How to use Salinity in a sentence
The average salinity of the whole surface of the oceans may be taken as 34.5 per mille.
The comparatively fresh equatorial belt of water, has a salinity of 35.
Observations in temperature and salinity have only been taken during summer.
They are connected with the ocean by narrow straits, the salinity of the water contained in them differs in a marked degree from that of the ocean, and the tidal waves are of small amplitude.
Two other facts are totally opposed to the origin of all the salinity of the oceans from the concentration of the washings of the land.Advertisement
The vertical distribution of salinity has only recently been investigated systematically, as the earlier expeditions were not equipped with altogether trustworthy apparatus for collecting water samples at great depths.
The causes of difference of salinity are mainly meteorological.
But in March the temperature, as also the salinity, was tolerably uniform throughout all the layers of water.
The elevation of the boilingpoint is of little practical importance, but the reduction of vapour pressure means that sea-water evaporates more slowly than fresh water, and the more slowly the higher the salinity.
All forms of plankton are more abundant in the shallow coastal waters of relatively low salinity.Advertisement
In each of the three oceans there are two maxima of salinity-one in the north, the other in the south tropical belt, separated by a zone of minimum salinity in the equatorial region, and giving place poleward to regions of still lower salinity.
In the tropical and subtropical belts of the Atlantic and Indian Oceans south of the equator the salinity diminishes rapidly from the surface downwards, and at 500 fathoms reaches a minimum of 34.3 or 34.4 p e r mille; after that it increases again to 800 fathoms, where it is almost 34.7 or 34.8, and this salinity holds good to the bottom, even to the greatest depths, as was first shown by the " Gauss " and afterwards by the " Planet " between Durban and Ceylon.
The distribution is, speaking Salinity.
Ruppin to increase with the salinity.
In the North Atlantic a strong submarine current flowing outward from the Mediterranean leaves the Strait of Gibraltar with a salinity of 38 per mille, and can be traced as far as Madeira and the Bay of Biscay in depths of from 600 to 2800 fathoms, still with a salinity of 35.6 per mille, whereas off the Azores at equal depths the salinity is from 0.5 to 0.7 per mille less.Advertisement
Our knowledge of the Pacific in this respect is still very imperfect, but it appears to be less salt than the other oceans at depths below 800 fathoms, as on the surface, the salinity at considerable depths being 34.6 to 34.7 in the Western part of the ocean, and about 34.4 to 34.5 in the eastern, so that, although the data are by no means satisfactory, it is impossible to assign a mass-salinity of more than 34.7 per mille for the whole body of Pacific water.
The belt of equatorial minimum salinity corresponds with the excessively rainy belt of calms and of the equatorial countercurrent, the salinity diminishing towards the east.
The penetration of warmth from the surface is effected by direct radiation, and by convection by particles rendered dense by evaporation increasing salinity.
The vertical distribution of temperature ' in the open ocean is much better known than that of salinity.
The differences of salinity support this method, and, especially in the northern European seas, often prove a sharper criterion of the boundaries than temperature itself; this is especially the case at the entrance to the Baltic. Evidence drawn from drift-wood, wrecks or special drift bottles is less distinct but still interesting and often useful; this method of investigation includes the use of icebergs as indicators of the trend of currents and also of plankton, the minute swimming or drifting organisms so abundant at the surface of the sea.Advertisement
The existence of a layer of water of low salinity at a depth of 500 fathoms in the tropical oceans of the southern hemisphere is to be referred to this action of the melting ice of the Antarctic regions.
Hence a strong surface current sets inwards through the Straits of Bab-el-Mandeb and Gibraltar, while an undercurrent flows outwards, raising the temperature and salinity of the ocean for a long distance beyond the straits.
Modern oceanography has found means to calculate quantitatively the circulatory movements produced by wind and the distribution of temperature and salinity not only at the surface but in deep water.
The surface waters of the North Pacific are relatively fresh, the salinity being on the whole much lower than in the other great Salinity.
