40
R. Ebinghaus et al.
mercury concentrations over the oceans, dry deposition fluxes are not
considered to be significant (Mason et al. 1994). However, recent measurements
of RGM in air (Lindberg and Stratton 1998) suggest the need to reassess dry
deposition near the continental margins.
It should be noted that a significant decrease in mercury deposition in
Scandinavia has been reported during the last few years (Iverfeldt 1995) and
reductions in concentrations in the remote marine atmosphere have also been
reported (Slemr 1996). However, accurate long-term data to assess actual trends
in atmospheric mercury concentrations do not yet exist. A long-term, fixed
network of continuous global monitoring sites (oceanic as well as land-based) is
essential for spotting global trends (Expert Panel 1994). Recently, results from
continuous monitoring of atmospheric mercury have been reported for Alert in
the Canadian Arctic (since 1995) (Schroeder and Schneeberger 1996), Mace Head
at the west Irish coast (since 1995) (Ebinghaus et al. 1996) the Wank summit in
the Bavarian Alps, Germany (since 1990) and Cape Point, South Africa (since
1995) (Slemr et al. 1996).
7
Summary and Conclusions
Compared with present knowledge on environmental and health effects of
mercury, much less information is available on the fluxes of the element and its
compounds to the air, water, and soils. Globally, it can be concluded that
mercury inputs to the air are comparable with direct inputs of the element to the
aquatic environment and are almost a half of direct releases to soils. The main
objective of this section is to summarize present knowledge on natural and
anthropogenic mercury fluxes to the atmosphere from various sources and their
relative importance on regional and global scales.
The major anthropogenic source of atmospheric mercury emissions on a
global scale is the combustion of fossil fuels to produce heat, steam, and
electricity. Other important anthropogenic sources include waste incineration,
mining, and smelting. The speciation of anthropogenically emitted mercury
depends upon the nature of the source of emission and includes gaseous
elemental mercury and gaseous or particulate oxidized forms of the metal.
Available information on mercury emissions to the air in North and parts of
South America, Western Europe, and parts of Asia allows a crude estimate of
regional mercury emissions for vast areas of the globe. However, more
information on mercury emissions is needed on a global scale, especially for
China and many developing countries.
Anthropogenic emissions of mercury are of the same order of magnitude as
the natural emissions. It has been estimated that approxiamtely 200 000 tons of
mercury have been emitted by anthropogenic sources since 1890 and the major
fraction has been deposited to soils. It is unclear to what extent anthropogenic
activities have affected natural emission rates.
R. Ebinghaus et al.
mercury concentrations over the oceans, dry deposition fluxes are not
considered to be significant (Mason et al. 1994). However, recent measurements
of RGM in air (Lindberg and Stratton 1998) suggest the need to reassess dry
deposition near the continental margins.
It should be noted that a significant decrease in mercury deposition in
Scandinavia has been reported during the last few years (Iverfeldt 1995) and
reductions in concentrations in the remote marine atmosphere have also been
reported (Slemr 1996). However, accurate long-term data to assess actual trends
in atmospheric mercury concentrations do not yet exist. A long-term, fixed
network of continuous global monitoring sites (oceanic as well as land-based) is
essential for spotting global trends (Expert Panel 1994). Recently, results from
continuous monitoring of atmospheric mercury have been reported for Alert in
the Canadian Arctic (since 1995) (Schroeder and Schneeberger 1996), Mace Head
at the west Irish coast (since 1995) (Ebinghaus et al. 1996) the Wank summit in
the Bavarian Alps, Germany (since 1990) and Cape Point, South Africa (since
1995) (Slemr et al. 1996).
7
Summary and Conclusions
Compared with present knowledge on environmental and health effects of
mercury, much less information is available on the fluxes of the element and its
compounds to the air, water, and soils. Globally, it can be concluded that
mercury inputs to the air are comparable with direct inputs of the element to the
aquatic environment and are almost a half of direct releases to soils. The main
objective of this section is to summarize present knowledge on natural and
anthropogenic mercury fluxes to the atmosphere from various sources and their
relative importance on regional and global scales.
The major anthropogenic source of atmospheric mercury emissions on a
global scale is the combustion of fossil fuels to produce heat, steam, and
electricity. Other important anthropogenic sources include waste incineration,
mining, and smelting. The speciation of anthropogenically emitted mercury
depends upon the nature of the source of emission and includes gaseous
elemental mercury and gaseous or particulate oxidized forms of the metal.
Available information on mercury emissions to the air in North and parts of
South America, Western Europe, and parts of Asia allows a crude estimate of
regional mercury emissions for vast areas of the globe. However, more
information on mercury emissions is needed on a global scale, especially for
China and many developing countries.
Anthropogenic emissions of mercury are of the same order of magnitude as
the natural emissions. It has been estimated that approxiamtely 200 000 tons of
mercury have been emitted by anthropogenic sources since 1890 and the major
fraction has been deposited to soils. It is unclear to what extent anthropogenic
activities have affected natural emission rates.