Biodiversity

Biodiversity

The variety or variability of organisms and ecosystem is referred to as biodiversity. 

The existence of million of plants, animals, and micro-organisms, their genetic backgrounds, and the complex ecosystems to which they belong show the immense biodiversity present in the biosphere.
Types of Biodiversity
•Genetic diversity - Diversity of genes within a species, i.e., genetic variability among the populations and the individuals of the same species.
• Species diversity- Diversity among species in an ecosystem. ‘Biodiversity hotspots’  are excellent examples of species diversity.
• Ecosystem diversity- Diversity at a higher level of organization, i.e., the ecosystem. It concerns the variety of ecosystems on Earth.
Value of  Biodiversity
•Survival

•Health and healing

•Food security

•Productive value

•Ethical value

•Aesthetic pleasure

•Ecological services

Hotspots of Biodiversity

Hotspots are the richest and the most threatened reservoirs of plant and animal life on earth.

Hotspots are classified on the basis of three criteria :

•The number of species present

•The number of those species that exist exclusively in the given                                                      ecosystem

•The degree of threat they face

Endangered Species

The species which are at the verge of extinction are known as endangered species. For example

•Asiatic elephant

•Great Indian Rhino

Endemic Species

The species which are confined to a particular region are known as endemic species.

These species remain limited in their distribution because of certain geographical barriers, such as sea, valley, mountain, etc.

Threats to Biodiversity

•Unplanned development and habitat destruction

•Poaching

•Environmental pollution

•Global climate change

•Invasion by introduced species

•Nature of legal systems

•Mining

•Exploitation of water resources

•Eutrophication

•Waste disposal

Conservation of Biodiversity

In situ Conservation

•National parks

•Wildlife sanctuaries

•Biosphere reserves

Ex situ Conservation

•Gene banks

•Botanical gardens

•Aquaria

•Tissue culture technique

•DNA technology

Biodiversity at Global  Level

On the Basis of  Vegetation

•Arctic  Zone

•Northern Temperate  Zone

•South Temperate Zone

•Tropical  Zone

On the Basis of  Fauna

 

•Oriental Region

•Australian Region

•Neotropical Region

•Nearctic Region

•Paleartic Region

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sewage treatment

    Sewage treatment

Sewage is a mixture of domestic and industrial wastes. It is more than 99% water, but the remainder contains some ions, suspended solids and harmful bacteria that must be removed before the water is released into the sea.

The treatment of wastewater is divided into three phases:

*Pretreatment,

*Primary treatment and
*Secondary treatment.
Pretreatment
Large solids (i.e. those with a diameter of more than 2cm) and grit (heavy solids) are removed by screening. These are disposed of in landfills.
Primary treatment
The water is left to stand so that solids can sink to the bottom and oil and grease can rise to the surface. The solids are scraped off the bottom and the scum is washed off with water jets. These two substances are combined to form sludge.
Secondary treatment
The sludge is further treated in 'sludge digesters': large heated tanks in which its chemical decomposition is catalysed by microorganisms. The sludge is largely converted to 'biogas', a mixture of CH4 and
CO2, which is used to generate electricity for the plant.
The liquid is treated by bacteria which break down the organic matter remaining in solution. It is then sent to oxidation ponds where heterotrophic bacteria continue the breakdown of the organics and solar UV light destroys the harmful bacteria.

The role of the laboratory:-

A wide variety of analytical tests are used to determine the purity of the wastewater at various stages of treatment so that the possibility of harm to either people or the environment is minimised.

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Soil Erosion

Soil Erosion

The detachment and transportation of the fertile layer of soil by water or air.
Causes of Soil Erosion
•Large-scale deforestation for meeting commercial as well as day-to-day needs
•Heavy floods in rivers
•Overgrazing by cattle
•Dry violent winds
•Improper agricultural techniques 
Effects of Soil Erosion
•Decrease in productivity of land
•Desertification of  land
•Reduction in the agricultural land at the banks of rivers
•Deposition of soil in river beds and canals causing diversion of
•their natural flow and hence leading to disasters
Methods of Controlling Soil Erosion
•Reduced tillage
•Contour bunding
•Vegetative bunds
•Strip cropping
•Terracing
•Afforestation on barren land
•Control of overgrazing
•Construction of small check dams
•Promotion of equitable use of water resources
•Prevention of excavation of rocks