http://www.physorg.com/ en-us Physorg.com internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine. Following the Clean Air Act Amendments of 1970 and 1990 acidic deposition in North America has declined significantly since its peak in 1973. Consequently, research has shifted from studying the effects of acidic deposition to the recovery of these aquatic and terrestrial ecosystems. Regional-scale studies have focused primarily on aquatic systems and while many of these ecosystems are showing signs of chemical recovery (increases in acid neutralizing capacity and pH, decreases in sulfate and aluminum concentrations), recovery is slower than expected based on the magnitude of the decline in acid deposition. http://www.physorg.com/news150988084.html Space & Earth Mon, 12 Jan 2009 13:08:04 EST news150988084