scholarly journals The Photic Environment of a Salmontd Nursery Lake

1992 ◽  
Vol 169 (1) ◽  
pp. 121-141 ◽  
Author(s):  
IÑIGO NOVALES-FLAMARIQUE ◽  
ANDREW HENDRY ◽  
CRAIG W. HAWRYSHYN
Keyword(s):  
Light Field ◽  
Relative Proportion ◽  
Spectral Characteristics ◽  
Polarized Light ◽  
Time Of Day ◽  
Water Molecules ◽  
Atmospheric Conditions ◽  
Suspended Particulates ◽  
Scuba Divers ◽  
Depth Restriction

The spectral characteristics of Lake Cowichan (Vancouver Island) were examined using a LiCor underwater spectroradiometer. The results were analyzed in terms of salmonid vision with special emphasis placed on the ultraviolet part of the spectrum. Irradiance measurements were taken by SCUBA divers every 3 m from 18m to the surface at each of seven locations. The measurements at each depth consisted of four scans from 300 to 850 nm of downwelling, upwelling and horizontal light in the sun and antisun directions. The study covered different times of day and variable atmospheric conditions. According to predictions from the absorptive properties of water molecules and scattering by these and suspended particulates, it was found that the ultraviolet part of the spectrum was the least transmitted. The light field varied in intensity and dominant wavelengths depending on direction and time of day. The relative proportion of ultraviolet, short and middle wavelengths with respect to the entire spectrum peaked during crepuscular periods; the opposite was true for long wavelengths. An analysis of the irradiance values with respect to salmonid vision showed that there was enough light to stimulate all the photoreceptor mechanisms found in juvenile salmonid retinae (sensitive to ultraviolet, short, middle and long wavelengths) at all depths studied. Nevertheless, 18 m was found to be the limiting depth for stimulation of the ultraviolet cone mechanism, which is required for perception of ultraviolet polarized light. This depth restriction may be linked to the observed salmonid movements close to the surface during crepuscular periods.

Spectral Characteristics of Salmonid Migratory Routes from Southern Vancouver Island (British Columbia)

1993 ◽  
Vol 50 (8) ◽  
pp. 1706-1716 ◽  
Author(s):  
Iñigo Novales Flamarique ◽  
Craig W. Hawryshyn
Keyword(s):  
Uv Light ◽  
Spectral Characteristics ◽  
Polarized Light ◽  
Vancouver Island ◽  
Spectral Irradiance ◽  
Atmospheric Conditions ◽  
Chl A ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Light Levels ◽  
Saanich Inlet

Spectral irradiance was measured from 300 to 850 nm under clear and overcast skies in Saanich Inlet and Trevor Channel (Vancouver Island) using an underwater spectroradiometer. The values obtained were corrected for ocular media transmission and pigment absorption of the four visual pigments in small rainbow trout, Oncorhynchus mykiss (UV, short, middle, and long wavelength sensitive), to estimate the light available to stimulate each of these photoreceptors. Light levels were compared with particle counts, Chl a, and dissolved organic matter (DOM) concentrations at various sites and with similar parameters previously measured for freshwater systems. There was sufficient light to stimulate all the photoreceptors down to 15 m, which was the limiting depth in Saanich Inlet for UV cone simulation and for stimulation of the β absorption band of middle wavelength cones. UV light levels diminished with increasing DOM and Chl a concentrations; however, no statistically discernable relationship was found between UV levels and Chl a concentrations with distance from the spawning rivers. Under completely overcast conditions, directionality of the sun's rays is maintained under some types of cloud cover. This indicates that navigation using polarized light may occur under variable atmospheric conditions provided enough polarized light is present in the water column.

Steady state of atoms in a monochromatic elliptically polarized light field

1998 ◽  
Vol 44 (1) ◽  
pp. 20-24 ◽  
Author(s):  
G Nienhuis ◽  
A. V Taichenachev ◽  
A. M Tumaikin ◽  
V. I Yudin
Keyword(s):  
Steady State ◽  
Light Field ◽  
Polarized Light ◽  
Elliptically Polarized Light ◽  
Elliptically Polarized

Structural and spectral characteristics of water molecules in aquacomplexes of uranyl nitrates

1996 ◽  
Vol 63 (5) ◽  
pp. 621-624
Author(s):  
A. P. Zazhogin ◽  
A. A. Zazhogin ◽  
A. I. Komyak ◽  
A. I. Serafimovich
Keyword(s):  
Spectral Characteristics ◽  
Water Molecules ◽  
Structural And Spectral Characteristics

The Nature of Infill Material on the Discontinuities of the Muntele Mare Granite (Beliş-Fantânele, Romania)

