Environmental Chemistry

Environmental chemistry studies chemical processes in air, water, and soil, analysing their origins, reactions, transport, and effects. It examines how natural and human activities influence ecosystems and human health. This field addresses pollution, climate change, and resource sustainability by identifying harmful substances and their impact. Key areas include atmospheric, water, and soil chemistry, along with pollution control and green chemistry solutions. Understanding environmental chemistry is crucial for developing eco-friendly practices, reducing pollutants, and mitigating environmental damage. 

Environmental Segment:

There are four environmental segments are present:

• Atmosphere: It is the protective layer of gases and supports life and a hostile environment of outer space. It can transmit only UV, visible, IR, and radio-waves. 

• Hydrosphere: It mainly covers more than 75% of the surface of the earth.  

• Lithosphere: It consists of three major layers such as crust, mantle, and outer, inner core. It significantly consists of minerals from the outer mantle of solid earth. 

• Biosphere: It replenishes us with foods, and there remains cycling of materials through excretion, expiration, and extinction of the form. 

Types of Pollution

1. Atmospheric Pollution 

• Tropospheric Pollution: This type of pollution occurs in the troposphere, the lowest layer of the atmosphere, due to human activities such as the burning of fossil fuels. Major pollutants include:

• Sulfur Oxides (SOₓ): Released from coal and oil combustion, contributing to acid rain.

• Nitrogen Oxides (NOₓ): Emitted by vehicles and industrial processes, leading to smog and respiratory problems.

• Carbon Monoxide (CO): A toxic gas produced by incomplete combustion, reducing oxygen transport in the bloodstream.

• Volatile Organic Compounds (VOCs): Organic chemicals that contribute to ground-level ozone and smog formation.

• Particulate Matter (PM): Fine particles that can penetrate deep into the lungs, causing respiratory and cardiovascular diseases.

• Stratospheric Pollution: 

Stratospheric pollution primarily involves the depletion of the ozone layer, which protects the Earth from harmful ultraviolet (UV) radiation.

Ozone Depletion: Caused by substances like chlorofluorocarbons (CFCs) found in refrigerants and aerosols. When CFCs break down, they release chlorine atoms that destroy ozone molecules, forming the ozone hole.

Impact: Increased UV radiation leads to higher skin cancer rates, cataracts, and weakened immune systems, as well as environmental consequences like reduced crop yields and marine ecosystem disruption.

2. Water Pollution

Water pollution results from the discharge of harmful substances into water bodies. Common pollutants include pathogens, organic wastes, heavy metals, and chemical fertilisers. These pollutants can disrupt aquatic ecosystems and pose health risks to humans. 

Water pollution results from the discharge of harmful substances into water bodies. Common pollutants include:

• Pathogens: Disease-causing microorganisms like bacteria and viruses.

• Organic Wastes: Materials that decompose, reducing oxygen levels in water.

• Heavy Metals: Toxic elements like lead and mercury that accumulate in organisms.

• Chemical Fertilisers: Nutrients that cause excessive algae growth, leading to eutrophication.

Water pollution can be categorized into:

• Point Source Pollution: Comes from specific, identifiable sources such as industrial discharge, sewage leaks, or oil spills.

• Non-Point Source Pollution: Diffuse pollution from multiple sources, such as agricultural runoff, urban stormwater, and acid rain.

3. Soil Pollution

Soil pollution results from the accumulation of harmful chemicals in the soil, reducing its fertility and affecting plant, animal, and human health.

Major causes of soil pollution:

• Excessive use of pesticides and herbicides: Leads to soil degradation and contamination of crops.

• Industrial Waste: Hazardous chemicals from factories and mining sites seep into the soil, making it toxic.

• Heavy Metal Contamination: Elements like lead (Pb), mercury (Hg), and cadmium (Cd) accumulate in soil, entering the food chain and causing long-term health issues.

• Plastic and E-Waste Pollution: Non-biodegradable waste affects soil composition and can leach toxic substances.

