_
SEA WATER
2'17
dissolved in the water may-vary from time to time and place
to place for various reasons.
The:ope ocean water, however, varies in its salinity within very small limits being
almost always between 34- and 36 parts of salt to a thousand
.
parts of water by weight.’ It is quite natural that in the
neighbourhood of land the amount of dissolved salt -is lower
than, in the open ocean owing to the fresh Water which
ows off the land dilutingit.
—
In the Baltic Sea, for instance, the salinity of the water
is very low, being always below twenty—nine parts per
_
thousand.
As we get down to the month of the Baltic,
however, where it joins the North Sea in the Skager Rack
we
notice 3. considerable rise in the salinity due to the
mingling of more saline waters coming from the North Sea
'
itself and from water carried round by the drift of the Gulf
Stream which penetrates the North Sea round the north
of Scotland.
Owing to its lessened sali'nity the stream of
_
Baltic water is quite recognizable as it ows up past the—
coast of Norway.
»
On the other hand the salinity of sea water may be
considerably higher than that of the open ocean owing to
constant evaporation of the water from the surface and a
consequentconcentration of :the salts=left behind. Such
conditions are to ”be feu-ndin the Red- Sea,where the highest
salinities in the world, ion-Open waters,viz._ iorty _
parts per thousand.
Here, under the fearful heat of the
_
_
_
sun, water is constantly evaporating at the sea surÏace'and
there are no rivers owin‘g down fromthe land with fresh,
water to dilute the sea once.
_The
'
eastern basin
_‘
‘
of
Mediterranean‘is also very salt-l compared with the
jopen waters of
—
.
(In
Dead
water has
been ‘
-
doWn for thousands of years into a comparatively
small lake in which constant evaÿorättion is taking place.
_