scholarly journals Syngenetic rapid growth of ellipsoidal silica concretions with bitumen cores

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hidekazu Yoshida ◽  
Ryusei Kuma ◽  
Hitoshi Hasegawa ◽  
Nagayoshi Katsuta ◽  
Sin-iti Sirono ◽  
...  
Keyword(s):  
Organic Matter ◽  
Early Diagenesis ◽  
Ph Change ◽  
Carbon Preference Index ◽  
Diffusion Growth ◽  
Silica Precipitation ◽  
Precipitated Silica ◽  
Preference Index ◽  
Decomposition Of Organic Matter ◽  
Growth Diagram

AbstractIsolated silica concretions in calcareous sediments have unique shapes and distinct sharp boundaries and are considered to form by diagenesis of biogenic siliceous grains. However, the details and rates of syngenetic formation of these spherical concretions are still not fully clear. Here we present a model for concretion growth by diffusion, with chemical buffering involving decomposition of organic matter leading to a pH change in the pore-water and preservation of residual bitumen cores in the concretions. The model is compatible with some pervasive silica precipitation. Based on the observed elemental distributions, C, N, S, bulk carbon isotope and carbon preference index (CPI) measurements of the silica-enriched concretions, bitumen cores and surrounding calcareous rocks, the rate of diffusive concretion growth during early diagenesis is shown using a diffusion-growth diagram. This approach reveals that ellipsoidal SiO2 concretions with a diameter of a few cm formed rapidly and the precipitated silica preserved the bitumen cores. Our work provides a generalized chemical buffering model involving organic matter that can explain the rapid syngenetic growth of other types of silica accumulation in calcareous sediments.

scholarly journals The riverine bioreactor: An integrative perspective on biological decomposition of organic matter across riverine habitats

2021 ◽  
Vol 772 ◽  
pp. 145494
Author(s):  
Ignacio Peralta-Maraver ◽  
Rachel Stubbington ◽  
Shai Arnon ◽  
Pavel Kratina ◽  
Stefan Krause ◽  
...  
Keyword(s):  
Organic Matter ◽  
Decomposition Of Organic Matter ◽  
Riverine Habitats ◽  
Biological Decomposition

INFLUENCE OF SOIL ACIDITY UPON THE DECOMPOSITION OF ORGANIC MATTER IN SOILS

Soil Science ◽  
1934 ◽  
Vol 37 (1) ◽  
pp. 1-14 ◽  
Author(s):  
J. W. WHITE ◽  
F. J. HOLBEN ◽  
C. D. JEFFRIES
Keyword(s):  
Organic Matter ◽  
Soil Acidity ◽  
Decomposition Of Organic Matter

The impact of porosity on organic matter cycling in a two-dimensional porous medium 

2021 ◽  
Author(s):  
Hanbang Zou ◽  
Pelle Ohlsson ◽  
Edith Hammer
Keyword(s):  
Porous Medium ◽  
Organic Matter ◽  
Carbon Sequestration ◽  
Soil Carbon ◽  
Pore Network ◽  
Pore Scale ◽  
Decomposition Of Organic Matter ◽  
Organic Matter Cycling ◽  
The Impact

