Variation in Pore Space and Structure of Organic‐rich Oil‐prone Shales from a Non‐marine Basin: Constraints from Organic Matter and Minerals

Abstract. This paper deals with the simulation of microbial degradation of organic matter in soil within the pore space at a microscopic scale. Pore space was analysed with micro-computed tomography and described using a sphere network coming from a geometrical modelling algorithm. The biological model was improved regarding previous work in order to include the transformation of dissolved organic compounds and diffusion processes. We tested our model using experimental results of a simple substrate decomposition experiment (fructose) within a simple medium (sand) in the presence of different bacterial strains. Separate incubations were carried out in microcosms using five different bacterial communities at two different water potentials of −10 and −100 cm of water. We calibrated the biological parameters by means of experimental data obtained at high water content, and we tested the model without changing any parameters at low water content. Same as for the experimental data, our simulation results showed that the decrease in water content caused a decrease of mineralization rate. The model was able to simulate the decrease of connectivity between substrate and microorganism due the decrease of water content.

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Factors Affecting Microbial Formation of Nitrate-Nitrogen in Soil and Their Effects on Fertilizer Nitrogen Use Efficiency

The Scientific World JOURNAL ◽

10.1100/tsw.2001.308 ◽

2001 ◽

Vol 1 ◽

pp. 122-129 ◽

Cited By ~ 7

Author(s):

Alan Olness ◽

Dian Lopez ◽

David Archer ◽

Jason Cordes ◽

Colin Sweeney ◽

...

Keyword(s):

Organic Matter ◽

Decision Aid ◽

Pore Space ◽

Organic Matter Content ◽

Clay Content ◽

Matter Content ◽

N Fertilizer ◽

Nitrate N ◽

Soil Clay ◽

Soil Clay Content

Mineralization of soil organic matter is governed by predictable factors with nitrate-N as the end product. Crop production interrupts the natural balance, accelerates mineralization of N, and elevates levels of nitrate-N in soil. Six factors determine nitrate-N levels in soils: soil clay content, bulk density, organic matter content, pH, temperature, and rainfall. Maximal rates of N mineralization require an optimal level of air-filled pore space. Optimal air-filled pore space depends on soil clay content, soil organic matter content, soil bulk density, and rainfall. Pore space is partitioned into water- and air-filled space. A maximal rate of nitrate formation occurs at a pH of 6.7 and rather modest mineralization rates occur at pH 5.0 and 8.0. Predictions of the soil nitrate-N concentrations with a relative precision of 1 to 4 μg N g–1of soil were obtained with a computerized N fertilizer decision aid. Grain yields obtained using the N fertilizer decision aid were not measurably different from those using adjacent farmer practices, but N fertilizer use was reduced by >10%. Predicting mineralization in this manner allows optimal N applications to be determined for site-specific soil and weather conditions.

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Obvious and less obvious processes of aggregate formation in soil

10.5194/egusphere-egu21-10597 ◽

2021 ◽

Author(s):

Hans-Jörg Vogel ◽

Maria Balseiro-Romero ◽

Philippe C. Baveye ◽

Alexandra Kravchenko ◽

Wilfred Otten ◽

...

Keyword(s):

