The Impact of Mining Activity upon the Aquatic Environment in the Southern Apuseni Mountains

In the Southern Apuseni Mountains, mining activities have taken place since Antiquity, leaving their marks upon the natural environment, the aquatic one inclusively. If the traditional technologies had a low impact upon the aquatic environment, the ones in the modern period have affected it up to the “dead water” level. It is about the disorganization of the hydrographical basins and especially about aggressive pollution of surface waters with some of the most toxic chemical substances such as cyanides, as well as by an increase in the contents of metallic ions, chlorides, sulphides, sulphates, suspensions and fixed residuum. The decrease in pH, and implicitly the acidification of waters, is also remarkable. It must be mentioned that no systematic studies of the impact of mining activities upon the aquatic environment have been conducted in the area in the last years. In these conditions, the data about water quality have been taken over from the studies conducted by author between 1996 and 1998. The cause of the lack of concern in the field is no other but the cease in ore valorization activities in the majority of the mining objectives in the area. As none of the tailings settling ponds has guard canals, the direct pluvial waters and the ones drained from the slopes transport tailings with noxes which they subsequently discharge in the local pluvial network. In these conditions, both the quality of the mine waters which run freely into the emissary and of the ones that flow from the waste dumps remain mainly in the qualitative parameters analyzed and presented in the study.