scholarly journals Some effects of ultraviolet radiation and climate on the reproduction of Calanus finmarchicus (Copepoda) and year class formation in Arcto-Norwegian cod (Gadus morhua)

2005 ◽  
Vol 62 (7) ◽  
pp. 1293-1300 ◽  
Author(s):  
Stig Skreslet ◽  
Angel Borja ◽  
Luca Bugliaro ◽  
Georg Hansen ◽  
Ralf Meerkötter ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Gadus Morhua ◽  
Calanus Finmarchicus ◽  
Coastal Current ◽  
Group Index ◽  
In Situ Experiments ◽  
Reproduction Period ◽  
Norwegian Coastal Current ◽  
Positive Effect

AbstractZooplankton sampling in 1997 identified the frontal zone of the Norwegian Coastal Current as a reproduction habitat for Calanus finmarchicus in June–August. This area is subject to considerable ultraviolet radiation (UVR), as calculated from satellite observations of ozone and cloudiness. While in situ experiments indicated UVR-induced mortality in reproducing C. finmarchicus, monthly UVR doses during the actual reproduction period did not appear to affect the abundance of the resulting generation of adolescent copepodites (CIV-V) that accumulated in a fjord habitat during October 1983–2000. Local UVR in the spawning grounds of Arcto-Norwegian cod at the Lofoten Islands in March–May was positively correlated with the stock's 0-group index, which resulted in the rejection of the hypothesis that local UVR leads to high mortality of cod eggs or reduces the abundance of prey for cod larvae. Rather, the result suggests an indirect positive effect of UVR on the survival of cod eggs and larvae, possibly by controlling harmful microbes.

On the Variability in the Onset of the Norwegian Coastal Current

2018 ◽  
Vol 48 (3) ◽  
pp. 723-738 ◽  
Author(s):  
Kai Håkon Christensen ◽  
Ann Kristin Sperrevik ◽  
Göran Broström
Keyword(s):  
Remote Sensing ◽  
High Frequency ◽  
Conceptual Models ◽  
Sea Water ◽  
Surface Current ◽  
Wind Forcing ◽  
Coastal Current ◽  
Norwegian Coastal Current ◽  
Forcing Mechanisms

AbstractA high-resolution reanalysis of the circulation in the Kattegat and Skagerrak is used to investigate the mechanisms that control the variability in the onset of the Norwegian Coastal Current. In the reanalysis, the authors have used all available in situ and remote sensing observations of salinity and temperature and use surface current observations from two coastal high-frequency radars that were ideally placed to monitor the exchange between the two basins. This study finds a strong correlation between the variability in the wind forcing in the Skagerrak and the transport in the Norwegian Coastal Current through the Torungen–Hirtshals section. Two cases with winds into and out of the Skagerrak are studied in more detail, and the results suggest asymmetries in the forcing mechanisms. For winds out of the Skagerrak, strong outflows of Baltic Sea Water associated with a deflection of the Kattegat–Skagerrak Front may disrupt local processes in the Skagerrak, which is not accounted for in previously published conceptual models for the variability of the coastal currents in this region.

scholarly journals Norwegian Sea net community production estimated from O<sub>2</sub> and prototype CO<sub>2</sub> optode measurements on a Seaglider

Ocean Science ◽  
2021 ◽  
Vol 17 (2) ◽  
pp. 593-614
Author(s):  
Luca Possenti ◽  
Ingunn Skjelvan ◽  
Dariia Atamanchuk ◽  
Anders Tengberg ◽  
Matthew P. Humphreys ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
Coastal Current ◽  
Net Community Production ◽  
Norwegian Sea ◽  
Chl A ◽  
Summer Maximum ◽  
Norwegian Coastal Current ◽  
Community Production

