Dissolved and particulate trace metals in surface waters over the Dogger Bank, Central North Sea

1991 ◽  
Vol 22 (5) ◽  
pp. 241-244 ◽  
Author(s):  
Catherine F. Fileman ◽  
M. Althaus ◽  
R.J. Law ◽  
I. Haslam
Keyword(s):  
Trace Metals ◽  
North Sea ◽  
Surface Waters ◽  
Dogger Bank ◽  
Central North Sea

Methane emissions from abandoned offshore wells– First data from a 2019 research cruise to the Dogger Bank, German North Sea

2020 ◽  
Author(s):  
Martin Blumenberg ◽  
Stefan Schlömer ◽  
Miriam Römer ◽  
Katja Heeschen ◽  
Hendrik Müller ◽  
...  
Keyword(s):  
Water Column ◽  
North Sea ◽  
Water Depth ◽  
Deep Water ◽  
Carbon Dioxide Emissions ◽  
Oil And Gas ◽  
Methane Emissions ◽  
Shallow Gas ◽  
Dogger Bank ◽  
Central North Sea

<p>Methane is the second most important greenhouse gas and, considering a period of 100 years, has a more than 30 times higher “global warming potential” than carbon dioxide. Emissions from the production, storage, distribution and use of fossil energy resources in recent years sum up to about 15 % of global methane emissions with numbers still being under discussion and topic of numerous research programs.</p><p>Abandoned oil and gas wells are one of the sources of methane from the oil and gas sector. Recent studies found escaping methane at selected abandoned drill holes in the central North Sea. Assuming this would hold for one third of the ~11.000 wells in the region, the process would introduce significant amounts of methane at shallow water depth. Interestingly, the collected methane was of biogenic rather than thermogenic origin, potentially escaping from shallow gas pockets. Likely, this methane was mobilized by mechanical disturbance of the sediments through the drilling operation and the well section has served as a pathway thereafter. However, little is known about the number of wells affected and the relevance for the amounts of methane realeased.</p><p>During a research cruise with the German research vessel Heincke in July, 2019, we studied seafloor characteristics, water column anomalies and sediment methane geochemistry and further inspected visually nine abandoned well sites at ~40 m water depth in the German sector of the central North Sea (Dogger Bank). The cruise targeted different situations, including known seeps in the Dutch part of the Dogger Bank, well sites of different ages and an area where abandoned wells penetrate shallow gas pockets. First data demonstrate that at none of the studied sites concentrations of dissolved methane were enriched in the upper water column. For most sites, sediment and deep water methane data demonstrate concentrations in the range known as background for that area (i.e., deep water methane close to ~ 10 nM). At one site with high indications for the presence of shallow gas pockets, we observed methane abundances several times enriched compared to background. However, the enrichments also occurred 500 m away from the drill site and did not increase towards the center. Based on our data we argue for an active natural seep situation rather than a leaking well and underline that natural seeps may challenge the identification of potentially leaking wells.</p>

scholarly journals Spatiotemporal variations of <i>f</i>CO<sub>2</sub> in the North Sea

Ocean Science ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 77-89 ◽  
Author(s):  
A. M. Omar ◽  
A. Olsen ◽  
T. Johannessen ◽  
M. Hoppema ◽  
H. Thomas ◽  
...  
Keyword(s):  
North Sea ◽  
Surface Waters ◽  
Phytoplankton Bloom ◽  
Co2 Exchange ◽  
Atmospheric Co2 ◽  
Total Alkalinity ◽  
Spatiotemporal Variations ◽  
The North ◽  
The North Sea ◽  
Central North Sea

Abstract. Data from two Voluntary Observing Ship (VOS) (2005–2007) augmented with data subsets from ten cruises (1987–2005) were used to investigate the spatiotemporal variations of the CO2 fugacity in seawater (fCO2sw) in the North Sea at seasonal and inter-annual time scales. The observed seasonal fCO2sw variations were related to variations in sea surface temperature (SST), biology plus mixing, and air-sea CO2 exchange. Over the study period, the seasonal amplitude in fCO2sw induced by SST changes was 0.4–0.75 times those resulting from variations in biology plus mixing. Along a meridional transect, fCO2sw normally decreased northwards (−12 μatm per degree latitude), but the gradient disappeared/reversed during spring as a consequence of an enhanced seasonal amplitude of fCO2sw in southern parts of the North Sea. Along a zonal transect, a weak gradient (−0.8 μatm per degree longitude) was observed in the annual mean fCO2sw. Annually and averaged over the study area, surface waters of the North Sea were CO2 undersaturated and, thus, a sink of atmospheric CO2. However, during summer, surface waters in the region 55.5–54.5° N were CO2 supersaturated and, hence, a source for atmospheric CO2. Comparison of fCO2sw data acquired within two 1°×1° regions in the northern and southern North Sea during different years (1987, 2001, 2002, and 2005–2007) revealed large interannual variations, especially during spring and summer when year-to-year fCO2sw differences (≈160–200 μatm) approached seasonal changes (≈200–250 μatm). The springtime variations resulted from changes in magnitude and timing of the phytoplankton bloom, whereas changes in SST, wind speed and total alkalinity may have contributed to the summertime interannual fCO2sw differences. The lowest interannual variation (10–50 μatm) was observed during fall and early winter. Comparison with data reported in October 1967 suggests that the fCO2sw growth rate in the central North Sea was similar to that in the atmosphere.

