Exercise 3. Read and translate the text. Exercise 1. a) Read and translate international words without a dictionary

TEXT 3

Exercise 1. a) Read and translate international words without a dictionary:

salt, gas, organism, material, to form, element, water, biological, portion, marine, identical, zone, to construct.

b) Check if you read correctly and understand the meaning of these terms with the help of a dictionary:

clorides, sulphate, sodium, magnesium, potassium, bromine, iodine, iron, silicon, carbonate, phosphate, gold, silver, radium, lime.

Exercise 2. Read and memorize the words from the text below:

The composition of sea water

Sea water is a "water" only in the sense that water is dominant substance present. Actually it is a solution of many salts and gases, not to mention a tremendous number of living organisms, most of which are very minute. Throughout the ages there has been the steady movement of enormous quantities of materials both in solution and suspension from the land into the ocean. According to the estimation made by scientists 451,702 km² of sea water evaporate and return to the осеаn in the form of rain or water from the rivers every year. The latter amounts to about 132,297 cubic kilometers of water annually, which brings 2,735,000,000 metric tons of salts to the ocean. In addition vast quantities of suspended mud and silt are carried into the ocean and deposited near the mouths of rivers.

The total quantity of soluble salts in the ocean is very great – about 5´10¹⁶ metric tons, which is enough to form a layer of dry salts about 180 metres deep over the surface of the land. Sea water is mainly the solution of clorides and sulphates sodium, magnesium and potassium; yet it contains the appreciable amount of bromine, iodine, iron, silicon, carbonate and phosphate. Gold, silver and radium have been found among the elements contained in sea water. Biological activity is undoubtedly of great importance controlling the concentrations of many of the elements in the ocean. For example, the growth of plants in the surface layers greatly reduces the quantity of nitrates and phosphates. Yet these compounds tend to accumulate in the comparatively stagnant depths. Large portion of marine animals use phosphate and carbonate of lime to construct their shells and bones and thus remove quantities of carbon dioxide, phosphate and lime from sea water. The calcium, carbonate and phosphate of their shells and bones are deposited on the ocean floor.

As to the salinity of sea water it should be said that it is not identical in various seas. There is bitter salt water, for example, and there is brackish water. There is also semi-fresh water though it tastes a little bitter. The strongest salinity is observed in the zone of trade winds between 20°–30° of the latitude. It diminishes towards the equator and in the polar regions. The degree of salinity depends upon the barometrical pressure, the direction of winds, the quantities of precipitation and, in the shore zone, upon the freshening of sea water by rivers.