Organic Matter ◽

Soil Structure ◽

Solid Phase ◽

Pore Space ◽

Imaging Techniques ◽

Mineral Soil ◽

Aggregate Formation ◽

Conceptual Approach ◽

Soil Matrix ◽

Biophysical Processes

Soil structure, lately referred to as the ''architecture'' is a key to explain and understand all soil functions. The development of sophisticated imaging techniques over the last decades has led to significant progress in the description of this architecture and in particular of the geometry of the hierarchically-branched pore space in which transport of water, gases, solutes and particles occurs and where myriads of organisms live. Moreover, there are sophisticated tools available today to also visualize the spatial structure of the solid phase including mineral grains and organic matter. Hence, we do have access to virtually all components of soil architecture.Unfortunately, it has so far proven very challenging to study the dynamics of soil architecture over time, which is of critical importance for soil as habitat and the turnover of organic matter. Several largely conflicting theories have been proposed to account for this dynamics, especially the formation of aggregates. We review these theories, and we propose a conceptual approach to reconcile them based on a consistent interpretation of experimental observations and by integrating known physical and biogeochemical processes. A key conclusion is that rather than concentrating on aggregate formation in the sense of how particles and organic matter reorganize to form aggregates as distinct functional units we should focus on biophysical processes that produce a porous, heterogeneous organo-mineral soil matrix that breaks into fragments of different size and stability when exposed to mechanical stress.&#160; The unified vision we propose for soil architecture and the mechanisms that determine its temporal evolution, should pave the way towards a better understanding of soil processes and functions.

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Dissolved organic matter in Antarctic sea ice

Annals of Glaciology ◽

10.3189/172756401781818338 ◽

2001 ◽

Vol 33 ◽

pp. 297-303 ◽

Cited By ~ 68

Author(s):

David N. Thomas ◽

Gerhard Kattner ◽

Ralph Engbrodt ◽

Virginia Giannelli ◽

Hilary Kennedy ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Sea Ice ◽

Pore Space ◽

Ice Cores ◽

Weddell Sea ◽

Poor Correlation ◽

First Year ◽

Mean Values ◽

Antarctic Sea Ice

AbstractIt has been hypothesized that there are significant dissolved organic matter (DOM) pools in sea-ice systems, although measurements of DOM in sea ice have only rarely been made. The significance of DOM for ice-based productivity and carbon turnover therefore remains highly speculative. DOM within sea ice from the Amundsen and Bellingshausen Seas, Antarctica, in 1994 and the Weddell Sea, Antarctica, in 1992 and 1997 was investigated. Measurements were made on melted sea-ice sections in 1994 and 1997 and in sea-ice brines in 1992. Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations in melted ice cores were up to 1.8 and 0.78 mM, respectively, or 30 and 8 times higher than those in surface water concentrations, respectively. However, when concentrations within the brine channel/pore space were calculated from estimated brine volumes, actual concentrations of DOC in brines were up to 23.3 mM and DON up to 2.2 mM, although mean values were 1.8 and 0.15 mM, respectively. There were higher concentrations of DOM in warm, porous summer second-year sea ice compared with colder autumn first-year ice, consistent with the different biological activity supported within the various ice types. However, in general there was poor correlation between DOC and DON with algal biomass and numbers of bacteria within the ice. The mean DOC/DON ratio was 11, although again values were highly variable, ranging from 3 to highly carbon-enriched samples of 95. Measurements made on a limited dataset showed that carbohydrates constitute on average 35% of the DOC pool, with highly variable contributions of 1−99%.

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Parameter Selection for the Evaluation of Compost Quality

Agronomy ◽

10.3390/agronomy10101567 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1567

Author(s):

Haydee Peña ◽

Heysa Mendoza ◽

Fernando Diánez ◽

Mila Santos

Keyword(s):

