Certified Crop Advisor Practice Exam

Which nutrient can contribute to eutrophication of surface water?

1. Nitrogen

2. Sulfur

3. P

4. Carbon

The correct answer is: P

Eutrophication is the process where water bodies, such as lakes and coastal areas, become overly enriched with nutrients, often leading to excessive growth of algae. The nutrient that is most commonly associated with contributing to eutrophication is phosphorus, which is represented by the chemical symbol P. When phosphorus enters water bodies in excess, typically from agricultural runoff, sewage discharge, or fertilizer application, it stimulates algal blooms. These algal blooms can deplete oxygen in the water, create dead zones where aquatic life cannot survive, and harm water quality. While nitrogen can also contribute to eutrophication, phosphorus is often considered the limiting nutrient in many freshwater ecosystems, meaning that its availability is what primarily controls the growth of algae. In many situations, if phosphorus is in sufficient supply, nitrogen may also become a factor, but phosphorus is the initial catalyst for the eutrophication process. Sulfur and carbon do not play a direct role in eutrophication, as they do not facilitate the excessive growth of algae in the same way that phosphorus does. Therefore, phosphorus is identified as the nutrient of concern in relation to eutrophication, making it the correct choice in this context.