title: Geochemical processes controlling water salinization in an irrigated basin in Spain: identification of natural and anthropogenic influence.
abstract: Salinization of water bodies represents a significant risk in water systems. The salinization of waters in a small irrigated hydrological basin is studied herein through an integrated hydrogeochemical study including multivariate statistical analyses and geochemical modeling. The study zone has two well differentiated geologic materials: (i) Quaternary sediments of low salinity and high permeability and (ii) Tertiary sediments of high salinity and very low permeability. In this work, soil samples were collected and leaching experiments conducted on them in the laboratory. In addition, water samples were collected from precipitation, irrigation, groundwater, spring and surface waters. The waters show an increase in salinity from precipitation and irrigation water to ground- and, finally, surface water. The enrichment in salinity is related to the dissolution of soluble mineral present mainly in the Tertiary materials. Cation exchange, precipitation of calcite and, probably, incongruent dissolution of dolomite, have been inferred from the hydrochemical data set. Multivariate statistical analysis provided information about the structure of the data, differentiating the group of surface waters from the groundwaters and the salinization from the nitrate pollution processes. The available information was included in geochemical models in which hypothesis of consistency and thermodynamic feasibility were checked. The assessment of the collected information pointed to a natural control on salinization processes in the Lerma Basin with minimal influence of anthropogenic factors.
authors.affiliation: Geological Survey of Spain - IGME, C/Manuel Lasala 44 9B, 50006 Zaragoza, Spain. Electronic address: d.merchan@igme.es.
authors.forename: D
authors.initials: D
authors.lastname: Merchán
authors.affiliation: University of Zaragoza - Department of Earth Sciences (Geochemical Modelling Group), C/Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: L F
authors.initials: LF
authors.lastname: Auqué
authors.affiliation: University of Zaragoza - Department of Earth Sciences (Geochemical Modelling Group), C/Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Acero
authors.affiliation: University of Zaragoza - Department of Earth Sciences (Geochemical Modelling Group), C/Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Gimeno
authors.affiliation: Geological Survey of Spain - IGME, C/Manuel Lasala 44 9B, 50006 Zaragoza, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Causapé
mesh_terms: D057914:Agricultural Irrigation; D004784:Environmental Monitoring; D060587:Groundwater / Q000737:chemistry*; D008962:Models, Theoretical; D015999:Multivariate Analysis; D054712:Salinity; D013030:Spain; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014876:Water Pollution / Q000517:prevention & control*
chemical_list: D014874:Water Pollutants, Chemical
keywords: Cation exchange reactions; Geochemical modeling; Mineral dissolution; Multivariate analysis; Nitrate pollution