<p>Carbon sequestration has been a popular research topic in recent years as the rapid elevation of carbon emission has significantly impacted our climate. Apart from carbon capture and storage in e.g. oil reservoirs, soil carbon sequestration offers a long term and safe solution for the environment and human beings. The net soil carbon budget is determined by the balance between terrestrial ecosystem sink and sources of respiration to atmospheric carbon dioxide. Carbon can be long term stored as organic matters in the soil whereas it can be released from the decomposition of organic matter. The complex pore networks in the soil are believed to be able to "protect" microbial-derived organic matter from decomposition. Therefore, it is important to understand how soil structure impacts organic matter cycling at the pore scale. However, there are limited experimental studies on understanding the mechanism of physical stabilization of organic matter. Hence, my project plan is to create a heterogeneous microfluidic porous microenvironment to mimic the complex soil pore network which allows us to investigate the ability of organisms to access spaces starting from an initial ecophysiological precondition to changes of spatial accessibility mediated by interactions with the microbial community.</p><p>Microfluidics is a powerful tool that enables studies of fundamental physics, rapid measurements and real-time visualisation in a complex spatial microstructure that can be designed and controlled. Many complex processes can now be visualized enabled by the development of microfluidics and photolithography, such as microbial dynamics in pore-scale soil systems and pore network modification mimicking different soil environments – earlier considered impossible to achieve experimentally. The microfluidic channel used in this project contains a random distribution of cylindrical pillars of different sizes so as to mimic the variations found in real soil. The randomness in the design creates various spatial availability for microbes (preferential flow paths with dead-end or continuous flow) as an invasion of liquids proceeds into the pore with the lowest capillary entry pressure. In order to study the impact of different porosity in isolation of varying heterogeneity of the porous medium, different pore size chips that use the same randomly generated pore network is created. Those chips have the same location of the pillars, but the relative size of each pillar is scaled. The experiments will be carried out using sterile cultures of fluorescent bacteria, fungi and protists, synthetic communities of combinations of these, or a whole soil community inoculum. We will quantify the consumption of organic matter from the different areas via fluorescent substrates, and the bio-/necromass produced. We hypothesise that lower porosity will reduce the net decomposition of organic matter as the narrower pore throat limits the access, and that net decomposition rate at the main preferential path will be higher than inside branches</p>

scholarly journals EXAMINING THE PROCESS OF DECOMPOSITION AND CARBON CYCLING IN 'FADAMA' COASTAL WETLANDS: A CASE STUDY OF HEAPING WETLANDS ECOSYSTEM

2020 ◽  
Vol 4 (3) ◽  
pp. 10-16
Author(s):  
George Dasat Shwamyil ◽  
G. Danjuma ◽  
E. S. Chundusu
Keyword(s):  
Organic Matter ◽  
Ecosystem Services ◽  
Carbon Cycling ◽  
Carbon Capture ◽  
Carbon Capture And Storage ◽  
Wetland Soil ◽  
Low Oxygen ◽  
Decomposition Of Organic Matter ◽  
Plateau State

Wetlands provide several ecosystem services including carbon capture and storage, water filtration, nutrient cycling, and support agriculture among others. The biogeochemical process and decomposition parameters in ‘Fadama' wetland soils comprising of Gada biyu, Pwomol and Kpang referred to as sites A, B, and C respectively all of Heipang District in Barkin Ladi, Plateau State was investigated using standard operating procedures (SOP). Results of investigations revealed that soils from Kpang had slightly higher water content (34.52%) than those from Pwomol (33.48%) and Gada biyu (32.03%). While soils from Gada biyu had the highest solid organic matter (SOM) (10.79%) followed by Pwomol (8.15%) as Kpang had the least (7.85%). Gada biyu soils had the lowest Phenol oxidases activity (1536.56 nmol dicq g-1 h-1) while those from Pwomol (5340.44 nmol dicq g-1 h-1) was highest. All sites had similar concentrations of soil phenolics (76.58 µg g-1, 79.98µg g-1, and 83.25µg g-1). The activity of hydrolyses (β-glucosidase) in Gada biyu soil (2.93 nmol g-1 min-1) was lower than those from Pwomol (6.13 nmol g-1 min-1). These parameters indicate the level of biogeochemical processes in the soil at each site. Gada biyu had the highest rate of CH4 (0.84 ug g-1h-1) flux. Decomposition of organic matter, carbon cycling and greenhouse gas storage in wetland soil, is due to the anoxic condition comprising of low oxygen availability, cool temperatures, anaerobic conditions, reduced microbial activity, and the quality of organic matter substrates in such soils.  Anthropogenic disturbances affecting wetlands must be discouraged to promote vital ecosystem services.

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