Remote sensing northern lake methane ebullition

Engram, Melanie; Anthony, K. M. Walter; Sachs, Torsten; Kohnert, Katrin; Serafimovich, Andrei; Grosse, Guido; Meyer, Franz J.

doi:10.1038/s41558-020-0762-8

Cited by 58 publications

(67 citation statements)

References 48 publications

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“…determined from interpolated MOD chamber measurements) was 542 ± 522 g CH 4 m −2 d −1 , thus showing no significant difference between the MOD and bubble-trap methods. The mean emission in the selected section of Esieh Lake is within the reported range for seepage (Etiope, 2015), 4 orders of magnitude higher than mean emissions from lakes north of 66 • N (Bastviken et al, 2011;Wik et al, 2013) and 2 orders of magnitude above the mean emission reported for wetlands (Kayranli et al, 2010). The total daily emission of the selected area, estimated to 4291 kg of CH 4 , is of the same magnitude as emissions reported for macroseepage globally (Etiope, 2015).…”

Section: Resultssupporting

confidence: 59%

“…The quantification of CH 4 macroseepage to the atmosphere is challenging, because it involves irregular gas flow rates, which, taken individually, can range from few milliliters to tens of liters per minute (Walter Anthony et al, 2012) and are spatially and temporally unevenly distributed. When the gas flow rate is low, measurements are standardly done through quantifying the gas accumulation within a chamber, located at the surface of the ground (Rolston, 1986) or water (Etiope, 2015). This approach, termed "closed chamber technique" in reference to the absence of a gas flowing through the chamber, is simple and easy to deploy and can be automated through a programmed venting device and a continuous gas analyzer, allowing repeated measurements over long-term periods without supervision (Davis et al, 2018;Martinsen et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Technical note: Mobile open dynamic chamber measurement of methane macroseeps in lakes

Thalasso

Anthony

Irzak³

et al. 2020

Hydrol. Earth Syst. Sci.

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Abstract. Methane (CH4) seepage (i.e., steady or episodic flow of gaseous hydrocarbons from subsurface reservoirs) has been identified as a significant source of atmospheric CH4. However, radiocarbon data from polar ice cores have recently brought into question the magnitude of fossil CH4 seepage naturally occurring. In northern high latitudes, seepage of subsurface CH4 is impeded by permafrost and glaciers, which are under an increasing risk of thawing and melting in a globally warming world, implying the potential release of large stores of CH4 in the future. Resolution of these important questions requires a better constraint and monitoring of actual emissions from seepage areas. The measurement of these seeps is challenging, particularly in aquatic environments, because they involve large and irregular gas flow rates, unevenly distributed both spatially and temporally. Large macroseeps are particularly difficult to measure due to a lack of lightweight, inexpensive methods that can be deployed in remote Arctic environments. Here, we report the use of a mobile chamber for measuring emissions at the surface of ice-free lakes subject to intense CH4 macroseepage. Tested in a remote Alaskan lake, the method was validated for the measurement of fossil CH4 emissions of up to 1.08 × 104 g CH4 m−2 d−1 (13.0 L m−2 min−1 of 83.4 % CH4 bubbles), which is within the range of global fossil methane seepage and several orders of magnitude above standard ecological emissions from lakes. In addition, this method allows for low diffusive flux measurements. Thus, the mobile chamber approach presented here covers the entire magnitude range of CH4 emissions currently identified, from those standardly observed in lakes to intense macroseeps, with a single apparatus of moderate cost.

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Section: Resultssupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Technical note: Mobile open dynamic chamber measurement of methane macroseeps in lakes

Thalasso

Anthony

Irzak³

et al. 2020

Hydrol. Earth Syst. Sci.

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“…More recent studies, however, provide strong evidence that the dominant mechanism is direct backscattering from a rough ice-water interface (Atwood et al, 2015;Engram et al, 2020Engram et al, , 2013Gunn et al, 2018). Engram et al (2020) showed a significant correlation between whole-lake methane emissions and whole-lake L-band backscatter from ice-covered Alaskan lakes in the case of superficial seeps (see Sect. 6 for details).…”

