Observations and assessment of iron oxide and green rust nanoparticles in metal-polluted mine drainage within a steep redox gradient

Environmental context Legacy contamination from mining operations is a serious and complex environmental problem. We examine a former uranium mine where groundwater leaving the site enters a stream with chemically dramatic effects resulting in a fundamental change in the way contaminant metals are transported to the surface environment. The results are important for our understanding of how these contaminants are dispersed, and how they could interact with the biosphere. Abstract In this study of iron- and silica-bearing nanoparticle and colloid aggregates in slightly acidic mine drainage, we combined bulk scale geochemistry techniques with detailed nanoscale analyses using high-resolution transmission electron microscopy (HR-TEM) to demonstrate the complexity of iron oxide formation and transformation at a steep redox gradient (groundwater outflow into a stream), and the resulting role in metal(loid) uptake. We also identified pseudohexagonal nanosheets of Zn-bearing green rust in outflowing groundwater using HR-TEM. This is only the second study where green rust was identified in groundwater, and the second to examine naturally occurring green rust with analytical TEM. In aerated downstream waters, we found aggregates of poorly crystalline iron oxide particles (20–200nm in diameter). Inductively coupled plasma–mass spectrometry (ICP-MS) analysis of water fractions shows that most elements such as Ni and Zn were found almost exclusively in the dissolved–nanoparticulate (<0.1μm) fraction, whereas Cu and As were primarily associated with suspended particles. In the underlying sediments composed of deposited particles, goethite nanoneedles formed on the ferrihydrite surfaces of larger aggregated particles (100–1000nm), resulting in more reactive surface area for metal(loid) uptake. Sequential extraction of sediments showed that many metal(loid)s, particularly As and Zn, were associated with iron oxides identified as ferrihydrite, goethite and possibly schwertmannite. Amorphous silica co-precipitation with iron oxides was prevalent at all sampling sites, but its effect on metal(loid) sorption is unknown. Fine-grained iron oxide sediments are easily remobilised during turbulent flow events, adding to the mobility of the associated metals.

[1]  M. Dykstra A Manual of Applied Techniques for Biological Electron Microscopy , 1993 .

[2]  José Miguel Nieto,et al.  Environmental assessment and management of metal-rich wastes generated in acid mine drainage passive remediation systems. , 2012, Journal of hazardous materials.

[3]  C. Koch,et al.  Conditions for biological precipitation of iron by Gallionella ferruginea in a slightly polluted ground water , 2001 .

[4]  T. Rennert,et al.  Iron species in soils on a mofette site studied by Fe K-edge X-ray absorption near-edge spectroscopy , 2012 .

[5]  J. Rimstidt,et al.  IRON DYNAMICS IN ACID MINE DRAINAGE 1 , 2006 .

[6]  P. Heikkinen,et al.  Trace metal and As solid-phase speciation in sulphide mine tailings - Indicators of spatial distribution of sulphide oxidation in active tailings impoundments , 2009 .

[7]  G. Bourrié,et al.  Fougerite a Natural Layered Double Hydroxide in Gley Soil: Habitus, Structure, and Some Properties , 2012 .

[8]  L. Legrand,et al.  The oxidation of carbonate green rust into ferric phases :solid-state reaction or transformation via solution , 2004 .

[9]  Tabatabai A Rapid Method for Determination of Sulfate in Water Samples , 1974 .

[10]  O. Atteia,et al.  The diversity of natural hydrous iron oxides. , 2000 .

[11]  J. Hazemann,et al.  Rietveld Studies of the Aluminium-Iron Substitution in Synthetic Goethite , 1991 .

[12]  K. Finster,et al.  Microbial Links between Sulfate Reduction and Metal Retention in Uranium- and Heavy Metal-Contaminated Soil , 2010, Applied and Environmental Microbiology.

[13]  C. Ayora,et al.  Sequential extraction and DXRD applicability to poorly crystalline Fe- and Al-phase characterization from an acid mine water passive remediation system , 2009 .

[14]  Paul D. Cotter,et al.  Nucleic acid-based approaches to investigate microbial-related cheese quality defects , 2012, Front. Microbio..

[15]  D. Akob,et al.  Heavy Metal Tolerance of Fe(III)-Reducing Microbial Communities in Contaminated Creek Bank Soils , 2011, Applied and Environmental Microbiology.

[16]  N. C. Scrivner,et al.  Surface complexation modeling of zinc sorption onto ferrihydrite. , 2004, Journal of colloid and interface science.

[17]  Y. Arai Spectroscopic evidence for Ni(II) surface speciation at the iron oxyhydroxides-water interface. , 2008, Environmental science & technology.

