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  • 1.
    Bastviken, David
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Natchimuthu, Sivakiruthika
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Reyier, Henrik
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Technical Note: Cost-efficient approaches to measure carbon dioxide (CO2) fluxes and concentrations in terrestrial and aquatic environments using mini loggers2015Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 12, nr 12, s. 3849-3859Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fluxes of CO2 are important for our understanding of the global carbon cycle and greenhouse gas balances. Several significant CO2 fluxes in nature may still be unknown as illustrated by recent findings of high CO2 emissions from aquatic environments, previously not recognized in global carbon balances. Therefore, it is important to develop convenient and affordable ways to measure CO2 in many types of environments. At present, direct measurements of CO2 fluxes from soil or water, or CO2 concentrations in surface water, are typically labor intensive or require costly equipment. We here present an approach with measurement units based on small inexpensive CO2 loggers, originally made for indoor air quality monitoring, that were tested and adapted for field use. Measurements of soil-atmosphere and lake-atmosphere fluxes, as well as of spatiotemporal dynamics of water CO2 concentrations (expressed as the equivalent partial pressure, pCO(2aq)) in lakes and a stream network are provided as examples. Results from all these examples indicate that this approach can provide a cost- and labor-efficient alternative for direct measurements and monitoring of CO2 flux and pCO(2aq) in terrestrial and aquatic environments.

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  • 2.
    Bastviken, David
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Treat, Claire C.
    Helmholtz Ctr Polar & Marine Res, Germany.
    Pangala, Sunitha Rao
    Univ Lancaster, England.
    Gauci, Vincent
    Univ Birmingham, England; Univ Birmingham, England.
    Enrich Prast, Alex
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Fed Univ Sao Paulo IMar UNIFESP, Brazil; Univ Fed Rio De Janeiro, Brazil.
    Karlson, Martin
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Centrum för klimatpolitisk forskning, CSPR.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Brandini Romano, Mariana
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sawakuchi, Henrique
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    The importance of plants for methane emission at the ecosystem scale2023Ingår i: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522, Vol. 184, artikel-id 103596Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Methane (CH4), one of the key long-lived atmospheric greenhouse gases, is primarily produced from organic matter. Accordingly, net primary production of organic matter sets the boundaries for CH4 emissions. Plants, being dominant primary producers, are thereby indirectly sustaining most global CH4 emissions, albeit with delays in time and with spatial offsets between plant primary production and subsequent CH4 emission. In addition, plant communities can enhance or hamper ecosystem production, oxidation, and transport of CH4 in multiple ways, e.g., by shaping carbon, nutrient, and redox gradients, and by representing a physical link be-tween zones with extensive CH4 production in anoxic sediments or soils and the atmosphere. This review focuses on how plants and other primary producers influence CH4 emissions with the consequences at ecosystem scales. We outline mechanisms of interactions and discuss flux regulation, quantification, and knowledge gaps across multiple ecosystem examples. Some recently proposed plant-related ecosystem CH4 fluxes are difficult to reconcile with the global atmospheric CH4 budget and the enigmas related to these fluxes are highlighted. Overall, ecosystem CH4 emissions are strongly linked to primary producer communities, directly or indirectly, and properly quantifying magnitudes and regulation of these links are key to predicting future CH4 emissions in a rapidly changing world.

