UGC NTA NET/JRF Exam, Environmental Sciences, March-2023

The period (P) of a sinusoidal sound wave (or any wave) is the time it takes for one complete cycle of the wave to pass a given point. In other words, it's the time between successive peaks or troughs.

Frequency (f) is the reciprocal of the period and denotes how many cycles occur in one second.

Wavelength (λ) refers to the spatial length of one full wave cycle (from peak to peak or trough to trough), while amplitude (A) measures the height of the wave from its mean value.

Radon is a naturally occurring radioactive gas that comes from the decay of uranium in soil, rock, and water. It's colorless, odorless, and tasteless, making it particularly challenging to detect without specialized equipment.

Radon can infiltrate buildings and homes, especially in basements and lower floors, where it can concentrate and pose significant health risks when inhaled. Prolonged exposure to high concentrations of radon has been linked to lung cancer, especially among smokers.

A sanitary landfill is an engineered method for disposing of solid waste on land. Unlike an open dump, where waste is merely piled up, a sanitary landfill involves spreading the waste in thin layers, compacting it, and then covering it with a layer of soil at the end of each day.

This daily cover minimizes the attraction of pests and helps control odors. The design of a sanitary landfill also incorporates systems for collecting leachate (liquid that has percolated through the waste) and gas.

Properly managed sanitary landfills have a much reduced environmental impact compared to open dumps, but they still have some environmental footprint, particularly if the liners or other containment systems fail.

The Plastic Waste Management Rules were first notified by the Ministry of Environment, Forest and Climate Change in India in 2016. This marked a significant step in addressing the challenges posed by plastic waste in the country.

The 2016 rules mandated the responsibility of producers, importers, and brand owners to adopt a system that ensures environmentally sound management of plastic products until the end of their life.

This is commonly referred to as the Extended Producer Responsibility (EPR). They also incorporated measures such as phasing out non-recyclable multi-layered plastics within two years, increasing the thickness of carry bags to promote reuse, and setting up plastic waste management systems in rural areas.

Рyrolysis is the thermal degradation of solid waste in the absence of oxygen. During pyrolysis, organic waste materials are chemically decomposed by heat, resulting in the production of liquid oil, gas, and solid char.

Pyrolysis of plastic waste can produce fuels that are similar to petroleum-based fuels. This process offers potential advantages for waste reduction, as well as the production of valuable products.

It differs from incineration, which is the combustion of waste with oxygen, often with the purpose of energy recovery.

When considering sustainable strategies for reducing solid waste, the "Timeput approach" is not a recognized or preferred method.

Generally, waste management focuses on strategies such as the "Input approach" which minimizes the generation of waste at the source, and the "Through-put approach" which emphasizes recycling and composting.

The "Output approach" is more about managing waste after its generation, like using landfills or incineration. Among the options provided, the "Input approach" and "Throughput approach" are crucial parts of the waste hierarchy which prioritizes waste prevention, followed by recycling, recovery, and disposal.

Brownfields are abandoned, idled, or under-used industrial and commercial facilities where expansion or redevelopment is complicated by real or perceived contamination.

These sites can be problematic due to potential environmental hazards, but they also offer opportunities for redevelopment. Revitalizing and reusing these properties can act as a catalyst for local economic growth and community revitalization.

It can also prevent urban sprawl by making use of existing infrastructure rather than building on previously undeveloped land, which is referred to as "Greenfields".

The Environmental Impact Assessment (EIA) Notification under the provision of the Environmental (Protection) Act, 1986, is primarily targeted at Development projects.

The EIA Notification mandates that specific developmental projects proposed in certain areas require an environmental clearance based on an assessment of their potential environmental impacts.

This process involves the evaluation of the environmental, social, and economic aspects of the proposed development.

The main objective is to ensure sustainable development by considering and mitigating the potential adverse environmental impacts before a project is approved.