Sizable pool of labile organic carbon in peat and mineral soils of permafrost peatlands, western Siberia

Geoderma ◽  
2022 ◽  
Vol 409 ◽  
pp. 115601
Author(s):  
Artem G. Lim ◽  
Sergey V. Loiko ◽  
Oleg S. Pokrovsky
Keyword(s):  
Organic Carbon ◽  
Western Siberia ◽  
Labile Organic Carbon ◽  
Mineral Soils

scholarly journals The undetected loss of aged carbon from boreal mineral soils

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Geert Hensgens ◽  
Hjalmar Laudon ◽  
Mark S. Johnson ◽  
Martin Berggren
Keyword(s):  
Organic Carbon ◽  
Boreal Forest ◽  
Soil C ◽  
Earth Systems ◽  
Nuclear Bomb ◽  
C Cycle ◽  
Water Extractable Organic Carbon ◽  
High Lability ◽  
Mineral Soils ◽  
Terrestrial Biomes

AbstractThe boreal forest is among the largest terrestrial biomes on earth, storing more carbon (C) than the atmosphere. Due to rapid climatic warming and enhanced human development, the boreal region may have begun transitioning from a net C sink to a net source. This raises serious concern that old biogenic soil C can be re-introduced into the modern C cycle in near future. Combining bio-decay experiments, mixing models and the Keeling plot method, we discovered a distinct old pre-bomb organic carbon fraction with high biodegradation rate. In total, 34 ± 12% of water-extractable organic carbon (WEOC) in podzols, one of the dominating boreal soil types, consisted of aged (~ 1000 year) labile C. The omission of this aged (i.e., Δ14C depleted) WEOC fraction in earlier studies is due to the co-occurrence with Δ14C enriched modern C formed following 1950s nuclear bomb testing masking its existence. High lability of aged soil WEOC and masking effects of modern Δ14C enriched C suggests that the risk for mobilization and re-introduction of this ancient C pool into the modern C cycle has gone undetected. Our findings have important implications for earth systems models in terms of climate-carbon feedbacks and the future C balance of the boreal forest.

scholarly journals Three representative UK moorland soils show differences in decadal release of dissolved organic carbon in response to environmental change

2011 ◽  
Vol 8 (12) ◽  
pp. 3661-3675 ◽  
Author(s):  
M. I. Stutter ◽  
D. G. Lumsdon ◽  
A. P. Rowland
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Environmental Change ◽  
Soil Properties ◽  
Process Models ◽  
Environmental Drivers ◽  
Specific Response ◽  
Soil C ◽  
Doc Concentration ◽  
Mineral Soils

Abstract. Moorland carbon reserves in organo-mineral soils may be crucial to predicting landscape-scale variability in soil carbon losses, an important component of which is dissolved organic carbon (DOC). Surface water DOC trends are subject to a range of scaling, transport and biotic processes that disconnect them from signals in the catchment's soils. Long-term soil datasets are vital to identify changes in DOC release at source and soil C depletion. Here we show, that moorland soil solution DOC concentrations at three key UK Environmental Change Network sites increased between 1993–2007 in both surface- and sub- soil of a freely-draining Podzol (48 % and 215 % increases in O and Bs horizons, respectively), declined in a gleyed Podzol and showed no change in a Peat. Our principal findings were that: (1) considerable heterogeneity in DOC response appears to exist between different soils that is not apparent from the more consistent observed trends for streamwaters, and (2) freely-draining organo-mineral Podzol showed increasing DOC concentrations, countering the current scientific focus on soil C destabilization in peats. We discuss how the key solubility controls on DOC associated with coupled physico-chemical factors of ionic strength, acid deposition recovery, soil hydrology and temperature cannot readily be separated. Yet, despite evidence that all sites are recovering from acidification the soil-specific responses to environmental change have caused divergence in soil DOC concentration trends. The study shows that the properties of soils govern their specific response to an approximately common set of broad environmental drivers. Key soil properties are indicated to be drainage, sulphate and DOC sorption capacity. Soil properties need representation in process-models to understand and predict the role of soils in catchment to global C budgets. Catchment hydrological (i.e. transport) controls may, at present, be governing the more ubiquitous rises in river DOC concentration trends, but soil (i.e. source) controls provide the key to prediction of future C loss to waters and the atmosphere.

scholarly journals Implications of changing from grazed or semi-natural vegetation to forestry for carbon stores and fluxes in upland organo-mineral soils in the UK

2007 ◽  
Vol 11 (1) ◽  
pp. 61-76 ◽  
Author(s):  
B. Reynolds
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Best Practice ◽  
Agricultural Soils ◽  
Relative Magnitude ◽  
International Studies ◽  
Best Practice Guidelines ◽  
Carbon Reservoir ◽  
Mineral Soils ◽  
The Uk

