Linked sediment and water-column methanotrophy at a man-made gas blowout in the North Sea: Implications for methane budgeting in seasonally stratified shallow seas

The Elbe is the largest river entering the German Bight. Its estuary is a heavily used waterway connecting the sea to Germany&#8217;s biggest port in Hamburg. The Elbe navigation channel is continuously dredged, and agricultural fertilizer input from the catchment ensuing large phytoplankton blooms in the river Elbe exerts additional anthropogenic pressure. Biogeochemistry in the estuary is additionally governed by the North Sea and its strong tidal cycles, which ensure an exchange of fresh and marine waters.The aims were to quantify the release of the carbon species total alkalinity (TA) and dissolved inorganic carbon (DIC) along the Elbe estuary, and to estimate the contribution of aerobe and anaerobe metabolic processes. Therefore, we used water samples collected continuously during a cruise in June 2019, to measure TA and DIC, and the stable isotopes of nitrate. We applied mass balances, to characterize the metabolic activity and detect their effect on the carbon speciesThe Elbe estuary could be subdivided into two parts: 1) an outer marine driven part, which is dominated by conservative mixing, also visible in higher TA than DIC values, and 2) an inner fresh water part in which metabolic processes play an important role.We found a strong increase in TA and DIC (several hundred &#181;mol kg-1) in the Hamburg port area, with higher DIC than TA values. We unraveled the water column impacts of nitrification and denitrification on TA and DIC by analyzing the stable isotopes &#948;15N-NO3- and &#948;18O-NO3-, and identified water column nitrification as a dominant pelagic process in the port of Hamburg and in the fresh water part further downstream. Because nitrification cannot explain the significant increase of TA and DIC in the port region, anaerobic processes such as denitrification in the sediment also appear to play an important role.&#160;

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Modelling water column processes in the North Sea

Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences ◽

10.1098/rsta.1993.0062 ◽

1993 ◽

Vol 343 (1669) ◽

pp. 509-517 ◽

Cited By ~ 6

Keyword(s):

Water Column ◽

North Sea ◽

Process Water ◽

Phytoplankton Dynamics ◽

Annual Cycles ◽

The North ◽

Field Investigations ◽

Southern Central ◽

The North Sea ◽

Northern North Sea

In the North Sea advective transports are not negligible. Nevertheless, physical properties like sea surface temperature (SST) can be hindcasted with sufficient precision by vertical process water column models. Annual cycles of SST in the southern, central, and northern North Sea can be simulated using physical upper layer models with relatively small RMS errors. For the Fladenground Experiment (FLEX’76) in the northern North Sea the RMS error is less 0.3 °C for the 2 months of the experiment. This justifies the initial use, at least, of vertical process water column models in simulations for investigating transfer processes in the planktonic ecosystem. Experiments have shown that the simulated entrainment velocities at the bottom of the mixed layer during summer are critically dependent on the resolution of the forcing variables. The effects of this resolution on the annual phytoplankton dynamics will be discussed. Phytoplankton dynamics are strongly influenced by those of the zooplankton, and vice versa. Several field investigations have shown that, seemingly, phytoplankton cannot sustain the observed stock of zooplankton in the northern North Sea: there exists a gap between the abundance of phytoplankton and the need for it to maintain the zooplankton. Revisiting FLEX’76, the simulations with water column models of increasing complexity concerning detritus suggest that pelagic detritus can fill the gap in food availability for the zooplankton. If it is assumed that the zooplankton feeds also on detritus, the zooplankton experiences no food shortage.

