Dissolved methane during hypoxic events at the Boknis Eck time series station (Eckernförde Bay, SW Baltic Sea)

Bange, Hermann W.; Bergmann, Kristin; Hansen, Hans Peter; Kock, Annette; Koppe, Regine; Malien, Frank; Ostrau, C.

doi:10.5194/bg-7-1279-2010

Cited by 85 publications

(68 citation statements)

References 24 publications

(23 reference statements)

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“…Bange et al (1998) described the seasonal distribution of methane and nitrous oxide in the Bodden Sea, using an equilibrator combined with a gas chromatograph, postulating that methane emissions from this area account for 17 % of the total Baltic Sea methane emissions. Monthly observations of the water column at Boknis Eck between 2006 and 2008 showed a bimodal seasonality of sedimentary release of methane and elevated methane concentrations in deep water layers after sedimentation of fresh organic material from phytoplankton blooms (Bange et al, 2010). Similar periodic changes of methane fluxes from the sediment into deeper water layers were observed in the coastal zone of Puck Bay along the Hel Peninsula (Reindl and Bolalek, 2012).…”

Section: Methane In the Baltic Seamentioning

confidence: 48%

One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity

et al. 2013

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Abstract. Methane and carbon dioxide were measured with an autonomous and continuous running system on a ferry line crossing the Baltic Sea on a 2-3 day interval from the Mecklenburg Bight to the Gulf of Finland in 2010. Surface methane saturations show great seasonal differences in shallow regions like the Mecklenburg Bight (103-507 %) compared to deeper regions like the Gotland Basin (96-161 %). The influence of controlling parameters like temperature, wind, mixing depth and processes like upwelling, mixing of the water column and sedimentary methane emissions on methane oversaturation and emission to the atmosphere are investigated. Upwelling was found to influence methane surface concentrations in the area of Gotland significantly during the summer period. In February 2010, an event of elevated methane concentrations in the surface water and water column of the Arkona Basin was observed, which could be linked to a wind-derived water level change as a potential triggering mechanism. The Baltic Sea is a source of methane to the atmosphere throughout the year, with highest fluxes occurring during the winter season. Stratification was found to promote the formation of a methane reservoir in deeper regions like Gulf of Finland or Bornholm Basin, which leads to long lasting elevated methane concentrations and enhanced methane fluxes, when mixed to the surface during mixed layer deepening in autumn and winter. Methane concentrations and fluxes from shallow regions like the Mecklenburg Bight are predominantly controlled by sedimentary production and consumption of methane, wind events and the change in temperature-dependent solubility of methane in the surface water. Methane fluxes vary significantly in shallow regions (e.g. Mecklenburg Bight) and regions with a temporal stratification (e.g. Bornholm Basin, Gulf of Finland). On the contrary, areas with a permanent stratification like the Gotland Basin show only small seasonal fluctuations in methane fluxes.

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Section: Methane In the Baltic Seamentioning

confidence: 48%

One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity

et al. 2013

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“…found by Bange et al (2010), which they also attributed to remineralisation. Ammonium accumulation is known to occur during the decomposition of organic matter, when further oxidation to nitrite and nitrate is hindered by low oxygen concentrations.…”

Section: Comparisons Of Observations At Be With Trends In the Baltic Seamentioning

confidence: 86%

Long-term trends at the Boknis Eck time series station (Baltic Sea), 1957–2013: does climate change counteract the decline in eutrophication?

et al. 2014

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Abstract. The Boknis Eck (BE) time series station, initiated in 1957, is one of the longest-operated time series stations worldwide. We present the first statistical evaluation of a data set of nine physical, chemical and biological parameters in the period of 1957-2013. In the past three to five decades, all of the measured parameters underwent significant long-term changes. Most striking is an ongoing decline in bottom water oxygen concentration, despite a significant decrease of nutrient and chlorophyll a concentrations. Temperature-enhanced oxygen consumption in the bottom water and a prolongation of the stratification period are discussed as possible reasons for the ongoing oxygen decline despite declining eutrophication. Observations at the BE station were compared with model output of the Kiel Baltic Sea Ice Ocean Model (BSIOM). Reproduced trends were in good agreement with observed trends for temperature and oxygen, but generally the oxygen concentration at the bottom has been overestimated.

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“…In addition, up to 90 % of the remaining methane that reaches the sediment surface may be oxidized aerobically at the sediment surface or in the water column (Reeburgh, 2007). However, methane concentrations in estuarine waters are almost always higher than the atmospheric equilibrium concentration (Bange et al, 2010), indicating that microbial oxidation processes and physical exchange with the atmosphere in estuaries are relatively inefficient in removing methane. Despite its obvious importance, only a few studies have specifically addressed anaerobic oxidation of methane by sulfate and aerobic oxidation in estuarine environments (e.g., Treude et al, 2005a;Thang et al, 2013).…”

Section: J E Sawicka and V Brüchert: Annual Variability And Regulamentioning

confidence: 99%

Annual variability and regulation of methane and sulfate fluxes in Baltic Sea estuarine sediments

Sawicka

Brüchert

2017

Biogeosciences

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Abstract. Marine methane emissions originate largely from near-shore coastal systems, but emission estimates are often not based on temporally well-resolved data or sufficient understanding of the variability of methane consumption and production processes in the underlying sediment. The objectives of our investigation were to explore the effects of seasonal temperature, changes in benthic oxygen concentration, and historical eutrophication on sediment methane concentrations and benthic fluxes at two type localities for open-water coastal versus eutrophic, estuarine sediment in the Baltic Sea. Benthic fluxes of methane and oxygen and sediment pore-water concentrations of dissolved sulfate, methane, and 35 S-sulfate reduction rates were obtained over a 12-month period from April 2012 to April 2013. Benthic methane fluxes varied by factors of 5 and 12 at the offshore coastal site and the eutrophic estuarine station, respectively, ranging from 0.1 mmol m −2 d −1 in winter at an open coastal site to 2.6 mmol m −2 d −1 in late summer in the inner eutrophic estuary. Total oxygen uptake (TOU) and 35 S-sulfate reduction rates (SRRs) correlated with methane fluxes showing low rates in the winter and high rates in the summer. The highest pore-water methane concentrations also varied by factors of 6 and 10 over the sampling period with the lowest values in the winter and highest values in late summerearly autumn. The highest pore-water methane concentrations were 5.7 mM a few centimeters below the sediment surface, but they never exceeded the in situ saturation concentration. Of the total sulfate reduction, 21-24 % was coupled to anaerobic methane oxidation, lowering methane concentrations below the sediment surface far below the saturation concentration. The data imply that bubble emission likely plays no or only a minor role in methane emissions in these sediments. The changes in pore-water methane concentrations over the observation period were too large to be explained by temporal changes in methane formation and methane oxidation rates due to temperature alone. Additional factors such as regional and local hydrostatic pressure changes and coastal submarine groundwater flow may also affect the vertical and lateral transport of methane.

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Dissolved methane during hypoxic events at the Boknis Eck time series station (Eckernförde Bay, SW Baltic Sea)

Cited by 85 publications

References 24 publications

One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity

One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity

Long-term trends at the Boknis Eck time series station (Baltic Sea), 1957–2013: does climate change counteract the decline in eutrophication?

Annual variability and regulation of methane and sulfate fluxes in Baltic Sea estuarine sediments

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