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 (option d).

Step 1: Identify DDT

DDT stands for Dichloro-Diphenyl-Trichloroethane. It is a chemical compound that was widely used as a pesticide.

Step 2: Understand Biodegradability

Biodegradable pollutants are substances that can be broken down by microorganisms into harmless, natural substances.

Step 3: Classify DDT as Biodegradable or Non-biodegradable

DDT is known to persist in the environment and accumulate in the food chain. It is not easily broken down by natural processes.

Step 4: Analyze Options

We need to find out which option correctly represents DDT. From Step 3, we conclude that DDT is a non-biodegradable substance.

Step 5: Choose the Correct Answer

Given the options, DDT fits the description of a 'Non-biodegradable pollutant' from option (d).

Key Concepts

Non-biodegradable pollutants

Non-biodegradable pollutants are substances that cannot be easily broken down by natural processes in the environment. This means they do not decompose into simpler forms over time. Instead, they persist for a long duration, causing potential harm. These pollutants build up in our surroundings, leading to adverse effects on ecosystems and human health.

Examples of non-biodegradable pollutants include plastic, certain metals like lead and mercury, and chemical compounds such as DDT. These materials accumulate as they make their way through various environmental mediums, such as water, soil, and the atmosphere.

• Plastics often end in water bodies, disrupting marine habitats.
• Heavy metals can contaminate soil and groundwater, posing health risks.
• Persistent chemical compounds can travel through the food chain, accumulating in living organisms.

To address non-biodegradable pollutants, strategies like recycling, sustainable waste management, and stricter regulation on harmful chemicals are essential. Without active management, these pollutants can significantly degrade environmental quality and biodiversity.

Pesticides

Pesticides are chemical substances designed for preventing, destroying, or controlling pests. These pests include insects, weeds, fungi, and rodents that can harm crops and spread diseases. Farmers widely use pesticides to enhance crop yield and agricultural productivity.

There are different types of pesticides based on their target. These include:

• Insecticides for insect control
• Herbicides for weed management
• Fungicides to eliminate fungal pathogens
• Rodenticides to control rodent populations

Pesticides can be synthetic or derived from natural sources. However, synthetic varieties, like DDT, have been infamous for their long-lasting effects on the environment.

While pesticides do offer advantages, they also have drawbacks like potential toxicity to non-target species, including humans. Thus, safer and eco-friendly alternatives, such as organic farming and integrated pest management (IPM), are gaining popularity.

Environmental impact of DDT

The environmental impact of DDT, a prime example of a synthetic pesticide, is profound and long-lasting. Initially, DDT gained popularity in the mid-20th century for combating malaria and agricultural pests. Despite its effectiveness, its ecological and health impacts became evident over time.

DDT is non-biodegradable, meaning it does not break down in the environment, causing it to accumulate. This persistence leads to bioaccumulation and biomagnification:

• Bioaccumulation: DDT tends to accumulate in the fatty tissues of living organisms.
• Biomagnification: As DDT moves up the food chain—from smaller organisms to larger predators—the concentration increases, posing significant risks to wildlife such as birds.

The discovery of its harmful impacts led to diverse actions, including DDT bans in many countries. Specifically, it was found to weaken the eggshells of birds like eagles, leading to declining populations.

Today, the legacy of DDT has steered global awareness towards the proper regulation of pesticides, aimed at protecting health and conserving the environment. The development of safer alternatives is essential to support sustainable agricultural practices.