The salt content of the water can be measured very precisely using the conductivity method. Salinity can also be measured with a hand held refractometer. A refractometer measures the change of direction or bending of the light as it passes from air to water. Light moves slower in water than air. The more salt in the water, the slower the light moves. You can see the effect of light bending (refracting) as it passes from the water into the air by placing a pencil in a glass of water. The pencil appears to bend where it enters the water.
Red blood cells and haemoglobin. Oxygen is one of the substances transported with the assistance of red blood cells. The red blood cells contain a pigment called haemoglobin, each molecule of which binds four oxygen molecules.Oxyhaemoglobin forms.he curve shows that: 1  at relatively low oxygen concentrations there is uncombined haemoglobin in the blood and little or no oxyhaemoglobin, e.g. in body tissue. 2  at relatively high oxygen concentrations there is little or no uncombined haemoglobin in the blood; it is in the form of oxyhaemoglobin, e.g. in the lungs.
Carbon dioxide is transported in the blood from the tissue to the lungs in three ways: (i) dissolved in solution; (ii) buffered with water as carbonic acid; (iii) bound to proteins, particularly haemoglobin.Approximately 75% of carbon dioxide is transport in the red blood cell and 25% in the plasma.arbon dioxide is transported in the blood from the tissue to the lungs in three ways: (i) dissolved in solution; (ii) buffered with water as carbonic acid; (iii) bound to proteins, particularly haemoglobin.