Proceedings of the Symposium on Global and Environmental Monitoring: Proceedings of the Symposium on Global and Environmental Monitoring

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Persistent identifier:: 856665355

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts ; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856665355

Language:: English

Document type:: Multivolume work

Volume

Persistent identifier:: 856669164

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Scope:: XIV, 912 Seiten

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856669164

Illustration:: Illustrationen, Diagramme, Karten

Signature of the source:: ZS 312(28,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [TP-2 SPECTRAL SIGNATURES]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Tank experiments for the fluorescence of phytoplankton. Peter Gege

Document type:: Multivolume work

Structure type:: Chapter

Tank experiments for the fluorescence of phytoplankton Peter Gcgc DLR, Institute of Optoelectronics, 0-8031 Oberpfaffcnhofcn Abstract In a tank experiment the changes of reflectance spectra around the fluorescence wavelength of in vivo chlorophyll a at 685 nm have been studied for two different algae species. The wavelength dependent, non-linear increase of the fluorescence intensity measured at increas ing chlorophyll concentration was used to derive spectra of absorption and emission effi ciencies. It was found that especially the fluorescence intensity depends considerably on algae species. 1. Introduction Each method of human technique harnessing the sun power is far away from the efficiency realized by the biological method photosynthesis. Nevertheless, the photosynthetic quantum efficiency is less than 100 % because of several loss mechanisms in the complex reaction chain. A part of the lost energy is emitted as fluorescence light. The wavelength of a fluorescence peak is characteristic for the corresponding loss mechanism. For photosynthesis, chlorophyll a is a "finger- print-molecule", thus the chlorophyll-a-specific fluorescence at 685 nm is a fingerprint for photosynthetic activities. Because water is transparent for radiation in the visible, the 685 nm fluorescence is suited for chlorophyll monitoring in the water as well as on the land [ESA86, Nev77, Gow81, Kim85]. In remote sensing, the chlorophyll content in water was estimated by the blue/green-ratio in the past, taking advan tage of the different absorption coefficient of chlorophyll at 440 nm (blue) and 550 nm (green). If no particular sub stances absorbing in these regions are dissolved, this method is well suited (case-I-waters, i.e. usually open ocean areas). But in many areas of interest (coastal zones, lakes), the water color is dominated by sediments and yellow substances, so that the blue/grecn-ratio is no longer a measure of chlorop hyll. For these cases the characteristic 685 nm peak is the only information for passive remote sensing which allows a relatively exact estimate of chlorophyll contents. The fluorescence peak shows a great variation in intensity. Only when these variations are understood or at least quan tified, an algorithm correlating the fluorescence intensity with chlorophyll concentration can be applied. In the fol lowing, experiments will be reported which were made to investigate these variations by spectral measurements at dif ferent algae species under controlled conditions. 2. Experimental Three different algae cultures were cultivated in tanks. Two cultures consisted of a single species (tank 1: Biddulphia sinensis, tank 2: Prorocentrum micans), the third culture was a mixture of several species living in the North Sea. In order to have reproducible light conditions, the tanks were in an artifically illuminated room. After the tanks were filled with desalted seawater, the algae as well as nutients were added. The algae growed about two weeks, then nutients were exhausted, and the algae concen tration decreased. After this, the tanks were cleaned and filled again for a second period of observation. Several biological parameters were measured periodically: chlorophyll a, phaeophytin (both photometric), cell num bers, scston, phosphate, nitrate, nitrite, ammonium, silicate. The spectrometric measurements were made with a TRA- COR Northern spectrometer. It disperses the light by a grating on a 512-element silicium diode array which records the spectrum from 398 to 811 nm, thus one diode integrates over 0.8 nm. The spectral resolution is about 3-5 nm. The spectrometer looked perpendicular to the water surface, measuring it's light energy output (radiance). Since the energy output depends on the energy input (irradiance), which shows a great variation in nature, it is common prac tice to normalize the radiance with the irradiance, that gives the reflectance. Irradiance was measured by recording the spectrum of the illuminating light reflected from a white card (barium sulfate) which was inserted into the light path. Cell Numbers (1/1) TANK 2 Figure 1: Chlorophyll concentration and Cell Numbers of Prorocentrum micans (tank 2) as a function of time.

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