title: Major hydrogeochemical processes in an acid mine drainage affected estuary.
abstract: This study provides geochemical data with the aim of identifying and quantifying the main processes occurring in an Acid Mine Drainage (AMD) affected estuary. With that purpose, water samples of the Huelva estuary were collected during a tidal half-cycle and ion-ion plots and geochemical modeling were performed to obtain a general conceptual model. Modeling results indicated that the main processes responsible for the hydrochemical evolution of the waters are: (i) the mixing of acid fluvial water with alkaline ocean water; (ii) precipitation of Fe oxyhydroxysulfates (schwertmannite) and hydroxides (ferrihydrite); (iii) precipitation of Al hydroxysulfates (jurbanite) and hydroxides (amorphous Al(OH)3); (iv) dissolution of calcite; and (v) dissolution of gypsum. All these processes, thermodynamically feasible in the light of their calculated saturation states, were quantified by mass-balance calculations and validated by reaction-path calculations. In addition, sorption processes were deduced by the non-conservative behavior of some elements (e.g., Cu and Zn).
authors.affiliation: Andalusian Earth Sciences Institute (CSIC-Universidad de Granada), Avenida de Las Palmeras 4, Armilla 18100, Granada, Spain. Electronic address: masta@iact.igr-csic.es.
authors.forename: Maria P
authors.initials: MP
authors.lastname: Asta
authors.affiliation: Andalusian Earth Sciences Institute (CSIC-Universidad de Granada), Avenida de Las Palmeras 4, Armilla 18100, Granada, Spain.
authors.forename: Maria Ll
authors.initials: ML
authors.lastname: Calleja
authors.affiliation: Department of Geology, University of Huelva, Campus 'El Carmen', 21071 Huelva, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Pérez-López
authors.affiliation: Department of Earth Sciences, University of Zaragoza, Petrology and Geochemistry Area, Pedro Cerbuna, 12, 50009 Zaragoza, Spain.
authors.forename: Luis F
authors.initials: LF
authors.lastname: Auqué
mesh_terms: D000143:Acids; D002980:Climate; D063366:Estuaries; D007220:Industrial Waste / Q000032:analysis; D008906:Mining; D008956:Models, Chemical; D045483:Rivers / Q000737:chemistry; D012623:Seawater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D014877:Water Pollution, Chemical / Q000032:analysis
chemical_list: D000143:Acids; D007220:Industrial Waste; D014874:Water Pollutants, Chemical
keywords: Acid water; Geochemical modeling; Huelva estuary; Hydrochemistry; Mixing; Ocean water