Physical protection of organic matter in minesoils assessed by low-temperature ashing (LTA)

Geoderma ◽  
2017 ◽  
Vol 288 ◽  
pp. 120-129 ◽  
Author(s):  
Luigi P. D'Acqui ◽  
Alessandra Bonetti ◽  
Roberto Pini ◽  
Giacomo Certini
Keyword(s):  
Organic Matter ◽  
Low Temperature ◽  
Physical Protection ◽  
Low Temperature Ashing

Effect of organic matter removal by low-temperature ashing on dispersion of undisturbed aggregates from a tropical crusting soil

Geoderma ◽  
1999 ◽  
Vol 93 (3-4) ◽  
pp. 311-324 ◽  
Author(s):  
L.P. D'Acqui ◽  
G.J. Churchman ◽  
L.J. Janik ◽  
G.G. Ristori ◽  
D.A. Weissmann
Keyword(s):  
Organic Matter ◽  
Low Temperature ◽  
Organic Matter Removal ◽  
Low Temperature Ashing

scholarly journals Low Temperature Illitization through Illite-Dioctahedral Vermiculite Mixed Layers in a Tropical Saline Lake Rich in Hydrothermal Fluids (Sochagota Lake, Colombia)

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 523
Author(s):  
Gabriel Ricardo Cifuentes ◽  
Juan Jiménez-Millán ◽  
Claudia Patricia Quevedo ◽  
Fernando Nieto ◽  
Javier Cuadros ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Organic Matter ◽  
Low Temperature ◽  
High Salinity ◽  
Source Rocks ◽  
Temperate Climate ◽  
Lake Basin ◽  
X Ray ◽  
Saline Waters ◽  
Mixed Layers

In this investigation, we showed that high salinity promoted by hydrothermal inputs, reducing conditions of sediments with high content in organic matter, and the occurrence of an appropriate clay mineral precursor provide a suitable framework for low-temperature illitization processes. We studied the sedimentary illitization process that occurs in carbonaceous sediments from a lake with saline waters (Sochagota Lake, Colombia) located at a tropical latitude. Water isotopic composition suggests that high salinity was produced by hydrothermal contribution. Materials accumulated in the Sochagota Lake’s southern entrance are organic matter-poor sediments that contain detrital kaolinite and quartz. On the other hand, materials formed at the central segment and near the lake exit (north portion) are enriched in organic matter and characterized by the crystallization of Fe-sulfides. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray spectrometry (EDX) data allowed for the identification of illite and illite-dioctahedral vermiculite mixed layers (I-DV), which are absent in the southern sediments. High humidity and temperate climate caused the formation of small-sized metastable intermediates of I-DV particles by the weathering of the source rocks in the Sochagota Lake Basin. These particles were deposited in the low-energy lake environments (middle and north part). The interaction of these sediments enriched in organic matter with the saline waters of the lake enriched in hydrothermal K caused a reducing environment that favored Fe mobilization processes and its incorporation to I-DV mixed layers that acted as mineral precursor for fast low temperature illitization, revealing that in geothermal areas clays in lakes favor a hydrothermal K uptake.

scholarly journals Potential Production of Carbon Gases and Their Responses to Paleoclimate Conditions: An Example From Xiaolongtan Basin, Southeast Tibetan Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Gen Wang ◽  
Yongli Wang ◽  
Zhifu Wei ◽  
Zepeng Sun ◽  
Wei He ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tibetan Plateau ◽  
Low Temperature ◽  
Organic Carbon ◽  
Carbon Cycle ◽  
Higher Plants ◽  
The Tibetan Plateau ◽  
Climate Conditions ◽  
Burial Flux ◽  
Carbon Gases

Uplift of the Tibetan Plateau plays a significant and lasting role in the variations of climate conditions and global carbon cycle. However, our knowledge is limited due to the lack of long-sequence records revealing rates of CO2 and CH4 production, hampering our understanding of the relationship between paleoclimatic conditions, carbon cycling and greenhouse gas flux. Here, we present a combination of paleoclimate records and low-temperature thermal simulation results from sediments of the Xiaolongtan Basin at the southeastern margin of the Qinghai-Tibetan Plateau, spanning the late Miocene (14.1 ∼ 11.6 Ma). The n-alkane-derived proxies suggested that the sources of organic matter were obviously different: a mixed source including lower organisms and terrestrial higher plants for the Dongshengqiao Formation from 14.1 to 12.6 Ma, and a predominant contribution from terrestrial higher plants for Xiaolongtan Formation between 12.6 and 11.6 Ma. The paleoclimate was generally warm and humid as reflected by the lipid biomarkers, consistent with previous studies. In addition, the carbon gases (including CO2 and hydrocarbon gases) generated by the low-temperature thermal simulation experiments indicated a production rate of CO2 and CH4 were as high as 88,000 ml/kg rock and 4,000 ml/kg rock, respectively, implying there were certain amounts of carbon gases generated and released into the atmosphere during their shallow burial stage. Besides, the calculated production rate of carbon gases and the estimated burial flux of organic carbon varied in response to the variations of paleoclimate conditions. Based on these observations, we propose that the climate conditions predominantly controlled the formation and accumulation of organic matter, which consequently affected the production of carbon gases and burial flux of organic carbon. The results presented here may provide a significant insight into the carbon cycle in the southeast of the Tibetan Plateau.

