scholarly journals Antarctic pack ice algal distribution: Floe-scale spatial variability and predictability from physical parameters

2017 ◽  
Vol 44 (14) ◽  
pp. 7382-7390 ◽  
Author(s):  
K. M. Meiners ◽  
S. Arndt ◽  
S. Bestley ◽  
T. Krumpen ◽  
R. Ricker ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Physical Parameters ◽  
Pack Ice ◽  
Algal Distribution

scholarly journals Spatial variability of organic matter molecular composition and elemental geochemistry in surface sediments of a small boreal Swedish lake

2017 ◽  
Vol 14 (7) ◽  
pp. 1773-1792 ◽  
Author(s):  
Julie Tolu ◽  
Johan Rydberg ◽  
Carsten Meyer-Jacob ◽  
Lorenz Gerber ◽  
Richard Bindler
Keyword(s):  
Trace Elements ◽  
Organic Matter ◽  
Spatial Variability ◽  
Organic Compounds ◽  
Molecular Composition ◽  
Gas Chromatography Mass Spectrometry ◽  
Physical Parameters ◽  
Biogeochemical Processes ◽  
Elemental Geochemistry ◽  
Strong Control

Abstract. The composition of sediment organic matter (OM) exerts a strong control on biogeochemical processes in lakes, such as those involved in the fate of carbon, nutrients and trace metals. While between-lake spatial variability of OM quality is increasingly investigated, we explored in this study how the molecular composition of sediment OM varies spatially within a single lake and related this variability to physical parameters and elemental geochemistry. Surface sediment samples (0–10 cm) from 42 locations in Härsvatten – a small boreal forest lake with a complex basin morphometry – were analyzed for OM molecular composition using pyrolysis gas chromatography mass spectrometry for the contents of 23 major and trace elements and biogenic silica. We identified 162 organic compounds belonging to different biochemical classes of OM (e.g., carbohydrates, lignin and lipids). Close relationships were found between the spatial patterns of sediment OM molecular composition and elemental geochemistry. Differences in the source types of OM (i.e., terrestrial, aquatic plant and algal) were linked to the individual basin morphometries and chemical status of the lake. The variability in OM molecular composition was further driven by the degradation status of these different source pools, which appeared to be related to sedimentary physicochemical parameters (e.g., redox conditions) and to the molecular structure of the organic compounds. Given the high spatial variation in OM molecular composition within Härsvatten and its close relationship with elemental geochemistry, the potential for large spatial variability across lakes should be considered when studying biogeochemical processes involved in the cycling of carbon, nutrients and trace elements or when assessing lake budgets.

Spatial variability of inorganic nutrients and physical parameters in the waters of Bahia Magdalena lagoon, Pacific Coast, Mexico

2017 ◽  
Vol 37 (3) ◽  
pp. 187-194 ◽  
Author(s):  
S.B. Sujitha ◽  
M.P. Jonathan ◽  
D.C. Escobedo-Urías ◽  
Fernando Aguirre-Bahena ◽  
Lorena Elizabeth Campos Villegas ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Pacific Coast ◽  
Inorganic Nutrients ◽  
Physical Parameters ◽  
Bahia Magdalena

scholarly journals Whole-lake spatial variability of organic matter molecular composition and elemental inorganic properties in a small boreal Swedish lake

2016 ◽  
Author(s):  
Julie Tolu ◽  
Johan Rydberg ◽  
Carsten Meyer-Jacob ◽  
Lorenz Gerber ◽  
Richard Bindler
Keyword(s):  
Trace Elements ◽  
Organic Matter ◽  
Spatial Variability ◽  
Organic Compounds ◽  
Molecular Composition ◽  
Gas Chromatography Mass Spectrometry ◽  
Physical Parameters ◽  
Biogeochemical Processes ◽  
Elemental Geochemistry ◽  
Strong Control

Abstract. The composition of organic matter (OM) exerts a strong control on biogeochemical processes in lakes, such as for carbon, nutrients and trace metals. While between-lake spatial variability of OM quality is increasingly investigated, we explored in this study how the molecular composition of sediment OM varies spatially within a single lake, and related this variability to physical parameters and elemental geochemistry. Surface sediment samples (0–10 cm) from 42 locations in Härsvatten – a small, boreal forest lake with a complex basin morphometry – were analyzed for OM molecular composition using pyrolysis-gas chromatography-mass spectrometry, and for the contents of twenty-three major/trace elements and biogenic silica. 160 organic compounds belonging to different biochemical classes (e.g., carbohydrates, lignins, lipids) were identified. Close relationships were found between the spatial patterns of sediment OM molecular composition and elemental geochemistry. Differences in the source types of OM (i.e. terrestrial, aquatic plant and algal OM) were linked to the individual basin morphometries and chemical status of the lake. The variability in OM molecular composition was further driven by the degradation status of these different source-pools, which appeared to be related to sedimentary physico-chemical parameters (e.g., redox conditions) and to the molecular structure of the organic compounds. Given the high spatial variation in OM molecular composition within Härsvatten and its close relationship with elemental geochemistry, the potential for large spatial variability across lakes should be considered when studying biogeochemical processes involved in the cycling of carbon, nutrients and trace elements or when assessing lake budgets.

scholarly journals A Field Study of Pixel-Scale Variability of Raindrop Size Distribution in the Mid-Atlantic Region

