Trace element-mineral associations in modern and ancient iron terraces in acid drainage environment Cruz-Hernández, Pablo Pérez-López, Rafael Parviainen, Annika Jenni Johana Lindsay, Matthew B.J. Nieto, José Miguel Schwertmannite Goethite Hematite Acid drainage Trace elements behavior This research was financed by the Spanish Ministry of Economy and Competitiveness through the EMPATIA project (Ref. CGL2013-48460-C2-1-R). The work of Dr. A. Parviainen was funded by the KAUTE Foundation, Finland. Dr. R. Pérez-López acknowledges the Spanish Ministry of Science and Innovation and the ‘Ramón y Cajal Subprogramme’ (MICINN-RYC 2011). P. Cruz-Hernández was supported by a graduate scholarship from the Spanish Ministry of Economy and Competitiveness (METODICA, CGL2010-21956-C02-02). Dr. Lindsay acknowledges support from the NSERC Discovery Grants Program (Grant No. RGPIN-2014-06589). Portions of this research were performed at GeoSoilEnviroCARS (Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation - Earth Sciences (EAR-1128799) and Department of Energy - GeoSciences (DE-FG02-94ER14466). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Iron-rich sediments commonly cover riverbeds that have been affected by acid drainage associated with sulfide-mineral oxidation. Freshly-formed precipitates correspond to poorly-crystalline oxyhydroxysulfates that recrystallize over time. This study examined the distribution and mineral association of trace elements (e.g., As, Cu, Zn) in modern and ancient (~ 6 Ma) Fe terraces in the Tinto river basin, Spain. The mineral composition of the terraces was determined by Raman μ-spectroscopy. Chemical digestions, electron probe microanalyses, and synchrotron-based μ-X-ray fluorescence mapping were used to examine As, Cu, and Zn distribution and corresponding mineral associations. Fresh precipitates at modern terrace surfaces were dominated by schwertmannite, which contained high As, Cu, Mn, and Zn concentrations. However, schwertmannite transforms into goethite over days to weeks in the deeper part of the current terraces and into hematite over centuries. Affinity for trace elements was generally highest for schwertmannite and lowest for hematite, which suggests that their retention by Fe terraces decreases during mineral transformation. Hence, schwertmannite acts as temporary sink for contaminants, which are again released over long time periods. These findings should be considered for management and treatment of possible water resources affected by acid mine drainage. 2024-10-29T11:25:48Z 2024-10-29T11:25:48Z 2016-12 journal article Cruz-Hernández, P., Pérez-López, R., Parviainen, A., Lindsay, M. B. J., & Nieto, J. M. (2016). Trace element-mineral associations in modern and ancient iron terraces in acid drainage environment. Catena, 147, 386-393. https://doi.org/10.1016/J.CATENA.2016.07.049 https://hdl.handle.net/10481/96448 10.1016/J.CATENA.2016.07.049 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ embargoed access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier