Mercury

6. What can be done to reduce mercury releases?

• 6.1 What are the possible ways of controlling mercury releases?
• 6.2 What is the best overall approach to reduce emissions?
• 6.3 What further research and information is needed?

6.1 What are the possible ways of controlling mercury releases?

Mercury releases from natural processes, and from human activity in the past, are largely beyond human control. Mercury releases from current human activity may be limited by either preventive measures or control measures. More...

6.1.1 Reducing the use of mercury-containing products and raw materials containing unwanted mercury impurities are examples of preventive measures.

• improving efficiency;
• using low-mercury fuels and alternatives, such as natural gas instead of coal; and
• using fuels with a composition that makes mercury easier to control.

Such measures are generally cost-effective, though sometimes there could be negative effects. For instance, greater demand for low-mercury fuel will lower the market price of high-mercury fuel and – if not regulated – may encourage its use. More...

6.1.2 Replacing products and processes that contain or use mercury with ones that do not is one of the most powerful preventive measures.

This may substantially reduce mercury in households, in the waste stream and in the environment.

Such steps tend to be cost-effective, especially as demand grows, but there are exceptions and possible trade-offs. Today, for example, low-energy fluorescent lamps that contain mercury may have a lower overall environmental impact than ordinary bulbs, because less mercury containing fuel may be burnt to generate the required electricity. More...

6.1.3 End-of-pipe techniques, such as filtering exhaust gases, are control methods at the point of emission. These techniques are useful when raw materials contain tiny amounts of mercury, that is in fossil-fueled power plants, cement production and metal mining and processing.

Control measures for other pollutants from coal-fired boilers and incinerators can also reduce mercury emissions, although their effectiveness depends very much on the type of coal, the design of the boiler and the equipment used. Technology aimed specifically at controlling mercury is being developed.

However, end-of-pipe techniques produce contaminated waste that could release mercury in the future unless properly managed or re-used. More...

6.1.4 Effective waste management is another control method which can reduce releases, for instance from spills or gradual leakage (e.g. from broken thermometers or auto switches and dental amalgams).

Wastes containing low concentrations of mercury are generally permitted in normal landfills. In some cases, the mercury content of the waste may first be rendered inert in order to minimise release in the future. Sweden requires waste with higher mercury concentrations to be deposited in specially equipped landfills to limit leaching and evaporation, or in ‘final storage’ deep underground.

In some countries, the cost of waste management is high enough to prompt producers to take preventive action and find alternatives that do not produce mercury-containing waste. More...

6.2 What is the best overall approach to reduce emissions?

A combination of both control and preventive measures is required for optimum reduction of mercury releases.

Useful approaches for some of the main sources are:

• municipal and medical waste incinerators may remove mercury-containing waste before burning. Waste separation in households and hospitals can be effective but costly. Substitution with non-mercury products avoids this problem. In the medium term, some mercury may also be removed from chimney exhaust;
• power-plant boilers, especially those burning coal, may use less fuel or change to better alternatives. Cleaning up the fuel before burning, or the chimney gases after burning, can also help but the mercury removed becomes a waste which needs to be managed;
• cement, mining and metal industries using raw materials containing trace contamination may use a better quality raw material or implement end-of-pipe controls;
• The scrap steel industry may separate out mercury containing components, such as lights and switches, beforehand;
• small-scale gold miners may receive training in safer methods using less or no mercury. Central refining facilities could be provided for the miners. It is difficult to enforce a ban;
• chlor-alkali producers may apply strict mercury accounting procedures, leak detection, exhaust air filtration and proper waste managemen
• mercury containing products may be substituted with non-mercury products
• dentists may prepare mercury amalgam fillings more efficiently, use other materials instead or install amalgam traps in the wastewater system;
• dental amalgams may be removed before cremation or chimney gases may be filtered. This may be avoided by switching to non-mercury tooth fillings; and
• uncontrolled disposal of mercury-containing products or wastes may be reduced by introducing and enforcing regulation and improving access to suitable waste facilities. Substitution with non-mercury products and processes may also help.

More...

6.3 What further research and information is needed?

6.3.1 Many industrialised countries have addressed potential problems caused by the use and release of mercury, with some success.

Some of the more common national initiatives include:

• environmental quality standards that set maximum acceptable mercury concentrations for different media, such as drinking water, surface waters, air and soil, and for foodstuffs like fish (in some countries);
• limits on the amount of mercury that industrial, mineral and power generation operations can release into the air and water, sometimes requiring the use of ‘best available technology’ (in many countries); and
• restriction of mercury use in specific products (in some countries).

Other actions have been taken, such as regulations on workplace exposures, recording and reporting mercury use and release by industry, consumer safety measures, and advice on fish consumption.

Legal restrictions are complemented by the promotion of safe mercury management. This includes developing and introducing safer alternatives and cleaner technology, the use of subsidies to promote substitutes and voluntary agreements with industry or mercury users. More...

6.3.2 Because mercury crosses national borders, some regional and international agreements have been reached to coordinate the reduction of mercury releases.

For example, substantial reductions have been achieved by legally binding agreements covering releases across central and eastern Europe, Canada and the USA, and by protecting the marine environment off the north-east Atlantic and the Baltic Sea.

Various non-binding initiatives also cover North America, the Arctic and Nordic regions, and the North Sea, agreeing common goals, strategies and programmes.

In addition, several voluntary private-sector initiatives supplement national regulatory measures and help information exchange, awareness raising and goal setting.

International trade in mercury chemicals and wastes is restricted by two general multilateral environmental agreements. More...