scholarly journals Nitrous oxide water column distribution during the transition from anoxic to oxic conditions in the Baltic Sea

2006 ◽  
Vol 3 (3) ◽  
pp. 729-764 ◽  
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.

scholarly journals Distribution of N<sub>2</sub>O in the Baltic Sea during transition from anoxic to oxic conditions

2006 ◽  
Vol 3 (4) ◽  
pp. 557-570 ◽  
Author(s):  
S. Walter ◽  
U. Breitenbach ◽  
H. W. Bange ◽  
G. Nausch ◽  
D. W. R. Wallace
Keyword(s):  
Nitrous Oxide ◽  
Baltic Sea ◽  
North Sea ◽  
Sea Water ◽  
Water Inflow ◽  
The Baltic Sea ◽  
The Baltic ◽  
Stagnation Period

Abstract. In January 2003, a major inflow of cold and oxygen-rich North Sea Water terminated an ongoing stagnation period in parts of the central Baltic Sea. In order to investigate the role of North Sea Water inflow in the production of nitrous oxide (N2O), we measured dissolved and atmospheric N

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

2017 ◽  
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.

scholarly journals Hypoxia and nitrogen processing in the Baltic Sea water column

2012 ◽  
Vol 57 (1) ◽  
pp. 325-337 ◽  
Author(s):  
Susanna Hietanen ◽  
Helena Jäntti ◽  
Christo Buizert ◽  
Klaus Jürgens ◽  
Matthias Labrenz ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Sea Water ◽  
The Baltic Sea ◽  
The Baltic

Anthropogenic microlitter in the Baltic Sea water column

2018 ◽  
Vol 129 (2) ◽  
pp. 918-923 ◽  
Author(s):  
Andrei Bagaev ◽  
Liliya Khatmullina ◽  
Irina Chubarenko
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Sea Water ◽  
The Baltic Sea ◽  
The Baltic

scholarly journals Effects of the 2014 major Baltic inflow on methane and nitrous oxide dynamics in the water column of the central Baltic Sea

2017 ◽  
Vol 8 (3) ◽  
pp. 817-826 ◽  
Author(s):  
Jukka-Pekka Myllykangas ◽  
Tom Jilbert ◽  
Gunnar Jakobs ◽  
Gregor Rehder ◽  
Jan Werner ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Baltic Sea ◽  
Water Column ◽  
Salt Water ◽  
Weighted Mean ◽  
Gotland Basin ◽  
Deep Waters ◽  
Bottom Waters ◽  
The Baltic ◽  
Mean Concentration

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. In the eastern basin, methane which had previously accumulated in the deep waters was largely removed during the year. Here, volume-weighted mean concentration below 70 m decreased from 108 nM in March to 16.3 nM over a period of 141 days (0.65 nM d−1), predominantly due to oxidation (up to 79 %) 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. Volume-weighted mean concentration of nitrous oxide below 70 m increased from 11.8 nM in March to 24.4 nM in 141 days (0.09 nM d−1). A transient extreme accumulation of nitrous oxide (877 nM) was observed in the deep waters of the Eastern Gotland Basin towards the end of 2015, when deep waters turned anoxic again, sedimentary denitrification was induced and methane was reintroduced to the bottom waters. The Western Gotland Basin gas biogeochemistry was not affected by the inflow.

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

2013 ◽  
Vol 10 (1) ◽  
pp. 81-99 ◽  
Author(s):  
W. Gülzow ◽  
G. Rehder ◽  
J. Schneider v. Deimling ◽  
T. Seifert ◽  
Z. 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 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.

scholarly journals Are recent changes in sediment manganese sequestration in the euxinic basins of the Baltic Sea linked to the expansion of hypoxia?

2015 ◽  
Vol 12 (16) ◽  
pp. 4875-4894 ◽  
Author(s):  
C. Lenz ◽  
T. Jilbert ◽  
D.J. Conley ◽  
M. Wolthers ◽  
C.P. Slomp
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
North Sea ◽  
The Baltic Sea ◽  
The Past ◽  
Gotland Deep ◽  
Carbonate Formation ◽  
The Baltic ◽  
Mn Oxides ◽  
Deep Area

