scholarly journals First pan-Arctic assessment of dissolved organic carbon in lakes of the permafrost region

2021 ◽  
Vol 18 (12) ◽  
pp. 3917-3936
Author(s):  
Lydia Stolpmann ◽  
Caroline Coch ◽  
Anne Morgenstern ◽  
Julia Boike ◽  
Michael Fritz ◽  
...  
Keyword(s):  
Climate Change ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Cycle ◽  
Dissolved Organic Carbon ◽  
Significant Relationship ◽  
Global Carbon Cycle ◽  
Doc Concentration ◽  
Global Carbon ◽  
Permafrost Regions

Abstract. Lakes in permafrost regions are dynamic landscape components and play an important role for climate change feedbacks. Lake processes such as mineralization and flocculation of dissolved organic carbon (DOC), one of the main carbon fractions in lakes, contribute to the greenhouse effect and are part of the global carbon cycle. These processes are in the focus of climate research, but studies so far are limited to specific study regions. In our synthesis, we analyzed 2167 water samples from 1833 lakes across the Arctic in permafrost regions of Alaska, Canada, Greenland, and Siberia to provide first pan-Arctic insights for linkages between DOC concentrations and the environment. Using published data and unpublished datasets from the author team, we report regional DOC differences linked to latitude, permafrost zones, ecoregions, geology, near-surface soil organic carbon contents, and ground ice classification of each lake region. The lake DOC concentrations in our dataset range from 0 to 1130 mg L−1 (10.8 mg L−1 median DOC concentration). Regarding the permafrost regions of our synthesis, we found median lake DOC concentrations of 12.4 mg L−1 (Siberia), 12.3 mg L−1 (Alaska), 10.3 mg L−1 (Greenland), and 4.5 mg L−1 (Canada). Our synthesis shows a significant relationship between lake DOC concentration and lake ecoregion. We found higher lake DOC concentrations at boreal permafrost sites compared to tundra sites. We found significantly higher DOC concentrations in lakes in regions with ice-rich syngenetic permafrost deposits (yedoma) compared to non-yedoma lakes and a weak but significant relationship between soil organic carbon content and lake DOC concentration as well as between ground ice content and lake DOC. Our pan-Arctic dataset shows that the DOC concentration of a lake depends on its environmental properties, especially on permafrost extent and ecoregion, as well as vegetation, which is the most important driver of lake DOC in this study. This new dataset will be fundamental to quantify a pan-Arctic lake DOC pool for estimations of the impact of lake DOC on the global carbon cycle and climate change.

scholarly journals First Pan-Arctic Assessment of Dissolved Organic Carbon in Permafrost-Region Lakes

2020 ◽  
Author(s):  
Lydia Stolpmann ◽  
Caroline Coch ◽  
Anne Morgenstern ◽  
Julia Boike ◽  
Michael Fritz ◽  
...  
Keyword(s):  
Climate Change ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Significant Relationship ◽  
Global Carbon Cycle ◽  
Doc Concentration ◽  
Relationship Of ◽  
Global Carbon ◽  
Permafrost Regions

Abstract. Lakes in permafrost regions are dynamic landscape components and play an important role for climate change feedbacks. Lake processes such as mineralization and flocculation of dissolved organic carbon (DOC), one of the main carbon fractions in lakes, contribute to the greenhouse effect and are part of the global carbon cycle. These processes are in focus of climate research but studies so far are limited to specific study regions. In our synthesis, we analysed 2,167 water samples from 1,833 lakes across the Arctic in permafrost regions of Alaska, Canada, Greenland, and Siberia to provide first pan-Arctic insights for linkages between DOC concentrations and the environment. Using published data and unpublished datasets from the author team we report regional DOC differences linked to latitude, permafrost zones, ecoregions, geology, near-surface soil organic carbon contents, and ground ice classification of each lake region. The lake DOC concentrations in our dataset range from 0 mg L−1 to 1,130 mg L−1 (10.8 mg L−1 median DOC concentration). Regarding the permafrost regions of our synthesis, we found median lake DOC concentrations of 12.4 mg L−1 (Siberia), 12.3 mg L−1 (Alaska), 10.3 mg L−1 (Greenland), and 4.5 mg L−1 (Canada). Our synthesis shows a significant relationship of lake DOC concentration and ecoregion of the lake. We found higher lake DOC concentrations in boreal permafrost sites compared to tundra sites. About 22 % of the lakes in our extensive dataset are located in regions with ice-rich syngenetic permafrost deposits (yedoma). Yedoma contains large amounts of easily erodible organic carbon and we found significantly higher DOC concentrations in yedoma lakes compared to non-yedoma lakes. Compared to previous studies we found a weak significant relationship of soil organic carbon content and lake DOC concentration as well as between ground-ice content and lake DOC. Our pan-Arctic dataset shows that the DOC concentration of a lake strongly depends on its environmental properties, especially on permafrost extent and ecoregion, as well as vegetation, which is the most important driver of lake DOC in this study. This new dataset will be fundamental to quantify a pan-Arctic lake DOC pool for estimations of the impact of lake DOC on the global carbon cycle and climate change.

