scholarly journals PCBs and organochlorine pesticides in phytoplankton and zooplankton in the Indian sector of the Southern Ocean

1991 ◽  
Vol 3 (4) ◽  
pp. 371-377 ◽  
Author(s):  
Claude R. Joiris ◽  
William Overloop
Keyword(s):  
Particulate Matter ◽  
Southern Ocean ◽  
North Sea ◽  
Dry Weight ◽  
Weight Basis ◽  
The North ◽  
The North Sea ◽  
Contamination Levels ◽  
The Antarctic ◽  
Indian Sector

Samples of phyto- and zooplankton were collected in the Indian sector of the Southern Ocean (38–67°S, 18–84°E) and analysed for organochlorine residues (PCBs and pesticides). The PCB concentration in particulate matter (mainly phytoplankton) appeared to be high and similar to that of temperate zones: 0.7 μg g−1 dry weight. Contamination levels were more constant expressed per water volume than per dry weight, and seven times lower (1.2 μg m−3) than in northern temperate zones (8.8 μm−3 in the North Sea). The Antarctic ecosystems are thus less contaminated than temperate ones — as expected — but the very low phytoplankton biomass present cause high PCB levels per unit of biomass. These results confirm the necessity of using different systems of units in order to correctly express the contamination levels and to identify the main mechanisms responsible for the accumulation of stable pollutants. PCB levels in netplankton samples (mainly zooplankton) were comparable with phytoplankton on a dry weight basis (0.7 μm−3), lower on a lipid weight basis (5.8 μg g−1 lw for netplankton, 16.3 for particulate matter) and were much higher per seawater volume (27.2 μg m−3 for netplankton, 1.2 for particulate matter). Netplankton contamination is comparable in the Antarctic (0.35 μg g−1 dw) and the North Sea (0.70) since zooplankton feeding on phytoplankton has similar levels of contamination in both ecosystems. Lindane, heptachlor epoxide, dieldrin, DDE and DDT were observed in various samples at trace levels. The high DDE/DDT ratio reflects the more recent origin of Antarctic organochlorines.

scholarly journals The Size of Diatoms II. Further Observations on Rhizosolenia styliformis (Brightwell)

1946 ◽  
Vol 26 (3) ◽  
pp. 271-284 ◽  
Author(s):  
R. S. Wimpenny
Keyword(s):  
North Sea ◽  
Indicator Species ◽  
Separate Species ◽  
Southern North Sea ◽  
Auxospore Formation ◽  
The North ◽  
The North Sea ◽  
Set Up ◽  
The Antarctic

1. Diameter measurements of Rhizosolenia styliformis from the Antarctic, the subtropical Atlantic and Pacific Oceans and from the North Sea and neighbouring waters have made it appear necessary to set up two varieties, oceanica and semispina, in addition to the type of the species R. styliformis. The type as I describe it has been called var. longispina by Hustedt, but elsewhere it has often been figured as the var. oceanica of this paper. Var. semispina is synonymous with the form represented by Karsten as R. semispina Hensen. It differs from R. semispina as drawn by Hensen and its synonym R. hebetata forma semispina Gran, but is thought likely to be linked by intermediates. If this is so R. hebetata may have to be extended to include and suppress R. styliformis, as var. semispina is linked to the type by intermediates. Var. oceanica has no intermediate forms and, if R. hebetata is to be extended, this variety should be established as a separate species.2. Var. oceanica is absent from the southern North Sea and appears to be an indicator species related to oceanic inflow.3. Auxospore formation was observed for the type in the southern North Sea in 1935 and biometric observations suggest that a period of 3-4 years elapsed between the production of auxospore generations in that area. Outside the southern North Sea for the type, measurements give no indication of auxospore generations occurring at intervals exceeding a year. While auxospore formation has been seen in var. oceanica from the Shetlands area samples of June 1935 and July 1938, this phenomenon has not been observed for var. semispina.

scholarly journals Association of Marine Archaea with the Digestive Tracts of Two Marine Fish Species

1998 ◽  
Vol 64 (8) ◽  
pp. 2894-2898 ◽  
Author(s):  
Marc J. E. C. van der Maarel ◽  
Rebekka R. E. Artz ◽  
René Haanstra ◽  
Larry J. Forney
Keyword(s):  
Particulate Matter ◽  
North Sea ◽  
Suspended Particulate Matter ◽  
Archaeal Community ◽  
Grey Mullet ◽  
The North ◽  
Suspended Particulate ◽  
The North Sea ◽  
Group Ii ◽  
Marine Archaea

