Biology

Learninsta presents the core concepts of Biology with high-quality research papers and topical review articles.

Organic Farming and its Implementation

It is a method of farming system which primarily aims at cultivating the land and raising crops in such a way, so as to keep the soil alive and in good health by use of organic wastes (crop, animal and farm wastes, aquatic wastes) and other biological materials along with beneficial microbes (biofertilizers) to release nutrients to crops for increased sustainable production in an eco-friendly pollution free environment.

organic farming systems by the farmers in the following ways:

• The selection of locations not contaminated with chemicals
• Appropriate local types of rice plant
• Programming of appropriate crop rotation
• Processing soil with tools not contaminated with chemicals
• Intermitten irrigation
• Use of

Organic agriculture can be defined as “an integrated farming system that strives for sustainability, the enhancement of soil fertility and biological diversity while, with rare exceptions, prohibiting synthetic pesticides, antibiotics, synthetic fertilizers, genetically modified organisms, and growth hormones”.

Organic agriculture considers the medium- and long-term effect of agricultural interventions on the agro-ecosystem. It aims to produce food while establishing an ecological balance to prevent soil fertility or pest problems.

Advantages of Organic Farming

• Minimises the external cost of farming.
• Efficient use of resources.
• Soil and the environment is a public good.
• Healthier food.
• Healthier animals.
• Potential profits.
• Time involved.
• More labour intensive.

Organic farming eliminates the use of synthetic products to maximize the yields that can be produced. It works on creating a healthier soil instead, encouraging the link between healthy plants and protected soils. No chemical herbicides or pesticides are used. Only natural soil enhancement techniques are permitted.

There are basically two types of organic farming: pure organic farming and integrated organic farming. With pure organic farming, the method includes the use of manures and biopesticides with complete avoidance of inorganic chemicals and pesticides.

In the process of pure farming, fertilizer and pesticides obtain from natural sources. It is called a pure form of organic farming. (b) Integrated organic farming – Integrated organic farming consists of integrated nutrients management and integrated pest management.

In a few words, organic farming involves growing techniques and methods that seek to protect the environment, humans, and animals, through sustainable agriculture. As fertilization methods, they mainly use manure, compost, or special organic synthetic fertilizers.

Learninsta presents the core concepts of Biology with high-quality research papers and topical review articles.

Eutrophication | Definition, Types, Causes, & Effects

When run-off from land containing nutrients reaches water bodies like lakes, it results in dense growth of plant life. This phenomenon is called Eutrophication. Natural aging of lakes also leads to nutrient enrichment of its water.

In a lake, the water is cold and clear (oligotrophic stage), supporting little life. With time, streams draining into the lake introduce nutrients such as nitrates and phosphates, which encourage the growth of aquatic organisms. Aquatic plants and animal life grow rapidly, and organic remains begin to be deposited on the lake bottom (mesotrophic stage) (Fig. 12.5).

Pollutants from anthropogenic activities like effluents from the industries and homes can radically accelerate the aging process. This phenomenon is known as Cultural or Accelerated Eutrophication.

Nutrients stimulate the growth of algae, water hyacinth and can cause clogging of canals, rivers and lakes as well as, displacing native plants. It causes unsightly foam and unpleasant odours, and deprives the water of dissolved oxygen.

Integrated Wastewater Management

Wastewater Treatment

Wastewater or sewage originates from domestic waste waters, industrial wastes and animal wastes. Realizing the importance of clean potable water, the Government passed the Water (Prevention and Control of Pollution) Act in 1974, which made it mandatory to treat wastewater in treatment plants. The main objective of a wastewater treatment process is to reduce organic and inorganic components in wastewater to a level that it no longer supports microbial growth and to eliminate other potentially toxic materials.

Microorganisms mainly bacteria and some protozoa play an essential part in the treatment of sewage to make it harmless. Sewage contains pathogenic bacteria. These bacteria must be destroyed in order to prevent the spread of diseases. Sewage treatment is usually performed in the following three stages (Fig. 12.6).

Primary treatment

Primary treatment involves the physical removal of solid and particulate organic and inorganic materials from the sewage through filtration and sedimentation. Floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.

Secondary treatment or biological treatment

The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into floc (masses of bacteria associated with fungal fiaments to form mesh like structures).

While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (Biochemical oxygen demand or Biological oxygen demand). BOD refers to the amount of the oxygen that would be consumed, if all the organic matter in one litre of water were oxidized by bacteria. The sewage water is treated till the BOD is reduced. The greater the BOD of the waste water more is its polluting potential.

Once the BOD of sewage water is reduced signifiantly, the effluent is then passed into a settling tank where the bacterial “flocs” are allowed to sediment. This sediment is called activated sludge. A small part of activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, the bacteria which grow anaerobically, digest the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and CO₂. These gases form biogas and can be used as a source of energy.

Tertiary treatment

Tertiary treatment is the final process that improves the quality of the waste water before it is reused, recycled or released into natural water bodies. This treatment removes the remaining inorganic compounds and substances, such as nitrogen and phosphorus.

UV is an ideal disinfectant for wastewater since it does not alter the water quality – except for inactivating microorganisms. UV is a chemicalfree process that can completely replace the existing chlorination system and also inactivates chlorine-resistant microorganisms like Cryptosporidium and Giardia.

Case Study:

Auroville, located in South India near Puducherry has been experimenting with natural wastewater recycling systems (Decentralized Waste Water Treatment System (DEWATS)) (Fig.12.7a). Such treatment plants have now also been implemented in Aravind Eye Hospital, Puducherry (Root Zone Wastewater Treatment (RZWT)) (Fig.12.7 b) and the Chennai Mathematical Institute, Siruseri IT Park, Chennai.

