Dynamic Stability of Soil Carbon: Reassessing the “Permanence” of Soil Carbon Sequestration

Dynarski, Katherine A.; Bossio, Deborah A.; Scow, Kate M.

doi:10.3389/fenvs.2020.514701

Cited by 113 publications

(78 citation statements)

References 194 publications

(240 reference statements)

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“…In recent years, physical fractionation methods, and in particular, the separation of size and/or density fractions, have been widely used (Lavallee et al, 2019; Poeplau et al, 2018). This is in line with the current understanding of the major pathways of SOM stabilization (Dynarski et al, 2020), with reduced accessibility of SOM by mineral association as a key mechanism (Dungait et al, 2012; Kögel‐Knabner et al, 2008). However, few warming studies have evaluated the response of different SOM fractions to in situ warming (Lavallee et al, 2019).…”

Section: Introductionsupporting

confidence: 83%

Long‐term geothermal warming reduced stocks of carbon but not nitrogen in a subarctic forest soil

Peplau

Schroeder

Gregorich

et al. 2021

Global Change Biology

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Section: Introductionsupporting

confidence: 83%

Long‐term geothermal warming reduced stocks of carbon but not nitrogen in a subarctic forest soil

Peplau

Schroeder

Gregorich

et al. 2021

Global Change Biology

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“…Modern soils are teeming with microbial biomass, often averaging 10 10 -10 11 bacterial cells and 10 3 and 10 4 species per gram of soil 10 . Modern soils also contain more organic carbon than global vegetation and the atmosphere combined 11,12 . Similarly, Earth's oldest soils also appear to have been highly habitable environments.…”

Section: Introductionmentioning

confidence: 99%

Detection of organic carbon in Mars-analog paleosols with thermal and evolved gas analysis

Broz¹,

Clark²,

Sutter³

et al. 2022

Preprint

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Decades of space exploration have shown that surface environments on Mars were habitable billions of years ago. Ancient, buried surface environments, or paleosols, may have been preserved in the geological record on Mars, and are considered high-priority targets for biosignature investigation. Studies of paleosols on Earth that are compositionally similar to putative martian paleosols can provide a reference frame for constraining their organic preservation potential on Mars. However, terrestrial paleosols typically preserve only trace amounts of organic carbon, and it remains unclear whether the organic component of paleosols can be detected with Mars rover-like instruments. Furthermore, the study of terrestrial paleosols is complicated by diagenetic additions of organic carbon, which can confound interpretations of their organic preservation potential. The objectives of this study were a) to determine whether organic carbon in ~30-million-year-old Mars-analog paleosols can be detected with thermal and evolved gas analysis, and b) constrain the age of organic carbon using radiocarbon (14C) dating to identify late diagenetic additions of carbon. Al/ Fe smectite-rich paleosols from the Early Oligocene (33 Ma) John Day Formation in eastern Oregon were examined with a thermal and evolved gas analyzer configured to operate similarly to the Sample Analysis at Mars Evolved Gas Analysis (SAM-EGA) instrument onboard the Mars Science Laboratory Curiosity rover. All samples evolved CO2 with peaks at ~400 °C and ~700° C from the thermal decomposition of refractory organic carbon and small amounts of calcium carbonate, respectively. Evolutions of organic fragments co-occurred with evolutions of CO2 from organic carbon decomposition. Total organic carbon (TOC) ranged from 0.002 - 0.032 ± 0.006 wt. %. Like modern soils, the near-surface horizons of all paleosols had significantly higher TOC relative to subsurface layers. Radiocarbon dating of four samples revealed an organic carbon age ranging between ~6,200 – 14,500 years before present, suggesting there had been inputs of exogenous organic carbon during diagenesis. By contrast, refractory carbon detected with EGA and enrichment of TOC in near-surface horizons of all three buried profiles were consistent with the preservation of trace amounts of endogenous organic carbon. This work demonstrates that near-surface horizons of putative martian paleosols should be considered high priority locations for in-situ biosignature investigation and reveals challenges for examining organic matter preservation in terrestrial paleosols.

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“…Hence, it is of great importance for nutrient cycling, plant nutrition and sustainable land management. Most authors agree that the stabile SOM pool is represented by the OM that is intimately associated with the mineral phase and thus stabilized for longer periods up to decades and centuries 5 , 12 , 13 . This pool is vital for the formation of a stable (micro)aggregate structure and the adsorption capacity of a soil.…”

Section: Introductionmentioning

confidence: 99%

Quantitative mapping and spectroscopic characterization of particulate organic matter fractions in soil profiles with imaging VisNIR spectroscopy

Steffens

Zeh

Rogge³

et al. 2021

Sci Rep

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Organic matter is an important constituent of soils that controls many soil functions and is of vital importance for ecosystem services like climate regulation and food security. Soil organic matter (SOM consists of a wide spectrum of different organic substances that are highly heterogeneous in terms of chemical composition, stability against microbial decomposition and turnover time. SOM is heterogeneously distributed in the soil profile impeding its fast assessment. A technique to accurately measure SOM quality and quantity with a high spatial resolution in the soil profile is presently lacking. Imaging visible light and near infrared spectroscopy (imVisIR) is a promising technique for the fast and spatially resolved assessment of SOM quality and quantity. In this study, we evaluate the potential of imVisIR to quantitatively map the labile particulate organic matter fraction in undisturbed cores from mineral soils.

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Dynamic Stability of Soil Carbon: Reassessing the “Permanence” of Soil Carbon Sequestration

Cited by 113 publications

References 194 publications

Long‐term geothermal warming reduced stocks of carbon but not nitrogen in a subarctic forest soil

Long‐term geothermal warming reduced stocks of carbon but not nitrogen in a subarctic forest soil

Detection of organic carbon in Mars-analog paleosols with thermal and evolved gas analysis

Quantitative mapping and spectroscopic characterization of particulate organic matter fractions in soil profiles with imaging VisNIR spectroscopy

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