Microbial Response to Accidental Organic Pollution in Selected Part of Iskar River

ABSTRACTThe assessment and control of water quality changes in upper part of Iskar River are important elements for application of complex strategy for management of Iskar Reservoir—the main drinking water source of Sofia city. The most critical factor with potential high risk level for formation of water quality in this river sector is the discharge of ineffectively treated wastewaters from Samokov WWTP and untreated sewages from the small villages. The adequate ecosystem response to this organic pollution is based on the self-purification capacity of the river and the advisable functional structure, activity and metabolism of the microbial communities. During the study period one significant deterioration in water quality has been registered in February 2004. The analyses of hydrochemical parameters showed an organic pollution in river waters below the WWTP influx. This impact activated the self-purification capacity of river ecosystem and the key microbial communities responded with changes on structur...