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

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

Biogeosciences Discussions ◽

10.5194/bgd-9-9897-2012 ◽

2012 ◽

Vol 9 (8) ◽

pp. 9897-9944 ◽

Cited By ~ 2

Author(s):

W. Gülzow ◽

G. Rehder ◽

J. Schneider v. Deimling ◽

T. Seifert ◽

Zs. Tóth

Keyword(s):

Surface Water ◽

Baltic Sea ◽

Water Column ◽

Gulf Of Finland ◽

Bornholm Basin ◽

The Baltic Sea ◽

Gotland Basin ◽

Methane Fluxes ◽

The Baltic ◽

Methane Concentrations

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 during the winter season. Stratification was found to intensify 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 rather 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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Nitrous oxide water column distribution during the transition from anoxic to oxic conditions in the Baltic Sea

Biogeosciences Discussions ◽

10.5194/bgd-3-729-2006 ◽

2006 ◽

Vol 3 (3) ◽

pp. 729-764 ◽

Cited By ~ 3

Author(s):

S. Walter ◽

U. Breitenbach ◽

H. W. Bange ◽

G. Nausch ◽

D. W. R. Wallace

Keyword(s):

Nitrous Oxide ◽

Baltic Sea ◽

Water Column ◽

North Sea ◽

Deep Water ◽

Sea Water ◽

The Baltic Sea ◽

Gotland Basin ◽

Water Renewal ◽

The Baltic

Abstract. In January 2003, a major inflow of cold and oxygen-rich North Sea Water in the Baltic Sea terminated an ongoing stagnation period in parts of the central Baltic Sea. In order to investigate the role of North Sea Water inflow to the Baltic Sea with regard to the production of nitrous oxide (N2O), we measured dissolved and atmospheric N2O at 26 stations in the southern and central Baltic Sea in October 2003. At the time of our cruise, water renewal had proceeded to the eastern Gotland Basin, whereas the western Gotland Basin was still unaffected by the inflow. The deep water renewal was detectable in the distributions of temperature, salinity, and oxygen concentrations as well as in the distribution of the N2O concentrations: Shallow stations in the Kiel Bight and Pomeranian Bight were well-ventilated with uniform N2O concentrations near equilibrium throughout the water column. In contrast, stations in the deep basins, such as the Bornholm and the Gotland Deep, showed a clear stratification with deep water affected by North Sea Water. Inflowing North Sea Water led to changed environmental conditions, especially enhanced oxygen (O2) or declining hydrogen sulfide (H2S) concentrations, thus, affecting the conditions for the production of N2O. Pattern of N2O profiles and correlations with parameters like oxygen and nitrate differed between the basins. The dominant production pathway seems to be nitrification rather than denitrification. No indications for advection of N2O by North Sea Water were found. A rough budget revealed a significant surplus of in situ produced N2O after the inflow. However, due to the permanent halocline, it can be assumed that the formed N2O does not reach the atmosphere. Hydrographic aspects therefore are decisive factors determining the final release of produced N2O to the atmosphere.

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Effects of the 2014 Major Baltic Inflow on methane and nitrous oxide dynamics in the water column of the Central Baltic Sea

10.5194/esd-2017-14 ◽

2017 ◽

Cited By ~ 1

Author(s):

Jukka-Pekka Myllykangas ◽

Tom Jilbert ◽

Gunnar Jakobs ◽

Gregor Rehder ◽

Jan Werner ◽

...

