Register      Login
Environmental Chemistry Environmental Chemistry Society
Environmental problems - Chemical approaches
RESEARCH FRONT

Multi-elemental scanning transmission X-ray microscopy–near edge X-ray absorption fine structure spectroscopy assessment of organo–mineral associations in soils from reduced environments

Chunmei Chen A B and Donald L. Sparks A
+ Author Affiliations
- Author Affiliations

A Department of Plant and Soil Sciences, Delaware Environmental Institute, University of Delaware, Newark, DE 19711, USA.

B Corresponding author. Email: cmchen@udel.edu

Environmental Chemistry 12(1) 64-73 https://doi.org/10.1071/EN14042
Submitted: 23 February 2014  Accepted: 29 September 2014   Published: 27 January 2015

Environmental context. Organo–mineral associations represent a fundamental process for stabilising organic carbon in soils. In this study, we employed scanning transmission X-ray microscopy–near edge X-ray absorption fine structure (STXM-NEXAFS) spectroscopy at C, Al and Si K-edges as well as Ca and Fe L-edges to conduct submicrometre-level investigations of the associations of C with mineral components in soils from reduced environments. This study provides the first insights into organo–mineral associations in reduced environments and shows progress towards examining, at the submicrometre level, compositional chemistry and associative interactions between organic matter and soil mineral components.

Abstract. Organo–mineral associations represent a fundamental process for stabilising organic carbon (OC) in soils. However, direct investigation of organo–mineral associations has been hampered by a lack of methods that can simultaneously characterise organic matter (OM) and soil minerals, and most investigations have focussed only on well drained soils. In this study, we employed scanning transmission X-ray microscopy–near edge X-ray absorption fine structure (STXM-NEXAFS) spectroscopy at C, Al and Si K-edges as well as Ca and Fe L-edges to conduct submicrometre-level investigations of the associations of C with mineral components in soils from reduced environments. Soils were collected from a forest footslope that is periodically poorly drained as well as a waterlogged wetland. OM was coated on mineral particles as thin films. Part of the mineral surface did not show detectable OM coverage with OC loadings of ≥1.3 mg C m–2 determined for the clay fractions from these soils. C was not preferentially associated with Fe oxides in the footslope soil. A generally good C–Ca association was found in the anoxic wetland soil, which is free of Fe oxides. It was demonstrated for the first time that OM composition varied spatially at the submicrometre scale in the reduced soils free of Fe oxides. The composition of OM in the organo–mineral interface in the anoxic environments was highly complex and composed of aromatic, phenolic, aliphatic, carboxyl, carboxylamide and O-alkyl C functional groups. There was no consistent pattern for the association of certain types of organics with specific mineral components in both soils. The anoxic conditions resulted in the reduction of Fe in the aluminosilicates. This study provides the first insights into organo–mineral associations in reduced environments.


References

[1]  J. A. Baldock, J. O. Skjemstad, Role of the soil matrix and minerals in protecting natural organic materials against biological attack. Org. Geochem. 2000, 31, 697.
Role of the soil matrix and minerals in protecting natural organic materials against biological attack.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXmsFSqu70%3D&md5=22120fd7af8ee37a76fdb803578e561cCAS |

[2]  D. Solomon, J. Lehmann, J. Harden, J. Wang, J. Kingangi, K. Heymann, C. Karunakaran, Y. S. Lu, S. Wirick, C. Jacobsen, Micro- and nano-environments of carbon sequestration: multi-element STXM-NEXAFS spectromicroscopy assessment of microbial carbon and mineral associations. Chem. Geol. 2012, 329, 53.
Micro- and nano-environments of carbon sequestration: multi-element STXM-NEXAFS spectromicroscopy assessment of microbial carbon and mineral associations.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XhtlymurzI&md5=2518c19db50c0fd00da16f84c5b59528CAS |

[3]  B. T. Christensen, Physical fractionation of soil and structural and functional complexity in organic matter turnover. Eur. J. Soil Sci. 2001, 52, 345.
Physical fractionation of soil and structural and functional complexity in organic matter turnover.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXntFKiu74%3D&md5=9baaa5e9d8bc0c2ff6a4c04b1b99152cCAS |

[4]  P. Sollins, P. Homann, B. A. Caldwell, Stabilisation and destabilisation of soil organic matter: mechanisms and controls. Geoderma 1996, 74, 65.
Stabilisation and destabilisation of soil organic matter: mechanisms and controls.Crossref | GoogleScholarGoogle Scholar |