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  • 3.
    Bastviken, David
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Wilk, Julie
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Nguyen, Thanh Duc
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Karlson, Martin
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Schmid Neset, Tina
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Opach, Tomasz
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Norwegian Univ Sci & Technol NTNU, Norway.
    Enrich Prast, Alex
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Biogas Research Center. Univ Fed Rio de Janeiro, Brazil.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Critical method needs in measuring greenhouse gas fluxes2022Ingår i: Environmental Research Letters, E-ISSN 1748-9326, Vol. 17, nr 10, artikel-id 104009Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reaching climate goals depends on appropriate and accurate methods to quantify greenhouse gas (GHG) fluxes and to verify that efforts to mitigate GHG emissions are effective. We here highlight critical advantages, limitations, and needs regarding GHG flux measurement methods, identified from an analysis of >13 500 scientific publications regarding three long-lived GHGs, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). While existing methods are well-suited for assessing atmospheric changes and local fluxes, they are expensive and have limited accessibility. Further, we are typically forced to choose between methods for very local GHG sources and sinks and their regulation (m(2)-scaled measurements), or methods for aggregated net fluxes at >ha or km(2) scales measurements. The results highlight the key need of accessible and affordable GHG flux measurement methods for the many flux types not quantifiable from fossil fuel use, to better verify inventories and mitigation efforts for transparency and accountability under the Paris agreement. The situation also calls for novel methods, capable of quantifying large scale GHG flux patterns while simultaneously distinguishing local source and sink dynamics and reveal flux regulation, representing key knowledge for quantitative GHG flux modeling. Possible strategies to address the identified GHG flux measurement method needs are discussed. The analysis also generated indications of how GHG flux measurements have been distributed geographically and across flux types, which are reported.

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  • 4.
    Bastviken, David
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Wilk, Julie
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Centrum för klimatpolitisk forskning, CSPR.
    Nguyen, Thanh Duc
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Karlson, Martin
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Centrum för klimatpolitisk forskning, CSPR.
    Schmid Neset, Tina-Simone
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Centrum för klimatpolitisk forskning, CSPR.
    Opach, Tomasz
    Dept. of Geography, Norwegian University of Science and Technology, Trondheim, Norway.
    Enrich Prast, Alex
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Measuring greenhouse gas fluxes: what methods do we have versus what methods do we need?2022Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Appropriate methods to measure greenhouse gas (GHG) fluxes are critical for our ability to detect fluxes, understand regulation, make adequate priorities for climate change mitigation efforts, and verify that these efforts are effective. Ideally, we need reliable, accessible, and affordable measurements at relevant scales. We surveyed present GHG flux measurement methods, identified from an analysis of >11000 scientific publications and a questionnaire to sector professionals and analysed method pros and cons versus needs for novel methodology. While existing methods are well-suited for addressing certain questions, this presentation presents fundamental limitations relative to GHG flux measurement needs for verifiable and transparent action to mitigate many types of emissions. Cost and non-academic accessibility are key aspects, along with fundamental measurement performance. These method limitations contribute to the difficulties in verifying GHG mitigation efforts for transparency and accountability under the Paris agreement. Resolving this mismatch between method capacity and societal needs is urgently needed for effective climate mitigation. This type of methodological mismatch is common but seems to get high priority in other knowledge domains. The obvious need to prioritize development of accurate diagnosis methods for effective treatments in healthcare is one example. This presentation provides guidance regarding the need to prioritize the development of novel GHG flux measurement methods.

  • 5.
    Gålfalk, Magnus
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Approaches for hyperspectral remote flux quantification andvisualization of GHGs in the environment2017Ingår i: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 191, s. 81-94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Methane (CH4) and nitrous oxide (N2O) are two very potent greenhouse gases, with highly heterogeneous distributionsin both space and time. Mapping hot-spots and source areas, and measuring fluxes in different environmentshas so far not been possible on a local scale using direct measurements. We have developed amethod for simultaneous mapping of methane (CH4) and nitrous oxide (N2O), also including water vapor(H2O), using ground-based remote sensing on a landscape-sized scale by utilizing Imaging Fourier TransformSpectrometers (IFTS) with high spectral resolution and imaging rates. The approach uses calculated libraries oftransmission spectra at the spectroscopic resolutions of the IFTS, based on the HITRAN database of spectroscopiclines and our own line-by-line radiative transfer model (LBLRTM). For each species, 1024 spectra have beenmade, resulting in 10243 combinations of column densities. Using an adaptive grid, solutions are found foreach line of sight at a spectral resolution of up to 0.25 cm−1 using the full spectral region of the detector. Themodeling ismulti-layered, calculating temperatures of the background, air, and any additional gas layers, also accountingfor reflected cold sky. Background distances can bemapped fromthe amount of water vapor in each lineof sight. The described approach can be used to identify sources, quantify gas distributions, and to calculate fluxes.Visualizations can produce gas distribution images, as well as air motion videos, which are used to map fluxesusing the same data set, without the need for additional instruments for wind measurements.

