Would adding scallop shells (Chlamys islandica) to the sea bottom enhance recruitment of commercial species?

The purposes of this study were to determine the variability of temperature and its relation to regional processes in the Senunu Bay. The result showed clear vertical stratifications i.e., mixed layer thickness about 39-119 m with isotherm of 27°C, thermocline layer thickness about 83-204 m with isotherm of 14–26°C, and the deeper layer from the thermocline lower limit to the sea bottom with isotherm <13°C. Temperature and the thickness of each layers varied with season in which during the Northwest Monsoon the temperature was warmer and the mixed layer was thicker than those during Southeast Monsoon. During Southeast Monsoon, the thermocline layer rose about 24 m. The 2001, 2006, and 2009 (weak La Nina years), the Indonesia Throughflow (ITF) carried warmer water, deepening thermocline depth and reducing upwelling strength. In 2003 and 2008 thickening of mixed layer occurred in transition season was believed associated with the arrival of Kelvin Wave from the west. In 2002 and 2004 (weak El Nino period,) ITF carries colder water shallowing thermocline depth and enhancing upwelling strength. In 2007 was believed to be related with positive IODM where the sea surface temperature were decreasing due to intensification of southeast wind which induced strong upwelling. The temperature spectral density of mixed layer and thermocline was influenced by annual, semi-annual, intra-annual and inter-annual period fluctuations. The cross-correlation between wind and temperature showed significant value in the annual period. Keywords: temperature, thermocline, variability, ENSO, IODM.

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Investigations of past climate and sea-ice variability in the fjord area by Station Nord, eastern North Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/geusb.v35.4941 ◽

1969 ◽

Vol 35 ◽

pp. 67-70 ◽

Cited By ~ 2

Author(s):

Niels Nørgaard-Pedersen ◽

Sofia Ribeiro ◽

Naja Mikkelsen ◽

Audrey Limoges ◽

Marit-Solveig Seidenkrantz

Keyword(s):

Sea Ice ◽

Outer Part ◽

Late Summer ◽

Field Work ◽

The Arctic ◽

Research Station ◽

Fjord System ◽

Sea Bottom ◽

Satellite Radar ◽

North Greenland

The marine record of the Independence–Danmark fjord system extending out to the Wandel Hav in eastern North Greenland (Fig. 1A) is little known due to the almost perennial sea-ice cover, which makes the region inaccessible for research vessels (Nørgaard-Pedersen et al. 2008), and only a few depth measurements have been conducted in the area. In 2015, the Villum Research Station, a new logistic base for scientific investigations, was opened at Station Nord. In contrast to the early exploration of the region, it is now possible to observe and track the seasonal character and changes of ice in the fjord system and the Arctic Ocean through remote sensing by satellite radar systems. Satellite data going back to the early 1980s show that the outer part of the Independence–Danmark fjord system is characterised by perennial sea ice whereas both the southern part of the fjord system and an area 20–30 km west of Station Nord are partly ice free during late summer (Fig. 1B). Hence, marine-orientated field work can be conducted from the sea ice using snow mobiles, and by drilling through the ice to reach the underlying water and sea bottom.

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ИССЛЕДОВАНИЯ АКУСТИЧЕСКИХ ХАРАКТЕРИСТИК ВЕРХНЕГО СЛОЯ МОРЯ МЕТОДОМ МНОГОЧАСТОТНОГО АКУСТИЧЕСКОГО ЗОНДИРОВАНИЯ

Podvodnye issledovaniia i robototehnika ◽

10.37102/24094609.2020.31.1.006 ◽

2020 ◽

Author(s):

V.A. Bulanov ◽

I.V. Korskov ◽

A.V. Storozhenko ◽

S.N. Sosedko

Keyword(s):