Abstract. We report on a pilot study using a CO2 optode deployed on a Seaglider in the Norwegian Sea from March to October 2014. The optode measurements required drift and lag correction and in situ calibration using discrete water samples collected in the vicinity. We found that the optode signal correlated better with the concentration of CO2, c(CO2), than with its partial pressure, p(CO2). Using the calibrated c(CO2) and a regional parameterisation of total alkalinity (AT) as a function of temperature and salinity, we calculated total dissolved inorganic carbon content, c(DIC), which had a standard deviation of 11 µmol kg−1 compared with in situ measurements. The glider was also equipped with an oxygen (O2) optode. The O2 optode was drift corrected and calibrated using a c(O2) climatology for deep samples. The calibrated data enabled the calculation of DIC- and O2-based net community production, N(DIC) and N(O2). To derive N, DIC and O2 inventory changes over time were combined with estimates of air–sea gas exchange, diapycnal mixing and entrainment of deeper waters. Glider-based observations captured two periods of increased Chl a inventory in late spring (May) and a second one in summer (June). For the May period, we found N(DIC) = (21±5) mmol m−2 d−1, N(O2) = (94±16) mmol m−2 d−1 and an (uncalibrated) Chl a peak concentration of craw(Chl a) = 3 mg m−3. During the June period, craw(Chl a) increased to a summer maximum of 4 mg m−3, associated with N(DIC) = (85±5) mmol m−2 d−1 and N(O2) = (126±25) mmol m−2 d−1. The high-resolution dataset allowed for quantification of the changes in N before, during and after the periods of increased Chl a inventory. After the May period, the remineralisation of the material produced during the period of increased Chl a inventory decreased N(DIC) to (-3±5) mmol m−2 d−1 and N(O2) to (0±2) mmol m−2 d−1. The survey area was a source of O2 and a sink of CO2 for most of the summer. The deployment captured two different surface waters influenced by the Norwegian Atlantic Current (NwAC) and the Norwegian Coastal Current (NCC). The NCC was characterised by lower c(O2) and c(DIC) than the NwAC, as well as lower N(O2) and craw(Chl a) but higher N(DIC). Our results show the potential of glider data to simultaneously capture time- and depth-resolved variability in DIC and O2 concentrations.

Developmental differences and a test for reciprocity in the tolerance of Chaoborus punctipennis larvae to ultraviolet radiation

2005 ◽  
Vol 62 (3) ◽  
pp. 483-491 ◽  
Author(s):  
A D Persaud ◽  
N D Yan
Keyword(s):  
Ultraviolet Radiation ◽  
Stratospheric Ozone ◽  
Lethal Dose ◽  
Developmental Differences ◽  
Fourth Instar ◽  
In Situ Experiments ◽  
Chaoborus Punctipennis ◽  
Lethal Time ◽  
Abundance And Distribution

We estimated the ultraviolet radiation (UVR) tolerance of Chaoborus punctipennis in five 2- to 4-day in situ experiments conducted with third and fourth instar larvae at 0.25, 1.25, 3.0, and 5.0 m in Ruth Roy Lake, a lake with low dissolved organic carbon levels (0.2 mg·L–1). UVR tolerance increased with larval age. Third and late fourth instar LD50 (median lethal dose) ranged from 52.3 to 62.2 J·cm–2 and from 82.4 to 119.6 J·cm–2, respectively, among the four depths. Reciprocity held for UVR exposure down to 5.0 m, i.e., toxicity was independent of dose rate. At any given depth, the LT50 (median lethal time) increased with larval stage, but even at 5.0 m, third and late fourth instars died in less than 10 and 20 h, respectively, under sunny skies. These results suggest that Chaoborus abundance and distribution might be affected by UVR, especially in clear lakes. If UVR levels continue to increase in some lakes because of stratospheric ozone loss and climate change, we predict that UVR damage to Chaoborus will increase in the future, thereby affecting trophic interactions in temperate freshwater food webs.

scholarly journals Modeling the effects of ultraviolet radiation on embryos of Calanus finmarchicus and Atlantic cod (Gadus morhua ) in a mixing environment

2000 ◽  
Vol 45 (8) ◽  
pp. 1797-1806 ◽  
Author(s):  
Penny S. Kuhn ◽  
Howard I. Browman ◽  
Richard F. Davis ◽  
John J. Cullen ◽  
Bruce L. McArthur
Keyword(s):  
Ultraviolet Radiation ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Calanus Finmarchicus

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

A computer-control program for TEM in situ fatigue experiments

1989 ◽  
Vol 47 ◽  
pp. 620-621
Author(s):  
Kenneth S. Vecchio ◽  
John A. Hunt
Keyword(s):  
Slow Crack Growth ◽  
Computer Control ◽  
Control Program ◽  
Video Tape ◽  
Computer Control System ◽  
Transmission Electron ◽  
In Situ Experiments ◽  
Tremendous Amount ◽  
And Control

