DEVELOPMENT OF AN ACTIVE FLUOROMETER FOR MEASURING PRIMARY PRODUCTIVITY IN THE OCEANS

AN ACTIVE FLUOROMETER USING A CONTAINED LIGHT SOURCE WILL BE DEVELOPED FOR RAPID MEASUREMENTS OF PRIMARY PRODUCTIVITY OF MARINE PHYTOPLANKTON IN SITU. THE FLUOROMETER CAN BE USED AS A WATER-PROFILING INSTRUMENT ON BOARD SHIP, OR AS A SELF-CONTAINED DEVICE ON MOORED OR DRIFTING BUOYS. THE INSTRUMENT WILL PERMIT PRECISE ESTIMATES OF OCEAN PRIMARY PRODUCTIVITY, BETTER UNDERSTANDING OF THE ENVIRONMENTAL FACTORS LIMITING CARBON FIXATION IN THE OCEAN, AND CALIBRATION OF AIRBORNE/SATELLITECOLOR OCEAN SENSORS. THE INSTRUMENT WILL STIMULATE PHOTO-SYSTEM II OF MARINE PHYTOPLANKTON IN THE ABSORPTION BAND OF 410-490 NM BY A SERIES OF FLASHES. USING HIGH-ENERGY, HIGH-REPETITION-RATE FLASHES, THE PHYTOPLANKTONFLUORESCENCE RESPONSE, MONITORED AT 685 NM, WILL BE A FUNCTION OF THE ABSORPTION CROSS-SECTION OF PHOTOSYSTEM II, THE TURNOVER TIME OF PHOTOSYNTHETIC APPARATUS, AND THE CURRENT PHOTOSYNTHETIC RATE UNDER AMBIENT IRRADIANCE. SEVERAL METHODS OF GENERATING THE EXCITATION SIGNAL WILL BE INVESTIGATED, SUCH AS XENON FLASHLAMPS, BLUE-LIGHT-EMITTING DIODES (LEDS), OR FREQUENCY-DOUBLED, SOLID-STATE LASERS. BASED ON A CHOICE OF THE EXCITATION SOURCE, A BENCH MODEL OF THE FLUOROMETER WILL BE DESIGNED AND TESTED. SUCCESSFUL COMPLETION OF THIS PROJECT WILL LEAD TO THE DEVELOPMENT OF ASUBMERSIBLE VERSION OF THE FLUOROMETER AND FURTHER EFFORTS TOWARD COMMERCIALIZATION OF THE INSTRUMENT. AN ACTIVE FLUOROMETER USING A CONTAINED LIGHT SOURCE WILL BE DEVELOPED FOR RAPID MEASUREMENTS OF PRIMARY PRODUCTIVITY OF MARINE PHYTOPLANKTON IN SITU. THE FLUOROMETER CAN BE USED AS A WATER-PROFILING INSTRUMENT ON BOARD SHIP, OR AS A SELF-CONTAINED DEVICE ON MOORED OR DRIFTING BUOYS. THE INSTRUMENT WILL PERMIT PRECISE ESTIMATES OF OCEAN PRIMARY PRODUCTIVITY, BETTER UNDERSTANDING OF THE ENVIRONMENTAL FACTORS LIMITING CARBON FIXATION IN THE OCEAN, AND CALIBRATION OF AIRBORNE/SATELLITECOLOR OCEAN SENSORS. THE INSTRUMENT WILL STIMULATE PHOTO-SYSTEM II OF MARINE PHYTOPLANKTON IN THE ABSORPTION BAND OF 410-490 NM BY A SERIES OF FLASHES. USING HIGH-ENERGY, HIGH-REPETITION-RATE FLASHES, THE PHYTOPLANKTONFLUORESCENCE RESPONSE, MONITORED AT 685 NM, WILL BE A FUNCTION OF THE ABSORPTION CROSS-SECTION OF PHOTOSYSTEM II, THE TURNOVER TIME OF PHOTOSYNTHETIC APPARATUS, AND THE CURRENT PHOTOSYNTHETIC RATE UNDER AMBIENT IRRADIANCE. SEVERAL METHODS OF GENERATING THE EXCITATION SIGNAL WILL BE INVESTIGATED, SUCH AS XENON FLASHLAMPS, BLUE-LIGHT-EMITTING DIODES (LEDS), OR FREQUENCY-DOUBLED, SOLID-STATE LASERS. BASED ON A CHOICE OF THE EXCITATION SOURCE, A BENCH MODEL OF THE FLUOROMETER WILL BE DESIGNED AND TESTED. SUCCESSFUL COMPLETION OF THIS PROJECT WILL LEAD TO THE DEVELOPMENT OF ASUBMERSIBLE VERSION OF THE FLUOROMETER AND FURTHER EFFORTS TOWARD COMMERCIALIZATION OF THE INSTRUMENT.