WASHINGTON, April 24 (TNSres) -- The American Geophysical Union issued the following news release: Warming temperatures are causing a steady rise in copper, zinc and sulfate in the waters of Colorado mountain streams affected by acid rock drainage. Concentrations of these metals have roughly doubled in these alpine streams over the past 30 years, a new study finds, presenting a concern for ecosystems, downstream water quality and mining remediation. Natural chemical weathering of bedrock is th  more