[18]  N. Terrill,et al.  Formation of green rust sulfate: a combined in situ time-resolved X-ray scattering and electrochemical study. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[19]  R. Bush,et al.  Iron and arsenic cycling in intertidal surface sediments during wetland remediation. , 2011, Environmental science & technology.

[20]  A. Putnis,et al.  A TEM study of samples from acid mine drainage systems: metal-mineral association with implications for transport , 1999 .

[21]  Huifang Xu,et al.  Can hematite nanoparticles be an environmental indicator , 2013 .

[22]  J. Génin,et al.  Nomenclature of the hydrotalcite supergroup: natural layered double hydroxides , 2012, Mineralogical Magazine.

[23]  E. L. Pamo,et al.  Iron terraces in acid mine drainage systems: A discussion about the organic and inorganic factors involved in their formation through observations from the Tintillo acidic river (Riotinto mine, Huelva, Spain) , 2007 .

[24]  Michael F. Hochella,et al.  Characterization and environmental implications of nano- and larger TiO(2) particles in sewage sludge, and soils amended with sewage sludge. , 2012, Journal of environmental monitoring : JEM.

[25]  K. Goto,et al.  Spectrophotometric determination of iron(II) with 1,10-phenanthroline in the presence of large amounts of iron(III). , 1974, Talanta.

[26]  G. Bourrié,et al.  In situ mössbauer spectroscopy : Evidence for green rust (fougerite) in a gleysol and its mineralogical transformations with time and depth , 2005 .

[27]  P Quevauviller,et al.  Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials. , 1999, Journal of environmental monitoring : JEM.

[28]  M. Hassellöv,et al.  Iron Oxides as Geochemical Nanovectors for Metal Transport in Soil-River Systems , 2008 .

[29]  T. Hofmann,et al.  Using FlFFF and aTEM to determine trace metal-nanoparticle associations in riverbed sediment. , 2010 .

[30]  J. Banfield,et al.  Aggregation-based crystal growth and microstructure development in natural iron oxyhydroxide biomineralization products. , 2000, Science.

[31]  E. Roden,et al.  Evidence for rapid microscale bacterial redox cycling of iron in circumneutral environments , 2002, Antonie van Leeuwenhoek.

[32]  J. Nieto,et al.  Seasonal variations in the formation of Al and Si rich Fe-stromatolites in the highly polluted acid mine drainage of Agua Agria Creek (Tharsis, SW Spain) , 2011 .

[33]  A. Kappler,et al.  Green rust formation during Fe(II) oxidation by the nitrate-reducing Acidovorax sp. strain BoFeN1. , 2012, Environmental science & technology.

[34]  T. Hiemstra,et al.  Nanoparticles in natural systems I: The effective reactive surface area of the natural oxide fraction in field samples , 2010 .

[35]  D. Sparks,et al.  Nanominerals, Mineral Nanoparticles, and Earth Systems , 2008, Science.

[36]  J. Rimstidt,et al.  The enigmatic iron oxyhydroxysulfate nanomineral schwertmannite: Morphology, structure, and composition , 2012 .

[37]  C. Grosbois,et al.  Transformation of natural As-associated ferrihydrite downstream of a remediated mining site , 2006 .

[38]  G. Faure,et al.  Removal of trace metals by coprecipitation with Fe, Al and Mn from natural waters contaminated with acid mine drainage in the Ducktown Mining District, Tennessee , 2002 .

[39]  C. Sangregorio,et al.  Genetic evolution of nanocrystalline Fe oxide and oxyhydroxide assemblages from the Libiola mine (eastern Liguria, Italy) : structural and microstructural investigations , 2005 .

[40]  W. Tan,et al.  Transformation of hydroxycarbonate green rust into crystalline iron (hydr)oxides: Influences of reaction conditions and underlying mechanisms , 2013 .

[41]  C. Chan Iron oxyhydroxide mineralization on microbial extracellular polysaccharides , 2009 .

[42]  Lynne A. Goodwin,et al.  Comparative genomics of freshwater Fe-oxidizing bacteria: implications for physiology, ecology, and systematics , 2013, Front. Microbiol..

[43]  P. Searson,et al.  Epitaxial Assembly in Aged Colloids , 2001 .

[44]  Colleen M. Hansel,et al.  Anaerobic methane oxidation in metalliferous hydrothermal sediments: influence on carbon flux and decoupling from sulfate reduction. , 2012, Environmental microbiology.

[45]  D. Nordstrom,et al.  Iron and Aluminum Hydroxysulfates from Acid Sulfate Waters , 2000 .

[46]  S. Stipp,et al.  Identification of green rust in groundwater. , 2009, Environmental science & technology.

