Substance flow analysis for mercury 2001
Summary and conclusions
This report presents a detailed analysis of mercury consumption and emissions to the environment in Denmark in 2001. The substance flow analysis is an update of an analysis from 1992/93.
The report has been prepared in accordance with the Danish Environmental Protection Agency's paradigm for substance flow analysis. The present knowledge is acquired through information from Statistics Denmark, the Danish Product Register, trade organisations, technical literature, private companies and governmental institutions.
The analysis was undertaken with the year 2001 as reference year and presents a comprehensive view of the turnover of mercury in Denmark.
Consumption
Consumption of mercury with applications in 2001 is shown in Table 1. The dominant use is amalgam for dental fillings. This alone accounts for 1/3 of the total use and 3/4 of the intended use.
Minor uses include mercury in lamps, batteries, thermometers, monitoring equipment and chemicals for laboratory purposes.
Unintended mobilisation of mercury due to impurity in coal and other commodities is estimated to account for approximately half of the total consumption.
Table 1
Consumption of mercury in Denmark in 2001
Use areas |
Consumption 2001 |
Trends |
% of |
Mercury metal |
|||
Dental fillings |
1.100-1.300 |
Decreasing |
34 |
Lamps |
60-170 |
Decreasing |
3 |
Electrical switches and relays |
0-24 |
Decreasing |
0 |
Thermometer |
16-24 |
Decreasing |
1 |
Monitoring equipment |
10-50 |
Decreasing |
1 |
Other uses |
35-60 |
Stag./Decrea. |
1 |
Chemical compounds |
|||
Batteries |
70-150 |
Decreasing |
3 |
Laboratory chemicals |
30-70 |
Decreasing |
1 |
Medical use |
0-1 |
Decreasing |
0 |
Other uses |
5-50 |
Stag./Decrea. |
1 |
Mobilised impurities |
|||
Coal |
600-1.000 |
Stagnating |
23 |
Other uses |
140-2.100 |
Stagnating |
32 |
Total |
2.100-5.000 |
|
100 |
Trends in consumption
The consumption of mercury is generally decreasing. The total consumption of mercury in 2001 has decreased to around 20% of the use in 1982/83. The intended use has decreased in the same period to 10% of the former intended use.
In spite of a drop in the mercury consumption with most intended uses, it is worth noting that uses which previously comprised large parts of the consumption and have been severely restricted nationally and internationally, have logically become more marginal. Instead, other uses which have not been subject to the same regulatory pressure, and maybe partly for this reason, have not changed so much during the last decades, appear as relatively larger remaining uses. Examples are dental fillings, button cell batteries of other types than mercury-oxide cells and light sources.
Also worth mentioning is the decline in the mobilisation of mercury present as impurities in coal; the primary reason for this being the intended shift in Denmark towards non-coal energy production due to the wish of reducing releases of carbon dioxide and a number of other atmospheric pollutants.
Mercury balance
Mercury balance for the Danish society is summarised in Figure 1.
Figure 1
Mercury balance for the Danish society in 2001 (all figures in kg
mercury/year)
* Most of this (1,900-2,900 kg mercury per year) is exported.
Releases to the environment
Disposal and releases of mercury to the environment are shown in Figure 1. The total releases to the environment were 820-2,000 kg mercury to air, 50- 460 kg mercury to water and 170-270 kg mercury to soil.
Emission to air
The principal source to emission to air is solid waste incineration, which is assessed in particular to be due to the supply of mercury with batteries, dental fillings and electrical switches and relays.
The second largest source for emission of mercury to air is coal-fired power plants with 193-310 kg mercury annually, while cremation contributes with 170-190 kg mercury per year to air.
Discharges to aquatic environments
Emissions to water are due to wastewater (treated) from municipal sewage treatment plants, which are primarily receiving mercury from dental clinics.
Releases to soil
Emission to soil is in particular due to sewage sludge from municipal sewage treatments plants (dental clinics) and churchyards (dental fillings).
Recycling
The ongoing collection of mercury and waste containing mercury is considerable. The yearly collection contains 2,000-3,900 kg of mercury of which the majority is exported.
Landfilling
About 2,400-3,700 kg of mercury was landfilled (including deposits, constructions work etc.). The main source was residues from solid waste incineration. Mercy in residues from solid waste incineration is primarily found in residues from flue gas cleaning; these products are exported to deposits abroad.
Stock building
As stated in Figure 1 the result is a negative stock building of mercury in the Danish society of 3,300-5,200 kg/year. These figures illustrate that the consumption of mercury is decreasing and that the existing stock of mercury in the Danish society (e.g. electrical switches and relays in old telephones) is being reduced.
The total stock of mercury in the Danish society (i.e. the mercury in use in miscellaneous products) was for 1992/93 estimated at 50-250 tonnes (Maag et al. 1996). The amount of mercury removed from the stock in the period up to 2001 is not known precisely, but may roughly be estimated at 40 tonnes. Thus, the existing stock of mercury may likely be estimated at around 10-210 tonnes. The continued flows of mercury to disposal indicate that the accumulated amount of mercury in the society may originally have been underestimated, and that the "detoxification" of the society therefore takes more time. There is however no basis for an actual quantification.