scholarly journals Comparative studies of pelagic microbial methane oxidation within the redox zones of the Gotland Deep and Landsort Deep (central Baltic Sea)

2013 ◽  
Vol 10 (12) ◽  
pp. 7863-7875 ◽  
Author(s):  
G. Jakobs ◽  
G. Rehder ◽  
G. Jost ◽  
K. Kießlich ◽  
M. Labrenz ◽  
...  
Keyword(s):  
Surface Water ◽  
Baltic Sea ◽  
Methane Oxidation ◽  
Deep Water ◽  
Methane Concentration ◽  
Vertical Mixing ◽  
Gotland Deep ◽  
Hydrographic Conditions ◽  
Redox Zone ◽  
Redox Zones

Abstract. Pelagic methane oxidation was investigated in dependence on differing hydrographic conditions within the redox zone of the Gotland Deep (GD) and Landsort Deep (LD), central Baltic Sea. The redox zone of both deeps, which indicates the transition between oxic and anoxic conditions, was characterized by a pronounced methane concentration gradient between the deep water (GD: 1233 nM, 223 m; LD: 2935 nM, 422 m) and the surface water (GD and LD < 10 nM). This gradient together with a 13C CH4 enrichment (δ13C CH4 deep water: GD −84‰, LD −71‰; redox zone: GD −60‰, LD −20‰; surface water: GD −47‰, LD −50‰; δ13C CH4 vs. Vienna Pee Dee Belemnite standard), clearly indicating microbial methane consumption within the redox zone. Expression analysis of the methane monooxygenase identified one active type I methanotrophic bacterium in both redox zones. In contrast, the turnover of methane within the redox zones showed strong differences between the two basins (GD: max. 0.12 nM d−1, LD: max. 0.61 nM d−1), with a nearly four-times-lower turnover time of methane in the LD (GD: 455 d, LD: 127 d). Vertical mixing rates for both deeps were calculated on the base of the methane concentration profile and the consumption of methane in the redox zone (GD: 2.5 × 10–6 m2 s−1, LD: 1.6 × 10–5 m2 s−1). Our study identified vertical transport of methane from the deep-water body towards the redox zone as well as differing hydrographic conditions (lateral intrusions and vertical mixing) within the redox zone of these deeps as major factors that determine the pelagic methane oxidation.

scholarly journals Comparative studies of pelagic microbial methane oxidation within two anoxic basins of the central Baltic Sea (Gotland Deep and Landsort Deep)

2013 ◽  
Vol 10 (7) ◽  
pp. 12251-12284 ◽  
Author(s):  
G. Jakobs ◽  
G. Rehder ◽  
G. Jost ◽  
K. Kießlich ◽  
M. Labrenz ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Methane Oxidation ◽  
Deep Water ◽  
Methane Concentration ◽  
Vertical Mixing ◽  
Depth Interval ◽  
Type I ◽  
Gotland Deep ◽  
Redox Zone ◽  
Redox Zones

Abstract. Pelagic methane oxidation was investigated in dependence on differing environmental conditions within the redox zone of the Gotland Deep (GD) and Landsort Deep (LD), central Baltic Sea. The redox zone of both deeps, which indicates the transition between oxic and anoxic conditions, was characterized by a pronounced methane concentration gradient between the deep water (GD: 1233 nM, LD: 2935 nM) and the surface water (GD and LD < 10 nM), together with a 13C CH4 enrichment (δ13C CH4 deep water: GD −84‰, LD −71‰ ; redox zone: GD −60‰, LD −20‰ ; δ13C CH4 vs. Vienna Pee Dee Belemnite standard), clearly indicating microbial methane consumption in that specific depth interval. Expression analysis of the methane monooxygenase identified one active type I methanotrophic bacterium in both redox zones. In contrast, the turnover of methane within the redox zones showed strong differences between the two basins (GD: max. 0.12 nM d–1 and LD: max. 0.61 nM d–1), with a four times higher turnover rate constant (k) in the LD (GD: 0.0022 d–1, LD: 0.0079 d–1). Vertical mixing rates for both deeps were calculated on the base of the methane concentration profile and the consumption of methane in the redox zone (GD: 2.5 × 10–6 m2 s–1 LD: 1.6 × 10–5 m2 s–1). Our study identified vertical transport of methane from the deep water body towards the redox zone as well as differing hydrographic conditions within the oxic/anoxic transition zone of these deeps as major factors that determine the pelagic methane oxidation.

scholarly journals Aerobic methanotrophy within the pelagic redox-zone of the Gotland Deep (central Baltic Sea)

2012 ◽  
Vol 9 (12) ◽  
pp. 4969-4977 ◽  
Author(s):  
O. Schmale ◽  
M. Blumenberg ◽  
K. Kießlich ◽  
G. Jakobs ◽  
C. Berndmeyer ◽  
...  
Keyword(s):  
Surface Water ◽  
Baltic Sea ◽  
Water Column ◽  
Methane Oxidation ◽  
Stable Carbon Isotope ◽  
Carbon Isotope Ratio ◽  
Depth Interval ◽  
Type I ◽  
Gotland Deep ◽  
Redox Zone

