Pollution Practice Questions

Correct answer: Ground-level ozone

Primary pollutants are emitted directly from a source, whereas secondary pollutants like ground-level ozone form when nitrogen oxides and volatile organic compounds react in the presence of sunlight. Ozone in the troposphere is a major component of photochemical smog.

Correct answer: Methylmercury contamination

Minamata disease was first discovered in Japan after industrial wastewater containing methylmercury was released into Minamata Bay. The toxin bioaccumulated in fish and shellfish, which were then consumed by the local population.

Correct answer: Noise pollution

Noise pollution is measured in decibels, a logarithmic unit that describes the pressure level of sound. Prolonged exposure to sounds above 85 dB can lead to permanent hearing loss and increased stress levels.

Correct answer: Biomagnification

Biomagnification occurs when toxins like DDT or heavy metals are ingested by organisms at the bottom of the food chain and become increasingly concentrated in the tissues of apex predators. This often leads to reproductive failure or death in high-level consumers.

Correct answer: The oxygen bacteria need to decompose organic matter

A high BOD value indicates that there is a large amount of organic matter in the water, requiring significant oxygen for decomposition. This process can deplete dissolved oxygen levels, leading to the death of aquatic animals.

Correct answer: Sulfur dioxide

Sulfur dioxide (SO2) and nitrogen oxides (NOx) are released into the atmosphere by burning fossil fuels. They react with water, oxygen, and other chemicals to form sulfuric and nitric acids, which fall to the ground as acid rain.

Correct answer: Coal

The Great Smog of London was a severe air-pollution event caused by weather conditions combined with the heavy use of coal for domestic heating and industrial processes. It led to thousands of premature deaths and the passage of the Clean Air Act 1956.

Correct answer: It lowers the water's dissolved oxygen level.

Thermal pollution occurs when industrial processes or power plants discharge heated water into natural water bodies. Warmer water holds less dissolved oxygen, which can cause 'thermal shock' and suffocation in fish and other aquatic organisms.

Correct answer: A specific factory discharge pipe

Point source pollution refers to contaminants that enter a waterway from a single, identifiable location, such as a pipe or a ditch. Non-point source pollution, like urban runoff, comes from many diffuse sources and is harder to regulate.

Correct answer: Chlorofluorocarbons (CFCs)

CFCs were widely used in refrigerants and aerosols. When they reach the stratosphere, UV radiation breaks them down, releasing chlorine atoms that catalyze the destruction of ozone molecules ($O_3$).

Correct answer: Burning of biomass fuels for cooking and heating

The use of wood, charcoal, or crop waste in inefficient stoves produces high levels of smoke and particulate matter indoors. This is a leading cause of respiratory illness and premature death in rural communities globally.

Correct answer: Cadmium

Itai-itai disease was caused by cadmium poisoning due to mining activities in Japan's Toyama Prefecture. It causes softening of the bones and kidney failure; the name literally translates to 'it hurts-it hurts'.

Correct answer: Eutrophication

Eutrophication is often caused by runoff containing nitrates and phosphates from fertilizers. The resulting 'algal blooms' block sunlight and consume oxygen during decomposition, creating 'dead zones' where aquatic life cannot survive.

Correct answer: Lichens

Lichens are highly sensitive to air pollutants because they lack a waxy cuticle and absorb nutrients and water directly from the air. A decline in lichen populations or diversity in an area is a strong indicator of high $SO_2$ levels.

Correct answer: Ambient air and surrounding soil

Fly ash consists of fine particles expelled from coal-fired power plants. If not captured by precipitators, it pollutes the air, and its disposal in ash ponds can lead to heavy metal leaching into the surrounding soil and groundwater.

Correct answer: Carbon monoxide

Carbon monoxide (CO) binds to hemoglobin in red blood cells with a much higher affinity than oxygen, forming carboxyhemoglobin. This prevents the blood from carrying sufficient oxygen to tissues and organs, which can be fatal.

Correct answer: They are ingested by marine life and enter the human food web.

Microplastics are particles less than 5mm in size that persist in the environment for centuries. They can absorb toxic chemicals and are often mistaken for food by marine organisms, leading to physical blockages and chemical toxicity.

Correct answer: Respiratory irritant and plant toxin

PAN is a secondary pollutant produced in photochemical smog. It is a powerful lacrymator (causes eye irritation) and is highly toxic to plants, as it can damage chloroplasts and inhibit photosynthesis.

Correct answer: Montreal Protocol

The Montreal Protocol on Substances that Deplete the Ozone Layer is considered one of the most successful environmental treaties. It has led to a significant recovery of the ozone layer by phasing out the use of CFCs and related chemicals.

Correct answer: Liquid that percolates through waste, dissolving contaminants

Leachate forms in landfills when rainwater filters through the waste, picking up heavy metals, organic compounds, and pathogens. If not properly collected, it can seep into and contaminate local groundwater supplies.