North of this salinity diminishes steadily, especially to the north-west, the Sea of Okhotsk showing the lowest salinity observed in any part of the globe.Advertisement
South of the Tropic of Capricorn the isohalines run nearly east and west, salinity diminishing quickly to the Southern Ocean.
The bottom waters have almost uniformly a salinity of 34.8 per mille, corresponding closely with the bottom waters of the South Atlantic, but fresher than those of the North Atlantic.
The load of silt borne down stream by the river finally, after many halts on the way, reaches the waters of the Gulf, where the decrease of velocity, aided by the salinity of the sea water, causes the formation of a remarkable delta, leaving less aggraded areas as shallow lakes (Lake Pontchartrain on the east, and Grand Lake on the west of the river).
In fact the salinity of the Caspian is only three-eights of that of the ocean.
In the northern section, which receives the copious volumes brought down by the Volga, Ural and Terek, the salinity is so slight (only 0.0075% in the surface layers) that the water is quite drinkable, its specific gravity being not higher than 1.0016.
In the middle section the salinity of the surface layers increases to o or 5%, though it is of course greater along the shores.
The salinity of the water is much less than that of the ocean, containing only 1.05% of salt, and the lake freezes every year for a great distance from its shores.
The salinity of the waters is relatively great, the highest recorded being 42.7 per mille (Gulf of Suez), and the lowest 36.2 (Perim harbour).
From the observations of salinity it is inferred that a surface current flows inwards to the Red Sea in the eastern channel of the Strait of Bab el-Mandeb, while a current of very salt water flows outward to the Indian Ocean, through the western channel, at a depth of 50 to loo fathoms from the surface.
Within certain definite limits of depth, temperature and salinity, the only requirement is a suitable place for attachment.
The saltest surface water is found in (a) the Arabian Sea and (b) along a belt extending from West Australia to South Africa, the highest salinity in this belt occurring at the Australian end.
South of the belt salinity falls quickly as latitude increases, while to the north of it, in the monsoon region, the surface water is very fresh off the African coast and to the north-east.
Little is known with certainty about the distribution of salinity in the depths, the number of trustworthy observations available being still very small.
This fact is probably due partly to the actual intrusion of warm water from the Mascarene current east of Madagascar, and partly to the circumstance that the different temperatures of the waters are so compensated by their differences of salinity that they have almost precisely the same specific gravity in situ.
In the great basins and hollows from Rugen to the Gulfs of Bothnia and Finland the upper layers of water, from 30 to 70 metres (16 to 38 fathoms) in thickness, have almost the same salinity throughout.
The "North Sea" water, of 34 to 35 pro male salinity, does not appear at the surface in the Skagerrak, except as a strip along part of the coast of Jutland, but it is always found as an undercurrent overlying the oceanic water.
The bank-water of 32 to 34 pro male salinity is found all along the continental coast of the North Sea and North Atlantic, and it may therefore enter the Skagerrak either from the North Sea or from the north along the coast of Norway.
Salinity is therefore a major factor in the density driven global scale thermohaline circulation.
Widewater Salinity Page 31 December 2002 Six little dabchicks (=Little Grebes) are spotted repeatedly diving beneath the flooded Widewater Lagoon.
However, there are regions where temperature and/or salinity differences between water masses result in stratification.
The water salinity; The lagoon shows a unique salinity gradient from Smallmouth to Abbotsbury.
These include examples of fully marine salinity, tide-swept sandbanks and relatively sheltered sandbanks.
A salinity of 50% of natural seawater, about 1.7% is recommended.
The lagoon now appears to be full strength seawater at a salinity of 35 (ppt ).
Although starry stonewort appears to tolerate slightly saline conditions, its performance may decline if salinity levels increase.
Due to the vertical stratification of salinity the sun's heat is stored in this layer, resulting in high summer surface temperatures.