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Vertical distribution of pre-settled sandeel (Ammodytes marinus) in the North Sea in relation to size and environmental variables

ICES Journal of Marine Science ◽

10.1016/s1054-3139(03)00150-4 ◽

2003 ◽

Vol 60 (6) ◽

pp. 1342-1351 ◽

Cited By ~ 14

Author(s):

Henrik Jensen ◽

Peter J Wright ◽

Peter Munk

Keyword(s):

Vertical Distribution ◽

Water Column ◽

North Sea ◽

Distribution Patterns ◽

Food Concentration ◽

The North ◽

Vertical Distributions ◽

The North Sea ◽

Drift Trajectory ◽

Vertical Positioning

Abstract Vertical distribution patterns of larval and juvenile sandeels were investigated at four locations in the North Sea. Sandeels between 6 and 65 mm were found to depths of 80 m, with vertical distributions dependent on both length and environmental factors. At one location with a stratified water column, the highest densities were found during the day in midwater where food concentration was also highest. In areas without marked vertical hydrographic gradients, larvae were relatively more abundant in surface waters during the day. At all locations, larvae of all sizes were generally more homogeneously distributed in the water column during night than during day. The extent of vertical migration, as measured by the standard deviation of the mean depth, increased generally with length. Gear avoidance was evident for larvae ≥20 mm. Catch efficiency generally depended on both length class and surface light intensity. A simulated drift pattern of larvae, based on ADCP current measurements from two locations, predicts that the horizontal drift trajectory would only be affected slightly by the vertical positioning of the larvae in the water column during the time of sampling. The implication of vertical migrations for dispersal of larvae away from the spawning grounds is discussed.

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Radium isotopes as a tracer of sediment-water column exchange in the North Sea

Global Biogeochemical Cycles ◽

10.1002/2014gb004825 ◽

2014 ◽

Vol 28 (8) ◽

pp. 786-804 ◽

Cited By ~ 15

Author(s):

W. J. Burt ◽

H. Thomas ◽

J. Pätsch ◽

A. M. Omar ◽

C. Schrum ◽

...

Keyword(s):

Water Column ◽

North Sea ◽

Radium Isotopes ◽

The North ◽

The North Sea

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A comparative study of manganese dynamics in the water column and sediments of intertidal systems of the North Sea

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2011.03.011 ◽

2012 ◽

Vol 100 ◽

pp. 3-17 ◽

Cited By ~ 36

Author(s):

Nicole Kowalski ◽

Olaf Dellwig ◽

Melanie Beck ◽

Maik Grunwald ◽

Claus-Dieter Dürselen ◽

...

Keyword(s):

Comparative Study ◽

Water Column ◽

North Sea ◽

The North ◽

The North Sea

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Modelling water column processes in the North Sea

Understanding the North Sea System ◽

10.1007/978-94-011-1236-9_10 ◽

1994 ◽

pp. 131-139 ◽

Cited By ~ 2

Author(s):

G. Radach ◽

M. Regener ◽

F. Carlotti ◽

W. Kühn ◽

A. Moll

Keyword(s):

Water Column ◽

North Sea ◽

The North ◽

The North Sea

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Modeling SPM in Shallow Seas: The North Sea

10.1142/9789811243639_0014 ◽

2021 ◽

pp. 415-445

Keyword(s):

North Sea ◽

The North ◽

The North Sea ◽

Shallow Seas

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Seasonal fluxes across the sediment-water interface, and processes within sediments

Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences ◽

10.1098/rsta.1993.0063 ◽

1993 ◽

Vol 343 (1669) ◽

pp. 519-529 ◽

Cited By ~ 24

Keyword(s):

Water Column ◽

North Sea ◽

Net Primary Production ◽

Nutrient Recycling ◽

Clay Fraction ◽

Central Area ◽

Water Interface ◽

Vertical Profiles ◽

The North ◽

The North Sea

Measurements of oxygen uptake across the sediment-water interface suggested that between 17-45% of the net primary production in the southern North Sea was degraded in the bottom sediments. Similar measurements of nutrient exchange fluxes showed that the sediments were significant sources of nutrients transferred to the water column. The sediments are, therefore, important sites of organic matter degradation and nutrient recycling, and must be included in any models for the North Sea. The sediments are also accumulators of radionuclides, particularly associated with the silt/clay fraction. At one site in the more central area of the North Sea where the water column stratifies during summer, vertical profiles of radionuclides ( 137 Cs, 239,240 Pu, 210 Pb) suggested a deposition rate of sediment of 0.3-0.6 cm a -1 , but at other sites vertical sediment profiles were unsuitable to measure deposition.

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