Recent recovery of lake water quality in southern Québec following reductions in sulfur emissions

Published in Water, Air, and Soil Pollution: Focus 4: 247-261

Since 1985, monitoring activities have been conducted in a network of 43 lakes comprising the Québec portion of the Long-Range Transport of Airborne Pollutants (LRTAP) program. The results to date indicate that Québec lakes generally are responding positively to the generalized decline in precipitation sulfate (SO₄^2-), with 40 of the 43 lakes now showing steep declines in S0₄^2- concentrations. The drop in SO₄^2- was associated with a significant decrease in Ca²⁺ concentrations in 77% of the lakes (67% for Mg²⁺ concentrations). Overall, the acid-neutralizing capacity was increasing in 19 lakes and decreasing only in three, while 21 lakes showed no temporal trends. Compared with previous trend studies of the LRTAP-Québec network for the period of 1985-1993, the longer period (1985-1999) shows a clear improvement, with the proportion of lakes that were acidifying changing from 24 to 7% and with the proportion of lakes that were recovering changing from 16 to 35%. These observations suggest that the recent drop in SO₄^2- deposition in the northeastern U.S. and eastern Canada was significant enough to allow chemical recovery for a significant proportion of Québec lakes.

Forests

Scientific Article

Ecosystems and Environment, Forest Ecology, Forestry Research, Forests

HOULE, Daniel, Christian GAGNON, Suzanne COUTURE and Alain KEMP

2004

Available at the Direction de la recherche forestière

acidification, environnement, pollution, alcalinité, lac, eau, sulfate, acid deposition, acidifaction reversibility, alkalinity, basic cations, lake chemistry, lake recovery, sulfate, surface water recovery, ecosystems and environment, écologie écosystèmes et environnement, écosystèmes et environnement