Monitorization of the atmospheric levels of H₂S caused by sulphatoreduction phenomena produced in the Besos river (Catalonia, Spain) and efficiency of the correcting measures adopted

On the late nineties, reccurent episodes of odour nuisance were produced on the Besos river basin (Catalonia, Spain). In order to gain more information about the phenomenon, an appropriate H₂S immission survey program was designed, by means of two monitorization stations, one fixed and another mobile, equipped with continuous real-time analyzers. During the 1994 summer period the measured levels of H₂S repeatedly exceeded the maximum accepted by the legislation. Extensive laboratory and field work carried out along the year 1995, allowed to point to the water of the Besos river as the source of the odour nuisance. H₂S was found to be the major chemical compound responsible of the odour but in less extent other volatile reduced sulphur compounds were also detected.