Abstract. Water column samples taken in summer 2008 from the stratified Gotland Deep (central Baltic Sea) showed a strong gradient in dissolved methane concentrations from high values in the saline deep water (max. 504 nM) to low concentrations in the less dense, brackish surface water (about 4 nM). The steep methane-gradient (between 115 and 135 m water depth) within the redox-zone, which separates the anoxic deep part from the oxygenated surface water (oxygen concentration 0–0.8 mL L−1), implies a methane consumption rate of 0.28 nM d−1. The process of microbial methane oxidation within this zone was evident by a shift of the stable carbon isotope ratio of methane between the bottom water (δ13C CH4 = −82.4‰ and the redox-zone (δ13C CH4 = −38.7‰. Water column samples between 80 and 119 m were studied to identify the microorganisms responsible for the methane turnover in that depth interval. Notably, methane monooxygenase gene expression analyses for water depths covering the whole redox-zone demonstrated that accordant methanotrophic activity was probably due to only one phylotype of the aerobic type I methanotrophic bacteria. An imprint of these organisms on the particular organic matter was revealed by distinctive lipid biomarkers showing bacteriohopanepolyols and lipid fatty acids characteristic for aerobic type I methanotrophs (e.g., 35-aminobacteriohopane-30,31,32,33,34-pentol), corroborating their role in aerobic methane oxidation in the redox-zone of the central Baltic Sea.

scholarly journals Microbial methane oxidation at the redoxcline of the Gotland Deep (Central Baltic Sea)

2012 ◽  
Vol 9 (7) ◽  
pp. 8783-8805 ◽  
Author(s):  
O. Schmale ◽  
M. Blumenberg ◽  
K. Kießlich ◽  
G. Jakobs ◽  
C. Berndmeyer ◽  
...  
Keyword(s):  
Surface Water ◽  
Baltic Sea ◽  
Water Column ◽  
Methane Oxidation ◽  
Water Depth ◽  
Stable Carbon Isotope ◽  
Depth Interval ◽  
Type I ◽  
Gotland Deep ◽  
Key Species

Abstract. Methane concentrations in the stratified water column of the Gotland Deep (Central Baltic Sea) show a strong gradient from high values in the saline deep water (max. 504nM) to low concentrations in the less dense, brackish surface water (about 4 nM). The steepest gradient is present within the redoxcline (between 115 and 135 m water depth) that separates the anoxic deep part from the oxygenated surface water, implying a methane consumption rate of 0.28 nM d−1. The process of microbial methane oxidation within the redoxcline is mirrored by a shift of the stable carbon isotope ratio of methane between the bottom water (δ13C CH4 = −82.4‰) and the suboxic depth interval (δ13C CH4 = −38.7‰). A water column sample from 100 m water depth was studied to identify the microorganisms responsible for the methane turnover at the redoxcline. Notably, methane monoxygenase gene expression analyses for the specific water depth demonstrated that accordant methanotrophic activity was due to only one microbial phylotype. An imprint of these organisms on the particular organic matter was revealed by distinctive lipid biomarkers showing bacteriohopanepolyols and lipid fatty acids characteristic for aerobic type I methanotrophic bacteria (e.g. 35-aminobacteriohopane-30,31,32,33,34-pentol). In conjunction with earlier findings, our results support the idea that biogeochemical cycles in Central Baltic Sea redoxclines are mainly driven by only a few microbial key species.

scholarly journals On the Vertical Mixing of Sea-Water and its Importance for the Algal Plankton

1924 ◽  
Vol 13 (2) ◽  
pp. 319-324 ◽  
Author(s):  
W. R. G. Atkins
Keyword(s):  
Surface Water ◽  
Deep Water ◽  
Thermal Stratification ◽  
Sea Water ◽  
Vertical Mixing ◽  
Phosphate Concentration ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
English Channel ◽  
Hydrogen Ion Concentration

1. Measurements of hydrogen ion concentration, of phosphate concentration, and of temperature all show at certain seasons a well-marked gradient from surface to bottom. The upper 10–20 metres is more alkaline, notably depleted of phosphates and warmer.2. Settled summer weather and deep water, free from irregularities of the bottom, favour the formation of such a gradient. Its breaking up is occasioned by wave action and the cooling of the surface water in autumn.3. Thermal stratification in the English Channel arises at each station, and is not due to the inflow of warm over colder water.

scholarly journals A Baltic Sea estuary as phosphorus source and sink

2017 ◽  
Author(s):  
Jakob Walve ◽  
Maria Sandberg ◽  
Ulf Larsson ◽  
Christer Lännergren
Keyword(s):  
Baltic Sea ◽  
Deep Water ◽  
Sewage Treatment ◽  
Vertical Mixing ◽  
Turnover Time ◽  
Nutrient Inputs ◽  
P Release ◽  
Oxygen Conditions ◽  
Tightly Coupled ◽  
P Balance

