On the face of dehydration – a process that occurs only at high temperatures, when the body is fighting the overheating have to expend a lot of water on the formation of sweat. It would seem that in the Arctic, a person is fully insured against dehydration. And yet at low temperatures water losses is so great that poses a serious threat to the body.
No coincidence that many polar explorers complained constant feeling of thirst. The reasons for its addition to the lack of drinking water may be different: sweating caused by heavy physical work in a warm, hindering the movement of clothing, low temperature and dryness of the air entering the lungs, which is there, heating, consumes a significant amount of moisture, and, finally, cold diuresis (increased urine output at low temperatures). Some authors see the cause of polyuria in reducing sweating at low temperatures.
To a sharp increase in the secretion of urine in humans and animals after the transition from a medium with a moderate temperature to a lower number of researchers have pointed out. Increased diuresis sometimes up to 7-15 times a day, associated with increased secretion of urine, we repeatedly observed in participants of high-latitude air expeditions and wintering drifting station in the first months in the Central Arctic. Similar data are in the works doctors drifting station SP-4, SP-5, etc. It is believed that at the heart of this process is, on the one hand, a significant redistribution of blood volume and increasing the outflow to the internal organs, and on the other – reducing the reabsorption water in the renal tubules due to the decrease of functional activity posterior pituitary, which produces antidiuretic hormone. However, with the cooling of the body by limiting water consumption can be significantly reduced urine output. Thus, in our experiments with the presence of the subjects in the snow shelters observed decrease in diuresis with 1300-1700 mL to 400-45 0 ml per day.
The increase in urine flow, accompanied by an increase in the loss of sodium chloride, can cause disruption of water and salt balance. Apparently, that's what explains the phenomenon of dehydration, which were observed during the experiments in the Arctic in subjects fed subkaloriynymi emergency rations, despite the good supply of water.
In subsequent studies, it was found that this process can be cut short intake of sodium bicarbonate (baking soda). For example, subjects who took daily 250 mEq (1.2 g) baking soda, water lost by 0.93 + 0.2 liters less than those who did not get it, although a portion of the water they had to 1 liter more.
The optimal dose, leading to positive sodium balance and eliminating acidosis and ketonuria was determined in 100 meq (0.5 g) of sodium bicarbonate. As for the daily requirement of water, according to experts, it should be at least 2 – 3 liters, although, according to some, we can restrict 1.2 liters / day.
In the summer in the high Arctic, any need for fresh water can be achieved by the so-called water-puddles formed on the surface of the ice field in the melting snow. Sometimes they are no more pools, but are sometimes real lake of fresh water up to hundreds of square meters. Melting snow is so intense that, for example, winterers drifting station during the summer had to contend with melted snow. The depth of puddles usually reaches 0.3 – 1.5 m water in them clean, clear, with a low of 0 to 3 mg% salt content. It is safe to drink without putting any boiling or chemical treatment. Interestingly, in the recent past polar explorers feared for drinking water, formed by the melting of ice and snow. Among them was reigning prejudice that melt water is harmful to the body. It saw one of the main causes of scurvy. That's why George W. De Long – Head of the American expedition to the North Pole on board (1879 – 1881 gg.) – Forbade use for drinking water from the melted snow puddles and required to distill it in a special cube, despite having to save fuel. "If we are fortunate enough to return home and avoid cases of scurvy, – he wrote in his diary – I we assign an extremely pure water that we drink."
Summer Tundra abundant water sources, marshes, streams, lakes. However, the water from them before consumption should be boiled or treated antibacterial tablets.
In the winter, the source of water in the high Arctic region is the "old ice". At the young ice gaps between the ice crystals are more or less uniformly filled with salt brine cells that stood out in the ice formation. Salinity of new ice from 5 to 25% of what makes it completely unsuitable for fresh water. When the temperature increases the amount of ice is included in a pickle, and the cells gradually become longer, turning into through the channels through which the brine penetrates between the ice crystals, sinking lower and lower. This process is particularly intense in the summer months, leading to a continuous desalination upper layers of ice, which gradually extended to its full depth. The older the ice, the less it contains salt. Therefore, the upper part of the multi-year pack ice, rising above the level of the ice field, often almost completely fresh. Desalination is pack ice in winter due to the temperature difference between the top and bottom of the ice. Old, freshened ice is recognized by its distinctive blue color, flattened shape and shine. Young, svezhevzlomanny ice has a dark green color and looks like the apt expression of Stepanov's fanssona, "on the boulders in the granite quarry or, if it is thin, on broken glass." Sometimes it resembles aquamarine with a touch of transparent green. The source of water can also serve as a dense, packed snow, but the yield of water from it is 7 – 15%, ie, to produce 1 liter of water to break the 10 – 15 thousand cubic meters. cm of snow, and it is associated with a high consumption of fuel, each gram of which in terms of autonomous existence as gold. Thus, the estimated Hawkins to receive one pint of water (0.6 L) at -45 ° air requires 100 kcal of heat, that is, it is necessary to burn 10 – 12 g of kerosene. On the ice in the high Arctic region for water use only the top layer (10 – 15 cm) of snow, the salt content of which is insignificant, only 7 – 10 mg%. Snow layer, adjacent to the ice, more saturated with salts, which affects the taste of drinking water. In the autonomous existence as necessary to save fuel is useful to use the experience of northern peoples. Eskimos, for example, fill bags with snow, made from the intestines of the walrus, and put them under a fur park. The residual heat of the body is enough to get 5 hours 1.13 liters of water. Using the half-liter jar of soft polyethylene, placed under the fur jacket, we were able to get in 10 hours 0.5 liters of water.