2021 ◽  
Author(s):  
Nicolae Har ◽  
Robert Gheorghiu
Keyword(s):  
Slope Stability ◽  
Atmospheric Oxygen ◽  
Polarized Light ◽  
Rock Slope Stability ◽  
Rock Properties ◽  
Iron Hydroxides ◽  
Atmospheric Conditions ◽  
Secondary Phases ◽  
Alteration Processes ◽  
Infill Material

Abstract The stability of rock massifs is strongly influenced by natural degradation processes. In combination with hydrothermal activity or atmospheric exposure, rock alteration processes can lead to the formation of secondary phases that ultimately control the rock quality and slope stability, which are particularly important for engineering works (e.g., road cuts, open pits, quarries, tunnels). The Bozgai open quarry in the Muntele Mare granite massif in the northern Apuseni Mountains (Romania) offers an excellent opportunity to investigate the influence of alteration processes on rock properties, especially owing to the extensive exposure of granite and specific mineral assemblages of hydrothermal genesis to atmospheric conditions. The alteration processes generated secondary phases located on the primary minerals of the affected rocks or deposited as infill material along the granite discontinuities. Natural and oriented samples of the Bozgai quarry infill material were investigated using polarized light, X-ray diffraction, and scanning electron microscopy to obtain images and identify their mineralogical composition. The hydrothermal vein material consists of kaolinite, illite, pyrite, marcasite, quartz, iron hydroxides, albite, and microcline. These samples were exposed to atmospheric oxygen and meteoric water and secondary sulphates (jarosite and gypsum) formed in an acidic environment generated by the oxidization of pyrite and marcasite. The sheeted structure of kaolinite and geochemical behavior of the sulphates in the presence of water play a particularly important role in the reduced rock slope stability in the Bozgai quarry.

scholarly journals The effect of atmospheric turbulence and chamber deployment period on autochamber CO<sub>2</sub> and CH<sub>4</sub> flux measurements in an ombrotrophic peatland

2012 ◽  
Vol 9 (2) ◽  
pp. 1439-1482 ◽  
Author(s):  
D. Y. F. Lai ◽  
N. T. Roulet ◽  
E. R. Humphreys ◽  
T. R. Moore ◽  
M. Dalva
Keyword(s):  
Atmospheric Turbulence ◽  
Concentration Gradient ◽  
Co2 Concentration ◽  
Time Of Day ◽  
Reliable Estimate ◽  
Organic Soils ◽  
Atmospheric Conditions ◽  
Near Surface ◽  
Ch4 Flux ◽  
Flux Measurements

Abstract. Accurate quantification of soil-atmosphere gas exchange is essential for understanding the magnitude and controls of greenhouse gas emissions. We used an automatic closed dynamic chamber system to measure the fluxes of CO2 and CH4 for several years at the ombrotrophic Mer Bleue peatland near Ottawa, Canada and found that atmospheric turbulence and chamber deployment period had a considerable influence on the observed flux rates. With a short deployment period of 2.5 min, CH4 flux exhibited strong diel patterns and both CH4 and nighttime CO2 effluxes were highly and negatively correlated with friction velocity as were the CO2 concentration gradients in the top 20 cm of peat. This suggests winds were flushing the very porous and relatively dry near surface peat layers, altering the concentration gradient and resulting in a 9 to 57% underestimate of CH4 flux at any time of day and a 13 to 21% underestimate of nighttime CO2 fluxes in highly turbulent conditions. Conversely, there was evidence of an overestimation of ~100% of CH4 and nighttime CO2 effluxes in calm atmospheric conditions possibly due to enhanced near-surface gas concentration gradient by mixing of chamber headspace air by fans. These problems were resolved by extending the deployment period to 30 min. After 13 min of chamber closure, the flux rate of CH4 and nighttime CO2 became constant and were not affected by turbulence thereafter, yielding a reliable estimate of the net biological fluxes. The measurement biases we observed likely exist to some extent in all chamber flux measurements made on porous and aerated substrate, such as peatlands, organic soils in tundra and forests, and snow-covered surfaces, but would be difficult to detect unless high frequency, semi-continuous observations are made.

scholarly journals INFRARED SPECTRA OF THIOSACCHARINATES OF CADMIUM AND LEAD COMPARISON WITH THE ANALOGOUS METAL SACCHARINATES

2017 ◽  
Vol 27 (1-2) ◽  
Author(s):  
Gligor Jovanovski ◽  
Adnan Kahil ◽  
Orhideja Grupče
Keyword(s):  
Infrared Spectra ◽  
Room Temperature ◽  
Spectral Characteristics ◽  
Crystalline Hydrate ◽  
Water Molecules ◽  
X Ray ◽  
Weak Hydrogen Bonds ◽  
Deuterated Analogue ◽  
The Fourier Transform ◽  
Cadmium And Lead