[5]  J. Six, H. Bossuyt, S. De Gryze, K. Denef, A history of research on the link between (micro) aggregates, soil biota, and soil organic matter dynamics. Soil Tillage Res. 2004, 79, 7.
A history of research on the link between (micro) aggregates, soil biota, and soil organic matter dynamics.Crossref | GoogleScholarGoogle Scholar |

[6]  S. Trumbore, Radiocarbon and soil carbon dynamics. Annu. Rev. Earth Planet. Sci. 2009, 37, 47.
Radiocarbon and soil carbon dynamics.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXmvVCktrk%3D&md5=d5cdf05bc6f972ea035410adf5b2f0ffCAS |

[7]  M. S. Torn, S. E. Trumbore, O. A. Chadwick, P. M. Vitousek, D. M. Hendricks, Mineral control of soil organic carbon storage and turnover. Nature 1997, 389, 170.
Mineral control of soil organic carbon storage and turnover.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2sXmtVSrsr8%3D&md5=fd0a4092cf99fb39aa710de9e60e1e88CAS |

[8]  V. M. Lützow, I. Kögel-Knabner, K. Ekschmitt, E. Matzner, G. Guggenberger, B. Marschner, H. Flessa, Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review. Eur. J. Soil Sci. 2006, 57, 426.
Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review.Crossref | GoogleScholarGoogle Scholar |

[9]  I. Kögel-Knabner, G. Guggenberger, M. Kleber, E. Kandeler, K. Kalbitz, S. Scheu, K. Eusterhues, P. Leinweber, Organo-mineral associations in temperate soils: integrating biology, mineralogy, and organic matter chemistry. J. Soil Sci. Plant Nutr. 2008, 171, 61.
Organo-mineral associations in temperate soils: integrating biology, mineralogy, and organic matter chemistry.Crossref | GoogleScholarGoogle Scholar |

[10]  D. L. Sparks, Sorption phenomena in soils, in Environmental Physical Chemistry (Ed D. L. Sparks) 1995, pp. 99–139 (Academic Press: New York).

[11]  C. Chen, J. J. Dynes, J. Wang, C. Karunakaran, D. L. Sparks, Soft X-ray spectromicroscopy study of mineral-organic matter associations in pasture soil clay fractions. Environ. Sci. Technol. 2014, 48, 6678.
Soft X-ray spectromicroscopy study of mineral-organic matter associations in pasture soil clay fractions.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXotFSlt7k%3D&md5=afeb1a5568343d2146fa2a008d3342b7CAS | 24837340PubMed |

[12]  M. Schumacher, I. Christl, A. C. Scheinost, C. Jacobsen, R. Kretzschmar, Chemical heterogeneity of organic soil colloids investigated by scanning transmission X-ray microscopy and C-1s NEXAFS microspectroscopy. Environ. Sci. Technol. 2005, 39, 9094.
Chemical heterogeneity of organic soil colloids investigated by scanning transmission X-ray microscopy and C-1s NEXAFS microspectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXhtFGmtb7J&md5=2ebc2adfd72928cc7f088b2d83c4cfb8CAS | 16382929PubMed |

[13]  J. Kinyangi, D. Solomon, B. Liang, M. Lerotic, S. Wirick, J. Lehmann, Nanoscale biogeocomplexity of the organo-mineral assemblage in soil: application of STXM microscopy and C 1s-NEXAFS spectroscopy. Soil Sci. Soc. Am. J. 2006, 70, 1708.
Nanoscale biogeocomplexity of the organo-mineral assemblage in soil: application of STXM microscopy and C 1s-NEXAFS spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28Xpsl2lsb0%3D&md5=d25183f281dffc5fa132150c3d5cd08eCAS |

[14]  J. Lehmann, J. Kinyangi, D. Solomon, Organic matter stabilization in soil microaggregates: implications from spatial heterogeneity of organic carbon contents and carbon form. Biogeochemistry 2007, 85, 45.
Organic matter stabilization in soil microaggregates: implications from spatial heterogeneity of organic carbon contents and carbon form.Crossref | GoogleScholarGoogle Scholar |

[15]  J. Lehmann, D. Solomon, J. Kinyang, L. Dathe, S. Wirick, S. Jacobsen, Spatial complexity of soil organic matter forms at nanometer scales. Nat. Geosci. 2008, 1, 238.
Spatial complexity of soil organic matter forms at nanometer scales.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXktVCisb0%3D&md5=3280abdd2e7f5ce7b971b420627f86e3CAS |

