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Open storages of organic material represent potentially large sources of the greenhouse gas methane (CH4), an emissions source that will likely become more common as a part of societal efforts toward sustainability. Hence, monitoring and minimizing CH4 emissions from such facilities are key, but effective assessment of emissions without disturbing the flux is challenging. We demonstrate the capacity of using a novel high-resolution hyperspectral camera to perform sensitive CH4 flux assessments at such facilities, using as a test case a biofertilizer storage tank for residual material from a biogas plant. The camera and simultaneous conventional flux chamber measurements showed emissions of 6.0 ± 1.3 and 13 ± 5.7 kg of CH4 h-1, respectively. The camera measurements covered the whole tank surface of 1104 m2, and the chamber results were extrapolated from measurements over 5 m2. This corresponds to 0.7-1.4% of the total CH4 production at the biogas plant (1330 N m3 h-1 corresponding to 950 kg h-1). The camera could assess the entire tank emission in minutes without disturbing normal operations at the plant and revealed additional unknown emissions from the inlet to the tank (17 g of CH4 h-1) and during the loading of the biofertilizer into trucks (3.1 kg of CH4 h-1 during loading events). This study illustrates the importance of adequate measurement capacity to map methane fluxes and to verify that methane emission mitigation efforts are effective. Given the high methane emissions observed, it is important to reduce methane emissions from open storage of organic material, for example by improved digestion in the biogas reactor, precooling of sludge before storage, or building gastight storage tanks with sealed covers. We conclude that hyperspectral, ground-based remote sensing is a promising approach for greenhouse gas monitoring and mitigation. © 2024 The Authors., This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (Grant 725546), the European Union’s Horizon 2020 Research and Innovation Programme under Grant 101015825 (TRIAGE), grants from the Swedish Research Council VR (Grant VR 2016-04829) and FORMAS (Grant 2018-01794), and a grant from Avfall Sverige (Project U 1000).

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, ≤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.

2023-04-06 Version 2.0 published. Minor changes in the structure of the data file. There were no changes in the data.2023-03-23 The title was changed fromSource data for “The effects of water column dissolved oxygen concentrations on lake methane emissions: Results from a whole-lake oxygenation experiment” to "Source data for ”Higher apparent gas transfer velocities for CO2 compared to CH4 in small lakes”"2022-11-30 Version 1.0 published.

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., Funding Agencies|FORMAS [2017-01944, 2018-01794, 2018-00570]; European Research Council (ERC) [725546]; European Union [101015825]; Swedish Research Council VR [2016-04829]; Swedish Energy Agency [35624-2]; Centre for Climate Science and Policy Research (CSPR); Biogas Research Center (BRC)

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., Funding Agencies|Swedish Research Council VRSwedish Research Council [2016-04829]; FormasSwedish Research Council Formas [2018-01794]; European Unions Horizon 2020 research and innovation programme [101015825]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW2010.0126]; European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programmeEuropean Research Council (ERC) [725546]

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.

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., Funding Agencies|Horizon 2020 [101015825, 732968]; European Unions Framework Programme for Research and Innovation

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., Funding Agencies|Swedish Environmental Protection Agency [NV-08026-19]; Swedish Research Council VRSwedish Research Council [201604829]; FormasSwedish Research Council Formas [2018-01794]; European Research Council (ERC) under the European UnionEuropean Research Council (ERC) [725546]; VinnovaVinnova [201801706]

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)., Funding Agencies|Swedish Research Council VR [VR 2012-48]; IZOMET project [VR 2014-6584]; IZOMET partner Marielle Saunois (Laboratoire des Sciences du Climat et de lEnvironnement (LSCE), Gif-sur-Yvette, France