[47]  P. Refait,et al.  Structure of the Fe(II-III) layered double hydroxysulphate green rust two from Rietveld analysis , 2003 .

[48]  C. Ayora,et al.  Synchrotron-based X-ray study of iron oxide transformations in terraces from the Tinto-Odiel river system: Influence on arsenic mobility , 2011 .

[49]  N. M. Price,et al.  Direct use of inorganic colloidal iron by marine mixotrophic phytoplankton , 2001 .

[50]  S. Tulaczyk,et al.  Schwertmannite in wet, acid, and oxic microenvironments beneath polar and polythermal glaciers , 2009 .

[51]  V. Ciobotă,et al.  Pelagic boundary conditions affect the biological formation of iron‐rich particles (iron snow) and their microbial communities , 2011 .

[52]  Mitsuhiro Murayama,et al.  Discovery and characterization of silver sulfide nanoparticles in final sewage sludge products. , 2010, Environmental science & technology.

[53]  Á. Aguilera,et al.  Acid rock drainage and rock weathering in Antarctica: important sources for iron cycling in the Southern Ocean. , 2013, Environmental science & technology.

[54]  D. Akob,et al.  Surprising abundance of Gallionella-related iron oxidizers in creek sediments at pH 4.4 or at high heavy metal concentrations , 2013, Front. Microbiol..

[55]  W. J. Deutsch Groundwater Geochemistry: Fundamentals and Applications to Contamination , 1997 .

[56]  D. Canfield,et al.  Green rust formation controls nutrient availability in a ferruginous water column , 2012 .

[57]  J. Corliss,et al.  Practical methods in electron microscopy , 1973 .

[58]  R. Hettich,et al.  Insights into the Structure and Metabolic Function of Microbes That Shape Pelagic Iron-Rich Aggregates (“Iron Snow”) , 2013, Applied and Environmental Microbiology.

[59]  K. Farley,et al.  Changes in Transition and Heavy Metal Partitioning during Hydrous Iron Oxide Aging , 1997 .

[60]  T. Tyliszczak,et al.  Composition and structural aspects of naturally occurring ferrihydrite , 2011 .

[61]  J. Puhakka,et al.  Competition for oxygen by iron and 2,4,6-trichlorophenol oxidizing bacteria in boreal groundwater. , 2003, Water research.

[62]  David Emerson,et al.  Iron-oxidizing bacteria: an environmental and genomic perspective. , 2010, Annual review of microbiology.

[63]  Andrew S. Madden,et al.  Naturally Occurring Inorganic Nanoparticles: General Assessment and a Global Budget for One of Earth's Last Unexplored Major Geochemical Components , 2012 .

[64]  J. Rimstidt,et al.  Metastability, nanocrystallinity and pseudo-solid solution effects on the understanding of schwertmannite solubility , 2013 .

[65]  J. Banfield,et al.  Nanoparticulate Iron Oxide Minerals in Soils and Sediments: Unique Properties and Contaminant Scavenging Mechanisms , 2005 .

[66]  K. Pedersen,et al.  Phylogeny and phenotypic characterization of the stalk-forming and iron-oxidizing bacterium Gallionella ferruginea. , 1993, Journal of general microbiology.

[67]  M. Taillefert,et al.  Reactive transport modeling of trace elements in the water column of a stratified lake: iron cycling and metal scavenging , 2000 .

[68]  C. Ayora,et al.  Hydrochemical performance and mineralogical evolution of a dispersed alkaline substrate (DAS) remediating the highly polluted acid mine drainage in the full-scale passive treatment of Mina Esperanza (SW Spain) , 2011 .

[69]  R. Raiswell,et al.  Nanoparticulate bioavailable iron minerals in icebergs and glaciers , 2008, Mineralogical Magazine.

[70]  F. Frondini,et al.  Mineralogical and chemical evolution of ochreous precipitates from the Libiola Fe–Cu-sulfide mine (Eastern Liguria, Italy) , 2012 .

[71]  D. Akob,et al.  Impact of biostimulated redox processes on metal dynamics in an iron-rich creek soil of a former uranium mining area. , 2010, Environmental science & technology.

[72]  Shenggao Lu,et al.  Occurrence, Structure and Mineral Phases of Nanoparticles in an Anthrosol , 2013 .

[73]  Amanda S. Barnard,et al.  Naturally occurring iron oxide nanoparticles: morphology, surface chemistry and environmental stability , 2013 .

[74]  A. Genovese,et al.  Ferrihydrite flocs, native copper nanocrystals and spontaneous remediation in the Fosso dei Noni stream, Tuscany, Italy , 2007 .