scholarly journals Spatiotemporal Differentiation of Soil Organic Carbon of Grassland and Its Relationship with Soil Physicochemical Properties on the Northern Slope of Qilian Mountains, China

2020 ◽  
Vol 12 (22) ◽  
pp. 9396
Author(s):  
Le Yang ◽  
Wenxiong Jia ◽  
Yang Shi ◽  
Zhiyuan Zhang ◽  
Hui Xiong ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Cycle ◽  
Physicochemical Properties ◽  
Soil Depth ◽  
Global Carbon Cycle ◽  
Qilian Mountains ◽  
Forest Steppe ◽  
Northern Slope ◽  
Global Carbon

The soil organic carbon pool is an important part of the global carbon cycle, and its accumulation and decomposition affect the balance of the global carbon cycle. It is important to understand scientifically the temporal and spatial variation of soil organic carbon (SOC) and its influencing factors, which could aid further understanding of the accumulation and decomposition of SOC. In order to reveal the relationship between soil organic carbon and soil’s physicochemical properties, six plots were selected on the east, middle and west of forest steppes and typical grasslands on the northern slope of Qilian Mountains during two consecutive growing seasons from 2013 to 2014. Soil samples under 0–30 cm were used to study the spatiotemporal differentiation of SOC and its relationship with the soil’s physicochemical properties in the grassland of the study area. The results show that the content of SOC in the grassland in 2013 was higher than that in 2014, and that it decreased gradually from east to west. The content of SOC is significantly different between the soil layer of 0–10 cm and the soil layers of 10–20 cm and 20–30 cm (p < 0.05), and it decreases with increases in soil depth. The SOC content on forest steppe is higher than that on typical grassland. Significant positive correlations appear between SOC with soil water content and soil nutrients (alkaline nitrogen, available phosphorus, available potassium) (p < 0.01), but there are significant negative correlations between SOC and soil temperature, soil pH, and soil electrical conductivity (p < 0.01).

scholarly journals Carbon content, carbon fixation yield and dissolved organic carbon release from diverse marine nitrifiers

2022 ◽  
Author(s):  
Barbara Bayer ◽  
Kelsey McBeain ◽  
Craig A Carlson ◽  
Alyson E Santoro
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Dissolved Organic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Global Carbon Cycle ◽  
Natural Seawater ◽  
Ammonia Oxidizing Bacteria ◽  
Biogeochemical Models ◽  
Marine Food ◽  
Global Carbon

Nitrifying microorganisms, including ammonia-oxidizing archaea, ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, are the most abundant chemoautotrophs in the ocean and play an important role in the global carbon cycle by fixing dissolved inorganic carbon (DIC) into biomass. The release of organic compounds by these microbes is less well known but may represent an as-yet unaccounted source of dissolved organic carbon (DOC) available to heterotrophic marine food webs. Here, we provide measurements of cellular carbon and nitrogen quotas, DIC fixation yields and DOC release of ten phylogenetically diverse marine nitrifiers grown in multiple culture conditions. All investigated strains released DOC during growth, making up on average 5-15% of the fixed DIC. Neither substrate concentration nor temperature affected the proportion of fixed DIC released as DOC, but release rates varied between closely related species. Our results also indicate previous studies may have underestimated DIC fixation yields of marine nitrite oxidizers due to partial decoupling of nitrite oxidation from CO2 fixation, and due to lower observed yields in artificial compared to natural seawater medium. The results of this study provide values for biogeochemical models of the global carbon cycle, and help to further constrain the implications of nitrification-fueled chemoautotrophy for marine food-web functioning and the biological sequestration of carbon in the ocean.

scholarly journals Oceanic efflux of ancient marine dissolved organic carbon in primary marine aerosol

2019 ◽  
Vol 5 (10) ◽  
pp. eaax6535 ◽  
Author(s):  
Steven R. Beaupré ◽  
David J. Kieber ◽  
William C. Keene ◽  
Michael S. Long ◽  
John R. Maben ◽  
...  
Keyword(s):  
Biological Activity ◽  
Organic Carbon ◽  
Carbon Cycle ◽  
Dissolved Organic Carbon ◽  
Global Carbon Cycle ◽  
Breaking Waves ◽  
Sea Surface ◽  
Marine Aerosol ◽  
Global Carbon ◽  
Marine Organic Carbon

