Evaluation de la qualité de l'eau de la Garonne par référencespéciale aux indices diatomique et chironomidien

Abstract

The diatoms of the epilithon and the benthic chironomids were used to assess the impacts of pollution of the Garonne river by a paper-mill effluent (Saint Gaudens) and by domestic and industrial wastewaters (Toulouse). The chironomid index (ICh) is more permanent in time and seems to reflect the medium global quality of the river. The diatom index (IPS) fluctuates in time and reflects more exactly the pin-point impacts of pollution. The IPS mean values are a little higher than the ICh values but these two indices reflect similarly the alteration of water quality. Other biological measures have to be considered for a more exact valuation of the quality of the lotic systems. © Gauthier-Villars, 1993.