Yearly changes in the seasonal frequency and duration of short-term acid pulses in some Nova Scotia, Canada streams

The seasonal frequency and duration of low pH events at three sites located in southwestern Nova Scotia were analyzed using measured and synthetic daily pH data. The basins varied in size from 0.3 to 300 km(2) and were subject to frequent snowmelt events in winter and spring, as well as occasional runoff events during summer and fall. Results showed that, in order to fill in missing data from periods where collection was interrupted, statistical approximations using discharge were not totally acceptable, as generated data consistently missed the extreme values measured. Despite a lack of totally accurate event pH estimates for periods where daily data were missing, analysis showed that in this region, low pH episodes can occur year-round including summer. The highest probabilities of low pH episodes nevertheless occurred in the winter and spring when snowmelts were frequent.