The aim of this paper was to verify hydrological and hydrochemical changes in the Iquiparí Lagoon water column, during three months, as related to an artificial sand bar opening. A drastic reduction in water volume occurred 28 hours after the sand bar opening, exposing the bottom sediment. This was densely colonized by submerged aquatic plants, which were dominant in the ecosystem metabolism, s...

Data on the distribution of dimethylsulphide (DMS) and dimethylsulphoniopropionate (DMSP) in relation to phytoplankton abundance in different oceanic environments is important to understand the biogeochemistry of DMS, which plays an important role in the radiation balance of the earth. During the summer monsoon of 2001 measurements were made for DMS and DMSPt (total DMSP) together with related ...

A comparison of spectrophotometry and submersible fluorescence probe as methods for quantification of chlorophyll a content and phytoplankton diversity was performed in lake Gransjön, located in middle of Sweden.The values ranged from 2.49 μg/l to 7.91 μg/l, but did not correspond between the tested methods. Algae communities were examined via FluoroProbe and inverted microscopy technique. Ther...

Natural phytoplankton assemblages from an offshore station in Lake Michigan were exposed to individual isomers of trichlorobenzene (TCB) and incubated in situ for a 24 h period. One set of exposures was initiated with a lake assemblage collected at 0330 h from 30 m and the TCB isomers added at 0400 h. The second exposure experiment was initiated with an assemblage from 30 m collected at 1530 h ...

In vitro chlorophyll a degradation by horseradish peroxidase in the presence of the resorcinol was investigated in this paper, and the influence of pH and temperature was particularly studied. Chlorophyll a degradation was followed by UV–Vis and HPLC. Chlorophyll a was degraded when hydrogen peroxide was added into reaction mixture containing chlorophyll fraction, horseradish peroxidase, resorc...

1. COHEN-BAZIRE, G. and STANIER, R. Y. Inhibition of carotenoid synthesis in photosynthetic bacteria. Nature 181: 250-254. 1958. 2. FRANK, S. The relation between carotenoid and chlorophyll pigments in Avena coleoptiles. Arch. Biochem. Biophys. 30: 52-61. 1951. 3. GRANICK, S. Magnesium vinyl pheoporphyrin-as, another intermediate in the biological synthesis of chlorophyll. Jour. Biol. Chem. 183...

The interconversion of chlorophyll a and chlorophyll b, referred to as the chlorophyll cycle, plays a crucial role in the processes of greening, acclimation to light intensity, and senescence. The chlorophyll cycle consists of three reactions: the conversions of chlorophyll a to chlorophyll b by chlorophyllide a oxygenase, chlorophyll b to 7-hydroxymethyl chlorophyll a by chlorophyll b reductas...

A method is described that allows the measurement of river periphyton chlorophyll a and pheophytin a both on rocks and in soft sediments. The method involves successive extractions directly from frozen samples with boiling methanol. Pigments are estimated by optical density measurements before and after acidification. Methanol is superior to acetone for the distinction of chlorophyll a and pheo...

Photosynthetic pigments in a warm core eddy of the East Australian Current were studied by In vjvo fluorometry, spectrophotometry and thin-layer chromatography. The Variosens i n sltu fluorometer gave only an approximate guide to the location and quantity of phytoplankton in the water column; spectrophotometric curve analysis revealed the presence of intact or detrital chlorophylls, and quantit...

The fluorescence lifetime of chlorophyll a gives information about the primary photo-physical events in photosynthesis. Most of the light energy absorbed by chlorophylls is utilized for photochemistry. There are two main additional pathways competing for the absorbed light energy: fluorescence and radiationless internal conversion (heat). Only a few percent of the absorbed energy proceeds along...