Marine plant life detective

Environmental scientists will soon have better information on the likely build up of carbon dioxide which causes global warming. They will measure more quickly and accurately the amount of phytoplankton which absorbs carbon dioxide in oceans, using an instrument developed by Chelsea Instruments of West Molesey. Called Fastracka, this new type of submersible fluorimeter detects […]

Environmental scientists will soon have better information on the likely build up of carbon dioxide which causes global warming. They will measure more quickly and accurately the amount of phytoplankton which absorbs carbon dioxide in oceans, using an instrument developed by Chelsea Instruments of West Molesey.

Called Fastracka, this new type of submersible fluorimeter detects the total levels of oceanic chlorophyll – a major constituent of phytoplankton. These plants play a major role in the photosynthetic cycle in which they take up carbon dioxide and release oxygen.

Fastracka works by pulsing light at fast intervals into the water. Some of this light is absorbed by photosynthetically active chlorophyll and re-emitted at a different wavelength. The device then detects this emitted light.

Other types of chlorophyll may be present which, in earlier instruments, have been masked due to chemical reaction or environmental pollutants.

The Fastracka uses an array of light emitting diodes (LEDs) and high frequency electronics to monitor the chlorophyll emissions and then undertakes high speed analysis. The LEDs are flashed at frequencies up to 200KHz. An array of 84 LEDs are focused very precisely to optimise the instrument’s performance. Software algorithms record and analyse the fluorescent light spectrum and determine the healthy state of the plankton.

Traditional fluorimeters use flashes of light from a pulsed xenon tube with a typical switching frequency of just 5Hz. The lamp requires a high voltage supply which can result in unwanted radio frequency emissions.

Fastracka will typically be used in a towed oceanographic vehicle. It is being used to monitor plankton levels in support of fisheries research.