280
A. NELSON-SMITH
partly sedimented oil are all liable to burial by wave-action. Spraying
with emulsifier also tends to cause the oil t o penetrate deeper and may
create a quicksand. British practice is to spray emulsifier while ploughing or " rotavating " the sand, preferably only just ahead of the rising
tide (Fig. 13), or to bulldoze the treated sand into the sea. I n Brittany,
the French used the " German Machine " (Wyllie and Taylor, 1967 ;
Wyllie, discussing Mayo, 1968) in which oily sand is roasted at a high
temperature. The product, although dark grey in colour, is clean and
does not stain. If there is advance warning of an approaching slick, it
is possible to bulldoze a stockpile of surface sand to the head of the
beach, providing clean material with which to cover any slight deposits
remaining after treatment. Absorbents might also be spread in advance.
Shingle and cobbles are more likely to trap oil and are less easy to
'' cultivate ". The best that can be done is probably to spray emulsifier
as vigorously as possible, just in advance of the tide. It will probably
be necessary to apply many treatments. Sait-marshes are unlikely to
be much used by the public, but as they are frequented by many birds
the worst of the oil should be removed ; it is often sufficient t o cut and
burn the emergent parts of reeds and grasses.
D. Mode of action and toxicity of solvent-emulsij2ers
A certain amount of confusion has arisen from misuse of the term
'' detergent ". Silsby (1968) pointed out that although this word
applies to any agent which aids in cleaning, it has become restricted
in popular usage to synthetic household washing agents, excluding
soap. It is therefore particularly unfortunate that solvent-emulsifiers,
so unlike domestic washing-up liquid, were referred to as " detergents "
by the press and in some scientific reports during the " Torrey Canyon )'
affair.
Synthetic household detergents came into widespread use after the
Second World War and numerous investigations were made of their
effects and toxicity, mostly upon fish and almost all in fresh water.
Reports of these studies have been reviewed by Matulovh (1964), Prat
and Giraud (1964) and Marchetti (1965a) and many are listed in a
recent bibliography (Nelson-Smith, 196%). The surfactants which
form the major part of these detergents are anionic (for example, alkyl
or aryl sulphonates) and many are now " soft ", i.e. more or less biodegradable. Those used in solvent-emulsifiers are non-ionic (for example, alkyl phenol-ethylene oxide condensates) and are mostly
" hard ') or not readily degraded, According to Jones (1964) and Marchetti, non-ionics are slightly less toxic than anionics, for which toxicities to a variety of fish species fall within the range 1-100 p.p.m. The
A. NELSON-SMITH
partly sedimented oil are all liable to burial by wave-action. Spraying
with emulsifier also tends to cause the oil t o penetrate deeper and may
create a quicksand. British practice is to spray emulsifier while ploughing or " rotavating " the sand, preferably only just ahead of the rising
tide (Fig. 13), or to bulldoze the treated sand into the sea. I n Brittany,
the French used the " German Machine " (Wyllie and Taylor, 1967 ;
Wyllie, discussing Mayo, 1968) in which oily sand is roasted at a high
temperature. The product, although dark grey in colour, is clean and
does not stain. If there is advance warning of an approaching slick, it
is possible to bulldoze a stockpile of surface sand to the head of the
beach, providing clean material with which to cover any slight deposits
remaining after treatment. Absorbents might also be spread in advance.
Shingle and cobbles are more likely to trap oil and are less easy to
'' cultivate ". The best that can be done is probably to spray emulsifier
as vigorously as possible, just in advance of the tide. It will probably
be necessary to apply many treatments. Sait-marshes are unlikely to
be much used by the public, but as they are frequented by many birds
the worst of the oil should be removed ; it is often sufficient t o cut and
burn the emergent parts of reeds and grasses.
D. Mode of action and toxicity of solvent-emulsij2ers
A certain amount of confusion has arisen from misuse of the term
'' detergent ". Silsby (1968) pointed out that although this word
applies to any agent which aids in cleaning, it has become restricted
in popular usage to synthetic household washing agents, excluding
soap. It is therefore particularly unfortunate that solvent-emulsifiers,
so unlike domestic washing-up liquid, were referred to as " detergents "
by the press and in some scientific reports during the " Torrey Canyon )'
affair.
Synthetic household detergents came into widespread use after the
Second World War and numerous investigations were made of their
effects and toxicity, mostly upon fish and almost all in fresh water.
Reports of these studies have been reviewed by Matulovh (1964), Prat
and Giraud (1964) and Marchetti (1965a) and many are listed in a
recent bibliography (Nelson-Smith, 196%). The surfactants which
form the major part of these detergents are anionic (for example, alkyl
or aryl sulphonates) and many are now " soft ", i.e. more or less biodegradable. Those used in solvent-emulsifiers are non-ionic (for example, alkyl phenol-ethylene oxide condensates) and are mostly
" hard ') or not readily degraded, According to Jones (1964) and Marchetti, non-ionics are slightly less toxic than anionics, for which toxicities to a variety of fish species fall within the range 1-100 p.p.m. The