[16]  J. M. Wan, T. Tyliszczak, T. K. Tokunaga, Organic carbon distribution, speciation, and elemental correlations with soil micro aggregates: applications of STXM and NEXAFS spectroscopy. Geochim. Cosmochim. Acta 2007, 71, 5439.
Organic carbon distribution, speciation, and elemental correlations with soil micro aggregates: applications of STXM and NEXAFS spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXht1GhurfJ&md5=f8b1e2d0bbe0204a453198fe38aac971CAS |

[17]  F. Hagedorn, K. Kaiser, H. Feyen, P. Schleppi, Effect of redox conditions and flow processes on the mobility of dissolved organic carbon and nitrogen in a forest soil. J. Environ. Qual. 2000, 29, 288.
Effect of redox conditions and flow processes on the mobility of dissolved organic carbon and nitrogen in a forest soil.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXot1eitg%3D%3D&md5=ce8d6df499aaf98495365e62f90e8a5bCAS |

[18]  K. H. Knorr, DOC-dynamics in a small headwater catchment as driven by redox fluctuations and hydrological flow paths – are DOC exports mediated by iron reduction/oxidation cycles? Biogeosciences 2013, 10, 891.
DOC-dynamics in a small headwater catchment as driven by redox fluctuations and hydrological flow paths – are DOC exports mediated by iron reduction/oxidation cycles?Crossref | GoogleScholarGoogle Scholar |

[19]  K. Eusterhues, C. Rumpel, I. Kögel-Knabner, Organo-mineral associations in sandy acid forest soils: importance of specific surface area, iron oxides and micropores. Eur. J. Soil Sci. 2005, 56, 753.
| 1:CAS:528:DC%2BD28Xjs1Gqsw%3D%3D&md5=0c28318799191b776407c7984abf911dCAS |

[20]  M. Kleber, R. Mikutta, M. S. Torn, R. Jahn, Poorly crystalline mineral phases protect organic matter in acid subsoil horizons. Eur. J. Soil Sci. 2005, 56, 717.
| 1:CAS:528:DC%2BD28Xjs1Grug%3D%3D&md5=1d2af657f50be676c02f80ab28440a67CAS |

[21]  R. A. Sloto, Geology, hydrology, and ground water quality of Chester County, Pennsylvania. Water-Resource Report 2 1994 (Chester County Water Resources Authority).

[22]  J. D. Newbold, R. L. Bott, L. A. Kaplan, B. W. Sweeney, R. L. Vannote, Organic matter dynamics in White Clay Creek, Pennsylvania, USA. J. N. Am. Benthol. Soc. 1997, 16, 46.
Organic matter dynamics in White Clay Creek, Pennsylvania, USA.Crossref | GoogleScholarGoogle Scholar |

[23]  R. C. Walter, D. J. Merritts, Natural streams and the legacy of water-powered mills. Science 2008, 319, 299.
Natural streams and the legacy of water-powered mills.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXmt1yjug%3D%3D&md5=64725f98f9af4837dd136bdca7d9e8b8CAS | 18202284PubMed |

[24]  W. Amelung, W. Zech, X. Zhang, R. F. Follett, H. Tiessen, E. Knox, K. W. Flach, Carbon, nitrogen, and sulfur pools in particle-size fractions as influenced by climate. Soil Sci. Soc. Am. J. 1998, 62, 172.
Carbon, nitrogen, and sulfur pools in particle-size fractions as influenced by climate.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1cXhtlarsL4%3D&md5=f5b28c45a3fa271b25f723cea9ac8604CAS |

[25]  K. V. Kaznatcheev, C. Karunakaran, U. D. Lanke, S. G. Urquhart, M. Obst, A. P. Hitchcock, Soft X-ray spectromicroscopy beamline at the CLS: commissioning results. Nucl. Instrum. Meth. A 2007, 582, 96.
Soft X-ray spectromicroscopy beamline at the CLS: commissioning results.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXhtF2rsLjL&md5=134ea7d716632ff27002d40cbe71c852CAS |

[26]  K. Benzerara, T. H. Yoon, T. Tyliszczak, B. Constantz, A. M. Spormann, G. E. Brown, Scanning transmission X-ray microscopy study of microbial calcification. Geobiology 2004, 2, 249.
Scanning transmission X-ray microscopy study of microbial calcification.Crossref | GoogleScholarGoogle Scholar |

