Long-term stable sensors for bio-optical measurements

Barth, Hans Peter; Heuermann, R.; Loquay, K.-D.; Reuter, R.; Stute, U.

doi:10.1016/s0422-9894(97)80019-0

Cited by 6 publications

(3 citation statements)

References 8 publications

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“…A bio-optical sensor package was used which includes a CTD probe (model OTS 3000, ME Meerestechnik Elektronik, Germany) with a Clark-type oxygen sensor, and a fluorometer with 270 and 420 nm excitation wavelengths (Barth et al 1997). The maximum operating depth of the sensor package is 3000 m. The fluorescence data presented in this paper were obtained with the following combinations of excitation and emission (ex/em) wavelengths in nanometres: (270/450) for gelbstoff, (420/680) for chlorophyll fluorescence measurements and (270/300) for measuring water Raman scatter, which is used for normalizing the fluorescence readings of other detection modules (Heuermann et al 1995).…”

Section: In Situ Measurementsmentioning

confidence: 99%

Enhanced red fluorescence emission in the oxygen minimum zone of the Arabian Sea

Breves¹,

Heuermann²,

Reuter³

2003

Ocean Dynamics

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Depth profiles of fluorescence at several excitation and emission wavelengths were measured along with CTD data during the cruise So119 of RV Sonne in the Arabian Sea from 12 May to 10 June 1997. In addition to chlorophyll fluorescence from phytoplankton in the near-surface layer, the profiles in the oxygen minimum region well below the euphotic zone show enhanced red fluorescence. Red fluorescence intensity is inversely related to the oxygen concentration in intermediate and deep waters. A relationship to characteristic water masses of the region cannot be found in the data, and this holds also with chemical data such as DOC. Absorbance spectra of water samples taken in the oxygen minimum zone show an absorption band at 420 nm wavelength with about 50 nm bandwidth, much weaker than gelbstoff absorbance in the same wavelength range. The absorption band remains stable after sample filtration with 0.45 lm glass fibre filters. Hence, the size of the absorbing matter is in the range of dissolved molecules or particles much smaller than 1 lm. Fluorescence spectra of unfiltered samples with 420 nm excitation show a weak emission band at 600 nm and a more pronounced one at 660 nm wavelength. The trailing edge of the 660 nm band falls into the range of chlorophyll emission, thus giving rise to the observed depth profiles of red fluorescence in the oxygen minimum zone. Red fluorescence measured on samples remain stable during a few hours after sampling even in the presence of oxygen. It is not detectable after several weeks of sample storage in the dark and cannot be reproduced even after depletion of dissolved oxygen.

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Section: In Situ Measurementsmentioning

confidence: 99%

Enhanced red fluorescence emission in the oxygen minimum zone of the Arabian Sea

Breves¹,

Heuermann²,

Reuter³

2003

Ocean Dynamics

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show abstract

“…During So119, a bio-optical sensor package was used, which includes a fluorometer with several excitation and emission wavelengths (Heuermann et al 1995), a CTD probe (model OTS 3000, ME Meerestechnik Elektronik, Germany) with a Clark type oxygen sensor, and a central unit for bi-directional data transmission (Barth et al 1997). The maximum operating depth of the sensor package is 3000 m.…”

Section: :4 In Situ Fluorescence Measurementsmentioning

confidence: 99%

Bio-optical properties of gelbstoff in the Arabian Sea at the onset of the southwest monsoon

Breves

Reuter

2000

J Earth Syst Sci

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As part of the German JGOFS Indian Ocean Programme, a cruise occurred in the Arabian Sea in May 1997 at the onset of the southwest monsoon. Data on gelbstoff, chlorophyll a and tryptophan-like fluorescence as well as gelbstoff absorption were obtained. They indicate, that these optical parameters support the interpretation of hydrographic and biogeochemical conditions. Tryptophan-like fluorescence seems to be a useful indicator of changes in the constitution of the biomass. A comparison of gelbstoff absorption and fluorescence data from the upper 100 m reveals only a weak covariance. Special emphasis is given to the fit procedure used for retrieving the exponential slope S of the spectral absorption coefficient. S values with a mean of 0.016 nm À1 are found in the 350 to 480 nm wavelength range. A mean slope S set to the frequently reported value of 0.014 nm À1 in the exponential description of gelbstoff absorption might lead to a systematic over/underestimation, and thus to systematic errors, if single-wavelength absorption values are extrapolated to other spectral regions on the basis of this parameter.

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“…In order to achieve a stable fluorescent and absorbing measurement in the water column, Barth et al [38] developed two instruments. One was a multichannel fluorometer which was emphasized by long-term stability.…”

Section: Optical Designmentioning

confidence: 99%

Development ofIn SituSensors for Chlorophyll Concentration Measurement

Zeng

2015

Journal of Sensors

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Chlorophyll fluorescence measurement is a sensitive and effective method to quantify and analyze freshwater and sea water phytoplanktonin situ. Major improvements in optical design, electronic technology, and calibration protocol have increased the accuracy and reliability of the fluorometer. This review briefly describes the improvement of probe design, excitation light sources, detectors, and calibrations ofin situfluorometers. Firstly, various optical designs for increasing the efficiency of fluorescence measurement are discussed. Next, the development of electronic technology to meet and improvein situmeasurement, including various light sources, detectors, and corresponding measurement protocols, is described. In addition, various calibration materials, procedures, and methods are recommended for different kinds of water. The conclusion discusses key trends and future perspectives forin situfluorescence sensors.

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Long-term stable sensors for bio-optical measurements

Cited by 6 publications

References 8 publications

Enhanced red fluorescence emission in the oxygen minimum zone of the Arabian Sea

Enhanced red fluorescence emission in the oxygen minimum zone of the Arabian Sea

Bio-optical properties of gelbstoff in the Arabian Sea at the onset of the southwest monsoon

Development ofIn SituSensors for Chlorophyll Concentration Measurement

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