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1

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Measurements and significance of bio-optical parameters for remote sensing in two subalpine lakes of different trophic state (1994)

Jaquet, J. M. ; Schanz, F. ; Bossard, P. ; [et al.]

Springer

Aquatic sciences 56 (1994), S. 263-303

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ISSN: 1420-9055

Keywords: Water optics ; remote sensing ; optochemical models ; measurement strategies

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Bio-optical measurements were carried out on eutrophic Lake Zug and oligotrophic Lake Lucerne, to provide data and models for thein situ calibration of multispectral imagery collected in 1991, during an AVIRIS flight over Central Switzerland. The results indicate that Secchi depth, chlorophyll and total suspended solid concentrations, vertical extinction coefficient, absorption coefficient and irradiance reflectance in the PAR region can be used to discriminate between the two lakes. Dissolved organics concentration, scattering and total attenuation coefficients estimates, as well as backscattering probability, are less acceptable, because of instrumental limitations. Relationships between optical and water quality parameters were investigated and found to behave according to accepted theoretical frameworks. Both lakes exhibited vertical and horizontal heterogeneities in chlorophyll and turbidity, and had contrasting mean bio-optical characteristics: although suspended solid concentrations were similar, transparency was lower in Lake Zug, but reflectance was substantially higher in Lake Lucerne. Water colour determined by chromaticity analysis was blue-green in Lake Lucerne and green in Lake Zug. Reflectance spectra simulated through a three-component optochemical model did not completely match those derived fromin situ measurements, because of lack of site-specific optical cross-sections for suspended minerals and dissolved organics. The monitoring of water quality in subalpine lakes by remote sensing, both with present and future technology, is discussed and considered as possible, provided that their optical behaviour is known, and preferably expressed by a valid optochemical model.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00879968

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2

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Basic concepts and associated statistical methodology in the geochemical study of lake sediments (1982)

Jaquet, J. -M. ; Gavaud, E. ; Vernet, J. -P.

Springer

Hydrobiologia 91-92 (1982), S. 139-146

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ISSN: 1573-5117

Keywords: lake sediments ; geochemistry ; statistical methods

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Description / Table of Contents: Résumé En se basant sur des données récoltées dans le Léman, on discute quelques-uns des concepts fondamentaux qui sous-tendent la méthodologie géochimique: le support sédimentaire des traces, la teneur naturelle, l'effet granulométrique et la variability spatiale des associations géochimiques. On souligne également le rôle capital joué par les méthodes statistiques dans l'expression, la mise à l'épreuve et l'affinement de ces concepts.

Notes: Abstract On the basis of data collected in Lac Léman (Switzerland), we discuss a few of the fundamental concepts that underlie geochemical investigations: the carrier substance, the natural background level, the grain-size effects and the areal variability of geochemical associations. The key role played by the statistical methods in expressing, testing, and refining these concepts is emphasized.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02391929

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3

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Basic concepts and associated statistical methodology in the geochemical study of lake sediments (1982)

Jaquet, J. -M. ; Gavaud, E. ; Vernet, J. -P.

Springer

Hydrobiologia 91-92 (1982), S. 139-146

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ISSN: 1573-5117

Keywords: lake sediments ; geochemistry ; statistical methods

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Description / Table of Contents: Résumé En se basant sur des données récoltées dans le Léman, on discute quelques-uns des concepts fondamentaux qui sous-tendent la méthodologie géochimique: le support sédimentaire des traces, la teneur naturelle, l'effet granulométrique et la variability spatiale des associations géochimiques. On souligne également le rôle capital joué par les méthodes statistiques dans l'expression, la mise à l'épreuve et l'affinement de ces concepts.

Notes: Abstract On the basis of data collected in Lac Léman (Switzerland), we discuss a few of the fundamental concepts that underlie geochemical investigations: the carrier substance, the natural background level, the grain-size effects and the areal variability of geochemical associations. The key role played by the statistical methods in expressing, testing, and refining these concepts is emphasized.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00940103

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4

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The manganese cycle in Lac Léman, Switzerland: the role ofMetallogenium (1982)

Jaquet, J. -M. ; Nembrini, G. ; Garcia, J. ; [et al.]

