title: Assessment of phosphogypsum impact on the salt-marshes of the Tinto river (SW Spain): role of natural attenuation processes.
abstract: About 120 Mton of phosphogypsum from the fertiliser industry were stack-piled on the salt-marshes of the Tinto river (Spain). This paper investigates the capacity of salt-marshes to attenuate contamination due to downward leaching from phosphogypsum. Solids and pore-waters were characterized at different depths of the pile to reach the marsh-ground. In superficial zones, metals were highly mobile, and no reduced sulphur was found. However, pollutant concentration decreased in the pore-water in deeper oxygen-restricted zones. Metal removal occurred by precipitation of newly formed sulphides, being this process main responsible for the contamination attenuation. Pyrite-S was the main sulphide component (up to 2528 mg/kg) and occurred as framboids, leading to high degrees of pyritization (up to 97%). The sulphidization reaction is Fe-limited; however, excess of acid-volatile sulphide over other metals cause precipitation of other sulphides, mainly of Cu and As. This decrease in metal mobility significantly minimises the impact of phosphogypsums on the salt-marshes.
authors: Institute of Environmental Assessment and Water Research, CSIC, Jordi Girona 18, 08034 Barcelona, Spain. rafael.perez@dgeo.uhu.es
authors: Rafael
authors: R
authors: Pérez-López
authors: Julio
authors: J
authors: Castillo
authors: Aguasanta M
authors: AM
authors: Sarmiento
authors: José M
authors: JM
authors: Nieto
mesh_terms: D002133:Calcium Sulfate / Q000032:analysis* / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods*; D005308:Fertilizers / Q000032:analysis* / Q000633:toxicity; D019015:Geologic Sediments / Q000032:analysis*; D008670:Metals / Q000737:chemistry / Q000378:metabolism; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000032:analysis* / Q000378:metabolism; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D013030:Spain; D013431:Sulfates / Q000737:chemistry / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism; D053833:Wetlands
chemical_list: D005308:Fertilizers; D008670:Metals; D012989:Soil Pollutants; D013431:Sulfates; D014874:Water Pollutants, Chemical; C077769:phosphogypsum; D010758:Phosphorus; D002133:Calcium Sulfate