Observations of salinity in the depths of the western Mediterranean are very deficient, but the average is probably between 38 o and 38 5.
The study of marine life has in recent years become more general, and has become associated with very precise investigations into the chemical composition of sea-water, changes in chemical equilibrium, the effect of variations in salinity and temperature, the processes set up by marine bacteria, and so on.
Aime estimated this depth at 150-200 fathoms, while the observations of the Austrian expedition in the eastern Mediterranean found it to be from 200 to nearly 400 fathoms. In the Red Sea, where a similar seasonal change occurs, the depth to which the surface layer warms up is about 275 fathoms. The great difference in salinity between the surface and the deep water excludes the possibility of effective convection in the seas of northern Europe, and in the open ocean the currents which are felt everywhere, and especially those with a vertical component, must exercise a very disturbing influence on convection.
Other marine forms are Rhizopoda (Rotalia and Textillaria), the sponge Amorphina, the Amphicteis worm, the molluscs Cardium edule and other Cardidae, and some Amphipods (Cumacea and Mysidae,), but they are forms which either tolerate variations in salinity or are especially characteristic of brackish waters.
The lagoon now appears to be full strength seawater at a salinity of 35 (ppt).
The temperature and salinity differences between the deep water in the Arctic and the warmer tropics drive a southward flow of deep water.
Due to the vertical stratification of salinity the sun 's heat is stored in this layer, resulting in high summer surface temperatures.
The controlled trickle irrigation system allows the precise control of salinity levels in the field.
In the equatorial region between these belts the salinity is markedly less, especially in the eastern part.
So also any exhaustive survey of the temperature and salinity of the sea at a great number of points on and below the surface reveals a complexity of conditions that may defy mathematical analysis and could not easily be predicted.
Sorensen and Martin Knudsen after a careful investigation decided to abandon the old definition of salinity as the sum of all the dissolved solids in sea-water and to substitute for it the weight of the dissolved solids in 1000 parts by weight of sea-water on the assumption that all the bromine is replaced by its equivalent of chlorine, all the carbonate converted into oxide and the organic matter burnt.
Besides the determination of salinity by titration of the chlorides, the method of determination by the specific gravity of the sea-water is still often used.
Sorensen, carried out a careful investigation of the relation between the amount of chlorine, the total salinity and the specific gravity of sea-water of different strengths including an entirely new determination of the thermal expansion of sea-water.
The refraction of light passing through sea-water is dependent on the salinity to the extent that the index of refraction is greater as the salinity increases.
Sarasin and longer series of experiments by Tornde and Kriimmel this relation is shown to be so close that the salinity of a sample can be ascertained by determining the index of refraction.
Any influence on transparency which may be exercised by the temperature or salinity of the water is quite insignificant.
On account of its salinity, sea-water has a smaller capacity for heat than pure water.
According to Thoulet and Chevallier the specific heat diminishes as salinity increases, so that for io per mille salinity it is o 968, for 35 per mille it is only o 932, that of pure water being taken as unity.
The thermal conductivity also diminishes as salinity increases, the conductivity for heat of sea-water of 35 per mille salinity being 4.2% less than that of pure water.
The alkalinity of North Atlantic water of 35 per mille salinity is 26.86 cc. per litre, corresponding to a total amount of carbonic acid of 49 07 cc. According to the researches of August Krogh,' the alkalinity is greatly increased by the admixture of land water.
Ruppin's analysis of Baltic water, which has an alkalinity of 16 to 18 instead of the 5 or 6 which would be the amount proportional to the salinity, while the water of the Vistula and the Elbe with a salinity of o 1 per mille has an alkalinity of 28 or more.
The Arctic Sea presents a great contrast between the salinity of the surface of the ice-free Norwegian Sea with 35 to 35.4 and that of the Central Polar Basin, which is dominated by river water and melted ice, and has a salinity less than 25 per mille in most parts.
