INSTRUMENTS ,

The Environmental Chemistry and Aerobiology and Environmental Toxicology research groups of the Technical University of Cartagena (UPCT) have been performing their monitoring activity of atmospheric pollution problems of the city of Cartagena since the 1970s. Over the years the techniques used have evolved, and one result of this evolution has been the acquisition of a lidar system as a consequence of the 2001 programme for the creation of technology parks (MCYT, P-2001-35). The lidar system is a DIAL commercial system with tuneable wavelengths in two ranges, between 255 and 290 nm, where it can be used to determine SO2, O3, benzene, toluene and xylene, and between 390 and 399 nm, for the determination of NO2. In either of the two ranges, the equipment is capable of determining the presence of aerosols by extinction. The backscattered signal is received by means of a 40 cm telescope, and the wavelengths are selected by means of filters of appropriate values. The UPCT has received funding within the REN-1997-2003 project of the National Research and Development Plan for the taking of three-dimensional measurements of atmospheric pollutants, in particular O3, in the industrialised zone of Cartagena. The particularity of the UPCT’s lidar lies in its wavelength tuning system, which uses an OPO (Optical Parametric Oscillator) to select any wavelength in the margins described above. This characteristic makes it possible to determine the presence of pollutants with very specific absorption spectra such as the aromatic compounds mentioned above, since the difference between the wavelengths to be used is very small and the task would be impossible without this tuning system. Another special characteristic of the equipment lies in the fact that it was conceived to be a mobile unit, which enables it to be located close to the transmission sources or moved in parallel with other stationary lidar units.