ABSTRACT Recent studies have shown that archaea which were always thought to live under strict anoxic or extreme environmental conditions are also present in cold, oxygenated seawater, soils, the digestive tract of a holothurian deep-sea-deposit feeder, and a marine sponge. In this study, we show, by using PCR-mediated screening in other marine eukaryotes, that marine archaea are also present in the digestive tracts of flounder and grey mullet, two fish species common in the North Sea, in fecal samples of flounder, and in suspended particulate matter of the North Sea water column. No marine archaea could be detected in the digestive tracts of mussels or the fecal pellets of a copepod species. The archaeal 16S ribosomal DNA clone libraries of feces of flounder and the contents of the digestive tracts of grey mullet and flounder were dominated by group II marine archaea. The marine archaeal clones derived from flounder and grey mullet digestive tracts and feces formed a distinct cluster within the group II marine archaea, with 76.7 to 89.8% similarity to previously described group II clones. Fingerprinting of the archaeal community of flounder digestive tract contents and feces by terminal restriction fragment length polymorphism of archaeal 16S rRNA genes after restriction withHhaI showed a dominant fragment at 249 bp, which is likely to be derived from group II marine archaea. Clones of marine archaea that were closely related to the fish-associated marine archaea clones were obtained from suspended particulate matter of the water column at two stations in the North Sea. Terminal restriction fragment length polymorphism fingerprinting of the archaeal community present in suspended particulate matter showed the same fragment pattern as was found for the archaeal community of the flounder digestive tract contents and feces. These data demonstrate that marine archaea are present in the digestive tracts and feces of very common marine fish. It is possible that the marine archaea associated with the digestive tracts of marine fish are liberated into the water column through the feces and subsequently contribute to the marine archaeal community of suspended particulate matter.

The Macrobenthic Infauna of the Offshore Northern North Sea

1989 ◽  
Vol 69 (1) ◽  
pp. 123-143 ◽  
Author(s):  
A. Eleftheriou ◽  
D.J. Basford
Keyword(s):  
North Sea ◽  
Dry Weight ◽  
Fine Sand ◽  
Surface Deposit ◽  
Number Of Species ◽  
The North ◽  
Deposit Feeders ◽  
The North Sea ◽  
Northern North Sea ◽  
Deposit Feeding

Between 1980 and 1985 ninety-seven stations were sampled by Smith-Mclntyre grab from the offshore northern section of the North Sea. Four hundred and nine infaunal species were identified from the 76 selected macrofaunal stations. The number of species per station varied from 25 to 80 with a maximum abundance of 9,600 individuals m−2. The biomass ranged from 0.13 to 18.86 g dry weight m−2. At most stations, however, biomass varied between 1 and 4 g dry weight m−2. Diversity and abundance were highest in the 120–140 m zone, characterised by fine sand containing variable amounts of silt. The highest biomasses were recorded in two areas; firstly where stronger currents predominate and the sediments are coarser (east of Shetland and west of the Norwegian Trough), and secondly in the fine sandy deposits of the centrally located area. In the silty sediments (Fladen Ground and smaller depressions) there was a predominantly subsurface deposit-feeding community, whereas in the coarser area east of the Shetlands carnivores predominated. Over the remaining area surface deposit feeders were dominant.

Determination of 206/207Pb isotope ratios by ICP-MS in particulate matter from the north sea environment

1993 ◽  
Vol 347 (8-9) ◽  
pp. 324-329 ◽  
Author(s):  
P. Krause ◽  
M. Kriews ◽  
W. Dannecker ◽  
C.-D. Garbe-Sch�nberg ◽  
M. Kersten
Keyword(s):  
Particulate Matter ◽  
North Sea ◽  
Isotope Ratios ◽  
The North ◽  
Icp Ms ◽  
The North Sea

scholarly journals The Seasonal Variation in Biological Composition of Certain Plankton Samples from the North Sea in Relation to their Content of Vitamin A, Carotenoids, Chlorophyll, and Total Fatty Matter

1939 ◽  
Vol 16 (1) ◽  
pp. 71-88
Author(s):  
A. E. GILLAM ◽  
M. S. EL RIDI ◽  
R. S. WIMPENNY
Keyword(s):  
Seasonal Variation ◽  
Vitamin A ◽  
North Sea ◽  
Chemical Constituents ◽  
Dry Weight ◽  
Biological Study ◽  
Total Carotenoids ◽  
The North ◽  
The North Sea ◽  
Total Fatty Matter

A combined chemical and biological study of the plankton of the southern North Sea has been made. Three vertical hauls, with a Hensen net (silk cone, 60 meshes to the inch) were taken at six positions between Flamborough Head and the South-West Patch of the Dogger Bank, monthly from January to November 1936. One haul was used for biological examination, the second for determinations of percentage of ether-soluble matter and the third to determine carotenoids, chlorophyll, vitamin A and total solids. The biological results showed that the total plankton depended on three diatom outbursts, the largest in May, another little inferior in numbers in August, and a small one in October. Peridinians and the zooplankton occurred successively in relatively greater numbers with each outburst, but reached their maximum in August when the mass of the plankton was at its greatest. Carotene, chlorophyll and vitamin A were definitely detected in the gross plankton extracts, whilst positive tests for fucoxanthin were only obtained on a few isolated occasions. An examination of a large phytoplankton sample (obtained by tow net) containing Rhizosolenia styliformis and Biddulphia sinensis only, showed that no vitamin A as such was present. Carotene and xanthophyll, however, were present, in the ratio of 1 : 1.82, which is comparable with the ratio typical of land plants. Total carotenoids equalled 0.1% calculated on dry weight. Of the chemical constituents the seasonal variation of chlorophyll most nearly coincided with the total mass of the plankton. The carotenoids reached their peak slightly before the maximal biological development, whilst the vitamin A content reached its maximum in the month after the spring diatom outburst and much preceded the maximum for the plankton crop as sampled by the Hensen net.