An under-current flows out from the Red Sea through the Strait of Bab-el-Mandeb, and from the Mediterranean through the Strait of Gibraltar, raising the salinity as well as the temperature of the part of the ocean outside the gates of the respective seas.
In the extreme west the salinity of the surface water is about 36 3 per mille, and it increases eastwards to 37 6 east of Sardinia and 39 0 and upwards in the Levant.
In all of these water of relatively high salinity usually appears for a long distance towards the north on the eastern side of the channel, while on the western side the water is comparatively fresh; but great variations occur at different seasons and in different years.
The chief facts already established are the greater saltness of the North Atlantic compared with the South Atlantic at all.depths, and the low salinity at all depths in the eastern equatorial region, off the Gulf of Guinea.
Water of less salinity flows outwards from the Black Sea as an upper current, and water of greater salinity from the Sea of Marmora flows into the Black Sea as an under-current.
Hence their tidal conditions are quite oceanic, though their salinity is usually rather lower than that of ocean water.
Solar radiation warms the tropical more than the polar waters, but, assuming equal salinity, this cause would not account for a difference of level of more than 20 ft.
One can look on sea-water as a mixture of very dilute solutions of particular salts, each one of which after the lapse of sufficient time fills the whole space as if the other constituents did not exist, and this interdiffusion accounts easily for the uniformity of composition in the sea-water throughout the whole ocean, the only appreciable difference from point to point being the salinity or degree of concentration of the mixed solutions.
Such a simple formula is only possible because the salts of sea-water are of such uniform composition throughout the whole ocean that the chlorine bears a constant ratio to the total salinity as newly defined whatever the degree of concentration.
Buchanan, which has an arbitrary scale and can be varied in weight by placing small metal rings on the stem so as to depress the scale to any desired depth in sea-water of any salinity, the specific gravity being calculated for each reading by dividing the total weight by the immersed volume; (3) the total immersion areometer, which has no scale and the weight of which can be adjusted so that the instrument can be brought so exactly to the specific gravity of the water sample that it remains immersed, neither floating nor sinking; this has the advantage of 'eliminating the effects of surface tension and in Fridtjof Nansen's pattern is capable of great precision.
As yet it is only possible to speak with confidence of the vertical distribution of salinity in the seas surrounding Europe, where there is a general increase of salinity with depth.
Our knowledge of the salinity of waters below the surface is as yet very defective, large areas being still unrepresented by a single observation.
During summer the surface salinity of the Black Sea is from 1.70 to 2'00% down to 50 fathoms, whereas in the greater depths it attains a salinity of 2.25%.
Its salinity is comparable to that of the eastern basin of the Mediterranean, which is greater than that of the Black Sea, viz.
These show the magnitudes of the layers of different salinity and temperature beneath the surface, and when a number of sections are compared the differences from season to season and from year to year can be seen.
Mohn has shown how the inequalities of what he terms the densitysurface can be found from the salinity and temperature; and he calculates that the level of the Skagerrak should be about 2 ft.
The North Atlantic maximum is the highest with water of 37.9 per mille salinity; the maximum in the South Atlantic is 37.6; in the North Indian Ocean, 36.7; the South Indian Ocean, 36.4; the South Pacific, 36.9; and the North Pacific has the lowest maximum of all, only 35'9.
Buchanan pointed out in 1876, that the great contrasts in surface salinity between the tropical maxima and the equatorial minima give place at the moderate depth of 200 fathoms to a practically uniform salinity in all parts of the ocean.
The determination of salinity was formerly carried out by evaporating a weighed quantity of sea-water to dryness and weighing the residue.
According to Knudsen the salinity is given in weight per thousand parts by the expression S = o 030+ I.
The advantage of the new definition lies in the fact that the estimation of the chlorine (or rather of the total halogen expressed as chlorine) is sufficient to determine the salinity by a very simple operation.
In the higher latitudes of the South Atlantic the salinity diminishes steadily and tends to be uniform from east to west, except near the southern extremity of South America, where the surface waters are very fresh.