Assess understanding of core principles of wetland ecosystem functions and how they contribute to water purification. Scope includes hydrology, vegetation and soils, physical sedimentation, biogeochemical processes (nutrient cycling, denitrification, phosphorus retention), microbial degradation of pollutants, factors affecting purification efficiency (hydraulic residence time, redox conditions, plant species), monitoring indicators, and design/management considerations for natural and constructed wetlands, including limitations and trade-offs.