carbon erosion
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2022 ◽  
Author(s):  
Kristof Van Oost ◽  
Jo Six

Abstract. The acceleration of erosion, transport and burial of soil organic carbon (C) in response to agricultural expansion represents a significant perturbation of the terrestrial C cycle. Recent model advances now enable improved representation of the relationships between sedimentary processes and C cycling and this has led to substantially revised assessments of changes in land C as a result of land cover and climate change. However, surprisingly a consensus on both the direction and magnitude of the erosion-induced land-atmosphere C exchange is still lacking. Here, we show that the apparent soil C erosion paradox, i.e., whether agricultural erosion results in a C sink or source, can be reconciled when comprehensively considering the range of temporal (from seconds to millennia) and spatial scales (from soil microaggregates to the Land Ocean Aquatic Continuum (LOAC)) at which erosional effects on the C cycle operate. Based on the currently available data (74 studies), we developed a framework that describes erosion-induced C sink and source terms across scales. Based on this framework, we conclude that erosion is a source for atmospheric CO2 when considering only small temporal and spatial scales, while both sinks and sources appear when multi-scaled approaches are used. We emphasize the need for erosion control for the benefits it brings for the delivery of ecosystem services, particularly in low-input systems, but our analysis clearly demonstrates that cross-scale approaches are essential to accurately represent erosion effects on the global C cycle.


2021 ◽  
Author(s):  
Jordon Hemingway ◽  
Daniel Rothman ◽  
Katherine Grant ◽  
Sarah Rosengard ◽  
Timothy Eglinton ◽  
...  

<p>The vast majority of organic carbon (OC) produced by life is respired back to carbon dioxide (CO<sub>2</sub>), but roughly 0.1% escapes and is preserved over geologic timescales. By sequestering reduced carbon from Earth’s surface, this “slow OC leak” contributes to CO<sub>2</sub> removal and promotes the accumulation of atmospheric oxygen and oxidized minerals. Countering this, OC contained within sedimentary rocks is oxidized during exhumation and erosion of mountain ranges. By respiring previously sequestered reduced carbon, erosion consumes atmospheric oxygen and produces CO<sub>2</sub>. The balance between these two processes—preservation and respiration—regulates atmospheric composition, Earth-surface redox state, and global climate. Despite this importance, the governing mechanisms remain poorly constrained. To provide new insight, we developed a method that investigates OC composition using bond-strength distributions coupled with radiocarbon ages. Here I highlight a suite of recent results using this approach, and I show that biospheric OC interacts with particles and becomes physiochemically protected during aging, thus promoting preservation. I will discuss how this mechanistic framework can help elucidate why OC preservation—and thus atmospheric composition, Earth-surface redox state, and climate—has varied throughout Earth history.</p>


2020 ◽  
Vol 13 (3) ◽  
pp. 1201-1222
Author(s):  
Victoria Naipal ◽  
Ronny Lauerwald ◽  
Philippe Ciais ◽  
Bertrand Guenet ◽  
Yilong Wang