  • 6.
    Gålfalk, Magnus
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Making methane visible2016Ingår i: Nature Climate Change, ISSN 1758-678X, E-ISSN 1758-6798, Vol. 6, s. 426-430Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Methane (CH4) is one of the most important greenhouse gases, and an important energy carrier in biogas and natural gas. Its large-scale emission patterns have been unpredictable and the source and sink distributions are poorly constrained. Remote assessment of CH4 with high sensitivity at a m2 spatial resolution would allow detailed mapping of the near-ground distribution and anthropogenic sources in landscapes but has hitherto not been possible. Here we show that CH4gradients can be imaged on the <m2 scale at ambient levels (~1.8 ppm) and filmed using optimized infrared (IR) hyperspectral imaging. Our approach allows both spectroscopic confirmation and quantification for all pixels in an imaged scene simultaneously. It also has the ability to map fluxes for dynamic scenes. This approach to mapping boundary layer CH4 offers a unique potential way to improve knowledge about greenhouse gases in landscapes and a step towards resolving source–sink attribution and scaling issues.

  • 7.
    Gålfalk, Magnus
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Remote sensing of methane and nitrous oxide fluxes from waste incineration2018Ingår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 75, s. 319-326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Incomplete combustion processes lead to the formation of many gaseous byproducts that can be challenging to monitor in flue gas released via chimneys. This study presents ground-based remote sensing approaches to make greenhouse gas (GHG) flux measurements of methane (CH4) and nitrous oxide (N2O) from a waste incineration chimney at distances of 150-200 m. The study found emission of N2O (corresponding to 30-40 t yr(-1)), which is a consequence of adding the reduction agent urea to decrease NOx emissions due to NOx regulation; a procedure that instead increases N2O emissions (which is approximately 300 times more potent as a GHG than CO2 on a 100-year time scale). CH4 emissions of 7-11 t yr(-1) was also detected from the studied chimney despite the usage of a high incineration temperature. For this particular plant, local knowledge is high and emission estimates at corresponding levels have been reported previously. However, emissions of CH(4 )are often not included in GHG emission inventories for waste incineration. This study highlights the importance of monitoring combustion processes, and shows the possibility of surveying CH4 and N2O emissions from waste incineration at distances of several hundred meters. (C) 2018 Elsevier Ltd. All rights reserved.

  • 8.
    Gålfalk, Magnus
    et al.
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Fredriksson, Sam
    University of Gothenburg, Sweden.
    Arneborg, Lars
    University of Gothenburg, Sweden.
    Determination of the piston velocity for water-air interfaces using flux chambers, acoustic Doppler velocimetry, and IR imaging of the water surface2013Ingår i: Journal of Geophysical Research: Biogeosciences, ISSN 2169-8953, Vol. 118, nr 2, s. 770-782Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The transport of gasses dissolved in surface waters across the water-atmosphere interface is controlled by the piston velocity (k). This coefficient has large implications for, e.g., greenhouse gas fluxes but is challenging to quantify in situ. At present, empirical k-wind speed relationships from a small number of studies and systems are often extrapolated without knowledge of model performance. This study compares empirical k estimates from flux chamber and surface water gas concentration measurements (chamber method), eddy cell modeling and dissipation rates of turbulent kinetic energy (dissipation method), and a surface divergence method based on IR imaging, at a fetch limited coastal observation station. We highlight strengths and weaknesses of the methods, and relate measured k values to parameters such as wave height, and surface skin velocities. The chamber and dissipation methods yielded k values in the same order of magnitude over a 24 h period with varying wind conditions (up to 10 m s−1, closest weather station) and wave heights (0.01–0.30 m). The surface divergence method most likely did not resolve the small turbulent eddies that cause the main divergence. Flux chamber estimates showed the largest temporal variability, with lower k values than the dissipation method during calm conditions, where the dissipation method failed as waves and instrument noise dominated over the turbulence signal. There was a strong correspondence between k from chambers, the RMS of surface velocities from IR imaging, and wave height. We propose a method to estimate area integrated values of k from wave measurements.

