The latter rule specifically addressed the reduction of SO2 and NOx emissions for power plants in the eastern United States; the lowered SO2 emissions limits required most existing coal-fired eastern US power plants to install newor to improve existing flue-gas desulfurization (FGD) equipment. For divalent forms of mercury (Hg2+), absorption in wet FGD processes is a highly
effective removal mechanism; promoting Hg oxidation upstream of wet FGD processes has been shown to be an effective means of reducing total Hg emissions from coal combustion