The role of mercury in the environment is now receiving close scrutiny because ultimately it can bioaccumulate as alkyl mercury in seafood with subsequent risk to human health through trophic transfer. Many industrial sources of mercury have been effectively reduced in recent years, but atmospheric emissions of mercury from the operation of coal-fired power plants still remain the largest single anthropogenic source in the United States. In order to comply with new federal and state reduction regulations, there is a need to establish a valid measurement system. Most of the emissions monitoring will be made using continuous emission monitoring systems (CEMS) instrumentation, but sorbent systems, based on real-time batch capture of mercury from the stack using halogenated (iodine and bromine) activated carbon traps are becoming increasingly popular. The traps are subsequently returned to a laboratory for accurate analysis by cold vapor atomic absorption or fluorescence. These measurement methods are prone to interferences, especially in the presence of halogens. There is therefore a critical need for halogenated activated carbon sorbent reference materials to support quality assurance and analytical method development activities by the utility industry.
The combustion of pulverized coal in electric power plants produces sulfur dioxide gas emissions. In compliance with the 1990 U.S. EPA Clean Air Act and amendments, the emissions are reduced using wet scrubber flue gas desulfurization (FGD) systems. These systems are designed to introduce an alkaline sorbent consisting of lime or limestone into the exhaust gas system. The alkali reacts with the SO2 and is collected in a slurry form (approximately 24 million tons annually for U.S. FGD scrubber systems) as calcium sulfite or calcium sulfate. The calcium sulfate generated is stabilized with inert filler material such as fly ash and is re-utilized in industrial products such as wall board, fertilizers, and cement.
With the recent focus on the emission of mercury from coal-fired power plants, there is now concern about the release of sequestered mercury during the various processing stages of these materials and the content of mercury in the finished products. The recycling of combustion by-products is a big industry and the potential release of mercury to the environment from both processing and disposal of such materials could be significant, therefore extensive measurement testing is being conducted by the U.S. EPA, the industry sector, and industry consultants. To support these measurement efforts, there is a need for a stable SRM material certified not only for mercury but also for other hazardous elements.