Unit 14: Water/Soil Pollution & Careers
Examining the impact of pollution on our water and soil, and exploring future careers in science.
14.5 Water and Soil Pollution
Water Pollution
Water pollution is the contamination of water bodies, which degrades water quality and harms aquatic ecosystems and human health. Pollutants can be classified as biodegradable or non-biodegradable.
- Biodegradable Pollutants: Substances that can be broken down by natural biological processes (e.g., by bacteria). Examples include domestic sewage and organic waste. While they can be broken down, they can still cause harm by depleting oxygen in the water.
- Non-biodegradable Pollutants: Substances that cannot be broken down by natural processes and persist in the environment for a long time. Examples include plastics, heavy metals (like lead and mercury), and certain pesticides.
Sources and Effects of Water Pollution:
- Agricultural Runoff: Rain washes excess fertilizers (nitrates and phosphates) from farmland into rivers and lakes. This leads to eutrophication: the fertilizers cause a rapid growth of algae (algal bloom), which blocks sunlight from underwater plants. When the algae and plants die, bacteria decompose them, using up dissolved oxygen in the water. This deoxygenation kills fish and other aquatic life.
- Industrial Waste: Factories may discharge untreated wastewater containing toxic chemicals and heavy metals, which are poisonous to aquatic life and can accumulate in the food chain.
- Domestic Sewage: Untreated sewage releases harmful bacteria and viruses into the water, spreading diseases. It also contains organic matter that depletes oxygen as it decomposes.
- Plastic Waste: Plastic bags, bottles, and microplastics accumulate in rivers and oceans, harming and killing marine animals.
Solved Examples:
-
What is eutrophication?
Solution: It is the process where a body of water becomes overly enriched with minerals and nutrients (like nitrates and phosphates from fertilizers), which induces excessive growth of algae and leads to the depletion of oxygen. -
Is a plastic bottle a biodegradable or non-biodegradable pollutant? Explain
why this is a problem.
Solution: It is non-biodegradable. This is a major problem because it does not break down naturally and will persist in the environment for hundreds of years, harming wildlife and breaking down into microplastics. - How does an algal bloom lead to the death of
fish?
Solution: The algal bloom blocks sunlight, killing underwater plants. Bacteria then decompose the dead algae and plants, a process that consumes large amounts of dissolved oxygen from the water. The fish die from a lack of oxygen (asphyxiation).
14.6 Soil Pollution
Soil pollution is the contamination of soil with harmful substances. It is closely linked to air and water pollution, as pollutants can be transferred between them.
Causes and Consequences:
- Industrial Waste: Improper disposal of industrial waste can contaminate soil with heavy metals and toxic chemicals.
- Agricultural Practices: The overuse of pesticides and herbicides can leave harmful chemical residues in the soil, which can then be absorbed by crops or washed into rivers.
- Landfills and Waste Dumps: Leachate (liquid seeping from waste) from poorly managed landfills can contaminate the surrounding soil and groundwater.
Polluted soil can become infertile, unable to support plant growth, and can make crops grown on it unsafe for consumption.
Solved Examples:
-
How can the use of pesticides on a farm lead to water
pollution?
Solution: Rain can wash the pesticide chemicals from the soil on the farm into nearby streams and rivers (a process called runoff), contaminating the water. -
What is a non-biodegradable pollutant?
Solution: A pollutant that cannot be broken down by natural organisms and processes, and therefore persists in the environment for a very long time.
14.7 Careers in Science and Technology
A strong foundation in chemistry opens up a vast range of rewarding career paths in science and technology across various sectors.
- Education: Becoming a science or chemistry teacher at the secondary level, a university lecturer, or a research scientist at a university.
- Health Sector: Pursuing further study to become a doctor, nurse, pharmacist, or midwife. A direct path is to work as a medical laboratory technician, analyzing patient samples.
- Industry: Working as a research chemist developing new products, a chemical engineer designing and running manufacturing processes, or an analytical chemist ensuring the quality and safety of products.
- Government and Non-Profit: Working as an environmental scientist to monitor pollution, develop environmental laws, and ensure industries comply with regulations.
Solved Examples:
-
What does an analytical chemist do in industry?
Solution: An analytical chemist is responsible for quality control. They use various techniques to test raw materials and final products to ensure they meet the required standards of purity and composition. -
Name a career that involves both chemistry and public policy.
Solution: An environmental scientist working for a government agency like the Environmental Protection Agency (EPA) uses their scientific knowledge to help create and enforce laws that protect the environment. - What is the role of a chemical
engineer?
Solution: A chemical engineer applies principles of chemistry, physics, and mathematics to design, operate, and optimize large-scale chemical manufacturing processes. - Name two careers in the health sector that require a strong chemistry
background.
Solution: Doctor and Pharmacist. - What is a key difference between a research scientist at a university and
one in industry?
Solution: A university researcher often focuses on fundamental, knowledge-driven science, while an industrial researcher typically focuses on applied science to develop new, commercially viable products.
🧠Quiz
Answer: A pollutant that can be broken
down by natural biological processes.
Answer: Eutrophication.
Answer: Pharmacist or medical
laboratory technician.
Answer: Industrial waste, agricultural
pesticides, or poorly managed landfills.
Answer: A rapid, excessive growth of
algae in a body of water, often caused by fertilizer runoff.
Answer: To monitor and protect the
environment from pollution and other damage.
Answer: Non-biodegradable.
Answer: When the large amount of algae
dies, bacteria decompose it, and this decomposition process consumes the
dissolved oxygen.
Answer: To design, build, and operate
large-scale chemical plants and processes.
Answer: Toxic, non-biodegradable metal
pollutants like lead and mercury from industrial waste.
Answer: Nitrates and phosphates.
Answer: Quality control, testing
substances to determine their composition and purity.
Answer: Biodegradable.
Answer: By contaminating crops grown on
the soil or by polluting groundwater used for drinking.
Answer: Chemistry teacher or university
lecturer.
Answer: A contaminated liquid that
seeps from a landfill.
Answer: Because they persist in the
environment for a very long time and can accumulate in the food chain.
Answer: Dispensing medications and
advising patients on their safe use, which requires a deep understanding of
chemistry.
Answer: They are often less
water-soluble, so their nutrients are released more slowly and are less likely
to be washed away into rivers.
Answer: To develop new chemical
products or improve existing manufacturing processes.