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

We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to 2009 September, for a total of 76 GRBs, and present an additional three pre-Swift GRBs not included in an earlier sample. Furthermore, we publish 840 additional new photometry data points on a total of 42 GRB afterglows, including large data sets for GRBs 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A, and 080810. We analyzed the light curves of all GRBs in the sample and derived spectral energy distributions for the sample with the best data quality, allowing us to estimate the host-galaxy extinction. We transformed the afterglow light curves into an extinction-corrected z = 1 system and compared their luminosities with a sample of pre-Swift afterglows. The results of a former study, which showed that GRB afterglows clustered and exhibited a bimodal distribution in luminosity space, are weakened by the larger sample. We found that the luminosity distribution of the two afterglow samples (Swift-era and pre-Swift) is very similar, and that a subsample for which we were not able to estimate the extinction, which is fainter than the main sample, can be explained by assuming a moderate amount of line-of-sight host extinction. We derived bolometric isotropic energies for all GRBs in our sample, and found only a tentative correlation between the prompt energy release and the optical afterglow luminosity at 1 day after the GRB in the z = 1 system. A comparative study of the optical luminosities of GRB afterglows with echelle spectra (which show a high number of foreground absorbing systems) and those without, reveals no indication that the former are statistically significantly more luminous. Furthermore, we propose the existence of an upper ceiling on afterglow luminosities and study the luminosity distribution at early times, which was not accessible before the advent of the Swift satellite. Most GRBs feature aftergl, authorCount :76

Aims. We search for young stellar objects (YSOs) in the L1641N cluster and characterize the star formation activity through determination of the age distribution, mass function, spatial distribution, and the star formation history.Methods. Multi-wavelength broad band photometry both from space and the ground are used to look for IR excess in order to separate field stars from YSOs and to sample the spectral energy distributions. Space-based observations were obtained using the ISO satellite (ISOCAM) in two filters, centred at 6.7 and 14.3 m, and Spitzer (IRAC) at 3.6, 4.5, 5.8, and 8.0 m. Our ground-based observations were made with the Nordic Optical Telescope (NOT) using ALFOSC (I band), NOTCam (J, and 2.12 m H2), and SIRCA (L'). More than 50 of the brightest I-band sources were then studied with follow-up optical spectroscopy (5780-8340 Å) to check for signs of accretion (H in emission) and youth (Li I in absorption) and to determine their effective temperatures. By comparing theoretical evolution tracks with our YSO sample in the H-R diagram, we calculated an age, luminosity, and mass distribution.Results. We detect a total of 216 (Spitzer or I band) sources in L1641N, 89 of which are YSO candidates. Most of the spectra are of M-type with H strongly in emission, and many have Li 6707 in absorption. The four brightest I band sources (F and G stars) are suggested as foreground stars, a, Part of urn:nbn:se:su:diva-7559

Mass is clearly the most important parameter of a star as it determines the phases it will go through, its physical parameters, the elements produced and its life span. Two important processes that occur simultaneously in young stars are directly related to the final mass a star ends up with; the accretion of material onto the star from a circumstellar disk and the bipolar outflow of material from the star. These processes are related since the infalling material drives the outflow. The life span of circumstellar disks is also important for the possibility of life, as this limits the time available for planet formation. This may depend on the stellar mass and its environment. Three detailed observational case-studies are presented, a globule (B335) that is forming only one or two stars, a medium-sized star formation region (L1551) and a large cluster of young stars (YSOs) in a part of our nearest giant molecular cloud (L1641N). The first part of this thesis concerns finding YSOs by looking for mid-IR excess, indicative of circumstellar disks, using the ISO and Spitzer satellites in combination with ground-based observations. Other signs of youth are also used; H-alpha in emission (accretion), Li 6707 in absorption (Li is destroyed with age) and cloud membership based on extinction. The detection of 15 new YSO candidates in L1551 (Paper I) and 89 YSOs in L1641N (Paper II) is presented. In L1641N, distributions are presented of stellar age and mass. An empirical extinction law is found and the star formation history is presented. There seems to be an accelerated star formation with time. This can however also be explained, at least partly, by migration of older stars from the cluster - a migration that may very well be mass dependent. The second part concerns bipolar outflows. The discovery of six Herbig-Haro objects and at least 15 H2 objects in B335 is presented (Paper III) as well as proper motions for previously known objects. A planar shock model is used to calcu