Springer

Hydrobiologia 91-92 (1982), S. 323-340

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ISSN: 1573-5117

Keywords: manganese cycle ; Metallogenium ; Lac Léman

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The manganese pathways in Lac Léman have been investigated on the basis of chemical analyses undertaken on water, suspended solids, bottom sediments and interstitial water samples. The various modes of occurrence of Mn have been determined by means of visual examination using SEM and TEM (scanning and transmission electron microscopy), by microanalysis (EDAX) of various sediment fractions, by chemical analysis of the dissolved phase, and by chemical speciation and XRD of bottom sediments. Fluxes to and from the sediment have also been computed. The time-depth variations of Mn in the water column are characterized by (a) a very steep gradient of Mn sol. from the sediment interstitial water (15 mg l−1) to the overlying water, 2 m above the bottom(500 µg l−1), (b) an accumulation of Mn part. between 280 m and the interface at 310 m, consisting of mineralized colonies ofMetallogenium. The abundance ofMetallogenium colonies is inversely related to O2 concentration; the optimal value for the bacterium Mn fixation is around 1 mg l−1. Because of the quasi-anoxic state of the bottom sediments and overlying water, Mn diffuses from a ‘source layer’, 2–5 cm below the interface (a) upwards across the interface, before being taken up byMetallogenium, and (b) downwards to a ‘sink layer’, in which large amounts of Mn-carbonate precipitate. Particulate Mn sedimentation rates measured in traps show that downwards Mn flux due toMetallogenium settling approximately balances the upwards soluble flux due to diffusion. Quantitatively, the process of Mn cycling in Lac Léman is, therefore, limited to the lowermost part of the hypolimnion. Although Zn and Cd seem to follow the same cycle as Mn, Fe behaves in a different manner; it was not taken up byMetallogenium at the time of our study.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00940123

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5

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The manganese cycle in Lac Léman, Switzerland: the role ofMetallogenium (1982)

Jaquet, J. -M. ; Nembrini, G. ; Garcia, J. ; [et al.]

Springer

Hydrobiologia 91-92 (1982), S. 323-340

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ISSN: 1573-5117

Keywords: manganese cycle ; Metallogenium ; Lac Léman

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The manganese pathways in Lac Léman have been investigated on the basis of chemical analyses undertaken on water, suspended solids, bottom sediments and interstitial water samples. The various modes of occurrence of Mn have been determined by means of visual examination using SEM and TEM (scanning and transmission electron microscopy), by microanalysis (EDAX) of various sediment fractions, by chemical analysis of the dissolved phase, and by chemical speciation and XRD of bottom sediments. Fluxes to and from the sediment have also been computed. The time-depth variations of Mn in the water column are characterized by (a) a very steep gradient of Mn sol. from the sediment interstitial water (15 mg l−1) to the overlying water, 2 m above the bottom(500 µg l−1), (b) an accumulation of Mn part. between 280 m and the interface at 310 m, consisting of mineralized colonies ofMetallogenium. The abundance ofMetallogenium colonies is inversely related to O2 concentration; the optimal value for the bacterium Mn fixation is around 1 mg l−1. Because of the quasi-anoxic state of the bottom sediments and overlying water, Mn diffuses from a ‘source layer’, 2–5 cm below the interface (a) upwards across the interface, before being taken up byMetallogenium, and (b) downwards to a ‘sink layer’, in which large amounts of Mn-carbonate precipitate. Particulate Mn sedimentation rates measured in traps show that downwards Mn flux due toMetallogenium settling approximately balances the upwards soluble flux due to diffusion. Quantitatively, the process of Mn cycling in Lac Léman is, therefore, limited to the lowermost part of the hypolimnion. Although Zn and Cd seem to follow the same cycle as Mn, Fe behaves in a different manner; it was not taken up byMetallogenium at the time of our study.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02391949

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6

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Comparison of automatic classification methods applied to lake geochemical samples (1975)

Jaquet, J. -M. ; Froidevaux, R. ; Vernet, J. -P.

Springer

Mathematical geology 7 (1975), S. 237-266

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ISSN: 1573-8868

Keywords: R- and Q-mode analysis ; cluster analysis ; lake geochemistry

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Mathematics

Notes: Abstract Geochemical samples from part of Lake Geneva were analyzed for 29oxides and trace elements. The variables and samples were subjected to R- and Q-mode analyses. The following techniques were applied in sequence: data transformation (normalization and standardization), data reduction (principal component and factor analysis), and automatic classification (dendrograph). The data were treated using various combinations of these techniques, and the resulting classifications evaluated by means of several criteria. The best classification of the samples is given by a cluster analysis performed on four principal components computed from standardized variables. The discriminatory power of the variables also was measured and determined to depend on their degree of intercorrelation. As a final result, the 29original variables were reduced to four components and the sediment samples classified into four facies, leading to easily interpretable geochemical maps.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02312723

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