Section: Introductionmentioning

confidence: 99%

Mapping potential signs of gas emissions in ice of Lake Neyto, Yamal, Russia, using synthetic aperture radar and multispectral remote sensing data

et al. 2021

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Abstract. Regions of anomalously low backscatter in C-band synthetic aperture radar (SAR) imagery of lake ice of Lake Neyto in northwestern Siberia have been suggested to be caused by emissions of gas (methane from hydrocarbon reservoirs) through the lake’s sediments. However, to assess this connection, only analyses of data from boreholes in the vicinity of Lake Neyto and visual comparisons to medium-resolution optical imagery have been provided due to a lack of in situ observations of the lake ice itself. These observations are impeded due to accessibility and safety issues. Geospatial analyses and innovative combinations of satellite data sources are therefore proposed to advance our understanding of this phenomenon. In this study, we assess the nature of the backscatter anomalies in Sentinel-1 C-band SAR images in combination with very high resolution (VHR) WorldView-2 optical imagery. We present methods to automatically map backscatter anomaly regions from the C-band SAR data (40 m pixel spacing) and holes in lake ice from the VHR data (0.5 m pixel spacing) and examine their spatial relationships. The reliability of the SAR method is evaluated through comparison between different acquisition modes. The results show that the majority of mapped holes (71 %) in the VHR data are clearly related to anomalies in SAR imagery acquired a few days earlier, and similarities to SAR imagery acquired more than a month before are evident, supporting the hypothesis that anomalies may be related to gas emissions. Further, a significant expansion of backscatter anomaly regions in spring is documented and quantified in all analysed years 2015 to 2019. Our study suggests that the backscatter anomalies might be caused by lake ice subsidence and consequent flooding through the holes over the ice top leading to wetting and/or slushing of the snow around the holes, which might also explain outcomes of polarimetric analyses of auxiliary L-band Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) data. C-band SAR data are considered to be valuable for the identification of lakes showing similar phenomena across larger areas in the Arctic in future studies.

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“…The magnitude of that potential CH4 release is unknown, but a carbon store of over 1,200 Pg trapped by the cryosphere cap has been estimated (Isaksen et al, 2001;Flores et al, 2004;Gautier et al, 2009;McGuire et al, 2009;Collett et al, 2011). Hence, the conversion and release of a small fraction of that carbon to CH4 may represent a significant input to the current atmospheric CH4 pool, estimated to 5 Pg (Isaksen et al, 2001;Engram et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…In northern latitudes, seasonal ice cover provides an unique opportunity to more accurately assess CH4 ebullition, since the physical impact of bubbles breaking at the water surface delays ice formation, resulting in bubble-induced open holes during early winter (Walter Anthony et al, 2012). Later during the winter, ebullition also results in heterogeneous ice cover with gas inclusions that can be detected by remote detection methods such as satellite SAR sensing (Engram et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Mobile open dynamic chamber measurement of methane macroseeps in lakes

Thalasso

Anthony

Irzak³

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. Methane (CH4) seepage; i.e., steady or episodic flow of gaseous hydrocarbons from subsurface reservoirs, has been identified as a significant source of atmospheric CH4. However, radiocarbon data from polar ice cores recently brought into question the magnitude of fossil CH4 seepage naturally occurring. In northern high latitudes, seepage of subsurface CH4 is impeded by permafrost and glaciers, which are under an increasing risk of thawing and melting in a globally warming world, implying the potential release of large stores of CH4 in the future. Resolution of these important questions requires a better constraint and monitoring of actual emissions from seepage areas. The measurement of these seeps is challenging, particularly in aquatic environments, because they involve large and irregular gas flowrates, unevenly distributed both spatially and temporally. Large macroseeps are particularly difficult to measure due to a lack of lightweight, inexpensive methods that can deployed in remote Arctic environments. Here, we report the use of a mobile chamber for measuring emissions at the surface of ice-free lakes subject to intense CH4 macroseepage. Tested in a remote Alaskan lake, the method was validated for the measurement of fossil CH4 emissions of up to 1.08 × 104 g CH4 m-2 d-1 (13.0 L m-2 min-1 of 83.4 % CH4 bubbles), which is within the range of global fossil methane seepage and several orders of magnitude above standard ecological emissions from lakes. In addition, this method allows for low diffusive flux measurements. Thus, the mobile chamber approach presented here covers the entire magnitude range of CH4 emissions currently identified, from those standardly observed in lakes to intense macroseeps, with a single apparatus of moderate cost.

show abstract

Remote sensing northern lake methane ebullition

Cited by 58 publications

References 48 publications

Technical note: Mobile open dynamic chamber measurement of methane macroseeps in lakes

Technical note: Mobile open dynamic chamber measurement of methane macroseeps in lakes

Mapping potential signs of gas emissions in ice of Lake Neyto, Yamal, Russia, using synthetic aperture radar and multispectral remote sensing data

Mobile open dynamic chamber measurement of methane macroseeps in lakes

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