Ta. Clair et al., REGIONAL PRECIPITATION AND SURFACE-WATER CHEMISTRY TRENDS IN SOUTHEASTERN CANADA (1983-1991), Canadian journal of fisheries and aquatic sciences, 52(1), 1995, pp. 197-212
We analyzed for trends of acidification related variables from 1983 to
1992 in precipitation concentrations and deposition at six sites and
surface water concentrations at 111 sites located from central Ontario
to eastern Newfoundland. Precipitation showed significantly decreasin
g H+ and SO42- concentrations and deposition in central and eastern On
tario and at one of two sites in Quebec (deposition only). For Ontario
surface water sites, only increasing or stable SO42- trends were obse
rved, and these had both concomitant increasing and decreasing trends
for pH and (or) acid-neutralizing capacity (ANC). Despite a considerab
le number of lakes showing decreasing SO42- trends in Quebec, pH and A
NC also decreased. Quebec was also the only region showing extensive e
vidence of increasing NO3-. The opposite situation was observed in Atl
antic Canada lakes where despite increasing SO42-, the dominant trend
observed for pH and ANC was increasing. Trends observed for pH and ANC
were used to classify the acidification status of our surface water s
ites: 60 of the 111 sites were found to be stable (i.e., showing no tr
ends), 17 were continuing to acidify, and 34 were improving.