scholarly journals Intermediate plumes of low oxygen in the southeastern Baltic Sea

Oceanologia ◽  
2021 ◽  
Author(s):  
Maria Golenko ◽  
Vadim Paka ◽  
Victor Zhurbas ◽  
Andrey Korzh ◽  
Alexey Kondrashov
Keyword(s):  
Baltic Sea ◽  
Low Oxygen

scholarly journals Sedimentary alkalinity generation and long-term alkalinity development in the Baltic Sea

2018 ◽  
Author(s):  
Erik Gustafsson ◽  
Mathilde Hagens ◽  
Xiaole Sun ◽  
Daniel C. Reed ◽  
Christoph Humborg ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Reactive Transport ◽  
Total Alkalinity ◽  
Biogeochemical Model ◽  
Co2 Uptake ◽  
Low Oxygen ◽  
The Baltic Sea ◽  
The Past ◽  
Oxygen Conditions ◽  
The Baltic

Abstract. Enhanced release of alkalinity from the seafloor, principally driven by anaerobic degradation of organic matter under low-oxygen conditions and associated secondary redox reactions, can increase the carbon dioxide (CO2) buffering capacity of seawater and therefore oceanic CO2 uptake. The Baltic Sea has undergone severe changes in oxygenation state and total alkalinity (TA) over the past decades. The link between these concurrent changes has not yet been investigated in detail. A recent system-wide TA budget constructed for the past 50 years using BALTSEM, a coupled physical-biogeochemical model for the whole Baltic Sea area, revealed an unknown TA source. Here we use BALTSEM in combination with observational data and one-dimensional reactive transport modelling of sedimentary processes in the Fårö Deep, a deep Baltic Sea basin, to test whether sulfate reduction coupled to iron (Fe) sulfide burial can explain the missing TA source in the Baltic Proper. We calculated that this burial can account for 26 % of the missing source in this basin, with the remaining TA possibly originating from unknown river inputs or submarine groundwater discharge. We also show that temporal variability in the input of Fe to the sediments since the 1970s drives changes in sulfur burial in the Fårö Deep, suggesting that Fe availability is the ultimate limiting factor for TA generation under anoxic conditions. The implementation of projected climate change and two nutrient load scenarios for the 21st century in BALTSEM shows that reducing nutrient loads will improve deep water oxygen conditions, but at the expense of lower surface water TA concentrations, CO2 buffering capacities and faster acidification. When these changes additionally lead to a decrease in Fe inputs to the sediment of the deep basins, anaerobic TA generation will be reduced even further, thus exacerbating acidification. This work highlights that Fe dynamics play a key role in the release of TA from sediments where Fe sulfide formation is limited by Fe availability, as exemplified for the Baltic Sea. Moreover, it demonstrates that burial of Fe sulfides should be included in TA budgets of low oxygen basins.

scholarly journals Sedimentary alkalinity generation and long-term alkalinity development in the Baltic Sea

2019 ◽  
Vol 16 (2) ◽  
pp. 437-456 ◽  
Author(s):  
Erik Gustafsson ◽  
Mathilde Hagens ◽  
Xiaole Sun ◽  
Daniel C. Reed ◽  
Christoph Humborg ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Reactive Transport ◽  
Total Alkalinity ◽  
Biogeochemical Model ◽  
Co2 Uptake ◽  
Low Oxygen ◽  
The Baltic Sea ◽  
The Past ◽  
Oxygen Conditions ◽  
The Baltic

