title: Global phosphorus retention by river damming.
abstract: More than 70,000 large dams have been built worldwide. With growing water stress and demand for energy, this number will continue to increase in the foreseeable future. Damming greatly modifies the ecological functioning of river systems. In particular, dam reservoirs sequester nutrient elements and, hence, reduce downstream transfer of nutrients to floodplains, lakes, wetlands, and coastal marine environments. Here, we quantify the global impact of dams on the riverine fluxes and speciation of the limiting nutrient phosphorus (P), using a mechanistic modeling approach that accounts for the in-reservoir biogeochemical transformations of P. According to the model calculations, the mass of total P (TP) trapped in reservoirs nearly doubled between 1970 and 2000, reaching 42 Gmol y(-1), or 12% of the global river TP load in 2000. Because of the current surge in dam building, we project that by 2030, about 17% of the global river TP load will be sequestered in reservoir sediments. The largest projected increases in TP and reactive P (RP) retention by damming will take place in Asia and South America, especially in the Yangtze, Mekong, and Amazon drainage basins. Despite the large P retention capacity of reservoirs, the export of RP from watersheds will continue to grow unless additional measures are taken to curb anthropogenic P emissions.
authors.affiliation: Ecohydrology Research Group, Water Institute, University of Waterloo, Waterloo, ON, Canada N2L 3G1; Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada N2L 3G1 tmaavara@uwaterloo.ca.
authors.forename: Taylor
authors.initials: T
authors.lastname: Maavara
authors.affiliation: Ecohydrology Research Group, Water Institute, University of Waterloo, Waterloo, ON, Canada N2L 3G1; Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Parsons
authors.affiliation: Ecohydrology Research Group, Water Institute, University of Waterloo, Waterloo, ON, Canada N2L 3G1; Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
authors.forename: Christine
authors.initials: C
authors.lastname: Ridenour
authors.affiliation: Ecohydrology Research Group, Water Institute, University of Waterloo, Waterloo, ON, Canada N2L 3G1; Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
authors.forename: Severin
authors.initials: S
authors.lastname: Stojanovic
authors.affiliation: Ecohydrology Research Group, Water Institute, University of Waterloo, Waterloo, ON, Canada N2L 3G1; Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
authors.forename: Hans H
authors.initials: HH
authors.lastname: Dürr
authors.affiliation: Ecohydrology Research Group, Water Institute, University of Waterloo, Waterloo, ON, Canada N2L 3G1; Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
authors.forename: Helen R
authors.initials: HR
authors.lastname: Powley
authors.affiliation: Ecohydrology Research Group, Water Institute, University of Waterloo, Waterloo, ON, Canada N2L 3G1; Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
authors.forename: Philippe
authors.initials: P
authors.lastname: Van Cappellen
mesh_terms: D005068:Eutrophication; D009010:Monte Carlo Method; D010758:Phosphorus / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*
chemical_list: D010758:Phosphorus
keywords: biogeochemical cycles; eutrophication; nutrient retention; phosphorus; river damming