title: Internal phosphorus load in a Mexican reservoir: forecast and validation.
abstract: To determine the internal phosphorus load (IPL) as a function of redox potential (Eh) in a Mexican reservoir, the results from a phosphorus (P) release experiment were extrapolated to temporal and spatial variations of Eh in sediments, and an IPL-Eh of 24.2 ± 2.5 t/yr was obtained. This result is compared with the P mass balance (MB) in the reservoir, where the IPL-MB is determined as the difference between P inputs to the reservoir and the outputs. Inputs of P are the sum of the external P load from the hydrological basin, the IPL, and P in atmospheric precipitation; outputs of P are the sum of sedimented P, and the removal of P in water and biomass, and the resulting IPL-MB, is 26.4 ± 4.9 t/yr. In addition, P concentrations in sediment cores (SCs) are analyzed, and the historical release of P from sediments determined, resulting in an IPL-SC of 23.5 ± 1.4 t/yr. The different IPL results are similar, as average values are within the standard deviation of IPL-MB. It is concluded that analysis of the variations in Eh in sediments allows determination of the reservoir's IPL. Six-weekly IPL-Eh and IPL-MB values are analyzed, and it can be seen that IPL occurs mainly during the period from May to August, when the water column is thermally stratified.
authors.affiliation: Mexican Institute of Water Technology, Hydrology Jiutepec, Morelos, Mexico.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Hansen
authors.affiliation: Mexican Institute of Water Technology, Hydrology Jiutepec, Morelos, Mexico.
authors.forename: Henri
authors.initials: H
authors.lastname: Márquez-Pacheco
mesh_terms: D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes / Q000737:chemistry*; D008800:Mexico; D010758:Phosphorus / Q000032:analysis*
chemical_list: D010758:Phosphorus
keywords: Mass Balance; Phosphorus release; Redox potential; Sediment; Sediment cores