Abstract. Enhanced release of alkalinity from the seafloor, principally driven by anaerobic degradation of organic matter under low-oxygen conditions and associated secondary redox reactions, can increase the carbon dioxide (CO2) buffering capacity of seawater and therefore oceanic CO2 uptake. The Baltic Sea has undergone severe changes in oxygenation state and total alkalinity (TA) over the past decades. The link between these concurrent changes has not yet been investigated in detail. A recent system-wide TA budget constructed for the past 50 years using BALTSEM, a coupled physical–biogeochemical model for the whole Baltic Sea area revealed an unknown TA source. Here we use BALTSEM in combination with observational data and one-dimensional reactive-transport modeling of sedimentary processes in the Fårö Deep, a deep Baltic Sea basin, to test whether sulfate (SO42-) reduction coupled to iron (Fe) sulfide burial can explain the missing TA source in the Baltic Proper. We calculated that this burial can account for up to 26 % of the missing source in this basin, with the remaining TA possibly originating from unknown river inputs or submarine groundwater discharge. We also show that temporal variability in the input of Fe to the sediments since the 1970s drives changes in sulfur (S) burial in the Fårö Deep, suggesting that Fe availability is the ultimate limiting factor for TA generation under anoxic conditions. The implementation of projected climate change and two nutrient load scenarios for the 21st century in BALTSEM shows that reducing nutrient loads will improve deep water oxygen conditions, but at the expense of lower surface water TA concentrations, CO2 buffering capacities and faster acidification. When these changes additionally lead to a decrease in Fe inputs to the sediment of the deep basins, anaerobic TA generation will be reduced even further, thus exacerbating acidification. This work highlights that Fe dynamics plays a key role in the release of TA from sediments where Fe sulfide formation is limited by Fe availability, as exemplified by the Baltic Sea. Moreover, it demonstrates that burial of Fe sulfides should be included in TA budgets of low-oxygen basins.

scholarly journals Changes in population depth distribution and oxygen stratification are involved in the current low condition of the eastern Baltic Sea cod (<i>Gadus morhua</i>)

2021 ◽  
Vol 18 (4) ◽  
pp. 1321-1331
Author(s):  
Michele Casini ◽  
Martin Hansson ◽  
Alessandro Orio ◽  
Karin Limburg
Keyword(s):  
Baltic Sea ◽  
Body Condition ◽  
Gadus Morhua ◽  
Depth Distribution ◽  
Low Oxygen ◽  
Commercial Fish ◽  
Spatial Overlap ◽  
The Past ◽  
Eastern Baltic ◽  
Baltic Cod

Abstract. During the past 20 years, hypoxic areas have expanded rapidly in the Baltic Sea, which has become one of the largest marine “dead zones” in the world. At the same time, the most important commercial fish population of the region, the eastern Baltic cod, has experienced a drastic reduction in mean body condition, but the processes behind the relation between deoxygenation and condition remain elusive. Here we use extensive long-term monitoring data on cod biology and distribution as well as on hydrological variations to investigate the processes that relate deoxygenation and cod condition during the autumn season. Our results show that the depth distribution of cod has increased during the past 4 decades at the same time of the expansion, and shallowing, of waters with oxygen concentrations detrimental to cod performance. This has resulted in a progressively increasing spatial overlap between the cod population and low-oxygenated waters after the mid-1990s. This spatial overlap and the actual oxygen concentration experienced by cod therein statistically explained a large proportion of the changes in cod condition over the years. These results complement previous analyses on fish otolith microchemistry that also revealed that since the mid-1990s, cod individuals with low condition were exposed to low-oxygen waters during their life. This study helps to shed light on the processes that have led to a decline of the eastern Baltic cod body condition, which can aid the management of this population currently in distress. Further studies should focus on understanding why the cod population has moved to deeper waters in autumn and on analyzing the overlap with low-oxygen waters in other seasons to quantify the potential effects of the variations in physical properties on cod biology throughout the year.

scholarly journals Reduced growth in Baltic Sea cod may be due to mild hypoxia

2020 ◽  
Vol 77 (5) ◽  
pp. 2003-2005 ◽  
Author(s):  
Keith Brander
Keyword(s):  
Baltic Sea ◽  
Food Consumption ◽  
Alternative Explanation ◽  
Metabolic Response ◽  
Low Oxygen ◽  
Hypoxic Conditions ◽  
Daily Food ◽  
Lower Production ◽  
Benthic Prey ◽  
Mild Hypoxia

Abstract Daily food consumption by small Baltic Sea cod has declined in recent decades, resulting in reduced growth and biomass. Declining oxygen may cause lower production of benthic prey for small cod, but an alternative explanation presented here is that the mildly hypoxic conditions that small cod experience reduces their rate of digestion and hence food consumption. Better information about the distribution and behaviour of small cod and their metabolic response to low oxygen levels is required.

scholarly journals Changes in population depth distribution and oxygen stratification explain the current low condition of the Eastern Baltic Sea cod (<i>Gadus morhua</i>)

2020 ◽  
Author(s):  
Michele Casini ◽  
Martin Hansson ◽  
Alessandro Orio ◽  
Karin Limburg
Keyword(s):  
Baltic Sea ◽  
Body Condition ◽  
Gadus Morhua ◽  
Depth Distribution ◽  
Fish Population ◽  
Low Oxygen ◽  
Commercial Fish ◽  
The Past ◽  
Eastern Baltic ◽  
Baltic Cod

