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How do wetlands filter polluted water?
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Wetland
Stately bald cypresses (Taxodium distichum) thriving in a Louisiana swamp.
Wetlands are often described as the "kidneys of the landscape" because of their vital role in cleansing polluted waters. They filter water through a combination of physical, chemical, and biological processes that occur as water moves slowly through the system.12
The filtration process is facilitated by several key factors:
- Slow Water Flow: The low gradient of the landscape and the presence of dense vegetation retard the movement of water. This lack of turbulence allows suspended sediments and pollutants to settle out of the water column.2
- Biological Activity: Wetland microorganisms, particularly bacteria, play a critical role in decomposing organic pollutants. These organisms can break down complex chemicals by using them as sources of carbon or energy.3
- Chemical Immobilization: Wetland soils, especially those rich in humus, act as sinks for inorganic nutrients and toxic metals. Humus can form strong complexes with metals, effectively immobilizing them and preventing their movement into groundwater.13
- Nutrient Cycling: Wetlands serve as important sinks for nutrients, helping to manage the export of organic materials and maintaining the integrity of the broader ecosystem.1
By naturally collecting, filtering, and storing water, these ecosystems provide essential services that protect water quality and combat water scarcity.1