[27]  J. J. Dynes, T. Tyliszczak, T. Araki, J. R. Lawrence, G. D. W. Swerhone, G. G. Leppard, A. P. Hitchcock, Speciation and quantitative mapping of metal species in microbial biofilms using scanning transmission X-ray microscopy. Environ. Sci. Technol. 2006, 40, 1556.
Speciation and quantitative mapping of metal species in microbial biofilms using scanning transmission X-ray microscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XlvFSnug%3D%3D&md5=d7133d0ea9a310c47a8b21d84f274852CAS | 16568770PubMed |

[28]  T. H. Yoon, S. B. Johnson, K. Benzerara, C. S. Doyle, T. Tyliszczak, D. K. Shuh, G. E. Brown, In-situ characterization of aluminum coating mineral-microorganism aqueous suspensions using scanning transmission X-ray microscopy. Langmuir 2004, 20, 10 361.
In-situ characterization of aluminum coating mineral-microorganism aqueous suspensions using scanning transmission X-ray microscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXptVamtbk%3D&md5=dfe9d99707fda753930823bed2655a54CAS |

[29]  D. Li, G. M. Bancroft, M. E. Fleet, X. H. Feng, Silicon K-edge XANES spectra of silicate minerals. Phys. Chem. Miner. 1995a, 22, 115.
Silicon K-edge XANES spectra of silicate minerals.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXlsVyru78%3D&md5=a7b2c6b9fdfd89bd03738b8c30bb9cb6CAS |

[30]  A. P. Hitchcock, aXis-2000 is an IDL-based analytical package 2000. http://unicorn.mcmaster.ca/aXis2000.html [Verified 19 December 2014].

[31]  M. Lerotic, B. Jacobsen, J. B. Gillow, Cluster analysis in soft X-ray spectromicroscopy: finding the patterns in complex specimens. J. Electron Spectrosc. Relat. Phenom. 2005, 144–147, 1137.
Cluster analysis in soft X-ray spectromicroscopy: finding the patterns in complex specimens.Crossref | GoogleScholarGoogle Scholar |

[32]  L. M. Mayer, Surface area control of organic carbon accumulation in continental shelf sediments. Geochim. Cosmochim. Acta 1994, 58, 1271.
Surface area control of organic carbon accumulation in continental shelf sediments.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2cXislGktbs%3D&md5=17027160e3bb4ff502d5163ae4754281CAS |

[33]  R. G. Keil, D. B. Montlucon, F. G. Prahl, J. I. Hedges, Sorptive preservation of labile organic matter in marine sediments. Nature 1994, 370, 549.
Sorptive preservation of labile organic matter in marine sediments.Crossref | GoogleScholarGoogle Scholar |

[34]  C. Vogel, C. W. Mueller, C. Höschen, F. Buegger, K. Heister, S. Schulz, M. Schloter, I. Kögel-Knabner, Submicron structures provide preferential spots for carbon and nitrogen sequestration in soils. Nat. Commun. 2014, 5, 2947.
Submicron structures provide preferential spots for carbon and nitrogen sequestration in soils.Crossref | GoogleScholarGoogle Scholar | 24399306PubMed |

[35]  A. W. Gillespie, F. L. Walley, R. E. Farrell, P. Leinweber, K. U. Eckhardt, T. Z. Regier, R. I. R. Blyth, XANES and pyrolysis-FIMS evidence of organic matter composition in a hummocky landscape. Soil Sci. Soc. Am. J. 2011, 75, 1741.
XANES and pyrolysis-FIMS evidence of organic matter composition in a hummocky landscape.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXht1CisrvJ&md5=83a94c7585ff17e26a9c02f6e5490b51CAS |

[36]  J. A. Brandes, C. Lee, S. Wakeham, M. Peterson, C. Jacoben, S. Wirick, G. Cody, Examining marine particulate organic matter at sub-micron scales using scanning transmission X-ray microscopy and carbon X-ray absorption near edge structure spectroscopy. Mar. Chem. 2004, 92, 107.
Examining marine particulate organic matter at sub-micron scales using scanning transmission X-ray microscopy and carbon X-ray absorption near edge structure spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXhtVChsL%2FM&md5=9ee35252d9fdc915ba89d9fa572e894dCAS |

