Adsorption and stabilization of organic carbon by mineral surfaces in soils

2006 ◽  
Vol 25 (S1) ◽  
pp. 263-264 ◽  
Author(s):  
Seunghun Kang ◽  
Saikat Ghosh ◽  
Baoshan Xing
Keyword(s):  
Organic Carbon ◽  
Mineral Surfaces

Coupled Manganese Redox Cycling and Organic Carbon Degradation on Mineral Surfaces

2020 ◽  
Vol 54 (14) ◽  
pp. 8801-8810 ◽  
Author(s):  
Dong Ma ◽  
Juan Wu ◽  
Peng Yang ◽  
Mengqiang Zhu
Keyword(s):  
Organic Carbon ◽  
Redox Cycling ◽  
Mineral Surfaces ◽  
Carbon Degradation

scholarly journals Age distribution, extractability, and stability of mineral-bound organic carbon in central European soils

2021 ◽  
Vol 18 (3) ◽  
pp. 1241-1257
Author(s):  
Marion Schrumpf ◽  
Klaus Kaiser ◽  
Allegra Mayer ◽  
Günter Hempel ◽  
Susan Trumbore
Keyword(s):  
Organic Carbon ◽  
Soil Depth ◽  
Coniferous Forest ◽  
Age Distribution ◽  
Chemical Oxidation ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Mineral Surfaces ◽  
Site Specific ◽  
13C Nuclear Magnetic Resonance

Abstract. The largest share of total soil organic carbon (OC) is associated with minerals. However, the factors that determine the amount and turnover of slower- versus faster-cycling components of mineral-associated carbon (MOC) are still poorly understood. Bioavailability of MOC is thought to be regulated by desorption, which can be facilitated by displacement and mobilization by competing ions. However, MOC stability is usually determined by exposure to chemical oxidation, which addresses the chemical stability of the organic compounds rather than the bonding strength of the OC–mineral bond. We used a solution of NaOH, a strong agent for desorption due to high pH, and NaF, adding F−, a strongly sorbing anion that can replace anionic organic molecules on mineral surfaces, to measure the maximum potentially desorbable MOC. For comparison, we measured maximal potential oxidation of MOC using heated H2O2. We selected MOC samples (> 1.6 g cm3) obtained from density fractionation of samples from three soil depth increments (0–5, 10–20, and 30–40 cm) of five typical soils of central Europe, with a range of clay and pedogenic oxide contents, and under different ecosystem types (one coniferous forest, two deciduous forests, one grassland, and one cropland). Extracts and residues were analysed for OC and 14C contents, and further chemically characterized by cross-polarization magic angle spinning 13C-nuclear magnetic resonance (CPMAS-13C-NMR). We expected that NaF–NaOH extraction would remove less and younger MOC than H2O2 oxidation and that the NaF–NaOH extractability of MOC is reduced in subsoils and soils with high pedogenic oxide contents. The results showed that a surprisingly consistent proportion of 58 ± 11 % (standard deviation) of MOC was extracted with NaF–NaOH across soils, independent of depth, mineral assemblage, or land use conditions. NMR spectra revealed strong similarities in the extracted organic matter, with more than 80 % of OC in the O/N (oxygen and/or nitrogen) alkyl and alkyl C region. Total MOC amounts were correlated with the content of pedogenic oxides across sites, independent of variations in total clay, and the same was true for OC in extraction residues. Thus, the uniform extractability of MOC may be explained by dominant interactions between OC and pedogenic oxides across all study sites. While Δ14C values of bulk MOC suggested differences in OC turnover between sites, these were not linked to differences in MOC extractability. As expected, OC contents of residues had more negative Δ14C values than extracts (an average difference between extracts and residues of 78 ± 36 ‰), suggesting that non-extractable OC is older. Δ14C values of extracts and residues were strongly correlated and proportional to Δ14C values of bulk MOC but were not dependent on mineralogy. Neither MOC extractability nor differences in Δ14C values between extracts and residues changed with depth along soil profiles, where declining Δ14C values might indicate slower OC turnover in deeper soils. Thus, the 14C depth gradients in the studied soils were not explained by increasing stability of organic–mineral associations with soil depth. Although H2O2 removed 90 ± 8 % of the MOC, the Δ14C values of oxidized OC (on average −50 ± 110 ‰) were similar to those of OC extracted with NaF–NaOH (−51 ± 122 ‰), but oxidation residues (−345 ± 227 ‰) were much more depleted in 14C than residues of the NaF–NaOH extraction (−130 ± 121 ‰). Accordingly, both chemical treatments removed OC from the same continuum, and oxidation residues were older than extraction residues because more OC was removed. In contrast to the NaF–NaOH extractions, higher contents of pedogenic oxides slightly increased the oxidation resistance of MOC, but this higher H2O2 resistance did not coincide with more negative Δ14C values of MOC nor its oxidation residues. Therefore, none of the applied chemical fractionation schemes were able to explain site-specific differences in Δ14C values. Our results indicate that total MOC was dominated by OC interactions with pedogenic oxides rather than clay minerals, as we detected no difference in bond strength between clay-rich and clay-poor sites. This suggests that site-specific differences in Δ14C values of bulk MOC and depth profiles are driven by the accumulation and exchange rates of OC at mineral surfaces.

