Which element is known to contribute to water quality problems through enrichment?

Phosphorus is recognized as a significant contributor to water quality problems primarily due to its role in nutrient enrichment, often referred to as eutrophication. Eutrophication occurs when excess nutrients, particularly phosphorus, enter water bodies, typically from agricultural runoff, wastewater discharge, or urban runoff. This nutrient enrichment leads to excessive growth of algae, known as algal blooms, which can deplete oxygen in the water and harm aquatic life, degrading overall water quality.

The activity of algae can cause various issues, including harmful algal blooms that produce toxins, creating risks for humans and wildlife. Once these blooms die off, their decomposition consumes oxygen in the water, leading to hypoxic or anoxic conditions that are detrimental to fish and other aquatic organisms.

In contrast, nitrogen can also contribute to nutrient enrichment and eutrophication; however, phosphorus is often the limiting nutrient in freshwater systems, meaning its presence in higher concentrations is the primary driver of these issues. This is why phosphorus is specifically highlighted when discussing water quality problems related to nutrient enrichment. Potassium and calcium, while essential nutrients for plant growth and development, do not have the same direct impact on aquatic ecosystems in terms of nutrient enrichment and water quality degradation.