One way we can quantify the amount of pollutants in our water is by measuring its turbidity. Turbidity is a measure of the cloudiness or murkiness of a water sample. Water becomes cloudy when it has tiny particles suspended within. These particles might include:

  • Soil and sediment
  • Algae
  • Microorganisms
  • Pesticides
  • Other organic matter

The more particles in the water, the cloudier it will appear. We therefore say very cloudy water has high turbidity. Highly turbid water often contributes to:

  • Less sunlight reaching underwater plants
  • Higher water temperatures
  • Reduced amounts of dissolved oxygen in water
  • Lower visibility for aquatic animals
  • Poorer health outcomes for humans and animals

SCIENCE CONNECTION

Based on what you’ve learned in your science classes so far:

1. Why do you think turbidity increases water temperature?

The particles in turbid water absorb and concentrate heat from the sun!

2. Why do you think turbidity decreases the amount of oxygen in water?

Turbidity can decrease the amount of dissolved oxygen in a few ways:

  • Reduced Light Penetration: Suspended particles block the sunlight, which is essential for photosynthesis by aquatic plants and algae. Photosynthesis produces oxygen, so less photosynthesis means less oxygen production.  
  • Increased Temperature: As mentioned earlier, turbid water heats up more easily. Warmer water holds less dissolved oxygen than colder water. This is a fundamental property of gases in liquids.  
  • Decomposition of Organic Matter: If the particles contributing to turbidity include organic matter (like dead algae or leaves), their decomposition by bacteria will consume oxygen.
3. Why do you think turbidity might lead to poorer health outcomes for living beings?

In drinking water, turbidity can shield harmful microorganisms from disinfection, potentially causing illness. For aquatic animals, suspended particles can damage gills, and settling particles can smother bottom-dwelling creatures.