Keyword(s):

Nitrous Oxide ◽

Baltic Sea ◽

Water Column ◽

Turbulent Mixing ◽

Salt Water ◽

The Baltic Sea ◽

Gotland Basin ◽

Deep Waters ◽

Water Oxygen ◽

The Baltic

Abstract. In late 2014, a large, oxygen-rich salt water inflow entered the Baltic Sea and caused considerable changes in deep water oxygen concentrations. We studied the effects of the inflow on the concentration patterns of two greenhouse gases, methane and nitrous oxide, during the following year (2015) in the water column of the Gotland Basin. Methane which had previously accumulated in anoxic deep waters was largely removed from the Eastern Gotland Basin during the year, predominantly due to oxidation following turbulent mixing with the oxygen-rich inflow. In contrast nitrous oxide, which was previously absent from deep waters, accumulated in deep waters due to enhanced nitrification following the inflow. A transient extreme accumulation of nitrous oxide was observed in the deep waters of the Eastern Gotland Basin towards the end of 2015, when deep waters turned anoxic again and sedimentary denitrification was induced. The Western Gotland Basin gas biogeochemistry was not affected by the inflow.

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Temporal and spatial sedimentation rate variabilities in the eastern Gotland Basin, the Baltic Sea

Boreas ◽

10.1080/03009480210645 ◽

2002 ◽

Vol 31 (1) ◽

pp. 65-74 ◽

Cited By ~ 12

Author(s):

Christian Christiansen ◽

Helmar Kunzendorf ◽

Kay-Christian Emeis ◽

Rudolf Endler ◽

Ulrich Struck ◽

...

Keyword(s):

Baltic Sea ◽

Sedimentation Rate ◽

The Baltic Sea ◽

Gotland Basin ◽

Temporal And Spatial ◽

The Baltic

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Bacteriohopanepolyols record stratification, nitrogen fixation and other biogeochemical perturbations in Holocene sediments of the central Baltic Sea

Biogeosciences ◽

10.5194/bg-10-2725-2013 ◽

2013 ◽

Vol 10 (4) ◽

pp. 2725-2735 ◽

Cited By ~ 30

Author(s):

M. Blumenberg ◽

C. Berndmeyer ◽

M. Moros ◽

M. Muschalla ◽

O. Schmale ◽

...

Keyword(s):

Baltic Sea ◽

Water Column ◽

Stable Stratification ◽

The Baltic Sea ◽

Allochthonous Input ◽

The North ◽

Water Column Stratification ◽

Gotland Deep ◽

History Of ◽

The Baltic

Abstract. The Baltic Sea, one of the world's largest brackish-marine basins, established after deglaciation of Scandinavia about 17 000 to 15 000 yr ago. In the changeable history of the Baltic Sea, the initial freshwater system was connected to the North Sea about 8000 yr ago and the modern brackish-marine setting (Littorina Sea) was established. Today, a relatively stable stratification has developed in the water column of the deep basins due to salinity differences. Stratification is only occasionally interrupted by mixing events, and it controls nutrient availability and growth of specifically adapted microorganisms and algae. We studied bacteriohopanepolyols (BHPs), lipids of specific bacterial groups, in a sediment core from the central Baltic Sea (Gotland Deep) and found considerable differences between the distinct stages of the Baltic Sea's history. Some individual BHP structures indicate contributions from as yet unknown redoxcline-specific bacteria (bacteriohopanetetrol isomer), methanotrophic bacteria (35-aminobacteriohopanetetrol), cyanobacteria (bacteriohopanetetrol cyclitol ether isomer) and from soil bacteria (adenosylhopane) through allochthonous input after the Littorina transgression, whereas the origin of other BHPs in the core has still to be identified. Notably high BHP abundances were observed in the deposits of the brackish-marine Littorina phase, particularly in laminated sediment layers. Because these sediments record periods of stable water column stratification, bacteria specifically adapted to these conditions may account for the high portions of BHPs. An additional and/or accompanying source may be nitrogen-fixing (cyano)bacteria, which is indicated by a positive correlation of BHP abundances with Corg and δ15N.