scholarly journals Evaluation of the lipid fraction of pyrochars organic matter in the aspect of negative effects on soil

2020 ◽  
Vol 17 ◽  
pp. 00156
Author(s):  
Rodion Okunev ◽  
Elena Smirnova ◽  
Kamil Giniyatullin ◽  
Irina Guseva
Keyword(s):  
Organic Matter ◽  
Low Temperature ◽  
Pyrolysis Temperature ◽  
Lipid Fraction ◽  
Total Content ◽  
Negative Effects ◽  
Polycyclic Aromatic ◽  
Negative Effect ◽  
Pahs Concentration ◽  
Low Temperature Pyrolysis

The evaluation of the possible negative effect of pyrochars on soils based on the analysis of the content of lipid fraction and polycyclic aromatic hydrocarbons (PAHs) of organic matter was evaluated. Eight species of pyrochar were obtained from the crop and wood residues (linden, willow, corn, millet) by two pyrolysis regimes: low-temperature pyrolysis (<400°C) and high-temperature pyrolysis (400–600°C). The largest amount of lipid fraction (from 0.54 to 2.78%) and PAHs were found in pyrochars obtained at a low pyrolysis temperature. The total content of PAHs in the studied samples ranged from 8.49 to 603.21 μg/kg. According to the PAHs content, pyrochar was the most adverse for application to the soil, obtained from the residues of millet of low-temperature pyrolysis, however, at a high pyrolysis temperature, the safest product with the lowest PAHs concentration and a significant amount of lipid fraction was formed. Using an incubation experiment by measuring substrate-induced respiration in soil-pyrochar mixtures, it was shown that the application of this meliorant can also increase the emission of carbon dioxide from soils in a short time. The results of the experiments showed that it is necessary to precisely control the conditions of pyrolysis and carefully select the material for pyrochar in order to obtain the products with most favourable amounts of lipid fraction and PAHs content.

scholarly journals Sandstone-Hosted Uranium Deposits as a Possible Source for Critical Elements: The Eureka Mine Case, Castell-Estaó, Catalonia

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 34 ◽  
Author(s):  
Montgarri Castillo-Oliver ◽  
Joan Carles Melgarejo ◽  
Lisard Torró ◽  
Cristina Villanova-de-Benavent ◽  
Marc Campeny ◽  
...  
Keyword(s):  
Organic Matter ◽  
Low Temperature ◽  
Black Shales ◽  
Hydrothermal Fluids ◽  
Uranium Deposits ◽  
Critical Metals ◽  
Fine Grained ◽  
Critical Elements ◽  
By Products ◽  
Red Bed

The Eureka deposit in Castell-estaó in the Catalan Pyrenees is a Cu–U–V deposit, hosted by Triassic red-bed sandstones, and classified here as a low-temperature, sandstone-hosted stratabound metamorphite U deposit. The main mineralisation is stratabound, related to coal-bearing units and produced during the Alpine deformation by migration of hydrothermal fluids. In this stage, the original sedimentary and diagenetic components (quartz and calcite, micas, hematite and locally apatite) were replaced by a complex sequence of roscoelite, fine-grained REE phosphates, sulphides and Ni–Co arsenides and sulpharsenides, Ag–Pb selenides, bismuth phases, sulphosalts and uraninite. The black shales of the Silurian sediments underlying the deposit and the nearby Carboniferous volcanoclastic rocks are interpreted as the source of the redox-sensitive elements concentrated in Eureka. The sulphur source is related to leaching of the evaporitic Keuper facies. The REE transport would be facilitated by SO4-rich solutions. The reduction of these solutions by interaction with organic matter resulted in the widespread precipitation of REE and redox-sensitive elements, including many critical metals (V, Bi, Sb, Co), whereas barite precipitated in the oxidized domains. The occurrence of similar enrichments in critical elements can be expected in other similar large uranium deposits, which could be a source of these elements as by-products.

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