Electrical Conductivity ◽

Organic Matter ◽

Pore Space ◽

Linear Regression Analysis ◽

Organic Matter Content ◽

Principal Component ◽

Primary Component ◽

Matter Content ◽

Germination Index ◽

Soil Restoration

This work studies variables measured from the first phase of composting through the acquisition of the final product, with the goal of identifying those that are more strongly related to quality and are most useful for developing an index. The necessity to establish quality control procedures thus exists for the classification of raw materials in the same way as for the finished products. To accomplish this, three mixtures were prepared, with the goal of achieving a C/N ratio of 30 and a moisture content of 60%. The primary component of each mixture was: fruit processing waste (C1), sewage sludge from the food industry (C2), and the manufacturing waste of fried foods (C3). Temperatures were measured over 107 days, with the corresponding data fit to a logistical model where T °C ~ α / ((1 + exp (− (Time − β) / − γ))) + δ, with interaction compost * time being statistically significant (p < 0.001). This allowed for the temperatures, in keeping with health concerns, to be confirmed. Likewise, a linear regression analysis demonstrated the decomposition of organic matter at 0.82%/week. Statistically, the parameters, measured during the process, with the least variability were selected, which differed in the average contrasts: germination index (cucumber), electrical conductivity, and average moisture. A principal component analysis (PCA) and Spearman’s correlation analysis revealed the best Germination Index (GI) values for C1, due to lower electrical conductivity (EC) and bulk density (Bd) along with higher organic matter content (TOM). For its part, C2 induced a higher Relative emergence (RE) of the cucumber thanks to its higher content of total nitrogen (TN) and lower contribution of Cu, Zn and K. C3 showed a higher presence of salts, less favorable physical characteristics (>Bd and <TPS, total pore space) and higher content of Zn and Cu. Composting carried out with appropriate mixtures can offer high-quality products for use as fertiliser, in soil restoration, and as an alternative substrate to peat and virgin mountain soil.

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Will no-till be the new panacea for degraded tropical landscapes?

10.5194/egusphere-egu2020-12254 ◽

2020 ◽

Author(s):

Tammo Steenhuis ◽

Misbah Hussein ◽

Habtamu muche ◽

Sisay Belay ◽

Azalu Gessess ◽

...

Keyword(s):

Organic Matter ◽

Soil Fauna ◽

Agricultural Soils ◽

Conservation Tillage ◽

Pore Space ◽

Soil Layer ◽

Water Runoff ◽

Soil Matrix ◽

Ethiopian Highlands ◽

No Till

General knowledge based on the good agricultural soils in temperate climates is that no-till and conservation-till practices increase infiltration of the rainwater and decrease runoff and erosion.&#160; Experiments in the semi-humid Ethiopian highlands do not often show the same benefits and in many cases no-till actually increases runoff above conventional and deep tillage. In contrast, for conservation-tillage with mulch at the surface, more of the water infiltrates and enhances plant growthReduced tillage systems increase infiltration through soil fauna that form soil macropores through which rainwater flows to the subsoil bypassing the soil matrix with limited conductivity. Most degraded soils (at least in the Ethiopian highlands) have a hardpan at shallow depths restricting downward movement of water. Runoff on conventionally tilled soils is caused by saturation excess when the perched water table in the plowed soil layer reaches the surface.&#160; Thus, the amount of runoff is determined by the water free pore space in the surface layer.&#160; Since this pore space is less under no-till, no-till has greater amounts of runoff than conventional till.&#160;Under mulch tillage, organic matter is introduced at the surface and soil fauna becomes well-developed which will improve the soil structure and porosity of the soil.&#160; This structure will be maintained because the mulch decreases the sediment concentration in the water and the pores will remain open. Under conventional tillage sediment concentrations are high and any pores formed will be filled up with sediment. Our expectation is that since organic matter under mixed farming is used to feed the cattle, widespread implementation of no-till and conservation tillage will be limited to areas with high value crops in which farmers can afford using organic matter as a mulch.

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Estimation of the density of the clay-organic complex in soil

International Agrophysics ◽

10.1515/intag-2015-0075 ◽

2016 ◽

Vol 30 (1) ◽

pp. 19-23 ◽

Cited By ~ 4

Author(s):

Ewa A. Czyż ◽

Anthony R. Dexter

Keyword(s):

