THE PROBLEM OF OIL POLLUTION OF THE SEA
249
(Baird & Girard) are particularly resistant with a median toxic limit
of 72 p.p.m. (Wallen, unpublished but quoted in McKee, 1956). Naphthenic acids occur in crude oils a t 0.05-2.5y0 generally and exceptionally at 4.5% (MBlbcea et al., 1964). These authors reported median
toxic limits of 29-36 p.p.m. for minnows and 92-118 p.p.m. for bitterling Rhodeus sericeus (Bloch) in 24 h and 48 h tests. Cairns and Scheier
(1962) found a value of 5.6-7-2 p.p.m. over 96 h for sunfish and a U.S.
Public Health Service guide (1939) reported that naphthenic acids
killed minnows in 72 h at 5 p.p.m. As with phenol, the poisoning effect
is irreversible. ‘‘ Naphthenic acids ” are carboxylic acids with one or
more alicyclic rings.
Russian work report3d by Gutsell (1921) and Galtsoff (1936) identified “ hexahydrobenzoic acid ” (cyclohexane carboxylic acid) as the
toxic principle of Baku petroleum. It killed test perch (Perca sp.) and
minnows at 4-16 p.p.m. The lower hydrocarbons themselves have
similar high toxicities, perhaps relating to their anaesthetic properties,
but their effects at low concentrations may be reversible (Schaut, 1939).
Shelford (1917) exposed sunfish for 1 h and found the following concentrations to be lethal : ethylene, 22-25 p.p.m. ; benzene, 35-37 p.p.m. ;
toluene, 61-65 p.p.m. and xylene, 47-48 p.p.m. I n experiments by
Hubault (1936), 10 p.p.m. cyclohexane, 10 p.p.m. benzene or 50 p.p.m.
methylcyclohexane killed roach (Rutilus sp.) in 3-4 h. Turnbull et al.
(1954) also found that 20 p.p.m. benzene was the median toxic limit
for sunfish in 24 h and 48 h tests, although in the tests of Toman and
StGta (1959), trout (Salnzo gairdneri Richardson) survived for one day
in 100 p.p.m. and almost indefinitely in 10 p.p.m. benzene. Mosquito
fish were again very resistant in Wallen’s tests, with median toxicities
of 386-395 p.p.m. benzene, 4 924 p.p.m. heptane and 15 500 p.p.m.
cyclohexane.
4, Molluscs
I n a catastrophic coastal oil spill, molluscs-usually attached to
rocks or buried in sand and, at best, literally sluggish-may suffer
heavy mortalities. Diesel oil from the “ Tampico Maru ” wreck in
1957 (North et al., 1964) killed enormous numbers of Pismo clams
Tivela stultorum (Mawe) and abalones (Haliotis spp.), with long-lasting
ecological consequences (see below, p. 259). I n 1963 a tank-barge was
stranded on the NW coast of the United States and its cargo of various
fuel-oils was pumped overboard against the protests of the state
Department of Fisheries. 300 000 dead razor clams Siliqua patula
(Dixon) were carefully counted during the first week of pollution but
were only a small fraction of the total mortality. The commercial
249
(Baird & Girard) are particularly resistant with a median toxic limit
of 72 p.p.m. (Wallen, unpublished but quoted in McKee, 1956). Naphthenic acids occur in crude oils a t 0.05-2.5y0 generally and exceptionally at 4.5% (MBlbcea et al., 1964). These authors reported median
toxic limits of 29-36 p.p.m. for minnows and 92-118 p.p.m. for bitterling Rhodeus sericeus (Bloch) in 24 h and 48 h tests. Cairns and Scheier
(1962) found a value of 5.6-7-2 p.p.m. over 96 h for sunfish and a U.S.
Public Health Service guide (1939) reported that naphthenic acids
killed minnows in 72 h at 5 p.p.m. As with phenol, the poisoning effect
is irreversible. ‘‘ Naphthenic acids ” are carboxylic acids with one or
more alicyclic rings.
Russian work report3d by Gutsell (1921) and Galtsoff (1936) identified “ hexahydrobenzoic acid ” (cyclohexane carboxylic acid) as the
toxic principle of Baku petroleum. It killed test perch (Perca sp.) and
minnows at 4-16 p.p.m. The lower hydrocarbons themselves have
similar high toxicities, perhaps relating to their anaesthetic properties,
but their effects at low concentrations may be reversible (Schaut, 1939).
Shelford (1917) exposed sunfish for 1 h and found the following concentrations to be lethal : ethylene, 22-25 p.p.m. ; benzene, 35-37 p.p.m. ;
toluene, 61-65 p.p.m. and xylene, 47-48 p.p.m. I n experiments by
Hubault (1936), 10 p.p.m. cyclohexane, 10 p.p.m. benzene or 50 p.p.m.
methylcyclohexane killed roach (Rutilus sp.) in 3-4 h. Turnbull et al.
(1954) also found that 20 p.p.m. benzene was the median toxic limit
for sunfish in 24 h and 48 h tests, although in the tests of Toman and
StGta (1959), trout (Salnzo gairdneri Richardson) survived for one day
in 100 p.p.m. and almost indefinitely in 10 p.p.m. benzene. Mosquito
fish were again very resistant in Wallen’s tests, with median toxicities
of 386-395 p.p.m. benzene, 4 924 p.p.m. heptane and 15 500 p.p.m.
cyclohexane.
4, Molluscs
I n a catastrophic coastal oil spill, molluscs-usually attached to
rocks or buried in sand and, at best, literally sluggish-may suffer
heavy mortalities. Diesel oil from the “ Tampico Maru ” wreck in
1957 (North et al., 1964) killed enormous numbers of Pismo clams
Tivela stultorum (Mawe) and abalones (Haliotis spp.), with long-lasting
ecological consequences (see below, p. 259). I n 1963 a tank-barge was
stranded on the NW coast of the United States and its cargo of various
fuel-oils was pumped overboard against the protests of the state
Department of Fisheries. 300 000 dead razor clams Siliqua patula
(Dixon) were carefully counted during the first week of pollution but
were only a small fraction of the total mortality. The commercial