A convenient method of color measurement of marine sediments by colorimeter.

Abstract

A convenient method has been developed for the determination of colors of wet and powdered marine sediments. The colors of the sediments are determined with a simple colorimeter and described in the second CIE 1976 color space (L*a*b* color space) . This method can sensitively detect color differences impossible to detect by the naked eye for wet and powdered sediment samples . It generally gives standard deviations of about 3% for replicate determinations of L*a*b* values for powdered samples of brown, dark brown, and greenish gray sediments , and less than 8% for wet black sediments. The color measurement of wet core samples on board the ship can be rapidly performed by this method , which is much more convenient and quantitative than the conventional visual color description using rock color chart. The effects of water content, grain size and oxidation artifact on color of sediments are also discussed.

The Use of Color to Quantify the Effects of pH and Temperature on the Crystallization Kinetics of Goethite under Highly Alkaline Conditions

“…However, studies using color to quantify the iron compounds have been scarce (Barron and Torrent, 1984; Kosmas et al, 1986). Recently rapid and quantitative color measurements using a colorimeter have been successfully applied to rocks (Nagano and Nakashima, 1989;Nakashima et al, 1992) and marine sediments (Nagao and Nakashima, 1991). We showed that the color, described using the second CIE (Commission Internationale d'Eclairage) 1976 color space (generally referred to as L*a*b* color space), was a simple and quantitative parameter for the crystallization progress of goethite (Nagano et al, 1992).…”

Color Variations Associated with Rapid Formation of Goethite from Proto-Ferrihydrite at pH 13 and 40°C

“…Since the color is dependent on the crystallinity of these phases (Schwertmann, 1988b), quantitative descriptions of the color change might be useful to examine these transformations. Recently, simple and instant color measurements of rocks and sediments became possible using a colorimeter (Nagano and Nakashima, 1989;Nagao and Nakashima, 1991;Nakashima et al, 1992). As a preliminary study to clarify a reaction mechanism for a crystallization of ferrihydrite to goethite in the natural system, a laboratory experiment was conducted to quantify colors of precipitates and to relate their changes to goethite crystallization at pH 13 and 40~ where the color change associated with the goethite crystallization is easily observed.…”

Is it possible to use "twin cores" as a unique sedimentary record?An experimental design based on sediment color

“…This observation is important because it could open the possibility to find "twin records" as punctual and exceptional cases but not as a rule. The CIE L variable, also known as reflectance, is believed to be linked either to the water content of the sediment [16], its grain size [17], or even its carbonate or silica content [18]. In the present case, the retrieved sediment was relatively dry (figure 4) but no water content was measured enabling to put aside the assumption than the observed differences in variance could be linked to changes in sediment moisture and not in composition.…”