acidité moyenne à long terme

CONT: While much emphasis has been placed on reducing sulphur dioxide emissions, NOx emissions must also viewed with concern due to their contribution to the pH depression associated with the snowpack melt episodes. This depression, when imposed on the surface waters where the acidity has already been increased due to excess sulphates, results in levels of acidity that may be critical and occur at sensitive life stages of many aquatic organisms, even though the long-term average acidity may be tolerated by a normal biological habitat.