Organic Matter ◽

Bulk Density ◽

Pore Space ◽

Organic Matter Content ◽

Soil Bulk Density ◽

Matter Content ◽

Gas Content ◽

Effective Density ◽

Organic Complex ◽

Arable Soils

Abstract Soil bulk density was investigated as a function of soil contents of clay and organic matter in arable agricultural soils at a range of locations. The contents of clay and organic matter were used in an algorithmic procedure to calculate the amounts of clay-organic complex in the soils. Values of soil bulk density as a function of soil organic matter content were used to estimate the amount of pore space occupied by unit amount of complex. These estimations show that the effective density of the clay-organic matter complex is very low with a mean value of 0.17 ± 0.04 g ml−1 in arable soils. This value is much smaller than the soil bulk density and smaller than any of the other components of the soil considered separately (with the exception of the gas content). This low value suggests that the clay-soil complex has an extremely porous and open structure. When the complex is considered as a separate phase in soil, it can account for the observed reduction of bulk density with increasing content of organic matter.

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The calcareous concretions (cementsten) in the Fur Formation (Paleogene, Denmark): isotopic evidence of early diagenetic growth

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-1996-43-09 ◽

1996 ◽

Vol 43 ◽

pp. 78-86

Author(s):

Gunver Krarup Pedersen ◽

Bjørn Buchardt

Keyword(s):

Organic Matter ◽

Oxygen Isotope ◽

Volcanic Ash ◽

Pore Space ◽

Sulphate Reduction ◽

Isotopic Evidence ◽

Carbon And Oxygen Isotope ◽

Marine Shell

The Paleogene Fur Formation in northwestem Denmark is a c. 60 m thick clayey diatomite that comprises calcite concretions, the so-called cementsten. The diatomite is interbedded with 179 isochronous and recognizable layers of volcanic ash, which demonstrate that the concretions occur at six stratigraphic levels throughout the Fur Formation. The concretions formed through precipitation of calcite in the pore space within the diatomite or the ash layers. Carbon and oxygen isotope compositions were determined on the concretionary calcite. 613C values around -20%0 to -16%0 indicate that most (bi)carbonate was of bacterial ongin, formed through metabolization of organic matter by sulphate reduction. 6180 values of -1%0 to -3%0 indicate that calcite precipitated at temperatures corresponding to those measured in contemporaneous marine shell materiai. It is speculated that rare blooms of phytoplankton made the six stratigraphic levels the preferred sites of nucleation of the concretions.

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Aridity-driven decoupling of δ13C between pedogenic carbonate and soil organic matter

Geology ◽

10.1130/g47241.1 ◽

2020 ◽

Vol 48 (10) ◽

pp. 981-985 ◽

Cited By ~ 2

Author(s):

Jiawei Da ◽

Yi Ge Zhang ◽

Gen Li ◽

Junfeng Ji

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Pore Space ◽

C4 Plants ◽

Atmospheric Co2 ◽

Chinese Loess Plateau ◽

Pedogenic Carbonate ◽

Chinese Loess ◽

Pedogenic Carbonates ◽

Soil Pore Space

Abstract Pedogenic carbonate is an invaluable archive for reconstructing continental paleoclimate and paleoecology. The δ13C of pedogenic carbonate (δ13Cc) has been widely used to document the rise and expansion of C4 plants over the Cenozoic. This application requires a fundamental presumption that in soil pores, soil-respired CO2 dominates over atmospheric CO2 during the formation of pedogenic carbonates. However, the decoupling between δ13Cc and δ13C of soil organic matter (δ13CSOM) have been observed, particularly in arid regions, suggesting that this presumption is not always valid. To evaluate the influence of atmospheric CO2 on soil δ13Cc, here we performed systematic δ13C analyses of paleosols across the Chinese Loess Plateau, with the sample ages spanning three intervals: the Holocene, the Late Pleistocene, and the mid-Pliocene warm period. Our paired δ13Cc and δ13CSOM data reveal broadly divergent trending patterns. Using a two-component CO2-mixing model, we show substantial incorporations of atmospheric CO2 (up to 60%) into soil pore space during carbonate precipitation. This result readily explains the enrichment of δ13Cc and its divergence from δ13CSOM. As a consequence, δ13C of pedogenic carbonates formed under semiarid and/or arid conditions are largely driven by regional aridity through its control on soil CO2 composition, and thus cannot be used to evaluate the relative abundance of C3 versus C4 plants. Nonetheless, these carbonates can be applied for atmospheric CO2 reconstructions, even for periods with low CO2 levels.