In-situ experiments conducted within a transmission electron microscope provide the operator a unique opportunity to directly observe microstructural phenomena, such as phase transformations and dislocation-precipitate interactions, “as they happen”. However, in-situ experiments usually require a tremendous amount of experimental preparation beforehand, as well as, during the actual experiment. In most cases the researcher must operate and control several pieces of equipment simultaneously. For example, in in-situ deformation experiments, the researcher may have to not only operate the TEM, but also control the straining holder and possibly some recording system such as a video tape machine. When it comes to in-situ fatigue deformation, the experiments became even more complicated with having to control numerous loading cycles while following the slow crack growth. In this paper we will describe a new method for conducting in-situ fatigue experiments using a camputer-controlled tensile straining holder.The tensile straining holder used with computer-control system was manufactured by Philips for the Philips 300 series microscopes. It was necessary to modify the specimen stage area of this holder to work in the Philips 400 series microscopes because the distance between the optic axis and holder airlock is different than in the Philips 300 series microscopes. However, the program and interfacing can easily be modified to work with any goniometer type straining holder which uses a penrmanent magnet motor.

Coliform transport in a pristine reservoir: modeling and field studies

1998 ◽  
Vol 37 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Elisa Garvey ◽  
John E. Tobiason ◽  
Michael Hayes ◽  
Evelyn Wolfram ◽  
David A. Reckhow ◽  
...  
Keyword(s):  
Model Development ◽  
Fate And Transport ◽  
Field Studies ◽  
Meteorological Conditions ◽  
Reservoir Modeling ◽  
Vertical Circulation ◽  
Quality Model ◽  
Circulation Patterns ◽  
In Situ Experiments

This paper reports on field studies and model development aimed at understanding coliform fate and transport in the Quabbin Reservoir, an oligotrophic drinking water supply reservoir. An investigation of reservoir currents suggested the importance of wind driven phenomena, and that both lateral and vertical circulation patterns exist. In-situ experiments of coliform decay suggested dependence on light intensity and yielded an appropriate decay coefficient to be used in CE-QUAL-W2, a two-dimensional hydrodynamic and water quality model. Modeling confirmed the sensitivity of reservoir outlet concentration to vertical variability within the reservoir, meteorological conditions, and location of coliform source.

scholarly journals Upscaling THM modeling from small-scale to full-scale in-situ experiments in the Callovo-Oxfordian claystone

2021 ◽  
Vol 144 ◽  
pp. 104582
Author(s):  
D.M. Seyedi ◽  
C. Plúa ◽  
M. Vitel ◽  
G. Armand ◽  
J. Rutqvist ◽  
...  
Keyword(s):  
Full Scale ◽  
Small Scale ◽  
In Situ Experiments

scholarly journals Memory Effect on a LDH/zeolite A Composite: An XRD In Situ Study

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2102
Author(s):  
Breno G. P. Bezerra ◽  
Lindiane Bieseki ◽  
Mariele I. S. de Mello ◽  
Djalma R. da Silva ◽  
Cristiane B. Rodella ◽  
...  
Keyword(s):  
Memory Effect ◽  
Inert Atmosphere ◽  
Effect Study ◽  
Physical Mixture ◽  
Zeolite A ◽  
Three Samples ◽  
In Situ Experiments ◽  
Double Hydroxide ◽  
Rehydration Process

In this memory effect study, hydrotalcite-type compounds in the lamellar double hydroxide-like (LDH)/zeolite A composite material were analyzed using X-Ray Diffration XRD) in situ experiments. Three samples were analyzed: Al,Mg-LDH, Al,Mg-LDH/ZA composite, and a physical mixture (50/50 wt%) of zeolite A and Al,Mg-LDH. The Al,Mg-LDH sample was treated at 500 °C in an O2 atmosphere and subsequently rehydrated. The Al,Mg-LDH/ZA composites had three treatments: one was performed at 300 °C in a He atmosphere, and two treatments were performed with an O2 atmosphere at 300 and 500 °C. In the physical mixture, two treatments were carried out under O2 flow at 500 °C and under He flow at 300 °C. Both went through the rehydration process. All samples were also analyzed by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The results show that the LDH phase in the Al,Mg-LDH/ZA compounds has memory effects, and thus, the compound can be calcined and rehydrated. For the LDH in the composite, the best heat treatment system is a temperature of 300 °C in an inert atmosphere.

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