oceans of the world. Mercury is also transported from land to the sea via the atmosphere which is said to contain around 12,000 t of mercury as dust particles (Williston
1968). But within this figure, it is not known what part of it comes from human
activity and what part from natural processes. In regions where minerals containing
mercury occur naturally, the air has a 20-fold higher concentration of mercury than
elsewhere (Saha 1972). Active volcanoes also emit mercury into the atmosphere and
mercury is washed out by rain and snow. Presumably, 50,000 t per year thereby reach
the surface of the sea (Jernelov 1975). Incidentally, mercury also seems to be transported to the ocean from the fairly deep strata of the Earth's crust, namely from where
material from the Earth's crust wells up and leads to sea floor spreading and continental drift. While mercury analyses of around a thousand seawater samples generally
showed values between 2 and 40 ng/l, concentrations of up to 1090 ng/l were measured in some seawater samples from a depth of 3200 m above the Middle Atlantic
Ridge (36°N, 33°W) (Carr et al. 1974). What consequences this input can have is still
totally unknown. An amount of 25,000 to 150,000 t of mercury annually is given
as an estimate for the entire input into the ocean from degassing of the lithosphere
(Table 36).
There are only a few mercury mines in the world. In all, mining produces 9000 t of
mercury per year. From the types of use, it is clear that the major portion of it can
sooner or later wind up in the environment, that is in the ocean as well. Mercury was
used in the U.S.A. in 1969 for the following purposes: 26% for chlorine fabrication
by electrolysis (see Chap. 3.2); 23% for electric systems and lighttubes; 12% for
paints hindering the growth of marine organisms in ships' hulls (see Chap. 4.4); 6.5%
for instruments; 3.5% as a catalyst in chemical processes (see Chap. 3.2); 3.5% as a
filling material by dentists; 3.5% as a fungicide in agriculture; and the remaining 22%
for various purposes, among others construction and new expansion of chlorine-alkaline plants (Saha 1972). Figures released in 1973 by the Bayerische Landesgewerbeanstalt in Niirnberg show that the situation in the Federal Republic of Germany in
1971 was similar: 660 t of mercury were imported; 250 t of this amount were used
for new chlorine-alkaline plants. Of the remaining 410 t, 25% were consumed by
chlorine-alkaline electrolysis and had to be replaced; 13% were used in the production of various chemicals; 12% for the production of pesticides; 11% was used as a
catalyst in the chemical industry; 8% in the electrotechnical industry; 7% for instrument manufacture; 7% as a poisonous ingredient in paints; 5% by dentists; and an
additional 12% served various other purposes. Every fluorescent candle contains
50 mg of mercury, and it is estimated that from this source alone, waste or broken
fluorescent candles, about 2 t of mercury per year become incorporated in scrap
(HUtter 1978).
Mostly in the range of around 1 mg/kg coal and petroleum contain mercury in highly
varied quantities. When coal is burned, over 90% of the mercury reaches the atmosphere. A 660-MW power plant emits around 2.5 kg of mercury per day (Table 34).
It is no wonder then that samples of air dust collected by a plane over San Francisco
contained up to 50 ng/m 3 , 10-100 times more than the 1-10 ng/m 3 of mercury in
air dust over unpolluted areas (Williston 1968). Rain and snow in the vicinity of big
cities contain 0.2-2 J.l.g/kg of mercury (Keckes and Miettinen 1972), in Sweden, by
contrast, 0.05-0.07 J.l.g/kg (Ackefors et al. 1970), if analytical techniques of these
153
1968). But within this figure, it is not known what part of it comes from human
activity and what part from natural processes. In regions where minerals containing
mercury occur naturally, the air has a 20-fold higher concentration of mercury than
elsewhere (Saha 1972). Active volcanoes also emit mercury into the atmosphere and
mercury is washed out by rain and snow. Presumably, 50,000 t per year thereby reach
the surface of the sea (Jernelov 1975). Incidentally, mercury also seems to be transported to the ocean from the fairly deep strata of the Earth's crust, namely from where
material from the Earth's crust wells up and leads to sea floor spreading and continental drift. While mercury analyses of around a thousand seawater samples generally
showed values between 2 and 40 ng/l, concentrations of up to 1090 ng/l were measured in some seawater samples from a depth of 3200 m above the Middle Atlantic
Ridge (36°N, 33°W) (Carr et al. 1974). What consequences this input can have is still
totally unknown. An amount of 25,000 to 150,000 t of mercury annually is given
as an estimate for the entire input into the ocean from degassing of the lithosphere
(Table 36).
There are only a few mercury mines in the world. In all, mining produces 9000 t of
mercury per year. From the types of use, it is clear that the major portion of it can
sooner or later wind up in the environment, that is in the ocean as well. Mercury was
used in the U.S.A. in 1969 for the following purposes: 26% for chlorine fabrication
by electrolysis (see Chap. 3.2); 23% for electric systems and lighttubes; 12% for
paints hindering the growth of marine organisms in ships' hulls (see Chap. 4.4); 6.5%
for instruments; 3.5% as a catalyst in chemical processes (see Chap. 3.2); 3.5% as a
filling material by dentists; 3.5% as a fungicide in agriculture; and the remaining 22%
for various purposes, among others construction and new expansion of chlorine-alkaline plants (Saha 1972). Figures released in 1973 by the Bayerische Landesgewerbeanstalt in Niirnberg show that the situation in the Federal Republic of Germany in
1971 was similar: 660 t of mercury were imported; 250 t of this amount were used
for new chlorine-alkaline plants. Of the remaining 410 t, 25% were consumed by
chlorine-alkaline electrolysis and had to be replaced; 13% were used in the production of various chemicals; 12% for the production of pesticides; 11% was used as a
catalyst in the chemical industry; 8% in the electrotechnical industry; 7% for instrument manufacture; 7% as a poisonous ingredient in paints; 5% by dentists; and an
additional 12% served various other purposes. Every fluorescent candle contains
50 mg of mercury, and it is estimated that from this source alone, waste or broken
fluorescent candles, about 2 t of mercury per year become incorporated in scrap
(HUtter 1978).
Mostly in the range of around 1 mg/kg coal and petroleum contain mercury in highly
varied quantities. When coal is burned, over 90% of the mercury reaches the atmosphere. A 660-MW power plant emits around 2.5 kg of mercury per day (Table 34).
It is no wonder then that samples of air dust collected by a plane over San Francisco
contained up to 50 ng/m 3 , 10-100 times more than the 1-10 ng/m 3 of mercury in
air dust over unpolluted areas (Williston 1968). Rain and snow in the vicinity of big
cities contain 0.2-2 J.l.g/kg of mercury (Keckes and Miettinen 1972), in Sweden, by
contrast, 0.05-0.07 J.l.g/kg (Ackefors et al. 1970), if analytical techniques of these
153