Problem 79 - A Complete Resource Book in Chemistry for JEE Main

Question

What is DDT among the following- (a) Biodegradable pollutant (b) A fertilizer (c) Greenhouse gas (d) Non - biodegradabl pollutant

Step-by-Step Solution

Answer

DDT is a non-biodegradable pollutant.

Step 1: Understanding the Question

The question asks us to determine which category DDT belongs to from the given options. The options include categories such as type of pollutant, fertilizer, and greenhouse gas.

Step 2: Analyzing DDT

DDT, or dichloro-diphenyl-trichloroethane, is a chemical used as a pesticide. It is known for its effectiveness in pest control.

Step 3: Determining Biodegradability

A chemical is considered biodegradable if it can be broken down naturally by bacteria or other organisms. DDT is notorious for its persistence in the environment, indicating it is not a biodegradable pollutant.

Step 4: Matching with Options

The given options include: (a) Biodegradable pollutant, (b) A fertilizer, (c) Greenhouse gas, and (d) Non-biodegradable pollutant. Since DDT is persistent in the environment and not easily broken down, it fits best with option (d).

Key Concepts

Pesticides

Pesticides are chemicals or substances used to eliminate or control pests. These pests might include insects, plants, fungi, or any other organisms that adversely affect crop production and livelihoods. DDT, which stands for dichloro-diphenyl-trichloroethane, is a well-known pesticide. It was widely used during the mid-20th century for its effectiveness in reducing mosquito populations, thus helping to control diseases like malaria. However, the use of DDT is now restricted or banned in many countries due to its adverse environmental impacts.

Pesticides work by interfering with biological systems of pests, but they can also pose risks to human health and non-target organisms. This is why understanding the type and application methods are crucial for safe usage. Each pesticide has a specific mode of action suitable for different pest control needs.

Biodegradability

Biodegradability refers to the ability of a substance to be broken down naturally by living organisms, such as bacteria, fungi, or other microorganisms. A biodegradable pollutant will decompose over time, reducing its impact on the environment. However, DDT is not biodegradable; it does not break down easily and can persist in the environment for a very long time.

The lack of biodegradability means DDT accumulates in the tissues of animals and humans, a process known as bioaccumulation. Eventually, these substances move up the food chain, which can have damaging effects on top predators, including humans. Therefore, biodegradable solutions are usually safer alternatives as they minimize long-term hazards.

Environmental Persistence

Environmental persistence describes how long a chemical remains in the environment without breaking down. DDT is infamous for its high level of persistence. Once introduced into the environment, it can remain active for many years, even decades. This persistence was part of the reason it was initially praised, as it meant less frequent applications were needed. However, we now understand that such persistence has severe drawbacks.

This persistence leads to several environmental issues:

• Contamination of soil and water sources
• Harm to wildlife, especially birds who suffer from thinning eggshells
• Potential risks to human health through the food chain

These concerns have prompted the search for more sustainable pest control alternatives that break down more quickly.

Pollutants

Pollutants are substances introduced into the environment that cause harm or discomfort to ecosystems, living organisms, and humans. DDT is categorized as a pollutant because it adversely affects both the environment and living organisms. Unlike biodegradable pollutants, DDT remains in the environment for an extended period without degrading, leading to its classification as a non-biodegradable pollutant.

The presence of pollutants like DDT in the environment can lead to serious implications such as:

• Disruption of ecosystems and food chains
• Bioaccumulation in wildlife and humans
• Long-term health issues, including cancer and reproductive harm

Thus, managing and reducing pollutants through regulation, innovation, and education is necessary to protect our environment and health. Developing better practices and safer alternatives can greatly mitigate the harmful impacts of pollutants like DDT.