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  • 9.
    Gålfalk, Magnus
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Karlson, Martin
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Centrum för klimatpolitisk forskning, CSPR.
    Crill, Patrick
    Stockholm Univ, Sweden.
    Bousquet, Philippe
    LSCE, France.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Technical note: A simple approach for efficient collection of field reference data for calibrating remote sensing mapping of northern wetlands2018Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, nr 5, s. 1549-1557Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The calibration and validation of remote sensing land cover products are highly dependent on accurate field reference data, which are costly and practically challenging to collect. We describe an optical method for collection of field reference data that is a fast, cost-efficient, and robust alternative to field surveys and UAV imaging. A lightweight, waterproof, remote-controlled RGB camera (GoPro HERO4 Silver, GoPro Inc.) was used to take wide-angle images from 3.1 to 4.5 m in altitude using an extendable monopod, as well as representative near-ground (amp;lt; 1 m) images to identify spectral and structural features that correspond to various land covers in present lighting conditions. A semi-automatic classification was made based on six surface types (graminoids, water, shrubs, dry moss, wet moss, and rock). The method enables collection of detailed field reference data, which is critical in many remote sensing applications, such as satellite-based wetland mapping. The method uses common non-expensive equipment, does not require special skills or training, and is facilitated by a step-by-step manual that is included in the Supplement. Over time a global ground cover database can be built that can be used as reference data for studies of non-forested wetlands from satellites such as Sentinel 1 and 2 (10 m pixel size).

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  • 10.
    Gålfalk, Magnus
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Påledal, Soren Nilsson
    Tekn Verken & Linkopint AB, Box 1500, S-58115 Linkoping, Sweden.
    Sehlén, Robert
    Tekn Verken & Linkopint AB, Box 1500, S-58115 Linkoping, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Ground-based remote sensing of CH4 and N2O fluxes from a wastewater treatment plant and nearby biogas production with discoveries of unexpected sources2022Ingår i: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 204, artikel-id 111978Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study is an attempt to assess CH4 and N2O emissions from all the treatment steps of a wastewater treatment plant (WWTP) in Sweden, serving 145 000 persons, and an adjacent biogas production facility. We have used novel mid-IR ground-based remote sensing with a hyperspectral camera to visualize and quantify the emissions on 21 days during a year, with resulting yearly fluxes of 90.4 +/- 4.3 tonne CH4/yr and 10.9 +/- 1.3 tonne N2O/yr for the entire plant. The most highly emitting CH4 source was found to be sludge storage, which is seldom included in literature as in-situ methods are not suitable for measuring emissions extended over large surfaces, still contributing 90 % to the total CH4 emission in our case. The dominating N2O source was found to be a Stable High rate Ammonia Removal Over Nitrite reactor, contributing 89 % to the total N2O emissions. We also discovered several unexpected CH4 sources. Incomplete flaring of CH4 gave fluxes of at least 30 kg CH4/min, corresponding to plume concentrations of 2.5 %. Such highly episodic fluxes could double the plant-wide yearly emissions if they occur 2 days per year. From a distance of 250 m we found a leak in the biogas production facility, corresponding to 1.1 % of the CH4 produced, and that loading of organic material onto trucks from a biofertilizer storage tank contributed with high emissions during loading events. These results indicate that WWTP emissions globally may have been grossly underestimated and that it is essential to have effective methods that can measure all types of fluxes, and discover new potential sources, in order to make adequate priorities and to take effective actions to mitigate greenhouse gas emissions from WWTPs.