Abstract. In the UK, as organo-mineral soils are a significant store of soil organic carbon (SOC), they may become increasingly favoured for the expansion of upland forestry. It is important, therefore, to assess the likely impacts on SOC of this potentially major land use change. Currently, these assessments rely on modelling approaches which assume that afforestation of organo-mineral soils is "carbon neutral". This review evaluates this assumption in two ways. Firstly, UK information from the direct measurement of SOC change following afforestation is examined in the context of international studies. Secondly, UK data on the magnitude and direction of the major fluxes in the carbon cycle of semi-natural upland ecosystems are assessed to identify the likely responses of the fluxes to afforestation of organo-mineral soils. There are few directly relevant measurements of SOC change following afforestation of organo-mineral soils in the UK uplands but there are related studies on peat lands and agricultural soils. Overall, information on the magnitude and direction of change in SOC with afforestation is inconclusive. Data on the accumulation of litter beneath conifer stands have been identified but the extent to which the carbon held in this pool is incorporated into the stable soil carbon reservoir is uncertain. The effect of afforestation on most carbon fluxes is small because the fluxes are either relatively minor or of the same magnitude and direction irrespective of land use. Compared with undisturbed moorland, particulate organic carbon losses increase throughout the forest cycle but the data are exclusively from plantation conifer forests and in many cases pre-date current industry best practice guidelines which aim to reduce such losses. The biggest uncertainty in flux estimates is the relative magnitude of the sink for atmospheric carbon as trees grow and mature compared with that lost during site preparation and harvesting. Given the size of this flux relative to many of the others, this should be a focus for future carbon research on these systems.

scholarly journals The Accumulation of Organic Carbon in Mineral Soils by Afforestation of Abandoned Farmland

PLoS ONE ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. e32054 ◽  
Author(s):  
Xiaorong Wei ◽  
Liping Qiu ◽  
Mingan Shao ◽  
Xingchang Zhang ◽  
William J. Gale
Keyword(s):  
Organic Carbon ◽  
Abandoned Farmland ◽  
Mineral Soils

scholarly journals Ground ice, organic carbon and soluble cations in tundra permafrost soils and sediments near a Laurentide ice divide in the Slave Geological Province, Northwest Territories, Canada

2020 ◽  
Vol 14 (12) ◽  
pp. 4341-4364
Author(s):  
Rupesh Subedi ◽  
Steven V. Kokelj ◽  
Stephan Gruber
Keyword(s):  
Organic Carbon ◽  
Landscape Change ◽  
Ice Sheet ◽  
Canadian Arctic ◽  
Landscape Changes ◽  
Ground Ice ◽  
Basal Ice ◽  
Permafrost Soils ◽  
Western Arctic ◽  
Mineral Soils

Abstract. The central Slave Geological Province is situated 450–650 km from the presumed spreading centre of the Keewatin Dome of the Laurentide Ice Sheet, and it differs from the western Canadian Arctic, where recent thaw-induced landscape changes in Laurentide ice-marginal environments are already abundant. Although much of the terrain in the central Slave Geological Province is mapped as predominantly bedrock and ice-poor, glacial deposits of varying thickness occupy significant portions of the landscape in some areas, creating a mosaic of permafrost conditions. Limited evidence of ice-rich ground, a key determinant of thaw-induced landscape change, exists. Carbon and soluble cation contents in permafrost are largely unknown in the area. Twenty-four boreholes with depths up to 10 m were drilled in tundra north of Lac de Gras to address these regional gaps in knowledge and to better inform projections and generalizations at a coarser scale. Excess-ice contents of 20 %–60 %, likely remnant Laurentide basal ice, are found in upland till, suggesting that thaw subsidence of metres to more than 10 m is possible if permafrost were to thaw completely. Beneath organic terrain and in fluvially reworked sediment, aggradational ice is found. The variability in abundance of ground ice poses long-term challenges for engineering, and it makes the area susceptible to thaw-induced landscape change and mobilization of sediment, solutes and carbon several metres deep. The nature and spatial patterns of landscape changes, however, are expected to differ from ice-marginal landscapes of western Arctic Canada, for example, based on greater spatial and stratigraphic heterogeneity. Mean organic-carbon densities in the top 3 m of soil profiles near Lac de Gras are about half of those reported in circumpolar statistics; deeper deposits have densities ranging from 1.3–10.1 kg C m−3, representing a significant additional carbon pool. The concentration of total soluble cations in mineral soils is lower than at previously studied locations in the western Canadian Arctic. This study can inform permafrost investigations in other parts of the Slave Geological Province, and its data can support scenario simulations of future trajectories of permafrost thaw. Preserved Laurentide basal ice can support new ways of studying processes and phenomena at the base of an ice sheet.

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