Problem 31 - A Complete Resource Book in Chemistry for JEE Main

Question

Acid rain (a) retards the growth of trees (b) effects big marble constructions (c) results in loss of flora and fauna (d) all of these

Step-by-Step Solution

Answer

(d) all of these

Step 1: Understanding Acid Rain

First, understand what acid rain is. Acid rain is rain that is unusually acidic due to the presence of pollutants like sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) in the atmosphere. When these compounds mix with water vapor, they form sulfuric and nitric acids, which then fall as precipitation.

Step 2: Effect on Trees

Acid rain impacts the health and growth of trees by leaching essential nutrients from the soil, such as calcium and magnesium, and harming leaves and bark. Therefore, it retards the growth of trees.

Step 3: Impact on Marble Constructions

Acid rain reacts with calcium carbonate present in marble, leading to chemical weathering known as dissolution. This affects the integrity of marble constructions, causing them to deteriorate.

Step 4: Impact on Flora and Fauna

Acid rain decreases the pH levels of water bodies and soil, which can be detrimental to local ecosystems, resulting in the loss of flora and fauna due to habitat changes and direct harm to species.

Step 5: Evaluating the Options

Consider each option provided: (a) retards the growth of trees, (b) affects big marble constructions, (c) results in loss of flora and fauna. Acid rain causes all of these impacts, therefore, the correct choice is the option that includes all of the stated effects.

Key Concepts

Impact on Trees

Acid rain poses a significant threat to trees by disrupting their growth and overall health. This phenomenon occurs because acid rain causes nutrients in the soil such as calcium and magnesium to leach away, leaving the roots of trees without the essential building blocks they need to thrive. When these nutrients are absent, trees struggle to perform critical functions, like photosynthesis and growth.
In addition, acid rain can directly affect tree foliage and bark. The acids in the rain can damage leaf structures, making it harder for trees to absorb sunlight. This damage then compromises the tree's ability to produce food and grow. Over time, the cumulative effect can lead to weakened trees that are more susceptible to diseases and pests, affecting entire forest ecosystems. Understanding this impact emphasizes the importance of addressing pollution sources to protect trees and their habitats.

Effects on Marble Constructions

The corrosive nature of acid rain is particularly damaging to marble constructions. Marble is primarily composed of calcium carbonate, a compound that reacts with sulfuric and nitric acids found in acid rain. This reaction leads to a chemical process known as dissolution.
As a result of this process, the marble surface gradually wears away. Over time, structures lose their detailed carvings and inscriptions, which are often seen in historical monuments. Icons of culture and history, such as statues and building facades, are especially vulnerable to this form of decay.

• Acid rain transforms the surface of marble into a powdery substance called gypsum, which can be easily washed away by rain and wind.
• Even a slight increase in acidity can accelerate the degradation process extensively.

Protection of these structures necessitates efforts to curb pollutants that contribute to acid rain. This ensures the preservation of cultural heritage sites for future generations.

Impact on Flora and Fauna

Ecosystems face substantial risks from acid rain, affecting both flora and fauna. As acid rain lowers the pH levels in soil and water bodies, the subtle balance needed for most plants and animals to survive is thrown off. Plants, much like trees, suffer from nutrient deficiencies due to soil acidification.
Aquatic life is particularly vulnerable. Lowered pH levels in water bodies can lead to environments that are hostile to many fish and aquatic organisms, leading to declines in biodiversity. For example, many freshwater fish are unable to survive in waterways with decreased pH, resulting in dying fish populations.

• Acidified water can release toxic metals, like aluminum, into the ecosystem, which harms fish gills and plant roots.
• The decline in fish populations affects animals higher up in the food chain, including birds and mammals that rely on aquatic species for food.

The interconnectedness of ecosystems means that the impact on flora and fauna can extend far beyond initial acidification, highlighting the importance of reducing emissions that lead to acid rain.