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  • 11.
    Gålfalk, Magnus
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Påledal, Sören Nilsson
    Tekniska Verken I Linkoping AB, S-58115 Linkoping, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sensitive Drone Mapping of Methane Emissions without the Need for Supplementary Ground-Based Measurements2021Ingår i: ACS Earth and Space Chemistry, E-ISSN 2472-3452, Vol. 5, nr 10, s. 2668-2676Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Methane (CH4) is one of the main greenhouse gas for which sources and sinks are poorly constrained and better capacity of mapping landscape emissions are broadly requested. A key challenge has been comprehensive, accurate, and sensitive emission measurements covering large areas at a resolution that allows separation of different types of local sources. We present a sensitive drone-based system for mapping CH4 hotspots, finding leaks from gas systems, and calculating total CH4 fluxes from anthropogenic environments such as wastewater treatment plants, landfills, energy production, biogas plants, and agriculture. All measurements are made onboard the drone, with no requirements for additional ground-based instruments. Horizontal flight patterns are used to map and find emission sources over large areas and vertical flight patterns for total CH4 fluxes using mass balance calculations. The small drone system (6.7 kg including batteries, sensors, loggers, and weather proofing) maps CH4 concentrations and wind speeds at 1 Hz with a precision of 0.84 ppb/s and 0.1 m/s, respectively. As a demonstration of the system and the mass balance method for a CH4 source that is difficult to assess with traditional methods, we have quantified fluxes from a sludge deposit at a wastewater treatment plant. Combining data from three 10 min flights, emission hotspots could be mapped and a total flux of 178.4 +/- 8.1 kg CH4 d(-1) was determined.

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  • 12.
    Karlson, Martin
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Centrum för klimatpolitisk forskning, CSPR.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Crill, Patrick
    Stockholm Univ, Sweden.
    Bousquet, Philippe
    LSCE, France.
    Saunois, Marielle
    LSCE, France.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Delineating northern peatlands using Sentinel-1 time series and terrain indices from local and regional digital elevation models2019Ingår i: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 231, artikel-id UNSP 111252Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The spatial extent of northern peatlands remains highly uncertain in spite of rapidly developing satellite observation datasets. This is limiting progress in the understanding of fundamental biogeochemical processes, such as the global carbon (C) cycle and climate feedback effects on C fluxes. In this study, we evaluated the capabilities of two new satellite datasets that enable regional scale mapping of peatland extent at high spatial resolution, including Sentinel-1 synthetic aperture radar (SAR) and the Arctic digital elevation model (ArcticDEM). Terrain indices and temporal features derived from these datasets provided input to Random Forest models for delineating four main land cover classes (forest, open upland, water and peatland) in an area in northern Sweden consisting of both lowland and mountainous terrain. The contribution of ArcticDEM to the classification accuracy was assessed by comparing the results with those derived when a high quality LiDAR based DEM (LiDEM) was used as alternative model input. This study shows that multi-seasonal SAR alone can produce reasonable classification results in terms of overall accuracy (OA; 81.6%), but also that it has limitations. The inclusion of terrain indices improved classification performance substantially. OA increased to 87.5% and 90.9% when terrain indices derived from ArcticDEM and LiDEM were included, respectively. The largest increase in accuracy was achieved for the peatland class, which suggests that terrain indices do have the ability to capture the features in the geographic context that aid the discrimination of peatland from other land cover classes. The relatively small difference in classification accuracy between LiDEM and ArcticDEM is encouraging since the latter provides circumpolar coverage. Thus, the combination of Sentinel-1 time series and terrain indices derived from ArcticDEM presents opportunities for substantially improving regional estimates of peatland extent at high latitudes.

