Wetlands remove nutrients and sediments from water as plants, bacteria, and physical processes interact.

Healthy wetland ecosystems are commonly seen as natural water filtration systems. Wetlands can remove sediments and nutrients from the surrounding soil or water, as part of the natural cycling that these elements do between land, water, and air. Nutrients like nitrogen and phosphorous, for example, are taken from the water by bacteria and wetland plants that consume these nutrients as they grow. Physical processes like filtering and sedimentation (particles settling out of the water) can also remove nutrients and particles from the water. These biological and physical processes interact with many other factors, such as temperature and land structure, to affect a wetland’s overall function.

For instance, dense communities of wetland plants slow down water flow, which gives more time for solid particles to settle out and nutrients to be consumed by plants and bacteria. In addition, the leaves, stems, and roots of wetland plants provide a large surface area on which bacteria and other microbes can attach. Certain wetland bacteria consume nitrate (an ion containing nitrogen) in the water and convert it into nitrogen gas, which is released into the atmosphere. This process of denitrification tends to be the way that most nitrogen is removed from the water in wetlands. The plants take up some nutrients, but this is temporary storage as the nutrients are released again when the plants die and decompose. Nonetheless, the presence of plants and their interaction with other organisms in the ecosystem facilitate the wetland’s ability to clean water flowing through.

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Last Updated December 4, 2017