266 black. PERMAFROST [Ch. 14 



Throughout the Arctic, however, the quality of water is commonly 

 poorer than in temperate regions. Hardness, principally in the form 

 of calcium and magnesium carbonate and iron or manganese, is com- 

 mon. Organic impurities and sulphur are abundant. In many places 

 ground water and surface water have been polluted by man or or- 

 ganisms. 



Muller (1945) presents a detailed discussion of sources of water and 

 the engineering problems in permafrost areas of distributing the water. 

 Joestings (1941) describes a partially successful method of locating 

 water-bearing formations in permafrost with resistivity methods. 



Sewage Disposal 



Sewage disposal for large camps in areas of continuous permafrost 

 is a most difficult problem. Wastes should be dumped into the sea, 

 as no safe place exists on the land for their disposal in a raw state. 

 As chemical reaction is retarded by cold temperatures, natural decom- 

 position and purification through aeration does not take place readily. 

 Large streams that have some water in them the year around are few 

 and should not be contaminated. Promiscuous dumping of sewage will 

 lead within a few years to serious pollution of the few deep lakes and 

 other areas of annual surface-water supply. Burning is costly. No 

 really satisfactory solution is known. In discontinuous and sporadic 

 permafrost zones, streams are larger and can handle sewage more eas- 

 ily, yet even there sewage disposal still remains in places one of the 

 most important problems. 



Agriculture 



Permafrost as a cold reserve has a deleterious effect on the growth 

 of plants. However, as an impervious horizon it tends to keep pre- 

 cipitation in the upper soil horizons, and in thawing provides water 

 from melting ground ice. Both deleterious and beneficial effects are 

 negligible after one or two years of cultivation, as the permafrost table 

 thaws, in that length of time, beyond the reach of roots of most annual 

 plants (Gasser, 1948) . 



Farming in permafrost areas that have much ground ice, however, 

 can lead to a considerable loss in time and money. Sub-Arctic farming 

 can be done only where a sufficient growing season is available for 

 plants to mature in the short summers. Such areas are in the discon- 

 tinuous or sporadic zones of permafrost. If the land is cleared of its 

 natural insulating cover of vegetation, the permafrost thaws. Over 

 a period of 2 to 3 years, large cave-in lakes have developed in Siberia, 

 and pits and mounds have formed in Alaska (Pewe, 1948a, 1949; 