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  • 13.
    MacIntyre, Sally
    et al.
    Univ Calif Santa Barbara, CA 93106 USA.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Arneborg, Lars
    Swedish Meteorol & Hydrol Inst, Sweden.
    Crowe, Adam T.
    Univ Calif Santa Barbara, CA 93106 USA.
    Karlsson, Jan
    Umea Univ, Sweden.
    Andersson, Andreas
    Uppsala Univ, Sweden; Mid Sweden Univ, Sweden.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Rutgersson, Anna
    Uppsala Univ, Sweden.
    Podgrajsek, Eva
    Uppsala Univ, Sweden.
    Melack, John M.
    Univ Calif Santa Barbara, CA 93106 USA.
    Turbulence in a small boreal lake: Consequences for air-water gas exchange2021Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 66, nr 3, s. 827-854Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hydrodynamics within small boreal lakes have rarely been studied, yet knowing whether turbulence at the air-water interface and in the water column scales with metrics developed elsewhere is essential for computing metabolism and fluxes of climate-forcing trace gases. We instrumented a humic, 4.7 ha, boreal lake with two meteorological stations, three thermistor arrays, an infrared (IR) camera to quantify surface divergence, obtained turbulence as dissipation rate of turbulent kinetic energy (epsilon) using an acoustic Doppler velocimeter and a temperature-gradient microstructure profiler, and conducted chamber measurements for short periods to obtain fluxes and gas transfer velocities (k). Near-surface epsilon varied from 10(-8) to 10(-6) m(2) s(-3) for the 0-4 m s(-1) winds and followed predictions from Monin-Obukhov similarity theory. The coefficient of eddy diffusivity in the mixed layer was up to 10(-3) m(2) s(-1) on the windiest afternoons, an order of magnitude less other afternoons, and near molecular at deeper depths. The upper thermocline upwelled when Lake numbers (L-N) dropped below four facilitating vertical and horizontal exchange. k computed from a surface renewal model using epsilon agreed with values from chambers and surface divergence and increased linearly with wind speed. Diurnal thermoclines formed on sunny days when winds were &lt; 3 m s(-1), a condition that can lead to elevated near-surface epsilon and k. Results extend scaling approaches developed in the laboratory and for larger water bodies, illustrate turbulence and k are greater than expected in small wind-sheltered lakes, and provide new equations to quantify fluxes.

    Ladda ner fulltext (pdf)
    fulltext
  • 14.
    Napier, Bruce
    et al.
    Vivid Components, Germany.
    Bang, Ole
    Tech Univ Denmark, Denmark.
    Markos, Christos
    Tech Univ Denmark, Denmark.
    Moselund, Peter
    NKT Photon AS, Denmark.
    Huot, Laurent
    NKT Photon AS, Denmark.
    Harren, Frans J. M.
    Radboud Univ Nijmegen, Netherlands.
    Khodabakhsh, Amir
    Radboud Univ Nijmegen, Netherlands.
    Martin, Hans
    Senseair AB, Sweden.
    Briano, Floria Ottonello
    Senseair AB, Sweden.
    Balet, Laurent
    CSEM SA, Switzerland.
    Lecomte, Steve
    CSEM SA, Switzerland.
    Petersen, Christian R.
    NORBLIS IVS, Denmark.
    Israelsen, Niels
    NORBLIS IVS, Denmark.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Kubiszyn, Lukasz
    VIGO Syst SA, Poland.
    Warzybok, Piotr
    VIGO Syst SA, Poland.
    Ultra-broadband infrared gas sensor for pollution detection: the TRIAGE project2021Ingår i: Journal of Physics; Photonics, ISSN 2515-7647, Vol. 3, nr 3, artikel-id 031003Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Air pollution is one of the largest risk factors for disease or premature death globally, yet current portable monitoring technology cannot provide adequate protection at a local community level. Within the TRIAGE project, a smart, compact and cost-effective air quality sensor network will be developed for the hyperspectral detection of gases which are relevant for atmospheric pollution monitoring or dangerous for human health. The sensor is based on a mid-infrared supercontinuum source, providing ultra-bright emission across the 2-10 mu m wavelength region. Within this spectral range, harmful gaseous species can be detected with high sensitivity and selectivity. The spectroscopic sensor, which includes a novel multi-pass cell and detector, enables a smart robust photonic sensing system for real-time detection. With built-in chemometric analysis and cloud connection, the sensor will feed advanced deep-learning algorithms for various analyses, ranging from long-term continental trends in air pollution to urgent local warnings and alerts. Community-based distributed pollution sensing tests will be verified on municipal building rooftops and local transport platforms.