Impact of Exotic Earthworms on Organic Carbon Sorption on Mineral Surfaces and Soil Carbon Inventories in a Northern Hardwood Forest

Ecosystems ◽  
2014 ◽  
Vol 18 (1) ◽  
pp. 16-29 ◽  
Author(s):  
Amy Lyttle ◽  
Kyungsoo Yoo ◽  
Cindy Hale ◽  
Anthony Aufdenkampe ◽  
Stephen D. Sebestyen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Hardwood Forest ◽  
Northern Hardwood Forest ◽  
Mineral Surfaces ◽  
Northern Hardwood ◽  
Exotic Earthworms

Organic carbon accumulation on soil mineral surfaces in paddy soils derived from tidal wetlands

Geoderma ◽  
2014 ◽  
Vol 228-229 ◽  
pp. 90-103 ◽  
Author(s):  
Livia Wissing ◽  
Angelika Kölbl ◽  
Peter Schad ◽  
Tino Bräuer ◽  
Zhi-Hong Cao ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Accumulation ◽  
Paddy Soils ◽  
Tidal Wetlands ◽  
Mineral Surfaces ◽  
Soil Mineral

scholarly journals The sorption and desorption of organic carbon onto tropical reclaimed-mining soils with coal fly-ash application

2020 ◽  
Vol 8 (2) ◽  
pp. 2643-2652
Author(s):  
Akhmad Rizalli Saidy ◽  
Bambang Joko Priatmadi ◽  
Meldia Septiana ◽  
Afiah Hayati
Keyword(s):  
Fly Ash ◽  
Organic Carbon ◽  
Sorption Capacity ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Mineral Surfaces ◽  
Surface Areas ◽  
Exchangeable Ca ◽  
Extraction Step ◽  
Mining Soils

Coal fly ash, resulted from coal combustion in power plants, with relatively high amounts of aluminium, iron, calcium, and magnesium oxides may modify the sorption capacity of soils. A batch experiment was conducted to examine the capacity of reclaimed mining soils (RMS) to adsorb organic carbon (OC) in response to coal fly ash application. Extraction of dissolved OC was carried out from dried albizia shoot residue and reacted with the RMS at dissolved OC concentrations varying from 0 to 175 mg C L-1 at pH 5.5. The results showed that the sorption capacity of the RMS for OC increased significantly with coal fly ash application, which may relate to increasing the contents exchangeable Ca and Mg, dithionite- and oxalate-extractable aluminium and iron, and surface areas of soils. Desorption experiment indicated that only 5-23% of the OC initially sorbed onto soil-coal fly ash interactions was freed using a single extraction step, suggesting that most of the OC is strongly sorbed to the mineral surfaces. Results of the study indicate an important role of fly ash in increasing OC sorption capacity of soils and reducing the percentage of OC sorption from the RMS-coal fly ash association.

