Carbon dioxide and methane fluxes from arctic mudboils

2010 ◽  
Vol 90 (3) ◽  
pp. 441-449 ◽  
Author(s):  
K S Wilson ◽  
E R Humphreys
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Vascular Plant ◽  
Organic Matter Content ◽  
Net Ecosystem Exchange ◽  
The Arctic ◽  
Plant Colonization ◽  
Patterned Ground ◽  
Organic C ◽  
C Balance

Climate change is expected to alter the Arctic’s carbon (C) balance and changes in these C-rich ecosystems may contribute to a positive feedback on global climate change. Low-center mudboils, a form of patterned ground in the Arctic, are distinct landforms in which the exchange of greenhouse gases between the atmosphere and soil has not been fully characterized, but which may have an important influence on the overall C balance of tundra ecosystems. Chamber systems were used to sample net ecosystem exchange of CO2 (NEE) and CO2 and CH4 effluxes along a 35-m transect intersecting two mudboils in a wet sedge fen in Canada’s Southern Arctic (lat. 64°52′N, long. 111°34′W) during the summer months in 2008. Mudboil features gave rise to dramatic variations in vegetation, soil temperature and thaw depth, and soil organic matter content along this transect. Variations in NEE were driven by variations in the amount of vascular vegetation, while CO2 and CH4 effluxes were remarkably similar among the two mudboil (CO2 effluxes: 1.1 ± 0.9 and 1.4 ± 0.7 µmol m-2 s-1; CH4 effluxes: 83.1 ± 189.4 and 23.1 ± 9.4 nmol m-2 s-1, ± 1 standard deviation) and the sedge fen (CO2 effluxes: 1.6 ± 0.7 mol m-2 s-1 ; CH4 effluxes: 28.0 ± 62.0 nmol m-2 s-1) sampling areas. Vegetation appeared to play an important role in limiting temporal variations in CH4 effluxes through plant mediated transport in both mudboil and sedge fen sampling areas. One of the mudboils had negligible vascular plant colonization presumably due to more active frost heave processes. The relatively high CO2 and CH4 efflux in this mudboil area was speculated to be a result of growth and decomposition of cryptogamic organisms, inflow of dissolved organic C, and warmer soil temperatures. Key words: Patterned ground, nonsorted circle, tundra, net ecosystem exchange, methane, carbon dioxide

Decadal carbon balance and its response to 2 degree warming among heterogenous Arctic landscapes

2020 ◽  
Author(s):  
Dan Kou ◽  
Tarmo Virtanen ◽  
Aleksi Räsänen ◽  
Sari Juutinen ◽  
Mika Aurela ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Arctic Region ◽  
The Arctic ◽  
Climate Feedbacks ◽  
Heterogeneous Landscapes ◽  
C Balance ◽  
Total Ecosystem Respiration ◽  
The Arctic Region

<p>The large amounts of carbon (C) stored in the Arctic region can strongly interact with the climate system through the exchange of carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) under the unmitigated environmental changes. Currently, there are still large uncertainties in the C exchange and the subsequent C-climate feedbacks between the land and atmosphere across the Arctic region, to which the highly heterogeneous landscapes make a key contribution. However, our knowledge on the present and future ecosystem C balance jointly considering the exchange of CO<sub>2</sub> and CH<sub>4</sub> in the Arctic region with heterogeneous landscapes is still limited. In this study, a process-based biogeochemistry model was calibrated and validated using the empirical data on concurrently measured CO<sub>2</sub> and CH<sub>4</sub> exchange observed using eddy covariance, automatic and manual chamber methods and associated climate, soil and plant data derived from several heterogeneous landscapes in the Kaamanen region. With the validated model, decadal C balance during 2005-2018 and its response to 2 <sup>o</sup>C warming were evaluated for the constituent land cover types (LCTs). Our results showed that most LCTs were a sink for atmospheric CO<sub>2</sub> and a source of CH<sub>4</sub> during 2005-2018. Under the 2 <sup>o</sup>C warming scenario, most ecosystems continued to be CO<sub>2</sub> sinks and CH<sub>4</sub> sources. Moreover, the CO<sub>2</sub> budget in most LCTs did not change significantly as the two major fluxes of gross primary productivity (GPP) and total ecosystem respiration (TER) increased simultaneously thus maintaining similar rates of net ecosystem exchange (NEE) in response to warming, while a significant increase in CH<sub>4</sub> emission from most LCTs was evident. Our results presented here provide us a better understanding and prediction of C dynamics and the inherent C-climate feedbacks in the Arctic region.</p>

