Aircraft to monitor pollution of lakes

Light aircraft will soon be used to monitor lakes and check for pollution, following the success of a technique developed by scientists at UCD and evaluated in a study commissioned by the Environmental Protection Agency.

The use of aircraft with special instrumentation to measure the greenness of the water and a camera pinned to their undercarriages overcomes many difficulties which make effective monitoring of some 5,000 lakes impossible. Many of these lakes make up some of Europe's most important freshwater ecosystems.

The study published by the EPA yesterday endorses the accuracy of the "low altitude airborne remote sensing" technique developed by Spectral Signatures, a campus company, and the department of physics at UCD. The Central Fisheries Board and the National Resources Development Centre at TCD also had an input to the £1.3 million research project, which was supported by the EU. The technology enables the environmental health of up to 100 lakes a day to be checked.

Cloud cover and other constraints mean satellite systems are not able to offer the same reliability or capability.

The technology determines the amount of algae by taking pictures, which indicate the level of chlorophyll in their cells. Aircraft including helicopters can be used with a portable spectrometer and camera mounted on it, the study finds.

The spectrometer measures green colour coming from the reflected chlorophyll. It can also distinguish different types of algae, including the most troublesome forms: blue-green algal species, some of which release toxins harmful to animals and humans. Green water in lakes and rivers is an indication of pollution which, usually, is a consequence of over-abundance of algae.

Footage from a video or digital camera is fed into a computer which generates an enhanced image. This allows for the creation of lake maps, indicating shorelines, submerged vegetation and surrounding land-use patterns.

Currently, lakes are monitored by taking sample bottles of water and evaluating their contents in laboratories, which is expensive and sometimes inaccurate.