scholarly journals How understanding past landscapes might inform present-day site investigations: a case study from Dogger Bank, southern central North Sea

2017 ◽  
Vol 15 (4) ◽  
pp. 403-414 ◽  
Author(s):  
Carol Cotterill ◽  
Emrys Phillips ◽  
Leo James ◽  
Carl-Fredrik Forsberg ◽  
Tor Inge Tjelta
Keyword(s):  
North Sea ◽  
Dogger Bank ◽  
Site Investigations ◽  
Southern Central ◽  
Central North Sea

Identifying Sources of Sulfate Aerosols Reaching Whiteface Mountain, NY

1985 ◽  
Vol 43 ◽  
pp. 98-101
Author(s):  
James S. Webber
Keyword(s):  
Trace Metals ◽  
Acid Deposition ◽  
Surface Waters ◽  
Dry Deposition ◽  
Coal Combustion ◽  
Public Awareness ◽  
Sulfate Aerosols ◽  
Wet And Dry Deposition ◽  
Whiteface Mountain ◽  
Toxic Trace Metals

INTRODUCTION“Acid rain” and “acid deposition” are terms no longer confined to the lexicon of atmospheric scientists and 1imnologists. Public awareness of and concern over this phenomenon, particularly as it affects acid-sensitive regions of North America, have increased dramatically in the last five years. Temperate ecosystems are suffering from decreased pH caused by acid deposition. Human health may be directly affected by respirable sulfates and by the increased solubility of toxic trace metals in acidified waters. Even man's monuments are deteriorating as airborne acids etch metal and stone features.Sulfates account for about two thirds of airborne acids with wet and dry deposition contributing equally to acids reaching surface waters or ground. The industrial Midwest is widely assumed to be the source of most sulfates reaching the acid-sensitive Northeast since S02 emitted as a byproduct of coal combustion in the Midwest dwarfs S02 emitted from all sources in the Northeast.

A new parameter set for anisotropic multiparameter full-waveform inversion and application to a North Sea data set

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. U25-U38 ◽  
Author(s):  
Nuno V. da Silva ◽  
Andrew Ratcliffe ◽  
Vetle Vinje ◽  
Graham Conroy
Keyword(s):  
North Sea ◽  
Waveform Inversion ◽  
Real Data ◽  
Model Parameters ◽  
Full Waveform Inversion ◽  
Radiation Patterns ◽  
Data Set ◽  
Full Waveform ◽  
Seismic Image ◽  
Central North Sea

Parameterization lies at the center of anisotropic full-waveform inversion (FWI) with multiparameter updates. This is because FWI aims to update the long and short wavelengths of the perturbations. Thus, it is important that the parameterization accommodates this. Recently, there has been an intensive effort to determine the optimal parameterization, centering the fundamental discussion mainly on the analysis of radiation patterns for each one of these parameterizations, and aiming to determine which is best suited for multiparameter inversion. We have developed a new parameterization in the scope of FWI, based on the concept of kinematically equivalent media, as originally proposed in other areas of seismic data analysis. Our analysis is also based on radiation patterns, as well as the relation between the perturbation of this set of parameters and perturbation in traveltime. The radiation pattern reveals that this parameterization combines some of the characteristics of parameterizations with one velocity and two Thomsen’s parameters and parameterizations using two velocities and one Thomsen’s parameter. The study of perturbation of traveltime with perturbation of model parameters shows that the new parameterization is less ambiguous when relating these quantities in comparison with other more commonly used parameterizations. We have concluded that our new parameterization is well-suited for inverting diving waves, which are of paramount importance to carry out practical FWI successfully. We have demonstrated that the new parameterization produces good inversion results with synthetic and real data examples. In the latter case of the real data example from the Central North Sea, the inverted models show good agreement with the geologic structures, leading to an improvement of the seismic image and flatness of the common image gathers.

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