A b s t r a c t: The Fourier transform (FT) infrared spectra of thiosaccharinates of cadmium and lead in the 4000–400 cm–1 region were studied. Although the observed resemblance between the spectra recorded in KBr pellets suggests a possible similarity between their structures as well, the powder X-ray diagrams show that these two compounds are not isomorphous. The presence of broad and intense bands in the region of the HOH stretchings shows that thiosaccharinate of cadmium is a crystalline hydrate and the spectral picture in the region of the O-D stretchings of the isotopically isolated HOD molecules in the partially deuterated analogue indicates that present in its structure are at least two types of crystallographically different water molecules involved in the formation of weak hydrogen bonds. The room temperature (RT) spectrum of lead thiosaccharinate in the region of the ν(HOH) modes differs significantly from the spectrum recorded at the boiling temperature of liquid nitrogen (LNT), which may perhaps be interpreted as an indication that a phase transition is taking place on lowering the temperature. The spectrum of lead thiosaccharinate was recorded in a Nujol mull as well. While the KBr and Nujol spectra are essentially identical in the region below 1600 cm–1, no bands are observed in the HOH stretching region of the mull spectra. In fact, it was shown that the appearance of the spectra of lead thiosaccharinates depends on the emulsion preparation rate. A comparison of the spectral characteristics of the thiosaccharinates of cadmium and lead with those of the corresponding saccharinates (their crystal structures are known) was made, special attention being paid to the analysis of the SO2 stretching region in the saccharinate and thiosaccharinate compounds.

Das Kombinationsschwingungsspektrum von Gips im Bereich von 10 000—1200 cm-1

1968 ◽  
Vol 23 (5) ◽  
pp. 708-715 ◽  
Author(s):  
V. Hohler ◽  
H. D. Lutz
Keyword(s):  
Hydrogen Bonds ◽  
Ir Spectrum ◽  
Room Temperature ◽  
Polarized Light ◽  
Water Molecules ◽  
Lattice Vibrations ◽  
Frequency Range ◽  
Sulfate Ions ◽  
Normal Vibrations

The IR-spectrum of gypsum (CaSO4·2 H2O) in the frequency range from 10 000 to 1200 cm-1 has been investigated with polarized light at room temperature. Between 3700 and 1200 cm-1, the measurements confirm the data of HASS and SUTHERLAND and as well as those of SCHAAK derived from IR and reflection measurements. The IR-spectrum shows a great number of bands, most of which can be assigned to combination and fundamental vibrations in terms of normal vibrations of the water molecules and the sulfate ions. The influence of the lattice vibrations is briefly discussed. The existence of hydrogen bonds between the water molecules and the sulfate ions gives rise to combinations of fundamental vibrations of both complexes.

Dual Open Cycle Peaking Gas Turbine Power Plant

2005 ◽  
Author(s):  
Rodger O. Anderson
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Waves ◽  
Waste Heat ◽  
Time Of Day ◽  
Atmospheric Conditions ◽  
Spinning Reserve ◽  
Open Cycle ◽  
Electrical Generation

The generation of electrical power is a complex matter that is dependent in part both on the anticipated demand and the actual amount of power required on the grid. Therefore, the amount of power being generated varies widely depending on the time of day, day of the week, and atmospheric conditions such as cold spells and heat waves. While the amount of power varies, it is recognized that maximum efficiencies are achieved by operating power generation systems at or near steady state conditions. With this in mind, there has been an increased use of gas turbine systems that may be quickly added online to the grid to provide additional power because gas turbine systems are typically well suited for being brought online quickly to provide spinning reserve or electrical generation. However, gas turbines are recognized as not being as efficient as other plant systems such as large steam plants because the gas turbine is an open cycle system where approximately 60 to 70 percent of the energy is lost as exhaust waste heat energy. One recognized method of increasing gas turbine efficiencies is to add a steam bottoming cycle to the exhaust system. However, these closed cycle systems are costly and they compromise the gas turbine’s quick starting capability. This paper discusses an open bottoming cycle that is simple, cost effective and well suited for peaking power generation service. It not only substantially improves the gas turbine simple cycle plant heat rate, but also provides the opportunity to greatly reduce the NOX emissions levels with the application of a low temperature SCR.

A polarized light field microscope with fast polarization switcher and microlens array reveals the 3-D birefringence distribution of complex anisotropic structures

2008 ◽  
Vol 14 (S2) ◽  
pp. 742-743
Author(s):  
R Oldenbourg
Keyword(s):  
New Mexico ◽  
Light Field ◽  
Polarized Light ◽  
Microlens Array ◽  
Anisotropic Structures ◽  
Fast Polarization

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

Sign in / Sign up

Export Citation Format

Share Document