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Air & Water Quality Cheat Sheet
A printable reference covering air pollutants, water quality indicators, AQI, ppm, pH, dissolved oxygen, BOD, eutrophication, and pollution controls for grades 7-12.
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Environmental Science: Air & Water Quality covers how scientists measure pollution in the atmosphere and in water systems. Students need this cheat sheet to connect common pollutants with their sources, health effects, environmental impacts, and control methods. It is useful for reviewing lab data, interpreting graphs, and preparing for tests on ecosystems, human health, and environmental policy. The most important ideas include pollutant concentration, Air Quality Index, pH, dissolved oxygen, biochemical oxygen demand, turbidity, and nutrient pollution. Air quality depends on pollutants such as particulate matter, ozone, nitrogen oxides, sulfur dioxide, carbon monoxide, and greenhouse gases. Water quality depends on chemical, physical, and biological indicators that show whether water can support life and human use. Laws, monitoring, and pollution controls help reduce emissions and protect clean air and water.
Key Facts
- Pollutant concentration is often measured in ppm, where ppm = parts of pollutant / 1,000,000 parts of mixture.
- Air Quality Index, or AQI, converts pollutant levels into a scale where higher values mean greater health risk.
- pH measures acidity or basicity, with pH 7 neutral, pH less than 7 acidic, and pH greater than 7 basic.
- Dissolved oxygen, or DO, is the amount of oxygen gas in water, and most aquatic animals need enough DO to survive.
- Biochemical oxygen demand, or BOD, measures how much oxygen decomposers use to break down organic matter in water.
- High BOD usually lowers dissolved oxygen because bacteria consume oxygen during decomposition.
- Eutrophication occurs when excess nitrogen or phosphorus causes algal blooms that can block light and reduce dissolved oxygen.
- Point-source pollution comes from one identifiable location, while nonpoint-source pollution comes from many spread-out sources such as runoff.
Vocabulary
- Particulate Matter
- Tiny solid or liquid particles in the air that can enter the lungs and harm human health.
- Air Quality Index
- A number scale that reports how clean or polluted the air is and what health effects may be expected.
- Dissolved Oxygen
- The amount of oxygen gas dissolved in water and available for aquatic organisms to use.
- Biochemical Oxygen Demand
- A measure of the oxygen used by microorganisms as they break down organic waste in water.
- Turbidity
- The cloudiness of water caused by suspended particles such as soil, algae, or pollution.
- Eutrophication
- A process where excess nutrients cause rapid algae growth and often lead to low oxygen in water.
Common Mistakes to Avoid
- Confusing ozone in the stratosphere with ground-level ozone is wrong because stratospheric ozone protects Earth, while ground-level ozone is a harmful air pollutant.
- Assuming clear water is always clean is wrong because dissolved chemicals, bacteria, or low oxygen may be present even when water looks transparent.
- Treating high dissolved oxygen and high BOD as the same is wrong because high BOD usually means decomposers are using up oxygen, which can lower DO.
- Ignoring units such as ppm, ppb, mg/L, and AQI is wrong because pollution data only makes sense when the measurement scale is known.
- Blaming only factories for pollution is wrong because vehicles, farms, homes, construction sites, and stormwater runoff can also be major sources.
Practice Questions
- 1 A sample of air contains 35 parts carbon monoxide per 1,000,000 parts of air. What is the carbon monoxide concentration in ppm?
- 2 A stream has dissolved oxygen of 9 mg/L upstream from a town and 3 mg/L downstream. What is the change in dissolved oxygen, and what might this suggest?
- 3 A lake receives fertilizer runoff that adds extra nitrogen and phosphorus. Explain how this can lead to an algal bloom and lower dissolved oxygen.
- 4 Why can nonpoint-source pollution be harder to control than point-source pollution?