Any undesirable change in the environment that can affect the physical, chemical, and biological components is known as environmental pollution. All the elements that are responsible for causing this undesirable change are known as pollutants. 

Pollutants are a major matter of concern in the environment. They remain in the environment for hundreds of years without degradation. However, some may also degrade with time. They are present in solid, liquid, or gaseous states in the environment. It is also said that most of them are formed as a result of human activities. However, some can also be a result of natural happenings. 

Common pollutants that are non-biodegradable and most harmful are: DDT, plastic, metal scraps, and so on. They are transported in air or water by human activities or dumped in the soil where they remain for centuries.

Our Earth is surrounded by a thick blanket known as the atmosphere. It is divided into several layers. They are:

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Ionosphere 
• Exosphere 

When the composition of the gases present in the atmosphere is harmed due to the addition of other harmful chemicals or elements, it is known as atmospheric pollution.

Tropospheric Pollution
Various elements cause tropospheric pollution. The major pollutants that cause the same are:

• Gaseous Air Pollutants: They are derived from factories, industries, power plants, pesticides, insecticides, oil refineries, etc. They release oxides of sulfur, oxides of nitrogen, and hydrocarbons into the environment.

 

• Particulate Pollutants: They are derived from metal extraction, pesticides, insecticides, threshing, cigarette smoking, etc.They release fumes, dust, and mists into the environment.

Global Warming and Greenhouse Effect

About 75% of the heat from the sun can be absorbed by the Earth’s surface. The rest is reflected back to the sun. However, this heat gets trapped due to the presence of carbon dioxide, ozone, methane, and CFC compounds. This, in turn, increases the Earth’s temperature. This is known as global warming.

This phenomenon is similar to that of the greenhouse effect that is used to grow plants in colder regions. The heat is trapped in the glass walls so that the plants can have enough heat and sunlight while growing. However, it doesn’t harm the environment, but global warming surely does. 

The gases that increase the temperature of Earth are known as greenhouse gases. They include methane, carbon dioxide, ozone, and so on. They are produced by burning fossil fuels, use of pesticides, dumping industrial waste, etc.

Ozone Depletion

The hole in the ozone layer is known as the ozone hole or ozone depletion. Due to the increase in CFCs in the environment, the ozone layer is depleting more than ever before. Ozone prevents harmful UV radiation from entering the Earth’s surface. However, the depletion of ozone means the entry of these rays into the Earth’s surface. They can cause skin cancer, kill aquatic life, and so on.

Acid Rain

Whenever the pH of the rain falls below 5.7, it gives rise to acid rain. It means that the rain has acidic elements like sulfuric or nitric acid. It can be in the form of rain, hail, fog, or even snow. 

It is formed by the mixing of harmful gases and oxides with rainwater. Industrial waste dumped into the open can mix with rainwater. The gases emitted by vehicles or industries can react with water to form acids. 

The reactions that can probably take place are:

S + O2 = SO2

N + O2 = NO2

C + O2 = CO2

SO2 + H2O = H2SO3

2H2SO3 + O2 = 2H2SO4

2NO2 + H2O = HNO3 + HNO2

2HNO2 + O2 = 2HNO3

CO2 + H2O = H2CO3

Causes of Acid Rain
They include:

• Burning of fossil fuels.
• Forest fires.
• Volcanic eruptions.
• Power plants.
• Industrial waste.
• Vehicles that run on petrol or diesel.

Prevention of Acid Rain
There are several ways to reduce acid rain. These are:

• Prevention of burning of fossil fuels.
• Using electric vehicles or cycles.
• Proper waste management from industries.
• Planting more trees.

The contamination of water resources due to various human activities is known as water pollution. The elements that cause water pollution are known as water pollutants. 

The various causes of water pollution are:

• Pathogens: They are disease-causing agents present in the water. They’re very harmful to humans and can cause gastrointestinal infections.
• Organic Waste: The presence of organic waste in water bodies like leaves, grass, and even phytoplanktons can pollute the water.
• Chemical Pollutants: Some inorganic chemicals or metals can mix with water to degrade it significantly. These include lead, mercury, nickel, etc. They’re sourced mainly from industrial waste.

The contamination of the soil due to various sources and human activities is known as soil pollution. The various pollutants that cause soil pollution are: 

• Pesticides: DDT came into use to prevent the spread of malaria and also to protect plants against pests. However, these synthetic chemicals can go deep into the soil and cause metabolic and physiological conditions later. 
• Detergents: We use detergents to clean our clothes. However, we do not pay attention to the chemicals used in making it. It is non-biodegradable and remains in the soil for many years, and pollutes it. 
• Industrial Waste: Industries and power plants dump their waste into the ground without treating it. They seep deep into the soil, harming it.

As mentioned above, it is quite obvious that industrial waste is one of the major causes of all types of environmental pollution. The waste generated by industries is in gaseous, liquid, or even solid form. They are further divided into categories: biodegradable and non-biodegradable wastes. 

Most of the industrial waste comes under the non-biodegradable category. This means that they remain in the environment for a long time and contaminate it. 

Management of industrial waste can greatly reduce the pollution in our environment. The waste should be treated properly before releasing it into the water, air, or soil.

As we discuss the Environmental Chemistry Class 11 NCERT chapter, it is important we also know ways and means to control environmental pollution. They are: 

• A thorough awareness about environmental pollution and how our activities are contributing towards the same. 
• A well-managed system that manages all kinds of wastes, including solid, gaseous, and liquid wastes.
• The segregation of biodegradable waste from non-biodegradable ones. 
• The proper collection and disposal of all types of waste.
• Adapting strategies that focus on the 3 Rs of the environment. They include: reduce, recycling, and reusing.

As we have discussed so far, it is clear that the overuse of fertilizers, pesticides, and weedicides is causing serious and permanent damage to the environment. The exploitation of our soil can lead to its infertility in the long run and leave huge yards barren. 

This is where green chemistry came into play. With green chemistry, scientists are looking at ways and means to implement the existing knowledge of chemistry towards the welfare of the environment. The main goal is to reduce environmental pollution and protect the environment for future generations. Green chemistry is one such important process that will bring about a great change in the environment.

1. What are the topics covered in environmental chemistry?

The topics covered are environmental pollution, atmospheric pollution, water pollution, soil pollution, industrial waste, strategies to reduce pollution, and green chemistry.

2. What are the key features of Class 11 Environmental Chemistry? 

It is the detailed study of all the physical and chemical processes that take place in water, air, soil, and the environment as a whole.

3. Why do we study environmental chemistry?

We study environmental chemistry to understand our surroundings better and how our activities affect them negatively. This will make us more aware of climate change, global warming, and environmental pollution. Hence, we will find strategies to reduce it all.