Abstract. Expanding hypoxia in the Baltic Sea over the past century has led to the development of anoxic and sulfidic (euxinic) deep basins that are only periodically ventilated by inflows of oxygenated waters from the North Sea. In this study, we investigate the potential consequences of the expanding hypoxia for manganese (Mn) burial in the Baltic Sea using a combination of pore water and sediment analyses of dated sediment cores from eight locations. Diffusive fluxes of dissolved Mn from sediments to overlying waters at oxic, hypoxic and euxinic sites are consistent with an active release of Mn from these areas. Although the present-day fluxes are significant (ranging up to ca. 240 μmol m−2 d−1), comparison to published water column data suggests that the current benthic release of Mn is small when compared to the large pool of Mn already present in the hypoxic and anoxic water column. Our results highlight two modes of Mn carbonate formation in sediments of the deep basins. In the Gotland Deep area, Mn carbonates likely form from Mn oxides that are precipitated from the water column directly following North Sea inflows. In the Landsort Deep, in contrast, Mn carbonate and Mn sulfide layers appear to form independently of inflow events, and are possibly related to the much larger and continuous input of Mn oxides linked to sediment focusing. Whereas Mn-enriched sediments continue to accumulate in the Landsort Deep, this does not hold for the Gotland Deep area. Here, a recent increase in euxinia, as evident from measured bottom water sulfide concentrations and elevated sediment molybdenum (Mo), coincides with a decline in sediment Mn content. Sediment analyses also reveal that recent inflows of oxygenated water (since ca. 1995) are no longer consistently recorded as Mn carbonate layers. Our data suggest that eutrophication has not only led to a recent rise in sulfate reduction rates but also to a decline in reactive Fe input to these basins. We hypothesize that these factors have jointly led to higher sulfide availability near the sediment–water interface after inflow events. As a consequence, the Mn oxides may be reductively dissolved more rapidly than in the past and Mn carbonates may no longer form. Using a simple diagenetic model for Mn dynamics in the surface sediment, we demonstrate that an enhancement of the rate of reduction of Mn oxides is consistent with such a scenario. Our results have important implications for the use of Mn carbonate enrichments as a redox proxy in marine systems.

Anthropogenic fibres in the Baltic Sea water column: Field data, laboratory and numerical testing of their motion

2017 ◽  
Vol 599-600 ◽  
pp. 560-571 ◽  
Author(s):  
A. Bagaev ◽  
A. Mizyuk ◽  
L. Khatmullina ◽  
I. Isachenko ◽  
I. Chubarenko
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Field Data ◽  
Sea Water ◽  
The Baltic Sea ◽  
Numerical Testing ◽  
The Baltic

Nutrient regeneration and benthic fluxes in the Coastal Baltic and North Sea

2020 ◽  
Author(s):  
Kirstin Dähnke ◽  
Andreas Neumann ◽  
Tina Sanders
Keyword(s):  
Stable Isotope ◽  
Baltic Sea ◽  
Water Column ◽  
North Sea ◽  
Surface Sediments ◽  
Nutrient Regeneration ◽  
The Baltic Sea ◽  
The North ◽  
The North Sea ◽  
The Baltic

&lt;p&gt;Sediments in the coastal ocean can play an important role in nutrient regeneration and in recharging the water column with dissolved inorganic nutrients. This function, however, depends on various variables, such as physical characteristics, but also on biological traits like fauna composition and activity. To unravel and quantify these effects, we investigated nutrient fluxes and nitrate stable isotope composition in water samples along a North Sea &amp;#8211; Skagerrak &amp;#8211; Baltic Sea gradient during the Maria S. Merian cruise MSM 50 in January 2016.&lt;/p&gt;&lt;p&gt;Especially in the North Sea and the Skagerrak region, d&lt;sup&gt;15&lt;/sup&gt;N values of nitrate were unexpectedly high, suggesting that underlying sediments with relatively enriched isotope signatures were a source of nitrate. This nitrification signal, however, resembled an autumn situation rather than the expected winter values. Parallel sediment incubations confirm that the benthic rates of oxygen consumption and nutrient turnover were indeed very similar to respective rates in autumn and that the sediment was a source of recycled nitrate. From the North Sea towards the Baltic Sea, we found, in accordance with previous studies, a depletion in nitrate stable isotope values. This is indicative of different nitrate sources in the respective basins: in the North Sea region, N of anthropogenic origin leads to high N values in surface sediments and in newly generated nitrate. Due to a higher share of nitrogen fixation, the nitrogen stable isotope signal of surface sediments in the Baltic Sea was depleted, which in turn was mirrored in lower nitrate isotope values in the water column above the sediment.&lt;/p&gt;&lt;p&gt;Overall, the data highlight the importance of nitrate regeneration. Parallel flux measurements reveal that faunal activity shifts the nutrient balance from sequestration to regeneration. Seasonal differences enable us to unravel seasonal effects of fauna and microbiota on nutrient budgets.&lt;/p&gt;

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