[37]  M. Kleber, P. S. Nico, A. Plante, T. Filley, M. Kramer, C. Swanston, P. Sollins, Old and stable soil organic matter is not necessarily chemically recalcitrant: implications for modeling concepts and temperature sensitivity. Glob. Change Biol. 2011, 17, 1097.
Old and stable soil organic matter is not necessarily chemically recalcitrant: implications for modeling concepts and temperature sensitivity.Crossref | GoogleScholarGoogle Scholar |

[38]  W. Keiluweit, J. J. Bougoure, L. H. Zeglin, D. D. Myrold, P. K. Weber, J. Pett-ridge, M. Kleber, P. S. Nico, Nano-scale investigation of the association of microbial nitrogen residues with iron (hydr)oxides in a forest soil O-horizon. Geochim. Cosmochim. Acta 2012, 95, 213.
Nano-scale investigation of the association of microbial nitrogen residues with iron (hydr)oxides in a forest soil O-horizon.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XhsVegs7rJ&md5=545915a2e3b73a235823c9bf6ce3c891CAS |

[39]  C. S. Chan, S. Fakra, D. C. Edwards, D. Emerson, J. F. Banfield, Iron oxyhydroxide mineralization on microbial polysaccharides. Geochim. Cosmochim. Acta 2009, 73, 3807.
Iron oxyhydroxide mineralization on microbial polysaccharides.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXmvVyktbo%3D&md5=a8d88d28cd7b02e46eeca9ffe8344d79CAS |

[40]  D. Solomon, J. Lehmann, J. Kinyangi, B. Liang, T. Schäfer, Carbon K-edge NEXAFS and FTIR-ATR spectroscopic investigation of organic carbon speciation in soils. Soil Sci. Soc. Am. J. 2005, 69, 107.
Carbon K-edge NEXAFS and FTIR-ATR spectroscopic investigation of organic carbon speciation in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXnvFGmtQ%3D%3D&md5=9d1c6e97f17747288f6e6fa0404425c4CAS |

[41]  B. Liang, J. Lehmann, D. Solomon, J. Kinyangi, J. Grossman, B. O'Neill, J. O. Skjemstad, J. Thies, F. J. Luizao, J. Petersen, E. G. Neves, Black carbon increases cation exchange capacity in soils. Soil Sci. Soc. Am. J. 2006, 70, 1719.
Black carbon increases cation exchange capacity in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28Xpsl2lsbo%3D&md5=ec778a2de8b3a9f1902d2212a7fefccaCAS |

[42]  X. R. Liu, K. Eusterhues, J. Thieme, V. Ciobota, C. Hoschen, C. W. Mueller, K. Kusel, I. K. Kogel-Knabner, P. Rosch, J. Popp, K. U. Totsche, STXM and NanoSIMS investigations on EPS fractions before and after adsorption to goethite. Environ. Sci. Technol. 2013, 47, 3158.
| 1:CAS:528:DC%2BC3sXjtlOqsbY%3D&md5=8bde548c4f87fc6a5eeeec65a9fe96f5CAS |

[43]  J. M. Oades, Soil organic matter and structural stability: mechanisms and implications for management. Plant Soil 1984, 76, 319.
Soil organic matter and structural stability: mechanisms and implications for management.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL2cXhvFSksbw%3D&md5=d07a3327a32b1e4d168422626b93b921CAS |

[44]  C. Chenu, Extracellular polysaccharides: an interface between microorganisms and soil constituents, in Environmental Impact of Soil Component Interactions: Natural and Anthropogenic Organics (Eds P. M. Huang, J. Berthelin, J. M. Bollag, W. B. McGill, A. L. Page) 1995, pp. 217–233 (CRC Press: Boca Raton, FL).

[45]  A. Omoike, J. Chorover, Adsorption to goethite of extracellular polymeric substances from Bacillus subtilis. Geochim. Cosmochim. Acta 2006, 70, 827.
Adsorption to goethite of extracellular polymeric substances from Bacillus subtilis.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XhtVamu7c%3D&md5=043c8a8f984821d597007cd3b66b9e6bCAS |

[46]  S. J. Naftel, T. K. Sham, Y. M. Yiu, B. W. Yates, Calcium L-edge XANES study of some calcium compounds. J. Synchrotron Radiat. 2001, 8, 255.
Calcium L-edge XANES study of some calcium compounds.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXhs1amu7g%3D&md5=43430e577f2ef3ab21922f7cae1433f8CAS | 11512744PubMed |

