Mercury pollution
Mercury is a global pollutant
Mercury is an environmental pollutant of global concern due to its toxicity, bioaccumulative properties and persistence in the environment. The metal can be transported thousands of kilometres through the atmosphere. There are various natural and man-made sources of which the largest man-made sources to the atmosphere include fossil fuel combustion and metal smelting.
The Sino-Norwegian Cooperative Project on Mercury (SINOMER) started in 2006, with a case study in Guizhou province. The project was the first international cooperation project regarding mercury for the Chinese Government. The project played an important role in building capacity and interest regarding mercury pollution in China, a type of pollution that had not previously received much priority. This situation has now changed and there is now considerable focus on mercury pollution in China.
Mercury pollution in China
According to estimates from UNEP, China is responsible for approximately one third of global yearly mercury emissions.
Mercury is also widely used in industrial processes and products and China is both a significant producer and user of mercury. The use of mercury as catalysts in PVC production represents the largest use of mercury in China, followed by production of batteries, medical devices and compact fluorescent lamps.
The resulting contamination of the local environment is considerable, and releases to water and soil are apparent. Policies and technology for reducing such releases as well as recovery of contaminated areas is essential for dealing with local, regional and global mercury contamination and furthermore is important to reduce the potential for subsequent health problems.
Mercury releases from coal combustion
Coal combustion is the dominant energy source in China and its usage will continue to grow in the future. Combustion of coal is responsible for more than half of China's mercury emissions to the atmosphere. Mercury specific emission control technology is not commonly in use, but air pollution control equipment targeting conventional air pollutants also reduce mercury emissions considerably. SINOMER 1 carried out comprehensive measurements of mercury emissions in power plants and industrial boilers to evaluate the mercury removal efficiency of devices targeting the reduction of particles and sulphur dioxide. SINOMER 2 will assess the additional potential for mercury emission reduction when implementing measures for reducing NOx emissions in the 12th five year plan and also assess the potential of technologies targeting mercury emissions specifically. As an increasing amount of mercury is retained from emissions to the atmosphere, increasing attention on proper handling of the solid waste from the flue gas treatment is important.
Mercury releases from zinc smelting
Production of non-ferrous metals is another major source of mercury releases because there are considerable amounts of mercury contained in the ores. Zinc smelting is the most significant within the non-ferrous sector in terms of mercury releases; Thus SINOMER uses zinc smelting as an example. Results from SINOMER I show that there is great potential for reducing emissions from this sector.
SINOMER 2 will evaluate the fate of mercury in typical zinc smelting processes, estimate emissions from zinc smelters in China, assess the mercury removal efficiency of existing pollution control devices, and analyse the cost-benefit of mercury removal technology adopted in non-ferrous metal smelting. Based on the experience of both China and other countries and the evaluation of mercury control technologies, atmospheric mercury emission control strategies for zinc smelting will be proposed.
Contaminated mercury mining sites
SINOMER uses the Wanshan area, Guizhou, as a case study for contaminated sites with legacy mercury pollution issues. Methyl mercury as well as other mercury species presented in paddy soil and rice is one of our concerns. Local government has initiated some remediation activities in this area. However, the focus of much of the remediation has been on the stabilisation of tailings and tailing ponds rather than the mercury contamination aspects. SINOMER will contribute with increased understanding and capacity on remediation through the project; the foreseen result is a more effective mercury pollution control. The data and results accumulated in SINOMER I provided basic knowledge on the conditions in Wanshan. SINOMER II will first evaluate the efficiency of mercury pollution control from current remediation measures and then carry out demonstration activities on other remediation methods.
Mercury use in industry
Chinese industry uses a lot of mercury, either as catalysts or directly in products such as batteries, medical instruments (thermometers, manometers) and fluorescent tubes. The Chinese PVC industry to a large extent uses coal as feedstock instead of oil and gas. This requires the use of a mercury containing catalyst. Flows and mass balances of mercury use in Chinese industry are currently uncertain. SINOMER 2 will contribute with estimates of mercury mass balance in the PVC industry and with budgets of mercury fluxes at the national level.
China and the UNEP convention on mercury
China is actively taking part in the negotiations for developing a global mercury convention under the United Nations Environment Programme (UNEP). SINOMER provides important information on the current status as well as policy and technology options needed in order to develop efficient measures.