Removal of Topside Units in a Single Lift: The Repsol Yme Field Case Study

2018 ◽  
Author(s):  
Beatriz Alonso Castro ◽  
Terje Birkenes ◽  
Huib Oosterveld
Keyword(s):  
North Sea ◽  
Ballast Water ◽  
Structural Integrity ◽  
Dry Weight ◽  
The North ◽  
Offshore Installations ◽  
Safety And Health ◽  
The North Sea ◽  
The Uk ◽  
Water Tanks

Decommissioning is an emerging sector in the UK and Norway, accounting for 2% of total industry expenditure in 2010 increasing to 8% in 2017. In accordance with existing regulations in the North Sea (OSPAR), dumping, and leaving wholly or partly in place disused offshore installations within the maritime area is prohibited. Over the next eight years, 200 platforms are expected to be removed in the North Sea. There are a number of methods to remove offshore installations: Piece small, Reverse installation and Single lift. In the Single lift approach the jacket or the topside is removed in one piece, minimizing significantly the time offshore and therefore the safety and health incidents. But the Piece Small and Reverse Installation are the most common methods and are established and secure although are time consuming and labor intensive [1]. Several potential candidates for single lift technology at varying levels of technical readiness were considered in the past. The majority of the concepts remained on the drawing board, while some were awaiting project commitment. The only that was matured further than this is the Pioneering Spirit. Yme, its first commercial lift, gave this concept the “proven” status. The Yme MOPU, owned by Repsol, was a jack-up type platform standing on three steel legs of 3.5 m diameter. The dry weight of the MOPU was approximately 13,500 t. The Yme MOPU was a challenging unit to remove mainly for three reasons: The platform motions due to the lack of stiffness in the leg support, its position in contact with the caisson wellhead platform, and the fact that the legs could not be pre-cut before the operation. The method selected to remove the platform was Single lift, using the dynamically positioned platform installation and removal vessel Pioneering Spirit. The lifting arrangement consisted of 12 lift beams combined and connected in pairs to yokes. Five specifically designed yokes were installed. The yokes connect the TLS with the MOPU. The structural integrity of each interface was assessed with FE analysis. The Ballast system was used to provide additional clearance. Pioneering Spirit has a total of eighty-seven ballast water tanks, including four so called ‘Quick Drop Ballast Water Tanks’. The removal of the MOPU was performed successfully the 22nd August 2016, after two days work offshore.

scholarly journals Turbulent Mixing due to Surface Waves Indicated by Remote Sensing of Suspended Particulate Matter and Its Implementation into Coupled Modeling of Waves, Turbulence, and Circulation

2011 ◽  
Vol 41 (4) ◽  
pp. 708-724 ◽  
Author(s):  
Andrey Pleskachevsky ◽  
Mikhail Dobrynin ◽  
Alexander V. Babanin ◽  
Heinz Günther ◽  
Emil Stanev
Keyword(s):  
Particulate Matter ◽  
Surface Waves ◽  
North Sea ◽  
Suspended Particulate Matter ◽  
Turbulent Mixing ◽  
Satellite Observations ◽  
Mean Flow ◽  
The North ◽  
Suspended Particulate ◽  
The North Sea

Abstract This paper studies the impact of the surface waves on the turbulent mixing. The satellite observations of suspended particulate matter (SPM) at the ocean surface as an indicator of turbulent quantities of the flow are used. In a water column, SPM builds a vertical profile depending on settling velocities of the particles and on vertical mixing processes; thus, SPM is a perfect marker to study the turbulent quantities of the flow. Satellite observations in the North Sea show that surface SPM concentrations, in locations of its deposition, grow rapidly and build plume-shaped, long (many kilometers) uninterrupted and consistent structures during a storm. Also, satellites reveal that SPM rapidly sinks to the seabed after the storm peak has passed and wave height decreases (i.e., in the absence of strong turbulence). The nonbreaking wave-induced turbulence has been discussed, parameterized, and implemented into an equation of evolution of turbulent kinetic energy (TKE) in the frame of mean-flow concept, which can be used in existing circulation models. The ratio between dissipated and total wave energy is used to describe the influence of wave damping on the mean flow. The numerical tests reproduce experiments in a wave tank very well and are supported by observations of SPM in the North Sea. Their results show that the motion of an individual nonbreaking wave includes turbulent fluctuations if the critical Reynolds number for wave motion is exceeded, independent of the presence of currents due to wind or tides. These fluctuations can produce high diffusivity and strongly influence mixing in the upper water layer of the ocean.

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