[47]  M. E. Fleet, X. Liu, Calcium L2,3-edge XANES of carbonates, carbonate apatite, and oldhamite (CaS). Am. Mineral. 2009, 94, 1235.
Calcium L2,3-edge XANES of carbonates, carbonate apatite, and oldhamite (CaS).Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhtVWksbjE&md5=c404c14da9df3136377e1d99951b4a26CAS |

[48]  Y. Politi, R. A. Metzler, M. Abrecht, B. Gilbert, F. H. Wilt, I. Sagi, L. Addadi, S. Weiner, P. U. P. A. Gilbert, Transformation mechanism of amorphous calcium carbonate into calcite in the sea urchin larval spicule. Proc. Natl. Acad. Sci. USA 2008, 105, 17 362.
Transformation mechanism of amorphous calcium carbonate into calcite in the sea urchin larval spicule.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXhsVWnsrrP&md5=3ca262352f9d3fae4df3894b1bacb73fCAS |

[49]  M. Obst, J. J. Dynes, J. R. Lawrence, G. D. W. Swerhone, C. Karunakaran, K. Kaznacheyev, K. Benzerara, T. Tyliszczak, A. P. Hitchcock, Precipitation of amorphous CaCO3 (aragonite) controlled by cyanobacteria: a multi-technique study of the influence of EPS on the nucleation process. Geochim. Cosmochim. Acta 2009, 73, 4180.
Precipitation of amorphous CaCO3 (aragonite) controlled by cyanobacteria: a multi-technique study of the influence of EPS on the nucleation process.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXmvVynsbk%3D&md5=2d18d3f78958fbfb96b24746beb2ec8fCAS |

[50]  G. Cailleau, O. Braissant, C. Dupraz, M. Aragno, E. P. Verrecchia, Biologically induced accumulations of CaCO3 in orthox soils of Biga, Ivory Coast. Catena 2005, 59, 1.
Biologically induced accumulations of CaCO3 in orthox soils of Biga, Ivory Coast.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXhtVSgtb7O&md5=c1a090dfcf6120cd95ba969890e70043CAS |

[51]  A. P. Hitchcock, J. J. Dynes, R. Lawrence, M. Obst, G. D. W. Swerhone, D. R. Korber, G. G. Leppardi, Soft X-ray spectromicroscopy of nickel sorption in a natural river biofilm. Geobiology 2009, 7, 432.
Soft X-ray spectromicroscopy of nickel sorption in a natural river biofilm.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhtFKnu7fJ&md5=581b94826ae0b5a2fa635a7040b18148CAS | 19656215PubMed |

[52]  J. P. Crocombette, M. Pollak, F. Jollet, N. Thromat, M. Gautier-Soyer, X-ray-absorption spectroscopy at the Fe L2,3 threshhold in iron oxides. Phys. Rev. B 1995, 52, 3143.
X-ray-absorption spectroscopy at the Fe L2,3 threshhold in iron oxides.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXntlGis7Y%3D&md5=b04266748c2c022a298960a873aae7e7CAS |

[53]  P. A. van Aken, B. Liebscher, Quantification of ferrous/ferric ratios in minerals: new evaluation schemes of Fe L2,3 electron energy-loss near-edge spectra. Phys. Chem. Miner. 2002, 29, 188.
Quantification of ferrous/ferric ratios in minerals: new evaluation schemes of Fe L2,3 electron energy-loss near-edge spectra.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38XisF2qt74%3D&md5=3301e55c8bf24e465d08363f973bd738CAS |

[54]  J. Miot, K. Benzerara, G. Morin, A. Kappler, S. Bernard, M. Obst, C. Férard, F. Skouri-Panet, J. M. Guigner, N. Posth, M. Galvez, G. E. Brown, F. Guyot, Iron biomineralization by anaerobic neutrophilic iron-oxidizing bacteria. Geochim. Cosmochim. Acta 2009, 73, 696.
Iron biomineralization by anaerobic neutrophilic iron-oxidizing bacteria.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXps1eisA%3D%3D&md5=5a79d3585cf051c482e3c88b23d4323bCAS |

[55]  B. K. G. Theng, Formation and Properties of Clay-Polymer Complexes 1979 (Elsevier, New York).