Abstract. Internal phosphorus (P) loading from sediments, controlled by hypoxia, is often assumed to hamper the recovery of lakes and coastal areas from eutrophic conditions. We use a box-model to calculate seasonal and annual inputs, export, retention and internal cycling of P in the inner archipelago of Stockholm, Sweden (Baltic Sea) in 1968–2015. The area receives freshwater from Lake Mälaren and treated sewage from the greater Stockholm area. The sewage treatment plants (STPs) have improved their nutrient removal in steps, starting with P in 1972 and nitrogen in 1996. In the first 10–20 years after the main P load reduction in 1972–76, the model shows, in comparison to the load, a small negative annual P balance, probably due to release from legacy sediment P stores. The now stabilized, near neutral P balance indicates no continued internal loading from legacy P, but P retention is low, despite improved oxygen conditions. Seasonally, sediments are a P sink in spring and a P source in summer and autumn. Most of the deep-water P release from sediments in summer-autumn appears to be derived from the settled spring bloom and is exported during winter. Oxygen consumption and P release in the deep water are generally tightly coupled, indicating limited control by P binding to iron-oxyhydroxides under oxic conditions. However, in years of deep-water hypoxia enhanced P release suggest contribution from redox-sensitive P stores. The oxygen conditions in the area have generally improved, probably due both to lower sedimentation of organic matter from the 1970s and lower STP ammonium loads from the late 1990s. Increased oxygen inputs to the intermediate and deep waters due to weakened stratification and enhanced vertical mixing have probably also contributed, while increased respiration rates due to elevated bottom water temperatures probably explain worsened oxygen conditions during the 1990s. Since the P turnover time is short and legacy P minute, measures to bind P in Stockholm inner archipelago sediments would primarily accumulate P imported from the Baltic Sea and from Lake Mälaren inflow, and management here should focus on reducing external nutrient inputs.

scholarly journals A system for the determination of surface water pCO2 in a highly variable environment, exemplified in the southern Baltic Sea

Oceanologia ◽  
2021 ◽  
Vol 63 (2) ◽  
pp. 276-282
Author(s):  
Marcin Stokowski ◽  
Przemysław Makuch ◽  
Krzysztof Rutkowski ◽  
Marcin Wichorowski ◽  
Karol Kuliński
Keyword(s):  
Surface Water ◽  
Baltic Sea ◽  
Variable Environment ◽  
Southern Baltic Sea ◽  
Southern Baltic

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

2013 ◽  
Vol 10 (4) ◽  
pp. 2725-2735 ◽  
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.

scholarly journals Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes (MIS 9–14) and their implications for the thermohaline circulation

2010 ◽  
Vol 6 (4) ◽  
pp. 531-552 ◽  
Author(s):  
A. H. L. Voelker ◽  
T. Rodrigues ◽  
K. Billups ◽  
D. Oppo ◽  
J. McManus ◽  
...  
Keyword(s):  
Surface Water ◽  
North Atlantic ◽  
Current System ◽  
Middle Pleistocene ◽  
Boundary Current ◽  
Upwelling System ◽  
The North ◽  
Eastern Boundary ◽  
Stable Conditions ◽  
Hydrographic Conditions

Abstract. Stable isotope and ice-rafted debris records from three core sites in the mid-latitude North Atlantic (IODP Site U1313, MD01-2446, MD03-2699) are combined with records of ODP Sites 1056/1058 and 980 to reconstruct hydrographic conditions during the middle Pleistocene spanning Marine Isotope Stages (MIS) 9–14 (300–540 ka). Core MD03-2699 is the first high-resolution mid-Brunhes record from the North Atlantic's eastern boundary upwelling system covering the complete MIS 11c interval and MIS 13. The array of sites reflect western and eastern basin boundary current as well as north to south transect sampling of subpolar and transitional water masses and allow the reconstruction of transport pathways in the upper limb of the North Atlantic's circulation. Hydrographic conditions in the surface and deep ocean during peak interglacial MIS 9 and 11 were similar among all the sites with relative stable conditions and confirm prolonged warmth during MIS 11c also for the mid-latitudes. Sea surface temperature (SST) reconstructions further reveal that in the mid-latitude North Atlantic MIS 11c is associated with two plateaus, the younger one of which is slightly warmer. Enhanced subsurface northward heat transport in the eastern boundary current system, especially during early MIS 11c, is denoted by the presence of tropical planktic foraminifer species and raises the question how strongly it impacted the Portuguese upwelling system. Deep water ventilation at the onset of MIS 11c significantly preceded surface water ventilation. Although MIS 13 was generally colder and more variable than the younger interglacials the surface water circulation scheme was the same. The greatest differences between the sites existed during the glacial inceptions and glacials. Then a north – south trending hydrographic front separated the nearshore and offshore waters off Portugal. While offshore waters originated from the North Atlantic Current as indicated by the similarities between the records of IODP Site U1313, ODP Site 980 and MD01-2446, nearshore waters as recorded in core MD03-2699 derived from the Azores Current and thus the subtropical gyre. Except for MIS 12, Azores Current influence seems to be related to eastern boundary system dynamics and not to changes in the Atlantic overturning circulation.

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