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    fulltext
  • 15.
    Natchimuthu, Sivakiruthika
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Klemedtsson, Leif
    University of Gothenburg, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Spatiotemporal variability of lake pCO(2) and CO2 fluxes in a hemiboreal catchment2017Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, nr 1, s. 30-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Globally, lakes are frequently supersaturated with carbon dioxide (CO2) and are major emitters of carbon to the atmosphere. Recent studies have generated awareness of the high variability in pCO(2aq) (the partial pressure corresponding to the concentration in water) and CO2 fluxes to the atmosphere and the need for better accounting for this variability. However, studies simultaneously accounting for both spatial and temporal variability of pCO(2aq) and CO2 fluxes in lakes are rare. We measured pCO(2aq) (by both manual sampling and mini loggers) and CO2 fluxes, covering spatial variability in open water areas of three lakes of different character in a Swedish catchment for 2years. Spatial pCO(2aq) variability within lakes was linked to distance from shore, proximity to stream inlets, and deepwater upwelling events. Temporally, pCO(2aq) variability was linked with variability in dissolved organic carbon, total nitrogen, and dissolved oxygen. While previous studies over short time periods (1 to 6h) observed gas transfer velocity (k) to be more variable than pCO(2aq), our work shows that over longer time (days to weeks) pCO(2aq) variability was greater and affected CO2 fluxes much more than k. We demonstrate that 8 measurement days distributed over multiple seasons in combination with sufficient spatial coverage (8 locations during stratification periods and 5 or less in spring and autumn) are a key for representative yearly whole lake flux estimates. This study illustrates the importance of considering spatiotemporal variability in pCO(2aq) and CO2 fluxes to generate representative whole lake estimates.

    Ladda ner fulltext (pdf)
    fulltext
  • 16.
    Natchimuthu, Sivakiruthika
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Klemedtsson, Leif
    Department of Earth Sciences, University of Gothenburg, Göteborg, Sweden.
    Crill, Patrick
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Danielsson, Åsa
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Spatio-temporal variability of lake CH4 fluxes and its influence on annual whole lake emission estimates2016Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 61, s. S13-S26Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lakes are major sources of methane (CH4) to the atmosphere that contribute significantly to the global budget. Recent studies have shown that diffusive fluxes, ebullition and surface water CH4 concentrations can differ significantly within lakes—spatially and temporally. CH4 fluxes may be affected at longer scales in response to seasons, temperature, lake mixing events, short term weather events like pressure variations, shifting winds and diel cycles. Frequent measurements of fluxes in the same system and integrated assessments of the impacts of the spatio-temporal variability are rare. Thereby, large scale assessments frequently lack information on this variability which can potentially lead to biased estimates. In this study, we analysed the variability of CH4 fluxes and surface water CH4 concentrations across open water areas of lakes in a small catchment in southwest Sweden over two annual cycles. Significant patterns in CH4 concentrations, diffusive fluxes, ebullition and total fluxes were observed in space (between and within lakes) and in time (over diel cycles to years). Differences observed among the lakes can be associated with lake characteristics. The spatial variability within lakes was linked to depth or distance to stream inlets. Temporal variability was observed at diel to seasonal scales and was influenced by weather events. The fluxes increased exponentially with temperature in all three lakes, with stronger temperature dependence with decreasing depth. By comparing subsets of our data with estimates using all data we show that considering the spatio-temporal variability in CH4 fluxes is critical when making whole lake or annual budgets.