Abstract. During the past twenty years, hypoxic areas have expanded exponentially in the Baltic Sea, which has become one of the largest marine dead zones in the world. At the same time, the most important commercial fish population of the region, the Eastern Baltic cod, has experienced a drastic reduction in mean body condition, but the processes relating hypoxia to condition remain elusive. Here we use extensive long-term monitoring data on cod biology and distribution as well as on hydrological variations, to investigate the processes that relate deoxygenation and cod condition during the autumn season. Our results show that the depth distribution of cod has increased during the past four decades at the same time of the expansion, and shallowing, of the waters with an oxygen concentration known to be detrimental for cod performance. This has resulted in a spatial overlap between the cod population and low-oxygenated waters after the mid-1990s, which relates with the observed decline in cod mean body condition. Complementary analyses on fish otolith microchemistry also revealed that since the mid-1990s, cod individuals with low condition were indeed exposed to low-oxygen waters during their life. This study helps to shed light on the processes that have led to a decline of the Eastern Baltic cod body condition, which can aid the management of this population currently in distress. Further studies should focus on understanding why the cod population has moved to deeper waters in autumn and on analysing the overlap with low-oxygen waters in other seasons to quantify the potential effects of the variations in physical properties on cod biology throughout the year.

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

Boreas ◽  
2002 ◽  
Vol 31 (1) ◽  
pp. 65-74 ◽  
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

HIF1-α-Mediated Gene Expression Induced by Vitamin B1 Deficiency

2013 ◽  
Vol 83 (3) ◽  
pp. 188-197 ◽  
Author(s):  
Rebecca L. Sweet ◽  
Jason A. Zastre
Keyword(s):  
Gene Expression ◽  
Thiamine Deficiency ◽  
Glucose Transporter ◽  
Neuroblastoma Cell ◽  
Hypoxia Inducible Factor ◽  
Clinical Manifestations ◽  
Vitamin B1 ◽  
Low Oxygen ◽  
Glucose Transporter 1 ◽  
Metabolic Intermediates

It is well established that thiamine deficiency results in an excess of metabolic intermediates such as lactate and pyruvate, which is likely due to insufficient levels of cofactor for the function of thiamine-dependent enzymes. When in excess, both pyruvate and lactate can increase the stabilization of the hypoxia-inducible factor 1-alpha (HIF-1α) transcription factor, resulting in the trans-activation of HIF-1α regulated genes independent of low oxygen, termed pseudo-hypoxia. Therefore, the resulting dysfunction in cellular metabolism and accumulation of pyruvate and lactate during thiamine deficiency may facilitate a pseudo-hypoxic state. In order to investigate the possibility of a transcriptional relationship between hypoxia and thiamine deficiency, we measured alterations in metabolic intermediates, HIF-1α stabilization, and gene expression. We found an increase in intracellular pyruvate and extracellular lactate levels after thiamine deficiency exposure to the neuroblastoma cell line SK-N-BE. Similar to cells exposed to hypoxia, there was a corresponding increase in HIF-1α stabilization and activation of target gene expression during thiamine deficiency, including glucose transporter-1 (GLUT1), vascular endothelial growth factor (VEGF), and aldolase A. Both hypoxia and thiamine deficiency exposure resulted in an increase in the expression of the thiamine transporter SLC19A3. These results indicate thiamine deficiency induces HIF-1α-mediated gene expression similar to that observed in hypoxic stress, and may provide evidence for a central transcriptional response associated with the clinical manifestations of thiamine deficiency.

Russian Oil: Production and Exports

2003 ◽  
pp. 136-146
Author(s):  
K. Liuhto
Keyword(s):  
Baltic Sea ◽  
Statistical Data ◽  
Oil Production ◽  
The Baltic Sea ◽  
North West ◽  
The North ◽  
Oil Transportation ◽  
Sea Ports ◽  
The Baltic

Statistical data on reserves, production and exports of Russian oil are provided in the article. The author pays special attention to the expansion of opportunities of sea oil transportation by construction of new oil terminals in the North-West of the country and first of all the largest terminal in Murmansk. In his opinion, one of the main problems in this sphere is prevention of ecological accidents in the process of oil transportation through the Baltic sea ports.

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