2016 ◽  
Vol 17 (6) ◽  
pp. 1855-1868 ◽  
Author(s):  
Ali Tokay ◽  
Leo Pio D’Adderio ◽  
David B. Wolff ◽  
Walter A. Petersen
Keyword(s):  
Spatial Variability ◽  
Field Study ◽  
Size Distribution ◽  
Exponential Function ◽  
Rain Rate ◽  
Rain Gauge ◽  
Separation Distance ◽  
Physical Parameters ◽  
Raindrop Size Distribution ◽  
Raindrop Size

Abstract The spatial variability of parameters of the raindrop size distribution and its derivatives is investigated through a field study where collocated Particle Size and Velocity (Parsivel2) and two-dimensional video disdrometers were operated at six sites at Wallops Flight Facility, Virginia, from December 2013 to March 2014. The three-parameter exponential function was employed to determine the spatial variability across the study domain where the maximum separation distance was 2.3 km. The nugget parameter of the exponential function was set to 0.99 and the correlation distance d0 and shape parameter s0 were retrieved by minimizing the root-mean-square error, after fitting it to the correlations of physical parameters. Fits were very good for almost all 15 physical parameters. The retrieved d0 and s0 were about 4.5 km and 1.1, respectively, for rain rate (RR) when all 12 disdrometers were reporting rainfall with a rain-rate threshold of 0.1 mm h−1 for 1-min averages. The d0 decreased noticeably when one or more disdrometers were required to report rain. The d0 was considerably different for a number of parameters (e.g., mass-weighted diameter) but was about the same for the other parameters (e.g., RR) when rainfall threshold was reset to 12 and 18 dBZ for Ka- and Ku-band reflectivity, respectively, following the expected Global Precipitation Measurement mission’s spaceborne radar minimum detectable signals. The reduction of the database through elimination of a site did not alter d0 as long as the fit was adequate. The correlations of 5-min rain accumulations were lower when disdrometer observations were simulated for a rain gauge at different bucket sizes.

Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types

1965 ◽  
Vol 5 ◽  
pp. 120-130
Author(s):  
T. S. Galkina
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Spectroscopic Investigation ◽  
Binary Systems ◽  
Quantitative Information ◽  
Close Binary ◽  
Physical Parameters ◽  
Absorption And Emission ◽  
Close Binary Systems ◽  
Quantitative Estimates

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.

A theory of contamination in electron microscopes by surface diffusion

1978 ◽  
Vol 36 (1) ◽  
pp. 116-117
Author(s):  
J.T. Fourie
Keyword(s):  
Electron Beam ◽  
Surface Diffusion ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Physical Parameters ◽  
Carbon Compounds ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Primary Electrons ◽  
Long Chain

Contamination in electron microscopes can be a serious problem in STEM or in situations where a number of high resolution micrographs are required of the same area in TEM. In modern instruments the environment around the specimen can be made free of the hydrocarbon molecules, which are responsible for contamination, by means of either ultra-high vacuum or cryo-pumping techniques. However, these techniques are not effective against hydrocarbon molecules adsorbed on the specimen surface before or during its introduction into the microscope. The present paper is concerned with a theory of how certain physical parameters can influence the surface diffusion of these adsorbed molecules into the electron beam where they are deposited in the form of long chain carbon compounds by interaction with the primary electrons.

Electron Microscopy in the Study of Natural Phytoplankton Assemblages

1985 ◽  
Vol 43 ◽  
pp. 620-623
Author(s):  
Linda Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Aquatic Environment ◽  
Size Range ◽  
Physical Parameters ◽  
Specific Information ◽  
Phytoplankton Assemblages ◽  
Phytoplankton Productivity ◽  
Ecosystem Effects ◽  
Time Of Year ◽  
Species Specific

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.

A New Numerical Model for Electron-Probe Analysis at High Depth Resolution

1996 ◽  
Vol 54 ◽  
pp. 490-491
Author(s):  
P.-F. Staub ◽  
C. Bonnelle ◽  
F. Vergand ◽  
P. Jonnard
Keyword(s):  
Electron Probe ◽  
Surface Segregation ◽  
Depth Distribution ◽  
Computing Time ◽  
Depth Resolution ◽  
Physical Parameters ◽  
Electron Probe Analysis ◽  
Interface Phases ◽  
Excitation Conditions ◽  
High Depth

Characterizing dimensionally and chemically nanometric structures such as surface segregation or interface phases can be performed efficiently using electron probe (EP) techniques at very low excitation conditions, i.e. using small incident energies (0.5<E0<5 keV) and low incident overvoltages (1<U0<1.7). In such extreme conditions, classical analytical EP models are generally pushed to their validity limits in terms of accuracy and physical consistency, and Monte-Carlo simulations are not convenient solutions as routine tools, because of their cost in computing time. In this context, we have developed an intermediate procedure, called IntriX, in which the ionization depth distributions Φ(ρz) are numerically reconstructed by integration of basic macroscopic physical parameters describing the electron beam/matter interaction, all of them being available under pre-established analytical forms. IntriX’s procedure consists in dividing the ionization depth distribution into three separate contributions:

Sampling and mapping of heterogeneous surfaces: multi-resolution tiling adjusted to spatial variability

1996 ◽  
Vol 10 (7) ◽  
pp. 851-876
Author(s):  
Ferenc Csillag ◽  
Miklos Kertesz ◽  
Agnes Kummert
Keyword(s):  
Spatial Variability ◽  
Heterogeneous Surfaces

Spatial variability induces generalization in contextual cueing.

2020 ◽  
Vol 46 (12) ◽  
pp. 2295-2313
Author(s):  
Yoko Higuchi ◽  
Yoshiyuki Ueda ◽  
Kazuhisa Shibata ◽  
Jun Saiki
Keyword(s):  
Spatial Variability ◽  
Contextual Cueing
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