    Ladda ner fulltext (pdf)
    fulltext
  • 17.
    Pajala, Gustav
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Rudberg, David
    Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Institutionen för tema, Tema Miljöförändring.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Melack, John Michael
    University of California, Santa Barbara, CA, United States.
    Macintyre, Sally
    University of California, Santa Barbara, CA, United States.
    Karlsson, Jan
    Umeå University, Umeå, Sweden.
    Sawakuchi, Henrique Oliveira
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Schenk, Jonathan
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sieczko, Anna Katarzyna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologisk och miljövetenskaplig modellering. Linköpings universitet, Tekniska fakulteten.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Nguyen, Thanh Duc
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Source data for ” Higher apparent gas transfer velocities for CO2 compared to CH4 in small lakes”2023Dataset
    Ladda ner fulltext (xlsx)
    dataset
  • 18.
    Pajala, Gustav
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Rudberg, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Melack, John Michael
    Univ Calif Santa Barbara, CA 93117 USA; Univ Calif Santa Barbara, CA 93106 USA.
    Macintyre, Sally
    Univ Calif Santa Barbara, CA 93117 USA; Univ Calif Santa Barbara, CA 93106 USA; Univ Calif Santa Barbara, CA 93117 USA.
    Karlsson, Jan
    Umea Univ, Sweden.
    Sawakuchi, Henrique
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Schenk, Jonathan
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sieczko, Anna
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Nguyen, Thanh Duc
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Higher Apparent Gas Transfer Velocities for CO2 Compared to CH4 in Small Lakes2023Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 57, nr 23, s. 8578-8587Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Highergas transfer velocities for CO2 than CH4 inlakes challenge previous results and commonly made assumptionsand highlight the importance of gas-specific transport in aquaticgreenhouse gas exchange. Large greenhousegas emissions occur via the release of carbondioxide (CO2) and methane (CH4) from the surfacelayer of lakes. Such emissions are modeled from the air-watergas concentration gradient and the gas transfer velocity (k). The links between k and the physicalproperties of the gas and water have led to the development of methodsto convert k between gases through Schmidt numbernormalization. However, recent observations have found that such normalizationof apparent k estimates from field measurements canyield different results for CH4 and CO2. Weestimated k for CO2 and CH4 from measurements of concentration gradients and fluxes in fourcontrasting lakes and found consistently higher (on an average 1.7times) normalized apparent k values for CO2 than CH4. From these results, we infer that several gas-specificfactors, including chemical and biological processes within the watersurface microlayer, can influence apparent k estimates.We highlight the importance of accurately measuring relevant air-watergas concentration gradients and considering gas-specific processeswhen estimating k.

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    fulltext
  • 19.
    Pajala, Gustav
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sawakuchi, Henrique
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Rudberg, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Schenk, Jonathan
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sieczko, Anna
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Seekell, David
    Umea Univ, Sweden.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Nguyen, Thanh Duc
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Karlsson, Jan
    Umea Univ, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    The Effects of Water Column Dissolved Oxygen Concentrations on Lake Methane Emissions-Results From a Whole-Lake Oxygenation Experiment2023Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 128, nr 11, artikel-id e2022JG007185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lakes contribute 9%-19% of global methane (CH4) emissions to the atmosphere. Dissolved molecular oxygen (DO) in lakes can inhibit the production of CH4 and promote CH4 oxidation. DO is therefore often considered an important regulator of CH4 emissions from lakes. Presence or absence of DO in the water above the sediments can affect CH4 production and emissions by (a) influencing if methane production can be fueled by the most reactive organic matter in the top sediment layer or rely on deeper and less degradable organic matter, and (b) enabling CH4 accumulation in deep waters and potentially large emissions upon water column turnover. However, the relative importance of these two DO effects on CH4 fluxes is still unclear. We assessed CH4 fluxes from two connected lake basins in northern boreal Sweden where one was experimentally oxygenated. Results showed no clear difference in summer CH4 emissions attributable to water column DO concentrations. Large amounts of CH4 accumulated in the anoxic hypolimnion of the reference basin but little of this may have been emitted because of incomplete mixing, and effective methane oxidation of stored CH4 reaching oxic water layers. Accordingly, &lt;= 24% of the stored CH4 was likely emitted in the experimental lake. Overall, our results suggest that hypolimnetic DO and water column CH4 storage might have a smaller impact on CH4 emissions in boreal forest lakes than previous estimates, yet potential fluxes associated with water column turnover events remain a significant uncertainty in lake CH4 emission estimates.

  • 20.
    Schenk, Jonathan
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sieczko, Anna Katarzyna
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Rudberg, David
    Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Institutionen för tema, Tema Miljöförändring.
    Pajala, Gustav
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sawakuchi, Henrique Oliveira
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Thanh Duc, Nguyen
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Tekniska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Evaluating Empirical Models of Lake Methane Emission and Surface Water Concentration across Hemiboreal to Subarctic Regions2022Dataset
    Ladda ner fulltext (xlsx)
    Table 1 in the corresponding manuscript
    Ladda ner fulltext (xlsx)
    Table 2 in the corresponding manuscript
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