scholarly journals Carbon Dioxide and Methane Flux Response and Recovery From Drought in a Hemiboreal Ombrotrophic Fen

2021 ◽  
Vol 8 ◽  
Author(s):  
J. B Keane ◽  
S. Toet ◽  
P. Ineson ◽  
P. Weslien ◽  
J. E. Stockdale ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Water Table ◽  
Net Ecosystem Exchange ◽  
Open Water ◽  
Calluna Vulgaris ◽  
Methane Flux ◽  
High Water ◽  
Peat Bogs ◽  
Flux Response

Globally peatlands store 500 Gt carbon (C), with northern blanket bogs accumulating 23 g C m−2 y−1 due to cool wet conditions. As a sink of carbon dioxide (CO2) peat bogs slow anthropogenic climate change, but warming climate increases the likelihood of drought which may reduce net ecosystem exchange (NEE) and increase soil respiration, tipping C sinks to sources. High water tables make bogs a globally important source of methane (CH4), another greenhouse gas (GHG) with a global warming potential (GWP) 34 times that of CO2. Warming may increase CH4 emissions, but drying may cause a reduction. Predicted species composition changes may also influence GHG balance, due to different traits such as erenchyma, e.g., Eriophorum vaginatum (eriophorum) and non-aerenchymatous species, e.g., Calluna vulgaris (heather). To understand how these ecosystems will respond to climate change, it is vital to measure GHG responses to drought at the species level. An automated chamber system, SkyLine2D, measured NEE and CH4 fluxes near-continuously from an ombrotrophic fen from August 2017 to September 2019. Four ecotypes were identified: sphagnum (Sphagnum spp), eriophorum, heather and water, hypothesizing that fluxes would significantly differ between ecotypes. The 2018 drought allowed comparison of fluxes between drought and non-drought years (May to September), and their recovery the following year. Methane emissions differed between ecotypes (p < 0.02), ordered high to low: eriophorum > sphagnum > water > heather, ranging from 23 to 8 mg CH4-C m−2 d−1. Daily NEE was similar between ecotypes (p > 0.7), but under 2018 drought conditions all ecotypes were greater sources of CO2 compared to 2019, losing 1.14 g and 0.24 g CO2-C m−2 d−1 respectively (p < 0.001). CH4 emissions were ca. 40% higher during 2018 than 2019, 17 mg compared to 12 mg CH4-C m−2 d−1 (p < 0.0001), and fluxes exhibited hysteresis with water table depth. A lag of 84–88 days was observed between rising water table and increased CH4 emissions. A significant interaction between ecotype and year showed fluxes from open water did not return to pre-drought levels. Our findings suggest that short-term drought may lead to a net increase in C emissions from northern wetlands.

Compositional pattern of lignin derived phenols of sediments as a proxy of accumulation of terrestrial organic matter in coastal zone of the Laptev Sea

2021 ◽  
Author(s):  
Alexander Ulyantsev ◽  
Svetlana Bratskaya ◽  
Nikolay Belyaev ◽  
Oleg Dudarev ◽  
Igor Semiletov
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Bottom Sediments ◽  
Vascular Plant ◽  
The Arctic ◽  
Laptev Sea ◽  
Terrestrial Organic Matter ◽  
Compositional Pattern ◽  
Subsea Permafrost ◽  
The Laptev Sea

<p>The modern East Siberian Arctic shelf represents a fascinating area with a vast expansion of subsea permafrost that holds a large pool of frozen immobilised organic carbon (OC). Amplified climate change at high latitudes has raised growing concerns about potential positive carbon–climate feedbacks. Degradation of permafrost in the Arctic could constitute a positive feedback to climate change due to activation of this OC stock, while recognizing the origin and peculiarities of organic matter (OM) is useful for predicting the potential for involving the ancient OC in modern carbon cycling. This paper emphasises the molecular composition of lignin-derived phenols (LDP) in bottom sediments and subsea permafrost from the Laptev Sea shelf as a proxy to describe the main sources, distribution, and preservation of terrestrial OM. The compositional pattern and concentration of LDP revealed irregular dynamics of terrigenous OM supply in the study area, that were governed primarily by continental flows. The OC concentration in the studied sediments varied from 0.04% to 23.1% (mean 1.74%, median 1.07%). The concentration of LDP in the studied 126 samples from five sediment cores obtained from Buor-Khaya Bay varied from 0.7 to 13191 (mean 539, median 63.5) µg/g of dry sediment as the sum of vanillyl, syringyl, and cinnamyl (VSC) compounds and from 0.03 to 27.6 (mean 1.61, median 0.76) mg/100 mg of OC content. All OC-rich samples showed higher concentrations of LDP and virtually non-oxidized lignin. Vegetation proxies suggested that vascular plant tissues account for a significant fraction of the lignin in the examined samples, with a strong share of gymnosperms. The concentration of LDP correlates to OC content, indicating a strong supply of terrestrial OC to the study area. Degradation proxies indicate a predominant supply of wood-rich non-oxidized terrestrial OM. The well-preserved lignin revealed in the studied deposits represents a specific feature of Quaternary lithodynamics of the Laptev Sea and is not typical for the majority of bottom sediments of the World Ocean. Good correlation between OC and lignin concentration suggests that terrigenous fluxes were the main contributor to OM supply. Distribution of specific lignin phenols and related ratios coupled with lithology and grain size revealed that fluvial processes have been leading here.</p><p>This research was supported through the Russian Scientific Foundation (grant no. 19-77-10044) within the framework of the state assignment of the Shirshov Institute of Oceanology RAS (grant no. 0149-2019-0006).</p>

scholarly journals Impact of Permafrost Thaw and Climate Warming on Riverine Export Fluxes of Carbon, Nutrients and Metals in Western Siberia

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1817
Author(s):  
Oleg S. Pokrovsky ◽  
Rinat M. Manasypov ◽  
Sergey G. Kopysov ◽  
Ivan V. Krickov ◽  
Liudmila S. Shirokova ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Warming ◽  
The Arctic ◽  
Climate Change Scenarios ◽  
Organic C ◽  
Permafrost Thaw ◽  
Boundary Shift ◽  
Continuous Permafrost ◽  
Riverine Export ◽  
The Impact

The assessment of riverine fluxes of carbon, nutrients, and metals in surface waters of permafrost-affected regions is crucially important for constraining adequate models of ecosystem functioning under various climate change scenarios. In this regard, the largest permafrost peatland territory on the Earth, the Western Siberian Lowland (WSL) presents a unique opportunity of studying possible future changes in biogeochemical cycles because it lies within a south–north gradient of climate, vegetation, and permafrost that ranges from the permafrost-free boreal to the Arctic tundra with continuous permafrost at otherwise similar relief and bedrocks. By applying a “substituting space for time” scenario, the WSL south-north gradient may serve as a model for future changes due to permafrost boundary shift and climate warming. Here we measured export fluxes (yields) of dissolved organic carbon (DOC), major cations, macro- and micro- nutrients, and trace elements in 32 rivers, draining the WSL across a latitudinal transect from the permafrost-free to the continuous permafrost zone. We aimed at quantifying the impact of climate warming (water temperature rise and permafrost boundary shift) on DOC, nutrient and metal in rivers using a “substituting space for time” approach. We demonstrate that, contrary to common expectations, the climate warming and permafrost thaw in the WSL will likely decrease the riverine export of organic C and many elements. Based on the latitudinal pattern of riverine export, in the case of a northward shift in the permafrost zones, the DOC, P, N, Si, Fe, divalent heavy metals, trivalent and tetravalent hydrolysates are likely to decrease the yields by a factor of 2–5. The DIC, Ca, SO4, Sr, Ba, Mo, and U are likely to increase their yields by a factor of 2–3. Moreover, B, Li, K, Rb, Cs, N-NO3, Mg, Zn, As, Sb, Rb, and Cs may be weakly affected by the permafrost boundary migration (change of yield by a factor of 1.5 to 2.0). We conclude that modeling of C and element cycle in the Arctic and subarctic should be region-specific and that neglecting huge areas of permafrost peatlands might produce sizeable bias in our predictions of climate change impact.

scholarly journals Effects of Cropland Conversion and Climate Change on Agrosystem Carbon Balance of China’s Dryland: A Typical Watershed Study

2018 ◽  
Vol 10 (12) ◽  
pp. 4508 ◽  
Author(s):  
Chaofan Li ◽  
Qifei Han ◽  
Geping Luo ◽  
Chengyi Zhao ◽  
Shoubo Li ◽  
...  
Keyword(s):  
Climate Change ◽  
Driving Forces ◽  
Arable Land ◽  
Northwest China ◽  
Mountain Lake ◽  
Agricultural Sustainability ◽  
Desert Grassland ◽  
Organic C ◽  
C Balance ◽  
C Cycle

Remarkable warm‒wet climate shifts and intensive cropland expansion strongly affected carbon (C) cycle and threaten agricultural sustainability in northwest China. In this study, we integrated a process-based ecosystem model and an empirical C bookkeeping model to investigate the coupled and isolated effects of arable land conversions and climate change (CLM) on regional C balance in a typical watershed of northwest China. Results revealed that the farmland area increased by 3367.31 km2 during 1979–2014. The combined effects of CLM with net cropland expansion enlarged the vegetation C (VEGC) and the soil organic C (SOC) stock by 2.83 and 11.83 Tg, respectively, and were strongest in 2008–2014. The conversions between desert grassland and cropland were the major driving forces for regional C balance. Cropland expansion shared equal effects on VEGC increase with CLM, but its effect on SOC increment was 53 times larger than CLM’s. VEGC was more responsive to CLM, whereas SOC gained more benefits from land management. The C sink from reclamation suffered from high water consumption and is facing great threats due to glaciers and mountain lake shrinking and groundwater overpumping. Water-saving irrigation techniques and environmentally friendly water use strategies are essential for local agricultural sustainability.

scholarly journals Monitoring of CO2 fluxes on Svalbard: land use alters the gas exchange in the arctic tundra

2019 ◽  
pp. 56-66 ◽  
Author(s):  
D. V. Karelin ◽  
E. P. Zazovskaya ◽  
V. A. Shishkov ◽  
A. V. Dolgikh ◽  
A. A. Sirin ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Land Use ◽  
Soil Layer ◽  
Arctic Tundra ◽  
Vegetation Period ◽  
The Arctic ◽  
Co2 Fluxes ◽  
Natural Ecosystems ◽  
C Balance ◽  
Soil Emissions

The article summarized the results of long-term observations (20142018) of soil emissions and net CO2 fluxes (20172018) in natural and anthropogenically modified (AI) ecosystems of Arctic tundra on the territory of the archipelago of Svalbard (Barentsburg, 7804N, 1413E). Anthropogenic controls associated with local land use, during the period of their active impact may redouble the emissions of carbon dioxide from soil (0.111 0.021 0.064 0.011 gС m2h1). During the same period, the net C-balance at the sites with active land use is estimated as a source to the atmosphere. Self-recovering after human influence plots (II) demonstrate intermediate values of soil emissions of СО2 between unaffected tundra (I) and plots with active land use (III). With that they demonstrate the greatest net C-sink within the observed range of Photosynthetically Active Radiation as compared to (I) and (III). At the height of the vegetation period unaffected tundra ecosystems demonstrate a neutral net C-balance. The greatest contribution to soil emissions variance make spatial controls (they explain 5666% of variance), whereas temporal factors are responsible for 3.85.5% only. Amongst spatial controls, the thickness of organogenic layer makes the greatest contribution. Inter-annual fluctuations of key factors, among which the most important are the soil moisture and temperature of the upper soil layer, both affect AI and natural ecosystems hence the spatial differences between them remain constant from year to year. According to preliminary estimates, unlike the carbon dioxide, the contribution of methane and nitrous oxide net fluxes in local ecosystems is insignificant and does not depend on human land use.

A MODELING SYSTEM FOR CLIMATE CHANGE RISK ASSESSMENT, MANAGEMENT AND HEDGING IN COASTAL AREAS

2017 ◽  
Author(s):  
Sergei Soldatenko ◽  
Sergei Soldatenko ◽  
Genrikh Alekseev ◽  
Genrikh Alekseev ◽  
Alexander Danilov ◽  
...  
Keyword(s):  
Climate Change ◽  
Risk Assessment ◽  
Coastal Areas ◽  
Mitigation Strategies ◽  
System Structure ◽  
The Arctic ◽  
Risk Modeling ◽  
Wide Range ◽  
Adverse Weather ◽  
The Impact

Every aspect of human operations faces a wide range of risks, some of which can cause serious consequences. By the start of 21st century, mankind has recognized a new class of risks posed by climate change. It is obvious, that the global climate is changing, and will continue to change, in ways that affect the planning and day to day operations of businesses, government agencies and other organizations and institutions. The manifestations of climate change include but not limited to rising sea levels, increasing temperature, flooding, melting polar sea ice, adverse weather events (e.g. heatwaves, drought, and storms) and a rise in related problems (e.g. health and environmental). Assessing and managing climate risks represent one of the most challenging issues of today and for the future. The purpose of the risk modeling system discussed in this paper is to provide a framework and methodology to quantify risks caused by climate change, to facilitate estimates of the impact of climate change on various spheres of human activities and to compare eventual adaptation and risk mitigation strategies. The system integrates both physical climate system and economic models together with knowledge-based subsystem, which can help support proactive risk management. System structure and its main components are considered. Special attention is paid to climate risk assessment, management and hedging in the Arctic coastal areas.

Climate-forced changes of bio-productivity of Belorussian terrestrial ecosystems

2019 ◽  
pp. 77-88
Author(s):  
S. A. Lysenko
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Vegetation Index ◽  
Precipitation Amount ◽  
Terrestrial Ecosystems ◽  
Vegetation Period ◽  
Climatic Trend ◽  
Vegetation Growth ◽  
Current Century ◽  
The Impact

The spatial and temporal particularities of Normalized Differential Vegetation Index (NDVI) changes over territory of Belarus in the current century and their relationship with climate change were investigated. The rise of NDVI is observed at approximately 84% of the Belarus area. The statistically significant growth of NDVI has exhibited at nearly 35% of the studied area (t-test at 95% confidence interval), which are mainly forests and undeveloped areas. Croplands vegetation index is largely descending. The main factor of croplands bio-productivity interannual variability is precipitation amount in vegetation period. This factor determines more than 60% of the croplands NDVI dispersion. The long-term changes of NDVI could be explained by combination of two factors: photosynthesis intensifying action of carbon dioxide and vegetation growth suppressing action of air warming with almost unchanged precipitation amount. If the observed climatic trend continues the croplands bio-productivity in many Belarus regions could be decreased at more than 20% in comparison with 2000 year. The impact of climate change on the bio-productivity of undeveloped lands is only slightly noticed on the background of its growth in conditions of rising level of carbon dioxide in the atmosphere.

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