Long-term Changes in Environmental Variables of Traunsee, an Oligotrophic Austrian Lake Impacted by the Salt Industry, and Two Reference Sites Hallstättersee and Attersee

摘要: Morphometric, hydrological and basic physico-chemicalcharacteristics of three deep Alpine lakes, Traunsee,Hallstattersee Attersee as well their long-termbahaviour are presented. The lakesHallstattersee Traunsee have been influenced by saltmining the traditional salt industry for over 100 years. Waste products from these activities, entering mainlyaffected chemistry water bodies, especially bysubstantially increasing chloride concentrations up to 170 mg L-1. As a consequence increased density, mixing conditions lakes were altered. resulting incomplete led oxygen depletionin deeper layers. In addition, nutrientload catchment rised trophic level in 70s 80sof last century turn, affecting content thehypolimnion. Finally situation developed where risk becamehigh become meromictic induced humanactivity. fact, Hallstattersee became facultativelymeromictic. This process was interrupted chlorideinput more than 30 L-1 due accidental wash outfrom an upstream mine rendering Hallstatterseehomogenous 1978 1980 complete over-turn. Conditions substantially improved both after miningpractices altered restoration measures againsteutrophication initiated. Chloride phosphorusconcentrations declined, while substantiallyimproved following Traunseesubstantially levels near sedimentdecreased less 140 third lakeconsidered here, Attersee, always remained near-naturalstate although some signs nutrient becamevisible late 1970s. around 3 mgL-1 this lake can be considered background levels.Attersee now serve reference site lakesbecause its ultra-oligotrophic pristine nature.