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Multi-proxy study of cannon-ball concretions with glendonites from Paleogene-Neogene sediments of Sakhalin Island: implication for concretion growth and ikaite-calcite trans-formation

10.5194/egusphere-egu2020-4041 ◽

2020 ◽

Author(s):

Kseniia Vasileva ◽

Victoria Ershova ◽

Oleg Vereshchagin ◽

Mikhail Rogov ◽

Marianna Tuchkova ◽

...

Keyword(s):

Organic Matter ◽

Pore Space ◽

Sakhalin Island ◽

Burial Diagenesis ◽

Geochemical Environment ◽

Low Magnesium ◽

Carbonate Concretions ◽

Sediment Formation ◽

Magnesium Calcite ◽

High Magnesium Calcite

The objects of the current study are glendonite pseudomorphs forming the central part of cannon-ball carbonate concretions found within Miocene terrigeneous sediments of Sakhalin island (easternmost part of Russia). Twelve samples of glendonites and host carbonate concretions were examined using optical and cathodoluminescence microscopy, EDX analysis, powder X-ray diffraction and isotopic analysis. The aim of the study is to determine the origin of the concretions and the relationships between the concretion and glendonite occurrence.Glendonites and host cannon-ball concretions were found within terrigeneous sediments of Bora (Lower Miocene) and Vengeri (Upper Miocene) formations. These formations are composed of laminated sandstones, siltstones, argillites and siliceous rocks. Dropstones are often found within these sediments as well as cannon-ball carbonate concretions, some of them with glendonites in central part. 60-90% of the cannon-ball concretion is occupied by sandy limestone (with high-magnesium calcite) and occasionally contains dolomite and pyrite. Central part of the cannon-ball concretion is occupied by glendonite (single crystal-like or star-like cluster of crystals). Glendonites are composed of several calcite generations. Rosette-like calcite crystals (&#8220;ikaite-derived calcite&#8221;) are composed of low-magnesium calcite, they are non-luminescent. Needle-like calcite cement is composed of high-magnesium calcite or dolomite and show bright-yellow cathodoluminescence. The rest of the glendonite is occupied with low-magnesium radiaxial fibrous or sparry calcite with dark-red cathodoluminescence.Isotopic ratios of glendonites are close to those of host concretions. For host concretions &#948;13&#1057; varies from -20.3 to -14.9 &#8240;PDB, &#948;18&#1054; varies from +1.7 to +2.7 &#8240;PDB; for glendonites &#948;13&#1057; varies from -18.1 to -1.9 &#8240;PDB, while &#948;18&#1054; varies from +0.7 to +3.4 &#8240;PDB.Close mineralogical and isotopic composition of the studied glendonites and host cannon-ball concretions suggest they were formed in similar geochemical environment. Association of glendonite occurrence along with dropstones is an indicator of cold conditions, which is well-corresponding with view on glendonites as a proxy for cooling events. Cementation of surrounding sediment (formation of the cannon-ball concretions) and glendonite formation was simultaneous and occurred during early diagenesis in the sulfate-reduction zone. The source of calcium and magnesium ions was seawater (&#948;18&#1054; values are characteristic for seawater). Ikaite was replaced with low-magnesium calcite; the replacement was favored by organic matter decay (&#948;13C values are characteristic for organic matter). Cementation of the cannon-ball concretion with high-magnesium calcite occurred together with needle-like high-magnesium calcite growth in the glendonite with increasing concentration of magnesium due to calcite extraction from the pore water. The remaining pore space was subsequently filled with radiaxial fibrous or blocky sparry calcite during burial diagenesis.The study is supported by RFBR, project number 20-35-70012.

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