Breaking waves produce bubble plumes that burst at the sea surface, injecting primary marine aerosol (PMA) highly enriched with marine organic carbon (OC) into the atmosphere. It is widely assumed that this OC is modern, produced by present-day biological activity, even though nearly all marine OC is thousands of years old, produced by biological activity long ago. We used natural abundance radiocarbon (14C) measurements to show that 19 to 40% of the OC associated with freshly produced PMA was refractory dissolved OC (RDOC). Globally, this process removes 2 to 20 Tg of RDOC from the oceans annually, comparable to other RDOC losses. This process represents a major removal pathway for old OC from the sea, with important implications for oceanic and atmospheric biogeochemistry, the global carbon cycle, and climate.

Time-scale dependence of climate-carbon cycle feedbacks for weak perturbations in CMIP5 models

2021 ◽  
Author(s):  
Guilherme Torres Mendonça ◽  
Julia Pongratz ◽  
Christian Reick
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Time Scales ◽  
Radiative Forcing ◽  
Global Carbon Cycle ◽  
Atmospheric Co2 ◽  
Ice Age ◽  
Cmip5 Models ◽  
Global Carbon ◽  
Different Time Scales

&lt;p&gt;The increase in atmospheric CO2 driven by anthropogenic emissions is the main radiative forcing causing climate change. But this increase is not only a result from emissions, but also from changes in the global carbon cycle. These changes arise from feedbacks between climate and the carbon cycle that drive CO2 into or out of the atmosphere in addition to the emissions, thereby either accelerating or buffering climate change. Therefore, understanding the contribution of these feedbacks to the global response of the carbon cycle is crucial in advancing climate research. Currently, this contribution is quantified by the &amp;#945;-&amp;#946;-&amp;#947; framework (Friedlingstein et al., 2003). But this quantification is only valid for a particular perturbation scenario and time period. In contrast, a recently proposed generalization (Rubino et al., 2016) of this framework for weak perturbations quantifies this contribution for all scenarios and at different time scales.&amp;#160;&lt;/p&gt;&lt;p&gt;Thereby, this generalization provides a systematic framework to investigate the response of the global carbon cycle in terms of the climate-carbon cycle feedbacks. In the present work we employ this framework to study these feedbacks and the airborne fraction in different CMIP5 models. We demonstrate (1) that this generalization of the &amp;#945;-&amp;#946;-&amp;#947; framework consistently describes the linear dynamics of the carbon cycle in the MPI-ESM; and (2) how by this framework the climate-carbon cycle feedbacks and airborne fraction are quantified at different time scales in CMIP5 models. Our analysis shows that, independently of the perturbation scenario, (1) the net climate-carbon cycle feedback is negative at all time scales; (2) the airborne fraction generally decreases for increasing time scales; and (3) the land biogeochemical feedback dominates the model spread in the airborne fraction at all time scales. This last result therefore emphasizes the need to improve our understanding of this particular feedback.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;P. Friedlingstein, J.-L. Dufresne, P. Cox, and P. Rayner. How positive is the feedback between climate change and the carbon cycle? Tellus B, 55(2):692&amp;#8211;700, 2003.&lt;/p&gt;&lt;p&gt;M. Rubino, D. Etheridge, C. Trudinger, C. Allison, P. Rayner, I. Enting, R. Mulvaney, L. Steele, R. Langenfelds, W. Sturges, et al. Low atmospheric CO2 levels during the Little Ice Age due to cooling-induced terrestrial uptake. Nature Geoscience, 9(9):691&amp;#8211;694, 2016.&lt;/p&gt;

First Pan-Arctic Assessment of Dissolved Organic Carbon Concentration in Permafrost-Region Lakes

2020 ◽  
Author(s):  
Lydia Stolpmann ◽  
Anne Morgenstern ◽  
Julia Boike ◽  
Michael Fritz ◽  
Ulrike Herzschuh ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Permafrost Region ◽  
Organic Carbon Content ◽  
Soil Organic Carbon Content ◽  
Doc Concentration ◽  
Deposit Type ◽  
Relationship Of ◽  
Global Carbon

