen by some plants, or are oxidized to nitrites or nitrates by two groups of specialised bacteria:

Nitrosamines bacteria promote transformation of ammonia into nitrite. Nitrite is then further transformed into nitrate by the bacteria Nitrobacter.

The nitrates synthesised by bacteria in the soil are taken up by plants and converted into amino acids, which are the building blocks of proteins.

These then go through higher trophic levels of the ecosystem.

During excretion and upon the death of all organisms nitrogen is returned to the soil in the form of ammonia.

Certain quantity of soil nitrates, being highly soluble in water, is lost to the system by being transported away by surface run-off or ground water. In the soil as well as oceans there are special denitrifying bacteria (e.g. Pseudomonas), which convert the nitrates/nitrites to elemental nitrogen. This nitrogen escapes into the atmosphere, thus  completing the cycle.

The periodic thunderstorms convert the gaseous nitrogen in the atmosphere to ammonia and nitrates which eventually reach the earth’s surface through precipitation and then into the soil to be utilized by plants.(Better if You Check Diagram)

5. Sedimentary Cycle

Phosphorus, calcium and magnesium circulate by means of the sedimentary cycle.

(a) Phosphorus Cycle

Phosphorus plays a central role in aquatic ecosystems and water quality.

Phosphorus occurs in large amounts as a mineral in phosphate rocks and enters the cycle from erosion and minning activities.

This is the nutrient considered to be the main cause of excessive growth of rooted and free-floating microscopic plants in lakes.

The main storage for phosphorus is in the earth’s crust.

On land phosphorus is usually found in the form of phosphates.

By the process of weathering and erosion phosphates enter rivers and streams that transport them to the ocean.

In the ocean once the phosphorus accumulates on continental shelves in the form of insoluble deposits

After millions of years, the crustal plates rise from the sea floor and expose the phosphates on land.

After more time, weathering will release them from rock and the cycle’s

geochemical phase begins again.

(b) Sulphur Cycle

The sulphur reservoir is in the soil and sediments where it is locked in organic

(coal, oil and peat) and inorganic deposits (pyrite rock and sulphur rock) in the

form of sulphates, sulphides and organic sulphur.

 

It is released by weathering of rocks, erosional runoff and decomposition of organic matter and is carried to terrestrial and aquatic ecosystems in salt solution.

The sulphur cycle is mostly sedimentary except two of its compounds hydrogen sulphide

(H2S) and sulphur dioxide (SO2) add a gaseous component to its normal sedimentary cycle.

Atmospheric sulphur dioxide is carried back to the earth after being dissolved in rainwater as weak sulphuric acid.

sulphur in the form of sulphates is take up by plants and incorporate through a series of metabolic processes into sulphur bearing amino acid which is incorporated in the  proteins of autotroph tissues. It then passes through the grazing food chain.

Sulphur bound in living organism is carried back to the soil, to the bottom of ponds and lakes and seas through excretion and decomposition of dead organic material.