284
A. NELSON-SMITII
observed by George, the coralline algae lining rock-pools which were
whitened by emulsifier treatment on many Cornish shores (Fig. 14)
showed little sign of recovery (Nelson-Smith, 1968b) ; the gradual return of pink and purple colours to these pools was more probably due
to recolonization.
Damage to lichens and maritime plants on the strandline or cliff
ledges after the " Torrey Canyon " spill was probably due mainly to
emulsifier spraying (Ranwell, 1968b). Clifftop and bacltshore vegetation was certainly killed by the spillage of undiluted cleansers, sometimes over a large area (Ranwell, 1968a). Tests on turves of Puccinellia
maritima (Baker, 1968) show that 10% BP 1002 is damaging, but only
the undiluted emulsifier kills it completely. Not only are non-ionic
surfactants bacteriologically " hard " ; the type used in B P 1002 is
actually recommended for use in mixtures to suppress bacterial decomposition of stored oils (Davis, 1967). It is thus not surprising that the
emulsifiers used in Cornwall kill most oil-degrading bacteria at 10 p.p.m.
Nevertheless, some survive 100 p.p.m. or more. These multiply rapidly,
utilizing the emulsifier solvent and probably also the oil dissolved by it.
Samples treated with 1 000 p.p.m., however, became sterile and remained so (Gunkel, 1968 ; Smith, 1968).
The aromatic solvent used in BP 1002 and similar cleansers is more
toxic than the surfactants or other components, as reported by Smith,
Crapp (1969a) and other authors. A scattered literature on the toxicity
of aromatic hydrocarbons has already been reviewed above (see pp.
249-256). Corner et al. (1968) found that BP 1002 solvent is very nearly
as toxic to barnacle larvae as the mixture, other components having
markedly less effect. However, although Wilson (1968b) demonstrated
that some material, toxic to polychaete larvae, remains on sand grains
for some days after their treatment with emulsifier and subsequent
thorough washing, experiments described by Smith (1968) show that
the solvent is readily volatile. Solutions of emulsifier from which it is
free to evaporate become increasingly less toxic. Small soles (Xolea
solea) suffer lOOyo mortality after 24 h in water containing 50 p.p.m
B P 1002, but if their introduction to the tank is delayed by 24 h this
mortality drops to 30%. After 48 h it is 10% and after 72 h the water
has become non-toxic (Portmann and Connor, 1968 ; Simpson, 1968).
It is now generally recognized that cleansing with solvent-emulsifiers
inflicts more biological damage than the original pollution. George
(unpublished ; see Nelson-Smith, 1967a) estimated that after a 1960
spill in Milford Haven, approximately 30% of shore life was damaged
by the oil alone whereas 90% was killed after emulsifier cleansing.
Cowell (1969b ; see also Crapp, 1969) found that 38% of the cordgrass
A. NELSON-SMITII
observed by George, the coralline algae lining rock-pools which were
whitened by emulsifier treatment on many Cornish shores (Fig. 14)
showed little sign of recovery (Nelson-Smith, 1968b) ; the gradual return of pink and purple colours to these pools was more probably due
to recolonization.
Damage to lichens and maritime plants on the strandline or cliff
ledges after the " Torrey Canyon " spill was probably due mainly to
emulsifier spraying (Ranwell, 1968b). Clifftop and bacltshore vegetation was certainly killed by the spillage of undiluted cleansers, sometimes over a large area (Ranwell, 1968a). Tests on turves of Puccinellia
maritima (Baker, 1968) show that 10% BP 1002 is damaging, but only
the undiluted emulsifier kills it completely. Not only are non-ionic
surfactants bacteriologically " hard " ; the type used in B P 1002 is
actually recommended for use in mixtures to suppress bacterial decomposition of stored oils (Davis, 1967). It is thus not surprising that the
emulsifiers used in Cornwall kill most oil-degrading bacteria at 10 p.p.m.
Nevertheless, some survive 100 p.p.m. or more. These multiply rapidly,
utilizing the emulsifier solvent and probably also the oil dissolved by it.
Samples treated with 1 000 p.p.m., however, became sterile and remained so (Gunkel, 1968 ; Smith, 1968).
The aromatic solvent used in BP 1002 and similar cleansers is more
toxic than the surfactants or other components, as reported by Smith,
Crapp (1969a) and other authors. A scattered literature on the toxicity
of aromatic hydrocarbons has already been reviewed above (see pp.
249-256). Corner et al. (1968) found that BP 1002 solvent is very nearly
as toxic to barnacle larvae as the mixture, other components having
markedly less effect. However, although Wilson (1968b) demonstrated
that some material, toxic to polychaete larvae, remains on sand grains
for some days after their treatment with emulsifier and subsequent
thorough washing, experiments described by Smith (1968) show that
the solvent is readily volatile. Solutions of emulsifier from which it is
free to evaporate become increasingly less toxic. Small soles (Xolea
solea) suffer lOOyo mortality after 24 h in water containing 50 p.p.m
B P 1002, but if their introduction to the tank is delayed by 24 h this
mortality drops to 30%. After 48 h it is 10% and after 72 h the water
has become non-toxic (Portmann and Connor, 1968 ; Simpson, 1968).
It is now generally recognized that cleansing with solvent-emulsifiers
inflicts more biological damage than the original pollution. George
(unpublished ; see Nelson-Smith, 1967a) estimated that after a 1960
spill in Milford Haven, approximately 30% of shore life was damaged
by the oil alone whereas 90% was killed after emulsifier cleansing.
Cowell (1969b ; see also Crapp, 1969) found that 38% of the cordgrass