60
The Suez Capal
Since the late fifties there has been no further decrease in the salinity of the
Bitter Lakes. Morcos (1960) was the first to accept this fact. Oren (1970) considers
that the minimum salinity was reached in 1958.
Another contradiction is evident when Morcos (1967 a) writes of salts which
are "gradually being dissolved". In fact, in the same paper, Morcos gives analyses
from the salt dome collected in 1955. Miller and Munns (1974) report that core
and grab sampIes taken in the Great Bitter Lake in 1965 by "Atlantis II" showed
that the salt deposits were probably exhausted. Mud and gypsum crystals were
the main constituents ofthe cores". Etam (personal communication) who sampled
cores in the Bitter Lake in December 1973 found only gypsum and no trace of
crystalline salto
It is therefore evident that since the early sixties the salinity of the Bitter Lakes
has been entirely determined by evaporation. Por (1971 b) stated that the salinity
of the Bitter Lakes will always remain above that of the open sea. Miller and
Munns (1974), reporting salinities between 43%0 and 48%0, consider the present
salinity -of the Lakes as being a seasonal phenomenon with a maximum in summer and a minimum in winter.
Muromtsev (1960, 1962) measured salinities in September 1959 and in July
1960. In the Bitter Lake he found 45.98-46.87%0, and 44.79-46.06%0 respectively.
The maximum salinity value found by this author was 48.06%0 at Km 155,
"caused by strong evaporation". The most recent measurements give 46.17%0 for
January 1969 (Por and Ferber, 1972) and 45%0 for December 1973 (Etam, unpublished).
To give an idea of the magnitude of the evaporation in this area, Miller and
Munns (1974) indicate values (seasonal?) between 3.9 to 6.0 mmjday. This would
add up to an average of 1.8-1.9 mjyear.
It is evident therefore, that the Bitter Lakes will behave in the future as one of
the littorallagoons ofthe Red Sea, with salinity fluctuating seasonally around the
value45%0.
There has always been a seasonal fluctuation in the salinities and it seems that
this even decreased over the years: it was 8%0 in 1924 (Wüst, 1935) and in 1954-55
about 5.5%0 (Morcos, 1967b). Presently I would suggest an amplitude of below
5%0.
It is hard to follow the actual decrease of salinities in the Bitter Lakes, however an attempt to show the data graphically is given in Figure 28.
A last point to be made ab out the Bitter Lakes' salinities is the tendency
towards a saline stratification. This was more evident several decades ago and
although still to be observed, shows at present only a narrow range of differences.
A difference between surface and bottom values of about 6%0 seems to have existed
in 1872 (Durand-Claye, 1874). In October 1924 the difference was less than 4%0
(Fox, 1926); however, in January-March 1925 it increased to some 8%0 (Wüst,
1935) (Fig.23). For 1954-55 Morcos (1960) gives less than 1.5%0 (Fig.25). However
in 1966, EI Sabh (1968) again gives a value of 2%0. In the salinity profiles of Miller
and Munns (1974) differences of 1.0-1.5%0 between surface and bottom appear.
Of special interest are the hyper saline la:goons and pools which border the
Bitter Lakes, especially along the eastern shores. The largest of these, in the
northeast corner ofthe Great Bitter Lake, had a salinity of 91.08%0 in January
The Suez Capal
Since the late fifties there has been no further decrease in the salinity of the
Bitter Lakes. Morcos (1960) was the first to accept this fact. Oren (1970) considers
that the minimum salinity was reached in 1958.
Another contradiction is evident when Morcos (1967 a) writes of salts which
are "gradually being dissolved". In fact, in the same paper, Morcos gives analyses
from the salt dome collected in 1955. Miller and Munns (1974) report that core
and grab sampIes taken in the Great Bitter Lake in 1965 by "Atlantis II" showed
that the salt deposits were probably exhausted. Mud and gypsum crystals were
the main constituents ofthe cores". Etam (personal communication) who sampled
cores in the Bitter Lake in December 1973 found only gypsum and no trace of
crystalline salto
It is therefore evident that since the early sixties the salinity of the Bitter Lakes
has been entirely determined by evaporation. Por (1971 b) stated that the salinity
of the Bitter Lakes will always remain above that of the open sea. Miller and
Munns (1974), reporting salinities between 43%0 and 48%0, consider the present
salinity -of the Lakes as being a seasonal phenomenon with a maximum in summer and a minimum in winter.
Muromtsev (1960, 1962) measured salinities in September 1959 and in July
1960. In the Bitter Lake he found 45.98-46.87%0, and 44.79-46.06%0 respectively.
The maximum salinity value found by this author was 48.06%0 at Km 155,
"caused by strong evaporation". The most recent measurements give 46.17%0 for
January 1969 (Por and Ferber, 1972) and 45%0 for December 1973 (Etam, unpublished).
To give an idea of the magnitude of the evaporation in this area, Miller and
Munns (1974) indicate values (seasonal?) between 3.9 to 6.0 mmjday. This would
add up to an average of 1.8-1.9 mjyear.
It is evident therefore, that the Bitter Lakes will behave in the future as one of
the littorallagoons ofthe Red Sea, with salinity fluctuating seasonally around the
value45%0.
There has always been a seasonal fluctuation in the salinities and it seems that
this even decreased over the years: it was 8%0 in 1924 (Wüst, 1935) and in 1954-55
about 5.5%0 (Morcos, 1967b). Presently I would suggest an amplitude of below
5%0.
It is hard to follow the actual decrease of salinities in the Bitter Lakes, however an attempt to show the data graphically is given in Figure 28.
A last point to be made ab out the Bitter Lakes' salinities is the tendency
towards a saline stratification. This was more evident several decades ago and
although still to be observed, shows at present only a narrow range of differences.
A difference between surface and bottom values of about 6%0 seems to have existed
in 1872 (Durand-Claye, 1874). In October 1924 the difference was less than 4%0
(Fox, 1926); however, in January-March 1925 it increased to some 8%0 (Wüst,
1935) (Fig.23). For 1954-55 Morcos (1960) gives less than 1.5%0 (Fig.25). However
in 1966, EI Sabh (1968) again gives a value of 2%0. In the salinity profiles of Miller
and Munns (1974) differences of 1.0-1.5%0 between surface and bottom appear.
Of special interest are the hyper saline la:goons and pools which border the
Bitter Lakes, especially along the eastern shores. The largest of these, in the
northeast corner ofthe Great Bitter Lake, had a salinity of 91.08%0 in January