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  • 1
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    BIRKHAUSER VERLAG AG
    In:  EPIC3Aquatic Sciences, BIRKHAUSER VERLAG AG, 81(: 12), ISSN: 1015-1621
    Publication Date: 2019-01-29
    Description: We conducted multiple small (2011–2012) and one large sampling campaign (2013) at selected profiles along the Elbe River. With the data we were able to outline spatial and temporal variability of methane concentration, oxidation and emissions in one of the major rivers of Central Europe. The highest methane concentrations were found in human-altered riverine habitats, i.e., in a harbor (1,888 nmol L−1), in a lock and weirs (1409 ± 1545 nmol L−1), and in general in the whole “impounded” river segment (383 ± 215 nmol L−1). On the other hand, the lowest methane concentrations were found in the “lowland” river segment (86 ± 56 nmol L−1). The methane oxidation rate was more efficient in the “natural” segment (71 ± 113 nmol L−1day−1, which means a turnover time of 49 ± 83 day−1) than in the “lowland” segment (4 ± 3 nmol L−1day−1, which means a turnover time of 39 ± 45 day−1). Methane emissions from the surface water into the atmosphere ranged from 0.4 to 11.9 mg m−2 day−1 (mean 2.1 ± 0.6 mg m−2 day−1) with the highest CH4 emissions at the Meissen harbor (94 kg CH4 year−1). Such human-altered riverine habitats (i.e., harbors and similar) have not been taken into consideration in the CH4 budget before, despite them being part of the river ecosystems, they may be significant CH4 hot-spots. The total CH4 diffusive flux from the whole Elbe was estimated to be approximately 97 t CH4 year−1.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
    Publication Date: 2015-12-15
    Description: Large amounts of the greenhouse gas methane are released from the seabed but liberation of methane to the atmosphere is mitigated by aerobic methanotrophs in the water column. The size and activity of methanotrophic communities are thought to be mainly determined by nutrient and redox dynamics, but little is known about the effects of water mass transport. Here, we show that cold bottom waters at methane seeps west off Svalbard, which contained a large number of aerobic methanotrophs, were rapidly displaced by warmer waters with a considerably smaller methanotrophic community. This water mass exchange, caused by short-term variations of the West Spitsbergen Current strongly reduced methanotrophic activity. Currents are common at many methane seeps and could thus be a globally important control on methane oxidation in the water column.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
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    BIRKHAUSER VERLAG AG
    In:  EPIC3Aquatic Sciences, BIRKHAUSER VERLAG AG, ISSN: 1015-1621
    Publication Date: 2016-10-13
    Description: Rivers represent a transition zone between terrestric and aquatic environments, and between methane rich and methane poor environments. The Elbe River is one of the most important rivers draining into the North Sea and, along with the Elbe, a potential importer of high amounts of methane into the water column of the North Sea. Twelve sampling cruises from October 2010 until June 2013 were conducted from Hamburg towards the mouth of the Elbe at Cuxhaven. The dynamic of methane concentration in the water column and its consumption via methane oxidation was measured. In addition, physico-chemical parameters were used to estimate their influence on the methanotrophic activity. We observed high methane concentrations at the stations in the area of Hamburg harbor (“inner estuary”) and about 10 times lower concentrations in the outer estuary (median of 416 versus 40 nmol/L, respectively). The methane oxidation (MOX) rate mirrored the methane distribution with high values in the inner estuary and low values in the outer estuary (median of 161 versus 10 nmol/L/d, respectively). Methane concentrations were significantly influenced by the river hydrology (falling water level) and the trophic state of the water (biological oxygen demand). In contrast to other studies no clear relation to the amount of suspended particulate matter (SPM) was found. Methane oxidation rates were significantly influenced by methane concentration and to a lesser extent by temperature. Methane oxidation accounted for 41 ± 12% of the total loss of methane in the summer/fall, but for only 5 ± 3% of the total loss in the winter/spring. We applied a modified box model taking into account the residence times of each water parcel depending on discharge and tidal impact. We observed almost stable methane concentrations in the outer estuary, despite a strong loss of methane through diffusion and oxidation. Thus, we postulate that the water column undergoes a balancing out in the outer Elbe estuary due to a strong additional input of methane, which could be provided by the extensive salt marshes near the river mouth.
    Repository Name: EPIC Alfred Wegener Institut
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  • 4
    Publication Date: 2022-06-16
    Description: This paper describes two gas‐emission craters (GECs) in permafrost regions of the Yamal and Gydan peninsulas. We show that in three consecutive years after GEC formation (2014–2017), both morphometry and hydrochemistry of the inner crater lakes can become indistinguishable from other lakes. Craters GEC‐1 and AntGEC, with initial depths of 50–70 and 15–19 m respectively, have transformed into lakes 3–5 m deep. Crater‐like depressions were mapped in the bottom of 13 out of 22 Yamal lakes. However, we found no evidence that these depressions could have been formed as a result of gas emission. Dissolved methane (dCH4) concentration measured in the water collected from these depressions was at a background level (45 ppm on average). Yet, the concentration of dCH4 from the near‐bottom layer of lake GEC‐1 was significantly higher (824–968 ppm) during initial stages. We established that hydrochemical parameters (dissolved organic carbon, major ions, isotopes) measured in GEC lakes approached values measured in other lakes over time. Therefore, these parameters could not be used to search for Western Siberian lakes that potentially resulted from gas emission. Temperature profiles measured in GEC lakes show that the water column temperatures in GEC‐1 are lower than in Yamal lakes and in AntGEC – close to values of Gydan lakes. Given the initial GEC depth 〉 50 m, we suggest that at least in GEC‐1 possible re‐freezing of sediments from below might take place. However, with the present data we cannot establish the modern thickness of the closed talik under newly formed GEC lakes.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
    Publication Date: 2023-06-21
    Description: This paper describes two gas‐emission craters (GECs) in permafrost regions of the Yamal and Gydan peninsulas. We show that in three consecutive years after GEC formation (2014–2017), both morphometry and hydrochemistry of the inner crater lakes can become indistinguishable from other lakes. Craters GEC‐1 and AntGEC, with initial depths of 50–70 and 15–19 m respectively, have transformed into lakes 3–5 m deep. Crater‐like depressions were mapped in the bottom of 13 out of 22 Yamal lakes. However, we found no evidence that these depressions could have been formed as a result of gas emission. Dissolved methane (dCH4) concentration measured in the water collected from these depressions was at a background level (45 ppm on average). Yet, the concentration of dCH4 from the near‐bottom layer of lake GEC‐1 was significantly higher (824–968 ppm) during initial stages. We established that hydrochemical parameters (dissolved organic carbon, major ions, isotopes) measured in GEC lakes approached values measured in other lakes over time. Therefore, these parameters could not be used to search for Western Siberian lakes that potentially resulted from gas emission. Temperature profiles measured in GEC lakes show that the water column temperatures in GEC‐1 are lower than in Yamal lakes and in AntGEC – close to values of Gydan lakes. Given the initial GEC depth 〉 50 m, we suggest that at least in GEC‐1 possible re‐freezing of sediments from below might take place. However, with the present data we cannot establish the modern thickness of the closed talik under newly formed GEC lakes.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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