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An integrated simulation model to evaluate national measures for the abatement of agricultural nutrients in the Baltic Sea

Agricultural and Food Science ◽

10.23986/afsci.5951 ◽

2009 ◽

Vol 18 (3-4) ◽

pp. 440-459 ◽

Cited By ~ 4

Author(s):

K. HYYTIÄINEN ◽

H. AHTIAINEN ◽

J. HEIKKILÄ

Keyword(s):

Water Quality ◽

Simulation Model ◽

Baltic Sea ◽

Arable Land ◽

Gulf Of Finland ◽

Nutrient Loads ◽

The Baltic Sea ◽

The Baltic ◽

Bothnian Bay ◽

The Gulf Of Finland

This study introduces a prototype model for evaluating measures to abate agricultural nutrients in the Baltic Sea from a Finnish national perspective. The stochastic simulation model integrates nutrient dynamics of nitrogen and phosphorus in the sea basins adjoining the Finnish coast, nutrient loads from land and other sources, benefits from nutrient abatement (in the form of recreation and other ecosystem services) and the costs of agricultural abatement activities. The aim of the study is to present the overall structure of the model and to demonstrate its potential using preliminary parameters. The model is made flexible for further improvements in all of its ecological and economic components. The results of a sensitivity analysis suggest that investments in reducing the nutrient load from arable land in Finland would become profitable only if the neighboring countries in the northern Baltic committed themselves to similar reductions. Environmental investments for improving water quality yield the highest returns for the Bothnian Bay and the Gulf of Finland, with smaller returns for the Bothnian Sea. Somewhat surprisingly, in the Bothnian Bay the abatement activities become profitable from the national viewpoint, because the riverine loads from Finland represent a high proportion of the total nutrient loads. In the Gulf of Finland, this proportion is low, but the size of the coastal population benefiting from improved water quality is high.;

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Environmental genotoxicity and cytotoxicity studies in fish blood erythrocytes and genotoxicity risk assessment in the Gotland Basin of the Baltic Sea

10.15388/vu.thesis.170 ◽

2021 ◽

Author(s):

◽

Janina Pažusienė

Keyword(s):

Risk Assessment ◽

Baltic Sea ◽

The Baltic Sea ◽

Gotland Basin ◽

Cytotoxicity Studies ◽

Fish Blood ◽

The Baltic ◽

Environmental Genotoxicity

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Nitrogen fixation in a diazotrophic post-bloom situation in the Baltic Sea

10.5194/egusphere-egu21-911 ◽

2021 ◽

Author(s):

Christian Reeder ◽

Carolin Löscher

Keyword(s):

Climate Change ◽

Surface Water ◽

Baltic Sea ◽

The Baltic Sea ◽

Biological Fixation ◽

Community Based ◽

Iron Iron ◽

The Baltic ◽

Metal Cofactors ◽

Diazotrophic Community

The Baltic Sea is characterised as a semi-enclosed brackish Sea that has experienced increased eutrophication, hypoxia, and increased temperature over the last ~100 years making Baltic Sea one of the most severely impacted oceanic environment by climate change. Biological fixation of dinitrogen gas (N2) is an essential process to make atmospheric N2 available for marine life. This process is carried out by specialised organisms called diazotrophs and is catalysed by the energetic-consuming enzyme nitrogenase. Nitrogenases exist in three subtypes depending on their metal cofactors, (1) the most common molybdenum-dependent (Nif), (2) the vanadium-dependent (Vnf) and (3) the Iron-Iron-dependent nitrogenase (Anf). To date, the effect of climate change on those three enzyme subtypes and their potential role a future ocean is yet to be explored. The predicted ongoing oxygen loss in the ocean may limit Mo's availability and trigger a shift from the abundant Nif-type nitrogenase to Vnf or Anf and, therefore, a potential shift in the diazotrophic community. This study explored the climate change-related pressures on N2 fixation and the diazotrophic community based on nifH and vnf/anfD amplicons. At the time of sampling, we found a post-bloom high-nutrient low-chlorophyll situation. Cyanobacterial groups, Nodularia and UCYN-A, dominated the diazotrophic community and showed a horizontal where UCYN-A were the dominant fixers at 20 m. Based on alternative nitrogenases amplicons, Rhodopseudomonas was the dominating microbe in the surface water. This paper presents the first hint of active nitrogenases in surface water and further establish UCYN-A as a significant player in Baltic Sea primary production.

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