A federal appeals court on Tuesday upheld the nation’s first-ever national standards requiring power plants to cut emissions of mercury and other hazardous air pollution. The federal rules, scheduled to take effect in April 2015, require the nation’s 600 coal and oil-fired power plants to comply with emissions limits set by the Environmental Protection Agency. The standards are a notable environmental accomplishment for President Barack Obama and a blow to the coal industry, which is the biggest source of mercury emissions in the U.S., according to EPA. A divided three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit in a 61-page ruling rejected several legal attacks raised by challengers. These challengers include more than 20 states with utilities that depend heavily on coal for energy production, and several industry groups and companies, including Peabody Energy Corp. , Corp. , and the National Mining Association. […]