Phosphate containing fertilisers cause water pollution. Addition of such compounds in water bodies causes`"…."`

Options

A. enhanced growth of algae
B. decrease in amount of dissolved oxygen in water
C. deposition of calcium phosphate
D. increase in fish population

Explanation

### Step-by-Step Solution:

1. **Understanding the Problem**: The question states that phosphate-containing fertilizers cause water pollution. We need to determine what happens when these fertilizers are added to water bodies.

2. **Identifying the Effects of Phosphate Fertilizers**: When phosphate fertilizers are introduced into water bodies, they lead to an increase in nutrients in the water. This nutrient enrichment promotes the growth of algae.

3. **Algal Bloom**: The rapid growth of algae due to the excess nutrients is referred to as an algal bloom. This is a significant effect of phosphate pollution in aquatic environments.

4. **Oxygen Consumption**: As algae grow and multiply, they consume a lot of dissolved oxygen in the water. This process reduces the amount of oxygen available for other aquatic organisms.

5. **Impact on Aquatic Life**: The decrease in dissolved oxygen makes the water less suitable for aquatic life, leading to the death of fish and other organisms that rely on oxygen for survival.

6. **Eutrophication**: The entire process described above, from nutrient enrichment to algal bloom and subsequent oxygen depletion, is known as eutrophication. It is a significant environmental issue caused by the addition of phosphates and other nutrients to water bodies.

7. **Evaluating the Options**: Based on the understanding of the process:
- **Option A**: Enhanced growth of algae - Correct.
- **Option B**: Decrease in the amount of dissolved oxygen in water - Correct.
- **Option C**: Deposit of calcium phosphate - Incorrect, as this is not a direct consequence of the addition of phosphates.
- **Option D**: Increases the fish population - Incorrect, as the fish population actually decreases due to the lack of oxygen.

8. **Conclusion**: The correct answers are options A and B, which reflect the consequences of adding phosphate-containing fertilizers to water bodies.