9 Global Pollution of the Oceans with Chlorinated
Hydrocarbons
9.1 General
The chemical industry produces, from chlorine, simple volatile chlorinated hydrocarbons with 1-2 carbon atoms, to a certain extent also chlorine-fluorine compounds.
The largest amounts are divided among dichlorethane (EDC, H3 C-CHC12 ; around
20 million t produced world-wide in 1973), cancerogenous vinylchloride (H2 C=CHCl;
10 million t), solvents used in industry, and byproducts which are not intentionally
released, but do, however, turn up in the environment, for example in the water and
sediment of the Bay of Liverpool (pearson and McConnell 1975). Practically the
entire production of many compounds reaches the environment, for example the solvent trichlorethylene (ClHC=CCI2; approximately 1 million t produced world-wide
in 1973), the degreasing solvent trichlorethane (CH3 -CCI3 ; 0.5 million t), the compounds perchlorethylene (Ch C=CCI2; 1 million t) and carbontetrachloride (CC4;
1 million t) used in the textile dry-cleaning, and chlorofluoro-hydrocarbons of various compounds used as a propellant gas in spray cans and as a coolant (freon, frigene;
1 million t). These substances are almost resistant to microorganisms. In the atmosphere, however, photo-oxydation into hydrochloric acid takes place under the influence of ultraviolet rays. Hydrolysis can be observed in the hydrosphere. The half-life
values are in the area of months.
So far, research just starts to reveal increasing concentrations of CCI3 F, CCl2 F2 and
trichlorethane in the air of regions as remote as the South Pole (Rasmussen et al.
1981), but only small accumulation takes place in organisms (Table 37) and an acute
threat to life in the sea has not been recognized. But on this question, research is still in
the initial stages. Special attention must be devoted to a number of more dangerous byproducts, for example to hexachlorobutadiene which accumulates up to a 1000 times
in organisms.
In the process of chlorinated hydrocarbon fabrication quite regularly several compounds are synthesized simultaneously, but only one compound is wanted. This
explains the large amounts of unwanted byproducts which, years ago, were released
into the environment. Intelligent techniques make it possible to reduce the waste by
utilizing waste products; of special importance is the perchloration method by which
more chlorine atoms are added to the compounds. Finally, however, there remains
a residue, a waste which up to a very few years ago could not be utilized further. This
waste is called EDC-tar. It had been dumped into the sea up to the 1960's and it is
now incincerated at sea in various sea areas (see Chap. 4.1).
If dichlorethane and viny1chloride are found to be present in a marine area, industrial
introduction, marine dumping of wastes or transportation via the atmosphere is
164
Hydrocarbons
9.1 General
The chemical industry produces, from chlorine, simple volatile chlorinated hydrocarbons with 1-2 carbon atoms, to a certain extent also chlorine-fluorine compounds.
The largest amounts are divided among dichlorethane (EDC, H3 C-CHC12 ; around
20 million t produced world-wide in 1973), cancerogenous vinylchloride (H2 C=CHCl;
10 million t), solvents used in industry, and byproducts which are not intentionally
released, but do, however, turn up in the environment, for example in the water and
sediment of the Bay of Liverpool (pearson and McConnell 1975). Practically the
entire production of many compounds reaches the environment, for example the solvent trichlorethylene (ClHC=CCI2; approximately 1 million t produced world-wide
in 1973), the degreasing solvent trichlorethane (CH3 -CCI3 ; 0.5 million t), the compounds perchlorethylene (Ch C=CCI2; 1 million t) and carbontetrachloride (CC4;
1 million t) used in the textile dry-cleaning, and chlorofluoro-hydrocarbons of various compounds used as a propellant gas in spray cans and as a coolant (freon, frigene;
1 million t). These substances are almost resistant to microorganisms. In the atmosphere, however, photo-oxydation into hydrochloric acid takes place under the influence of ultraviolet rays. Hydrolysis can be observed in the hydrosphere. The half-life
values are in the area of months.
So far, research just starts to reveal increasing concentrations of CCI3 F, CCl2 F2 and
trichlorethane in the air of regions as remote as the South Pole (Rasmussen et al.
1981), but only small accumulation takes place in organisms (Table 37) and an acute
threat to life in the sea has not been recognized. But on this question, research is still in
the initial stages. Special attention must be devoted to a number of more dangerous byproducts, for example to hexachlorobutadiene which accumulates up to a 1000 times
in organisms.
In the process of chlorinated hydrocarbon fabrication quite regularly several compounds are synthesized simultaneously, but only one compound is wanted. This
explains the large amounts of unwanted byproducts which, years ago, were released
into the environment. Intelligent techniques make it possible to reduce the waste by
utilizing waste products; of special importance is the perchloration method by which
more chlorine atoms are added to the compounds. Finally, however, there remains
a residue, a waste which up to a very few years ago could not be utilized further. This
waste is called EDC-tar. It had been dumped into the sea up to the 1960's and it is
now incincerated at sea in various sea areas (see Chap. 4.1).
If dichlorethane and viny1chloride are found to be present in a marine area, industrial
introduction, marine dumping of wastes or transportation via the atmosphere is
164