Question

Discuss four indicators of water quality and give one significance of each of them.

Hint:

Remember the inverse relationship: As \textbf{Organic Pollution} increases, \textbf{BOD} increases, while \textbf{DO} decreases.

Answer 1

Step 1: Understanding the Concept:
Water quality indicators are physical, chemical, and biological parameters used to assess the health of an aquatic ecosystem and its suitability for specific uses.

Step 2 : Detailed Explanation:
1.
Dissolved Oxygen (DO): The amount of gaseous oxygen dissolved in the water.
{Significance:} It is vital for the survival of fish and other aquatic organisms. Low DO levels (hypoxia) can lead to mass "fish kills."
2.
Biological Oxygen Demand (BOD): The amount of oxygen required by aerobic microorganisms to decompose organic matter in water.
{Significance:} High BOD indicates a high level of organic pollution (like sewage), which depletes oxygen and harms aquatic life.
3.
pH Level: A measure of how acidic or basic the water is on a scale of 0 to 14.
{Significance:} Most aquatic organisms prefer a neutral range (6.5–8.5). Extreme pH can be toxic and affects the solubility of heavy metals.
4.
Turbidity: A measure of water clarity based on the amount of suspended solids.
{Significance:} High turbidity blocks sunlight, preventing photosynthesis in aquatic plants and can clog the gills of fish.

Step 3: Final Answer:
The primary indicators are DO (essential for life), BOD (measures pollution), pH (chemical health), and Turbidity (clarity/light penetration).