Phosphorus retention in constructed freshwater riparian marshes

• Published in: Ecological applications 1995-08, Vol.5 (3), p.830-845
• Main Authors: Mitsch, William J., Cronk, Julie K., Wu, Xinyuan, Nairn, Robert W., Hey, Donald L.
• Format: Article
• Language: English
• Subjects: ABSORCION DE SUSTANCIAS NUTRITIVAS; ABSORPTION DE SUBSTANCES NUTRITIVES; AGUA; AQUATIC PLANTS; BIOMASA; BIOMASS; BIOMASSE; CALIDAD DEL AGUA; constructed marshes; CONTROL DE LA CONTAMINACION; COURS D'EAU; CURSOS DE AGUA; DEBIT; EAU; Ecological engineering; experimental wetlands; FITOPLANCTON; FLOW RATE; FOSFORO; Fresh water; Freshwater; GASTO; GEOLOGIA; GEOLOGICAL SEDIMENTATION; GEOLOGIE; GEOLOGY; high flow wetlands; Hydrology; ILLINOIS; Lakes; low flow wetlands; LUTTE ANTIPOLLUTION; Macrophytes; MARISMA; MARSHES; Modeling; NUTRIENT CONTENT; NUTRIENT UPTAKE; NUTRITIVE VALUE; PHOSPHORE; PHOSPHORUS; PHYTOPLANCTON; PHYTOPLANKTON; PLANTAS ACUATICAS; PLANTE AQUATIQUE; POLLUTION CONTROL; POLLUTION DE L'EAU; POLUCION DEL AGUA; PRAIRIE MARECAGEUSE; PURIFICACION DEL AGUA; PURIFICATION DE L'EAU; QUALITE DE L'EAU; RIVERS; TERRE HUMIDE; TIERRAS HUMEDAS; VALEUR NUTRITIVE; VALOR NUTRITIVO; WATER; WATER POLLUTION; WATER PURIFICATION; WATER QUALITY; WETLANDS
• ISSN: 1051-0761; 1939-5582
• DOI: 10.2307/1941991

Four constructed freshwater riparian marshes in northeastern Illinois, USA, each experimentally subjected to either high or low loadings of turbid river water over a 3-yr period, were investigated for phosphorus retention and fate. Average phosphorus concentrations decreased by 64-92% in low-flow wetlands (to 11-40 @mg P/L) and by 53-90% (to 12-57 @mg P/L) in high-flow wetlands. Intensive sampling at 4-h intervals during spring and summer of the final year showed phosphorus mass decreases of 81-74% for low- and high-flow wetlands, respectively. During this frequent sampling, inflow averaged 176 @mg P/L, while outflows were 34 @mg P/L for the low-flow wetland and 45 @mg P/L for the high-flow wetland. Spatial patterns of isopleths showed clear gradients in high-flow wetlands and near-homogeneous concentrations in low-flow wetlands. Annual budgets illustrated that most inflowing phosphorus was retained through sedimentation with some capacity for phosphorus retention by macrophytes and a lesser amount by microbial (periphyton and planktonic) communities. A simple Vollenweider-type model predicted well the retention of phosphorus in these wetlands for low- and high-flow wetlands with 3 yr of data, i.e., the model was calibrated and verified with six independent data sets. A mean deviation of only 9.3% between measured and simulated retention was found when the retention coefficient was k = 6.51 wk^-^1. Adding a factor for seasonal temperature fluctuation did not improve the fit, whereas using a model where the retention is a function of flow provided the best overall fit to the data (mean deviation of 6.3% between data and predictions). These constructed wetlands retained about the same amount of phosphorus per unit area (0.5-3 g P@?m^-^2@?yr^-^1) as have several other natural and constructed wetlands receiving similar concentrations of phosphorus.