title: Arsenic speciation in the dispersible colloidal fraction of soils from a mine-impacted creek.
abstract: Arsenic and iron speciation in the dispersible colloid fraction (DCF; 10-1000 nm) from an As-rich mine waste pile, sediments of a streambed that collects runoff from waste pile, the streambed subsoil, and the sediments of a downstream pond were investigated by combining asymmetrical-flow field-flow fractionation (AsFlFFF)/inductively-coupled plasma-mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and X-ray absorption (XAS) spectroscopy. Calcium, Fe and As (Fe/As molar ratio ∼ 1) were the main components of the DCF from waste pile. TEM/EDS and As and Fe XAS analysis revealed the presence of nanoparticle scorodite in this same DCF, as well as Fe nanoparticles in all samples downstream of the waste pile. Arsenic and Fe XAS showed As(V) adsorbed onto nanoparticulate ferrihydrite in the DCF of downstream samples. Micro-X-ray fluorescence indicated a strong correlation between Fe and As in phyllosilicate/Fe(3+) (oxi) hydroxide aggregates from the sediment pond. Fractionation analysis showed the mean particle size of the DCF from the streambed sample to be smaller than that of the streambed subsoil and sediment ponds samples. These results show that an important and variable fraction of As may be bound to dispersible colloids that can be released from contaminated soils and transported downstream in natural systems.
authors.affiliation: Institute of Agrochemistry and Food Technology, CSIC, Agustín Escardino 7, 46980 Paterna, Valencia, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Serrano
authors.affiliation: National Museum of Natural Sciences, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Gomez-Gonzalez
authors.affiliation: School of Natural Sciences,University of California, Merced, CA 95343, USA.
authors.forename: Peggy A
authors.initials: PA
authors.lastname: O'Day
authors.affiliation: Group of Analytical Spectroscopy and Sensors (GEAS), Institute of Environmental Sciences (IUCA), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Laborda
authors.affiliation: Group of Analytical Spectroscopy and Sensors (GEAS), Institute of Environmental Sciences (IUCA), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Bolea
authors.affiliation: National Museum of Natural Sciences, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain. Electronic address: fernando.garrido@mncn.csic.es.
authors.forename: Fernando
authors.initials: F
authors.lastname: Garrido
mesh_terms: D001151:Arsenic / Q000032:analysis*; D001152:Arsenicals / Q000032:analysis; D003102:Colloids / Q000737:chemistry*; D005843:Geography; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis; D046529:Microscopy, Electron, Transmission; D008906:Mining; D053758:Nanoparticles / Q000737:chemistry; D010316:Particle Size; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D013030:Spain; D056928:X-Ray Absorption Spectroscopy
chemical_list: D001152:Arsenicals; D003102:Colloids; D012987:Soil; D012989:Soil Pollutants; C548094:scorodite; D007501:Iron; D001151:Arsenic