Journal ArticleDOI
Soft X-ray Spectromicroscopy Study of Mineral-Organic Matter Associations in Pasture Soil Clay Fractions
TLDR
STXM-NEXAFS spectroscopy was used to investigate C associations with Ca, Fe, Al, and Si species in soil clay fractions from an upland pasture hillslope and showed similar correlation with Fe to Al and Si, implying a similar association of Fe oxides and aluminosilicates with organic matter in organo-mineral associations.Abstract:
There is a growing acceptance that associations with soil minerals may be the most important overarching stabilization mechanism for soil organic matter. However, direct investigation of organo-mineral associations has been hampered by a lack of methods that can simultaneously characterize organic matter (OM) and soil minerals. In this study, STXM-NEXAFS spectroscopy at the C 1s, Ca 2p, Fe 2p, Al 1s, and Si 1s edges was used to investigate C associations with Ca, Fe, Al, and Si species in soil clay fractions from an upland pasture hillslope. Bulk techniques including C and N NEXAFS, Fe K-edge EXAFS spectroscopy, and XRD were applied to provide additional information. Results demonstrated that C was associated with Ca, Fe, Al, and Si with no separate phase in soil clay particles. In soil clay particles, the pervasive C forms were aromatic C, carboxyl C, and polysaccharides with the relative abundance of carboxyl C and polysaccharides varying spatially at the submicrometer scale. Only limited regions in the...read more
Citations
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Journal ArticleDOI
The contentious nature of soil organic matter
Johannes Lehmann,Markus Kleber +1 more
TL;DR: It is argued that the available evidence does not support the formation of large-molecular-size and persistent ‘humic substances’ in soils, and instead soil organic matter is a continuum of progressively decomposing organic compounds.
Journal ArticleDOI
The importance of anabolism in microbial control over soil carbon storage
TL;DR: This Perspective looks at how microbial anabolism and the soil microbial carbon pump control microbial necromass accumulation and stabilization; the ‘entombing effect’.
Journal ArticleDOI
Properties of Fe-Organic Matter Associations via Coprecipitation versus Adsorption
TL;DR: This study compared the properties of Fe-OM complexes formed from adsorption (reaction of OM to postsynthesis ferrihydrite) versus coprecipitation (formation of Fe solids in the presence of OM), helping to understand C and Fe cycling in the natural environments with periodically fluctuating redox conditions.
Journal ArticleDOI
Dissimilatory microbial iron reduction release DOC (dissolved organic carbon) from carbon-ferrihydrite association
TL;DR: In this paper, anaerobic incubation experiments were conducted to investigate the biodegradability of ferrihydrite (Fe-oxide)-adsorbed natural DOC with known Fe-reducing bacterium, Shewanella oneidensis MR-1.
Journal ArticleDOI
Internal Domains of Natural Porous Media Revealed: Critical Locations for Transport, Storage, and Chemical Reaction.
John M. Zachara,Susan L. Brantley,Jon D. Chorover,Robert P. Ewing,Sebastien N. Kerisit,Chongxuan Liu,Edmund Perfect,Gernot Rother,Andrew G. Stack +8 more
TL;DR: Analytical methods to characterize IDPM, evaluate information on their size distributions, connectivity, and extended structures; determine whether they exhibit unique chemical reactivity; and assess the potential for their inclusion in reactive transport models are discussed.
References
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Journal ArticleDOI
Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review
Margit von Lützow,Ingrid Kögel-Knabner,Klemens Ekschmitt,Egbert Matzner,Georg Guggenberger,Bernd Marschner,Heinz Flessa +6 more
TL;DR: In this article, a review of the mechanisms that are currently, but often contradictorily or inconsistently, considered to contribute to organic matter (OM) protection against decomposition in temperate soils is presented.
Journal ArticleDOI
Black Carbon Increases Cation Exchange Capacity in Soils
Biqing Liang,Johannes Lehmann,Dawit Solomon,James Kinyangi,Julie M. Grossman,B. O'Neill,Jan O. Skjemstad,Janice E. Thies,Flávio J. Luizão,James B. Petersen,Eduardo Góes Neves +10 more
TL;DR: In this article, the authors investigated the source of the higher surface charge of BC compared with non-BC by mapping crosssectional areas of BC particles with diameters of 10 to 50 mm for C forms.
Book ChapterDOI
Soil organic matter and structural stability: mechanisms and implications for management
TL;DR: In this paper, two categories of aggregates macro- (> 250 μm) and micro- (< 250μm) depend on organic matter for stability against disruptive forces caused by rapid wetting.
Journal ArticleDOI
The macromolecular organic composition of plant and microbial residues as inputs to soil organic matter
TL;DR: In this paper, an overview is given on the amount of litter input, the proportion of various plant parts and their distribution (below-ground/above-ground), as well as the relative proportion of different plant tissues.
Journal ArticleDOI
Adsorption and desorption of natural organic matter on iron oxide: mechanisms and models.
TL;DR: Results indicated that ligand exchange between carboxyl/hydroxyl functional groups of NOM and iron oxide surfaces was the dominant interaction mechanism, especially under acidic or slightly acidic pH conditions.