Learninsta presents the core concepts of Biology with high-quality research papers and topical review articles.

Biomagnification Definition and its Effects

Food chains are components of all ecosystems. Producers and consumers form trophic levels in a chain through which energy flow is carried out by the process of eating and being eaten. Usage, storage and transformation of food and biomolecules by metabolism are a normal process. Degradation or breakdown is an essential part of any food chain and hence all naturally occurring substances are degradable.

Biomagnifiation of DDT

When non-degradable substances enter the food chain, they do not get metabolized or broken down or expelled and instead get transferred up the tropic levels of the food chain. During this process, they show an increase in concentration which is referred to as biomagnification.

This results in increased toxicity and may even be lethal. This phenomenon is well established for mercury and DDT. Fig 12.4 schematically shows biomagnifiation of DDT in an aquatic food chain where the concentration of DDT is enhanced at successive trophic levels.

Biomagnification is the method of accruing toxic elements by different organisms within a food chain. A prominent example of it is the presence of mercury within predatory fish. This level is so high that consuming these can cause cancer.

What are the substances responsible for biomagnification. Biomagnification refers to the accumulation of toxic substances in the food chain. The pesticides and chemicals such as DDT, and mercury released into the lakes and rivers are ingested by the aquatic organisms.

Bioaccumulation refers to the accumulation of a toxic chemical in the tissue of a particular organism. Biomagnification refers to the increased concentration of a toxic chemical the higher an animal is on the food chain.

Biomagnification is the accumulation of a chemical by an organism from water and food exposure that results in a concentration that is greater than would have resulted from water exposure only and thus greater than expected from equilibrium.

Biomagnification is the increase of harmful substances or chemicals in the normal food chain process. It is bad because many living things die due increase in harmful chemicals.

Biomagnification can occur in both terrestrial and aquatic environments, but it is generally used in relation to aquatic situations. Most often, biomagnification occurs in the higher trophic levels of the food chain/web , where exposure to chemicals takes place mostly through food consumption rather than water uptake.

Bioaccumulation is when a harmful substance (pesticides or organic chemicals) gets absorbed by an organism at a higher rate than it can be excreted. Even if the environment doesn’t have a high amount of toxin in it, accumulation through the food chain can be devastating for organisms.

Learninsta presents the core concepts of Biology with high-quality research papers and topical review articles.

An Overview of Agrochemicals

Chemicals which are used in agriculture for growth of plants and pest control are called agrochemicals or agrichemicals. Overuse of agrochemicals have been observed to generate residues that cause nutrient imbalance. In addition,

1. May kill beneficial bacteria and soil organisms.
2. Can cause eutrophication in water bodies.
3. Affect aquatic animals and their productivity.
4. Pesticide containing water, even in trace quantities is unfi for human consumption.
5. Particles (aerosols) and residues of these chemicals cause air pollution.
6. Inhalation of contaminated air can cause respiratory problems.
7. Consumption can lead to poisoning, side effects and after effects.
8. Chemicals can cause skin rashes and irritation of eyes.
9. Many of these chemicals are reported to be carcinogenic.
10. They can trigger hormonal disorders and neurotoxicity.
11. Beneficial insects and animals can be affected.

Learninsta presents the core concepts of Biology with high-quality research papers and topical review articles.

Noise Pollution | Definition, Examples, Effects and its Causes

Sound that is unwanted and undesirable or can disrupts one’s quality of life is called as Noise. When there is lot of ‘noise’ in the environment, it is termed as Noise Pollution. The intensity of noise is meaured in decibels (dB).

Sources of Noise Pollution

Vehicle engines, air horns, audio video systems, trains, low flying aircrafts, factory machines, sirens, motors, drillers and crushers, compressor machines, crackers, explosives, modern supersonic transports are the common sources of noise pollution.

The threshold of pain is about 120 db. World Health Organization has proposed that noise must be recognized as a major threat to human well-being. This is applicable for all living organisms.

Effect of Noise Pollution

• According to the USEPA (United States Environmental Protection Agency) there are direct links between noise and health.
• Heart disease, high blood pressure, stress related illness, sleep disruption, hearing loss (deafness), and productivity loss are the problems related to noise pollution.
• Increased stress and tension, nervousness, irritability, anxiety, depression and panic attacks.
• Peptic ulcer, severe head ache, memory loss.
• Marine animals are affected by noise pollution from offshore activities and port activities.
• Fire crackers frighten animals. Birds are often affected by increased air traffic.

Control

• Planting trees in and around noise sources is an effective solution for noise pollution as plants are known to absorb noise and bring down sound levels.
• Regular servicing and tuning of automobile engines can effectively reduce noise pollution by vehicles and machinery.
• Workers should be provided with ear plugs and earmuffs at work sites that generate high noise levels.
• Lubrication of machinery and regular servicing minimizes noise levels.
• Regulations should be imposed to restrict the usage of loudspeakers in crowded areas and public places.

Legal Protection

Article 48-A and Article 51-A of the Constitution of India, Noise Pollution (Regulation and Control) Rules 2000, and Tamil Nadu State Environment Policy 2017 are some of the legal relief from noise pollution.

According to Noise Pollution (Regulation and Control) Rules, 2000, the permissible limit of noise in areas categorized as commercial is 65 decibels (dB) during day and 55 dB during night.