Eutrophication includes all, except

Options

A. Heavy growth of BGA
B. Decreased BOD
C. Death of submerged organism
D. Finally decreased COD

Answer

**Step-by-Step Solution:**

1. **Understanding Eutrophication**: Eutrophication is a process that occurs in water bodies (like ponds, lakes, and rivers) due to the excessive accumulation of nutrients, primarily nitrogen and phosphorus. These nutrients often come from agricultural runoff, sewage, and detergents.

2. **Effects of Eutrophication**: The increase in nitrogen and phosphorus leads to a rapid growth of algae, particularly blue-green algae (BGA). This phenomenon is known as algal bloom.

3. **Consequences of Algal Bloom**: As algae proliferate, they cover the surface of the water, blocking sunlight from reaching submerged plants. This results in a decrease in photosynthesis and oxygen production.

4. **Impact on Aquatic Life**: The decomposition of the dead algae consumes oxygen in the water, leading to a decrease in dissolved oxygen levels. This creates a condition known as hypoxia, which can be fatal for aquatic organisms, leading to their death.

5. **Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD)**:
- BOD measures the amount of oxygen that microorganisms will consume while decomposing organic matter in the water. In eutrophication, BOD typically increases due to the decomposition of algae.
- COD measures the total oxygen required to chemically oxidize organic and inorganic matter in the water. In the case of eutrophication, COD tends to increase as well due to the higher organic load from decomposing algae.

6. **Identifying the Exception**: The question asks for what is NOT included in eutrophication. The options provided are:
- Heavy growth of BGA (included)
- Decreased BOD (not included, as BOD typically increases)
- Death of submerged organisms (included)
- Decreased COD (not included, as COD typically increases)

7. **Conclusion**: The correct answer is "decreased BOD" since eutrophication leads to an increase in BOD rather than a decrease.