High Frequency ◽

Wave Motion ◽

High Spatial Resolution ◽

Wind Waves ◽

Acoustic Parameter ◽

Sea Surface ◽

Near Surface ◽

Acoustical Properties ◽

Acoustic Spectroscopy ◽

Sea Bottom

Описано применение акустического зондирования для исследования акустических характеристик верхнего слоя моря с использованием широкополосных остронаправленных инвертированных излучателей,устанавливаемых на дно. В основу метода положен принцип регистрации обратного рассеяния и отраженияот поверхности моря акустических импульсов с различной частотой, позволяющий одновременно измерятьрассеяние и поглощение звука и нелинейный акустический параметр морской воды. Многочастотное зондирование позволяет реализовать акустическую спектроскопию пузырьков в приповерхностных слоях моря,проводить оценку газосодержания и получать данные о спектре поверхностного волнения при различных состояниях моря вплоть до штормовых. Применение остронаправленных высокочастотных пучков ультразвукапозволяет разделить информацию о планктоне и пузырьках и определить с высоким пространственным разрешением структуру пузырьковых облаков, образующихся при обрушении ветровых волн, и структуру планктонных сообществ. Участие планктона в волновом движении в толще морской воды позволяет определитьпараметры внутренних волн спектр и распределение по амплитудам в различное время.This paper represents the application of acoustic probingfor the investigation of acoustical properties of the upperlayer of the sea using broadband narrow-beam invertedtransducers that are mounted on the sea bottom. Thismethod is based on the principle of the recording of thebackscattering and reflections of acoustic pulses of differentfrequencies from the sea surface. That simultaneouslyallows measuring scattering and absorption of the soundand non-linear acoustic parameter of seawater. Multifrequencyprobing allows performing acoustic spectroscopy ofbubbles in the near-surface layer of the sea, estimating gascontent, and obtaining data on the spectrum of the surfacewaves in various states of the sea up to a storm. Utilizationof the high-frequency narrow ultrasound beams allows us toseparate the information about plankton and bubbles and todetermine the structure of bubble clouds, created during thebreaking of wind waves, along with the structure of planktoncommunities with high spatial resolution. The participationof plankton in the wave motion in the seawater columnallows determining parameters of internal waves, such asspectrum and distribution of amplitudes at different times.

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Plutonium and americium in the deep Black Sea bottom sediments

Journal of Environmental Radioactivity ◽

10.1016/j.jenvrad.2021.106540 ◽

2021 ◽

Vol 229-230 ◽

pp. 106540

Author(s):

Vladislav Yu. Proskurnin ◽

Nataliya N. Tereshchenko ◽

Artem A. Paraskiv ◽

Olga D. Chuzhikova-Proskurnina

Keyword(s):

Black Sea ◽

Bottom Sediments ◽

Sea Bottom

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Preliminary evaluation for quality of dimension lumber in four common softwoods in Mongolia

Journal of Wood Science ◽

10.1186/s10086-020-01919-7 ◽

2020 ◽

Vol 66 (1) ◽

Author(s):

Murzabyek Sarkhad ◽

Futoshi Ishiguri ◽

Ikumi Nezu ◽

Bayasaa Tumenjargal ◽

Yusuke Takahashi ◽

...

Keyword(s):

Pinus Sylvestris ◽

Modulus Of Rupture ◽

Preliminary Evaluation ◽

Pinus Sibirica ◽

Bending Properties ◽

Picea Obovata ◽

Dimension Lumber ◽

Commercial Species ◽

Characteristic Values

Abstract The quality of dimension lumber (2 by 4 lumber) was preliminarily investigated in four common Mongolian softwoods: Pinus sylvestris L., Pinus sibirica Du Tour, Picea obovata Ledeb., and Larix sibirica Ledeb. to produce high quality dimension lumber for structural use. In total 61, 39, 67, and 37 pieces of lumber were prepared for Pinus sylvestris, Pinus sibirica, Picea obovata, and L. sibirica, respectively. The lumber was visually graded and then tested in static bending to obtain the 5% lower tolerance limits at 75% confidence level (f0.05) of the modulus of elasticity (MOE) and the modulus of rupture (MOR). In addition, the effects of sawing patterns on bending properties were also analyzed. The f0.05 of the MOE and MOR were 4.75 GPa and 15.6 MPa, 3.39 GPa and 11.0 MPa, 3.78 GPa and 11.7 MPa, and 6.07 GPa and 22.3 MPa for Pinus sylvestris, Pinus sibirica, Picea obovata, and L. sibirica, respectively. These results suggested that with a few exceptions, characteristic values of MOR in the four common Mongolian softwoods resembled those in similar commercial species already used. In visual grading, over 80% of total lumber was assigned to select structural and No. 1 grades in Pinus sylvestris and Pinus sibirica, whereas approximately 40% of total lumber in L. sibirica was No. 3 and out of grades. Sawing patterns affected bending properties in Pinus sylvestris and L. sibirica, but did not affect Pinus sibirica and Picea obovata. Dynamic Young's modulus was significantly correlated with bending properties of dimension lumber for the four species. Based on the results, it was concluded that dimension lumber for structural use can be produced from the four common Mongolian softwoods.

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