Abstract. Soil erosion by rainfall and runoff is an important process behind the redistribution of soil organic carbon (SOC) over land, thereby impacting the exchange of carbon (C) between land, atmosphere, and rivers. However, the net role of soil erosion in the global C cycle is still unclear as it involves small-scale SOC removal, transport, and redeposition processes that can only be addressed over selected small regions with complex models and measurements. This leads to uncertainties in future projections of SOC stocks and complicates the evaluation of strategies to mitigate climate change through increased SOC sequestration. In this study we present the parsimonious process-based Carbon Erosion DYNAMics model (CE-DYNAM) that links sediment dynamics resulting from water erosion with the C cycle along a cascade of hillslopes, floodplains, and rivers. The model simulates horizontal soil and C transfers triggered by erosion across landscapes and the resulting changes in land–atmosphere CO2 fluxes at a resolution of about 8 km at the catchment scale. CE-DYNAM is the result of the coupling of a previously developed coarse-resolution sediment budget model and the ecosystem C cycle and erosion removal model derived from the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model. CE-DYNAM is driven by spatially explicit historical land use change, climate forcing, and global atmospheric CO2 concentrations, affecting ecosystem productivity, erosion rates, and residence times of sediment and C in deposition sites. The main features of CE-DYNAM are (1) the spatially explicit simulation of sediment and C fluxes linking hillslopes and floodplains, (2) the relatively low number of parameters that allow for running the model at large spatial scales and over long timescales, and (3) its compatibility with global land surface models, thereby providing opportunities to study the effect of soil erosion under global changes. We present the model structure, concepts, limitations, and evaluation at the scale of the Rhine catchment for the period 1850–2005 CE (Common Era). Model results are validated against independent estimates of gross and net soil and C erosion rates and the spatial variability of SOC stocks from high-resolution modeling studies and observational datasets. We show that despite local differences, the resulting soil and C erosion rates, as well as SOC stocks from CE-DYNAM, are comparable to high-resolution estimates and observations at subbasin level. We find that soil erosion mobilized around 66±28 Tg (1012 g) of C under changing climate and land use over the non-Alpine region of the Rhine catchment over the entire period, assuming that the erosion loop of the C cycle was nearly steady state by 1850. This caused a net C sink equal to 2.1 %–2.7 % of the net primary productivity of the non-Alpine region over 1850–2005 CE. This sink is a result of the dynamic replacement of C on eroding sites that increases in this period due to rising atmospheric CO2 concentrations enhancing the litter C input to the soil from primary production.


2019 ◽  
Vol 93 ◽  
pp. 43-52 ◽  
Author(s):  
Adrian Chappell ◽  
Nicholas P. Webb ◽  
John F. Leys ◽  
Cathleen M. Waters ◽  
Susan Orgill ◽  
...  

2019 ◽  
Vol 124 (2) ◽  
pp. 432-449 ◽  
Author(s):  
Rebecca B. Abney ◽  
Timothy J. Kuhn ◽  
Alex Chow ◽  
William Hockaday ◽  
Marilyn L. Fogel ◽  
...  

2018 ◽  
Vol 24 (6) ◽  
pp. 612-622 ◽  
Author(s):  
Mike B. Matthews ◽  
Stuart L. Kearns ◽  
Ben Buse

AbstractElectron beam-induced carbon contamination is a balance between simultaneous deposition and erosion processes. Net erosion rates for a 25 nA 3 kV beam can reduce a 5 nm C coating by 20% in 60 s. Measurements were made on C-coated Bi substrates, with coating thicknesses of 5–20 nm, over a range of analysis conditions. Erosion showed a step-like increase with increasing electron flux density. Both the erosion rate and its rate of change increase with decreasing accelerating voltage. As the flux density decreases the rate of change increases more rapidly with decreasing voltage. Time-dependent intensity (TDI) measurements can be used to correct for errors, in both coating and substrate quantifications, resulting from carbon erosion. Uncorrected analyses showed increasing errors in coating thickness with decreasing accelerating voltage. Although the erosion rate was found to be independent of coating thickness this produces an increasing absolute error with decreasing starting thickness, ranging from 1.5% for a 20 nm C coating on Bi at 15 kV to 14% for a 5 nm coating at 3 kV. Errors in Bi Mα measurement are <1% at 5 kV or above but increase rapidly below this, both with decreasing voltage and increasing coating thickness to 20% for a 20 nm coated sample at 3 kV.


2018 ◽  
Vol 917 ◽  
pp. 122-126
Author(s):  
Yurii Bauman ◽  
Ilya Mishakov ◽  
Denis Korneev ◽  
Aleksey Vedyagin

The way to produce the nanostructured carbon filaments via H2-assisted catalytic decomposition of CF2Cl2 over self-organizing Ni-based catalyst has been reported. The self-organizing 6%Ni/CNM catalyst, where CNM is a carbon nanomaterial, resulted from carbon erosion of bulk Ni-Cr alloy (nichrome) in C2H4Cl2 vapors was also shown to be effective for catalytic chemical vapor deposition of CF2Cl2 with formation of bimodal carbon structures. It was demonstrated that interaction of nichrome with CF2Cl2/H2 reaction mixture at 600 °C leads to its rapid disintegration caused by carbon erosion to form disperse active Ni-particles catalyzing the growth of carbon filaments. The resulted filamentous carbon material is characterized with high textural parameters.


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