[56]  P. M. Huang, Soil mineral-organic matter-microorganism interactions: fundamentals and impacts. Adv. Agron. 2004, 82, 391.
Soil mineral-organic matter-microorganism interactions: fundamentals and impacts.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXnvVymsA%3D%3D&md5=f434ad2c52b3f7c10f7305377362986fCAS |

[57]  M. Kleber, P. Sollins, R. Sutton, A conceptual model of organo-mineral interactions in soils: self-assembly of organic molecular fragments into zonal structures on mineral surfaces. Biogeochemistry 2007, 85, 9.
A conceptual model of organo-mineral interactions in soils: self-assembly of organic molecular fragments into zonal structures on mineral surfaces.Crossref | GoogleScholarGoogle Scholar |

[58]  K. Kaiser, G. Guggenberger, W. Zech, Sorption of DOM and DOM fractions to forest soils. Geoderma 1996, 74, 281.
Sorption of DOM and DOM fractions to forest soils.Crossref | GoogleScholarGoogle Scholar |

[59]  G. Guggenberger, K. M. Haider, Effect of mineral colloids on biogeochemical cycling of C, N, P, and S in soil, in Interactions between Soil Particles and Microorganisms: Impact on the Terrestrial Ecosystem (Eds P. M. Huang, J. M. Bollag, N. Senesi) 2002, IUPAC Series on Analytical and Physical Chemistry of Environmental Systems, pp. 267–322 (Wiley: Chichester, UK).

[60]  R. Mikutta, C. Mikutta, K. Kalbitz, T. Scheel, K. Kaiser, R. Jahn, Biodegradation of forest floor organic matter bound to minerals via different binding mechanisms. Geochim. Cosmochim. Acta 2007, 71, 2569.
Biodegradation of forest floor organic matter bound to minerals via different binding mechanisms.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXkvFahurg%3D&md5=b3f7de6e4b6887ea9eef37a8f45b8251CAS |

[61]  C. Chenu, A. F. Plante, Clay-sized organo-mineral complexes in a cultivation chronosequence: revisiting the concept of the ‘primary organo-mineral complex. Eur. J. Soil Sci. 2006, 57, 596.
Clay-sized organo-mineral complexes in a cultivation chronosequence: revisiting the concept of the ‘primary organo-mineral complex.Crossref | GoogleScholarGoogle Scholar |

[62]  D. Li, G. M. Bancroft, M. E. Fleet, X. H. Feng, Y. Pan, Al K-edge XANES spectra of aluminosilicate minerals. Am. Mineral. 1995, 80, 432.
| 1:CAS:528:DyaK2MXms1Wlu70%3D&md5=c74f57aa1689739a88104d5b9fc80eacCAS |

[63]  P. Ildefonse, D. Cabaret, P. Sainctavit, G. Calas, A. M. Flank, P. Lagarde, Aluminum X-ray absorption near edge structure in model compounds and Earth's surface minerals. Phys. Chem. Miner. 1998, 25, 112.
Aluminum X-ray absorption near edge structure in model compounds and Earth's surface minerals.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1cXksVOnsg%3D%3D&md5=2b95a91b6b0187c1d1e954c60c8a9673CAS |

[64]  C. S. Doyle, S. J. Traina, H. Ruppert, T. Kendelewicz, J. J. Rehr, G. E. Brown, XANES studies at the AI K-edge of aluminum-rich surface phases in the soil environment. J. Synchrotron Radiat. 1999, 6, 621.
XANES studies at the AI K-edge of aluminum-rich surface phases in the soil environment.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1MXksFCnu7s%3D&md5=9bac95b3ca2f7d008007c0763e11b5fdCAS | 15263401PubMed |

[65]  S. A. Shaw, D. Peak, M. J. Hendry, Investigation of acidic dissolution of mixed clays between pH 1.0 and 3.0 using Si and Al X-ray absorption near edge structure. Geochim. Cosmochim. Acta 2009, 73, 4151.
Investigation of acidic dissolution of mixed clays between pH 1.0 and 3.0 using Si and Al X-ray absorption near edge structure.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXmvVynsbs%3D&md5=9cc4ec00dbf496a752cb72e4196a1dedCAS |

[66]  D. Li, G. M. Bancroft, M. Kasrai, M. E. Fleet, X. H. Feng, K. H. Tan, B. X. Yang, High-resolution Si K- and L2,3-edge XANES of a-quartz and stishovite. Solid State Commun. 1993, 87, 613.
High-resolution Si K- and L2,3-edge XANES of a-quartz and stishovite.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2cXhvVWrtw%3D%3D&md5=400befbae6b98221553778cd85482f54CAS |