Water Pollution

Step 1: Understanding the Concept:
Eutrophication is the process of nutrient enrichment of a water body, which leads to excessive growth of algae and other aquatic plants (algal blooms). The question asks for the primary nutrients that cause this process.

Step 3: Detailed Explanation:
In most aquatic ecosystems, the growth of algae is limited by the availability of certain key nutrients. The two most important limiting nutrients are nitrogen (N) and phosphorus (P). When agricultural fertilizers, which are rich in nitrates (a form of nitrogen) and phosphates (a form of phosphorus), wash into lakes and rivers, they remove this limitation. This sudden influx of nutrients causes an explosive growth of algae. When this large amount of algae dies, its decomposition by bacteria consumes a large amount of dissolved oxygen in the water, leading to hypoxia or anoxia (low or no oxygen), which can kill fish and other aquatic organisms.

Step 4: Final Answer:
The primary nutrients responsible for eutrophication are Nitrogen and Phosphorus.