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Title: Estimating phytoplankton photosynthesis by active fluorescence

Abstract

Photosynthesis can be described by target theory, At low photon flux densities, photosynthesis is a linear function of irradiance (I), The number of reaction centers (n), their effective absorption capture cross section {sigma}, and a quantum yield {phi}. As photosynthesis becomes increasingly light saturated, an increased fraction of reaction centers close. At light saturation the maximum photosynthetic rate is given as the product of the number of reaction centers (n) and their maximum electron transport rate (I/{tau}). Using active fluorometry it is possible to measure non-destructively and in real time the fraction of open or closed reaction centers under ambient irradiance conditions in situ, as well as {sigma} and {phi} {tau} can be readily, calculated from knowledge of the light saturation parameter, I{sub k} (which can be deduced by in situ by active fluorescence measurements) and {sigma}. We built a pump and probe fluorometer, which is interfaced with a CTD. The instrument measures the fluorescence yield of a weak probe flash preceding (f{sub 0}) and succeeding (f{sub 0}) a saturating pump flash. Profiles of the these fluorescence yields are used to derive the instantaneous rate of gross photosynthesis in natural phytoplankton communities without any incubation. Correlations with short-term simulated inmore » situ radiocarbon measurements are extremely high. The average slope between photosynthesis derived from fluorescence and that measured by radiocarbon is 1.15 and corresponds to the average photosynthetic quotient. The intercept is about 15% of the maximum radiocarbon uptake and corresponds to the average net community respiration. Profiles of photosynthesis and sections showing the variability in its composite parameters reveal a significant effect of nutrient availability on biomass specific rates of photosynthesis in the ocean.« less

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Lab., Upton, NY (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
7034128
Report Number(s):
BNL-47937; CONF-9204164-2
ON: DE93000369
DOE Contract Number:  
AC02-76CH00016
Resource Type:
Conference
Resource Relation:
Conference: International symposium on the measurement of primary production from the molecular to global scale, La Rochelle (France), 19-26 Apr 1992
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; CARBON CYCLE; GLOBAL ASPECTS; FLUORIMETERS; PERFORMANCE TESTING; PHYTOPLANKTON; FLUORESCENCE SPECTROSCOPY; CLIMATIC CHANGE; PHOTOSYNTHESIS; AQUATIC ORGANISMS; CHEMICAL REACTIONS; EMISSION SPECTROSCOPY; MEASURING INSTRUMENTS; PHOTOCHEMICAL REACTIONS; PLANKTON; PLANTS; SPECTROSCOPY; SYNTHESIS; TESTING; 540310* - Environment, Aquatic- Basic Studies- (1990-)

Citation Formats

Falkowski, P G, and Kolber, Z. Estimating phytoplankton photosynthesis by active fluorescence. United States: N. p., 1992. Web.
Falkowski, P G, & Kolber, Z. Estimating phytoplankton photosynthesis by active fluorescence. United States.
Falkowski, P G, and Kolber, Z. 1992. "Estimating phytoplankton photosynthesis by active fluorescence". United States. https://www.osti.gov/servlets/purl/7034128.
@article{osti_7034128,
title = {Estimating phytoplankton photosynthesis by active fluorescence},
author = {Falkowski, P G and Kolber, Z},
abstractNote = {Photosynthesis can be described by target theory, At low photon flux densities, photosynthesis is a linear function of irradiance (I), The number of reaction centers (n), their effective absorption capture cross section {sigma}, and a quantum yield {phi}. As photosynthesis becomes increasingly light saturated, an increased fraction of reaction centers close. At light saturation the maximum photosynthetic rate is given as the product of the number of reaction centers (n) and their maximum electron transport rate (I/{tau}). Using active fluorometry it is possible to measure non-destructively and in real time the fraction of open or closed reaction centers under ambient irradiance conditions in situ, as well as {sigma} and {phi} {tau} can be readily, calculated from knowledge of the light saturation parameter, I{sub k} (which can be deduced by in situ by active fluorescence measurements) and {sigma}. We built a pump and probe fluorometer, which is interfaced with a CTD. The instrument measures the fluorescence yield of a weak probe flash preceding (f{sub 0}) and succeeding (f{sub 0}) a saturating pump flash. Profiles of the these fluorescence yields are used to derive the instantaneous rate of gross photosynthesis in natural phytoplankton communities without any incubation. Correlations with short-term simulated in situ radiocarbon measurements are extremely high. The average slope between photosynthesis derived from fluorescence and that measured by radiocarbon is 1.15 and corresponds to the average photosynthetic quotient. The intercept is about 15% of the maximum radiocarbon uptake and corresponds to the average net community respiration. Profiles of photosynthesis and sections showing the variability in its composite parameters reveal a significant effect of nutrient availability on biomass specific rates of photosynthesis in the ocean.},
doi = {},
url = {https://www.osti.gov/biblio/7034128}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1992},
month = {Wed Jan 01 00:00:00 EST 1992}
}

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