Which ecosystem can filter pollutants, trap sediment, absorb nutrients, and protect water quality?

• A. Deserts and pollution
• B. Wetlands and pollution
• C. Forests and climate
• D. Oceans and pollution

Answer: (B)

Wetlands perform that combo of natural water purification: their saturated soils and plant life slow down runoff, trap and settle out sediments, host microbial processes that break down pollutants, and take up nutrients through plant uptake and microbial cycling. This combination directly improves water quality by reducing turbidity, limiting nutrient runoff, and preventing pollutants from moving downstream. Deserts don’t provide this filtration and sediment-trapping function because water flow is limited. Forests help protect water quality by reducing erosion and aiding infiltration, but they don’t filter dissolved pollutants and trap sediments as effectively as wetlands. Oceans dilute and transport pollutants rather than protecting inland water quality, so they don’t match the described benefits.