What is the function of a wetland in water quality improvement?

Wetlands play a significant role in improving water quality through various natural processes. One of their primary functions is to filter pollutants from water as it moves through the wetland ecosystem. The vegetation found in wetlands, such as reeds and sedges, can trap sediment and absorb nutrients, particularly nitrogen and phosphorus. These nutrients, when present in excess, can lead to harmful algal blooms and degraded water quality. By absorbing these excess nutrients and filtering out contaminants, wetlands act as natural water purification systems.

Furthermore, the complex soil structure in wetlands can help break down organic pollutants by providing habitats for microorganisms that degrade these substances. This bioremediation process is vital in maintaining clean water in adjacent ecosystems and can significantly improve the overall quality of downstream water bodies.

In contrast, the other options do not accurately reflect the true nature of wetlands. While wetlands do provide flood control benefits and can influence evaporation rates, their primary and most critical function concerning water quality improvement lies in their ability to filter pollutants and absorb excess nutrients. The assertion that wetlands do not support wildlife is also incorrect; in fact, they are vital habitats for a diverse range of species.