How do wetlands contribute to mitigating non-point source pollutants?

How do wetlands contribute to mitigating non-point source pollutants?

• A. They primarily store floodwater with little pollutant removal.
• B. They remove pollutants only by sedimentation.
• C. They remove pollutants only by microbial processing.
• D. They remove pollutants via sedimentation, sorption, microbial processing, denitrification, and floodwater storage.

Answer: (D)

Wetlands act as natural filters for runoff, reducing non-point source pollutants through several processes that occur simultaneously. As water slows in a wetland, suspended particles settle out, taking with them attached pollutants like sediments and some nutrients. Pollutants such as nutrients and some contaminants can also adhere to soil and organic matter in the wetland, a process called sorption, which helps keep them from moving with the water. Microbial communities in wetlands break down many organic pollutants and transform nutrients into less harmful forms through microbial processing. In waterlogged, low-oxygen soils, denitrifying bacteria convert nitrate into nitrogen gas, lowering nitrogen pollution downstream. The floodwater storage aspect of wetlands slows and stores water, increasing the time available for these processes to occur and reducing the magnitude of pollutant peaks entering streams. Because all these mechanisms work together, wetlands effectively mitigate a broad range of non-point source pollutants.

Wetlands act as natural filters for runoff, reducing non-point source pollutants through several processes that occur simultaneously. As water slows in a wetland, suspended particles settle out, taking with them attached pollutants like sediments and some nutrients. Pollutants such as nutrients and some contaminants can also adhere to soil and organic matter in the wetland, a process called sorption, which helps keep them from moving with the water. Microbial communities in wetlands break down many organic pollutants and transform nutrients into less harmful forms through microbial processing. In waterlogged, low-oxygen soils, denitrifying bacteria convert nitrate into nitrogen gas, lowering nitrogen pollution downstream. The floodwater storage aspect of wetlands slows and stores water, increasing the time available for these processes to occur and reducing the magnitude of pollutant peaks entering streams. Because all these mechanisms work together, wetlands effectively mitigate a broad range of non-point source pollutants.