Integrating mineral interactions with organic carbon in thawing permafrost to assess climate feedbacks

2020 ◽  
Author(s):  
Sophie Opfergelt ◽  
Catherine Hirst ◽  
Arthur Monhonval ◽  
Elisabeth Mauclet ◽  
Maxime Thomas
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Clay Minerals ◽  
Metal Cations ◽  
Mineral Surfaces ◽  
Microbial Decomposition ◽  
Fe Oxides ◽  
Physico Chemical ◽  
Thawing Permafrost ◽  
Chemical Conditions

<p>Permafrost contains 1400-1660 Gt of organic carbon (OC), from which 5-15% will likely be emitted as greenhouse gases (GHG) by 2100. The soil organic carbon stock is distributed between a pool of particulate organic matter (POM), and a pool of mineral-associated OM (MOM). POM can be free, i.e., more readily available for microbial decomposition, or occluded within soil aggregates (involving clay minerals or Fe-Al (hydr)oxides), i.e., spatially inaccessible for microorganisms. MOM includes OC sorbed onto mineral surfaces (such as clay minerals or Fe-oxides) and OC complexed with metal cations (e.g., Al, Fe, Ca), i.e., stabilized OC. The interactions between OC and minerals influence the accessibility of OC for microbial decomposition and OC stability and are therefore a factor in controlling the C emissions rate upon thawing permafrost.</p><p>In the warming Arctic, there is growing evidence for soil disturbance such as coastal erosion, thermokarst and soil drainage as a consequence of abrupt and gradual permafrost thaw. These disturbances induce changes in the physico-chemical conditions controlling mineral solubility in permafrost soils which directly affect the stability of the MOM and of the occluded POM. As a consequence, a portion of OC can be unlocked and transferred into the free POM. This additional pool of freely available OC may be degraded and amplify C emissions from permafrost to the atmosphere. Conversely, the concomitant release of metal cations upon permafrost thaw may partly mitigate permafrost C emissions by stabilization of OC via complexation or sorption onto mineral surfaces and return a portion of freely available OC to the MOM. The majority of C is emitted as CO<sub>2</sub> but 1.5 and 3.5% of the total permafrost C emissions will be released as CH<sub>4</sub>, with implications for the atmospheric radiative forcing balance. Importantly, the proportion CH<sub>4</sub> emitted relative to CO<sub>2</sub> is likely to increase with increasing abrupt thaw and associated anoxic conditions, but a portion of CH<sub>4</sub> emissions could be mitigated by the anoxic oxidation of methane mediated by the presence of Fe-oxides exposed by abrupt thaw of deep permafrost.</p><p>This contribution aims at assessing how changing soil physico-chemical conditions affect interactions between mineral surfaces and OC in thawing permafrost. Scenarios of mineral-organic interactions during gradual thaw, including changes in water drainage and talik formation, and abrupt thaw including shifting redox conditions associated with thermokarst will be presented. Approaches to quantify changes in mineral-organic interactions will be discussed. By integrating the most recent studies from the permafrost carbon community with soil mineralogy, soil chemistry and soil hydrology, this contribution demonstrates that the fate of mineral-organic interactions upon thawing must be considered given their potential implications for GHG emissions. If we do not include the role of mineral-organic interactions in this puzzle, the complexities involved in soil carbon decomposition may propagate large uncertainties into coupled soil carbon-climate feedback predictions.</p>

Scanning Electron Microscope Study of Bacteria on Mineral Surfaces

1976 ◽  
Vol 34 ◽  
pp. 130-131
Author(s):  
V.K. Berry
Keyword(s):  
Oxidation Reaction ◽  
Electron Microscope Study ◽  
Elemental Sulfur ◽  
Thiobacillus Ferrooxidans ◽  
Physical Contact ◽  
Metal Sulfides ◽  
Low Grade ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
Scanning Electron Microscope Study

There are two strains of bacteria viz. Thiobacillus thiooxidansand Thiobacillus ferrooxidanswidely mentioned to play an important role in the leaching process of low-grade ores. Another strain used in this study is a thermophile and is designated Caldariella .These microorganisms are acidophilic chemosynthetic aerobic autotrophs and are capable of oxidizing many metal sulfides and elemental sulfur to sulfates and Fe2+ to Fe3+. The necessity of physical contact or attachment by bacteria to mineral surfaces during oxidation reaction has not been fairly established so far. Temple and Koehler reported that during oxidation of marcasite T. thiooxidanswere found concentrated on mineral surface. Schaeffer, et al. demonstrated that physical contact or attachment is essential for oxidation of sulfur.

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