&lt;p&gt;Permafrost-region lakes are dynamic landscape systems and play an important role for climate change feedbacks. Lake processes such as mineralization and flocculation of DOC, one of the main carbon fraction in lakes, contribute to the global carbon cycle. These processes are in focus of climate research but studies have been limited in geographic extent. We synthesized published datasets and unpublished datasets from the author team totaling 1,691 water samples from 1,387 lakes across the Subarctic and Arctic in permafrost regions of Alaska, Canada, Siberia, and Greenland to provide first insights for linkages between DOC concentration to the basin. In our synthesis, we find regional differences in DOC concentration of permafrost-region lakes. We focussed on relations between lake DOC concentration and latitude, permafrost zones, ecoregions, lake surrounding deposit type, and ground ice classification of each lake basin. Additionally, we analysed the lake surrounding soil organic carbon content from 0-100 cm depth and 0-300 cm depth. Individual lake DOC concentrations of our dataset range from below detection limit assigned to 0 mg L&lt;sup&gt;-1&lt;/sup&gt; (North Slope, Alaska) to 1,130 mg L&lt;sup&gt;-1&lt;/sup&gt; (Yukon Flats, Alaska). We found regional median lake DOC concentrations of 18.8 mg L&lt;sup&gt;-1&lt;/sup&gt; (Greenland, n=25), 12.2 mg L&lt;sup&gt;-1&lt;/sup&gt; (Alaska, n= 1,135), 9.6 mg L&lt;sup&gt;-1&lt;/sup&gt; (Siberia, n=252), and 7.2 mg L&lt;sup&gt;-1&lt;/sup&gt; (Canada, n=279). Lakes in the isolated permafrost zone had the highest median DOC concentration compared to lakes in the sporadic, discontinuous, and continuous permafrost zones. Our synthesis shows increasing lake DOC concentration with decreasing latitude and, due to a larger availability of biomass and organic carbon, a significant relationship of lake DOC concentration and ecoregion of the lake. We found higher lake DOC concentrations in boreal permafrost sites compared to tundra sites. About 22 % of lakes in our dataset are located in regions with ice-rich syngenetic permafrost deposits (yedoma). Because yedoma contains large amounts of organic carbon, we assumed to find higher DOC concentrations in yedoma lakes compared to non-yedoma lakes. Our analysis shows a significant relationship of lake DOC concentration and surrounding deposit type but not a higher DOC concentration in yedoma lakes compared to non-yedoma lakes. Finally, we found a relationship of soil organic carbon content from 0-100 cm depth and lake DOC concentration. In contrast, a comparison of soil organic carbon content from 0-300 cm depth and lake DOC concentration shows no significant correlation. This was also found for ground-ice content and lake DOC concentration. Our dataset of lakes across the Arctic shows that the DOC concentration of a lake strongly depends on its environmental properties. This dataset will be fundamental to establish a pan-Arctic lake DOC pool for estimations of the impact of lake DOC on the global carbon cycle and further on climate change.&lt;/p&gt;

scholarly journals Global soil organic carbon removal by water erosion under climate change and land use change during 1850–2005 AD

2018 ◽  
Author(s):  
Victoria Naipal ◽  
Philippe Ciais ◽  
Yilong Wang ◽  
Ronny Lauerwald ◽  
Bertrand Guenet ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Soil Erosion ◽  
Organic Carbon ◽  
Land Use Change ◽  
Soil Organic Carbon ◽  
Climate Variability ◽  
Carbon Cycle ◽  
Atmospheric Co2 ◽  
Terrestrial Carbon

Abstract. The onset and expansion of agriculture has accelerated soil erosion by rainfall and runoff substantially, mobilizing vast quantities of soil organic carbon (SOC) globally. Studies show that at timescales of decennia to millennia this mobilized SOC can significantly alter previously estimated carbon emissions from land use change (LUC). However, a full understanding of the impact of erosion on land-atmosphere carbon exchange is still missing. The aim of our study is to better constrain the terrestrial carbon fluxes by developing methods compatible with Earth System Models (ESMs) in order to explicitly represent the links between soil erosion by rainfall and runoff and carbon dynamics. For this we use an emulator that represents the carbon cycle of a land surface model, in combination with the Revised Universal Soil Loss Equation model. We applied this modeling framework at the global scale to evaluate the effects of potential soil erosion (soil removal only) in the presence of other perturbations of the carbon cycle: elevated atmospheric CO2, climate variability, and LUC. We found that over the period 1850–2005 AD acceleration of soil erosion leads to a total potential SOC removal flux of 100 Pg C of which 80 % occurs on agricultural, pasture and natural grass lands. Including soil erosion in the SOC-dynamics scheme results in a doubling of the cumulative loss of SOC over 1850–2005 due to the combined effects of climate variability, increasing atmospheric CO2 and LUC. This additional erosional loss decreases the cumulative global carbon sink on land by 5 Pg for this specific period, with the largest effects found for the tropics, where deforestation and agricultural expansion increased soil erosion rates significantly. We also show that the potential effects of soil erosion on the global SOC stocks cannot be ignored when compared to the effects of climate change or land use change on the carbon cycle. We conclude that it is necessary to include soil erosion in assessments of LUC and evaluations of the terrestrial carbon cycle.

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