Florida Wastewater Practice Test

What happens to the pH in a pond during the daytime?

1. It remains constant

2. It increases

3. It decreases

4. It fluctuates rapidly

The correct answer is: It decreases

During the daytime, the pH in a pond typically increases as a result of photosynthesis conducted by aquatic plants and algae. When these organisms photosynthesize, they utilize carbon dioxide from the water, reducing its concentration. Since carbon dioxide contributes to the formation of carbonic acid, its reduction leads to a decrease in acidity, thereby raising the pH. In addition, as the plants thrive in sunlight, they produce oxygen and absorb carbon compounds, facilitating a higher pH level compared to nighttime conditions when respiration causes an increase in carbon dioxide, which can lead to a drop in pH. This understanding of the relationship between photosynthesis and pH levels is crucial for managing water quality in freshwater ecosystems, as pH directly affects the solubility of various nutrients and the overall health of aquatic life.