Consequences of Soil Pollution:

• Loss of Soil Fertility: Reduces agricultural productivity.

• Bioaccumulation: Toxic substances enter the food chain, leading to health hazards.

• Groundwater Contamination: Pollutants seep into underground water sources, making drinking water unsafe.

Toxic Chemicals in the Environment:

The chemicals present in the atmosphere are both toxic and non-toxic in nature. Those toxic chemicals are continuously gushing from the industries into the air, water, soil, and finally to human food from the environment. Once these toxic chemicals are associated with the biological process, they create pernicious effects on the environment. 

There is an abundance of toxic elements found in the environment, and many of them are still unknown. These toxic metals are significantly known to provide detrimental effects to animals and human beings. These toxic metals are Al, Cu, Pb, Mo, Ag, In, Ti, Zn, Hg, As, Cd, Be, Ba, W, U, etc. All of these toxic metals are required in the least quantities for the development of animals. 

Classification of Toxic Matters:

Toxic matters are differentiated according to their effects and functions. These are:

• Mutagens: In the field of genetics, a mutagen is mainly known to change the genetic material, which is DNA. There are a plethora of chemicals directly interacting with DNA, such as PAH, benzenes, aromatic amines, etc. But these are not mutagenic in nature, but they produce mutagenic compounds in cells through metabolic procedures. 

• Carcinogens: These are mainly known as cancer-causing substances in animals and humans. There are plenty of carcinogens present such as radioactive isotopes, asbestos, radon, arsenic, and other heavy metals.   

• Pesticides: These are known as the chemicals to protect the fodders and grains from insects. One superior example of pesticides is DDT. 

• Food Additives: These are being applied to the food substances to conserve its flavor and elevates its appearance and taste. These are the types of food additives illustrated below:

1. Anti-caking Agents: It is known to protect elements from getting lumpy such as potassium aluminum silicate, calcium polyphosphate, etc.  

2. Antioxidants: It protects foods from going vapid or oxidized. Example: Vitamin C, disodium EDTA, etc.

3. Artificial Sweeteners: Enhance the sweetness. Example: aspartame, saccharin, etc.

4. Emulsifiers: Restrains fat from clotting together. Example: dimethyl polysiloxane.

5. Colors: example: nicotinamide, turmeric, tartrazine, etc.

6. Food Acids: Sustain the correct acid level in the food, such as 1,4-butyrolactone, potassium or sodium fumarate, etc.  

MCQ on Environmental Chemistry

This environmental chemistry MCQ for NEET will significantly help you to crack this examination:

1. Green Chemistry Defines Such Reactions Which:

1. curtail the usage and production of detrimental chemicals

2. Produce colors during various reactions

3. Study the reactions in plants

4. Are concerned with the depletion of the ozone layer.

Ans: (b) Produce colors during various reactions

2. Which of the Following Statement is not True:

1. Clean water should possess the BOD value of less than 5 ppm

2. The pH of drinking water should be in between 5.5-9.5

3. The concentration of DO should be lower than 6 ppm is best for the growth of fish.

4.  Oxides of nitrogen, sulfur, and carbon are the most extensive air pollutant

Ans: (a) Clean water should possess the BOD value of less than 5 ppm.

3. What is Biosphere?

1. The name of a bird

2. By which life evolved

3. In which isolated interact with each other

4. An organic compound

Ans: (c) In which isolated people interact with each other.

4. The Vital Air Pollutant Amidst the Following is:

1. CO2

2. CO

3. Sulfur

4. N2

Ans: (b) CO. 

5.  The Pollution can be Controlled by:

1. Checking atomic blasts

2. Manufacturing electrically operated vehicles

3. Treatment of Sewage

4.  All of these

Ans: (d) All of these.

Conclusion 

Understanding environmental chemistry is crucial for addressing the challenges posed by pollution and developing sustainable solutions. For NEET aspirants, a thorough grasp of these concepts not only aids in examination preparation but also fosters a deeper appreciation of the intricate balance within our environment.

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