Morphology and Physicochemical Properties of Soils of the Bear Islands Archipelago (Northeastern Yakutia)

The soils of the Arctic islands of Krestovsky and Chetyrekhstolbovoi (the Medvezh’i Ostrova Federal Reserve) in the East Siberian Sea and their morphological and physicochemical properties have been studied. The soils of the coastal strip in the zone of direct influence of the sea, the soils of river valleys, arctic tundra soils, and the soils developing on outcrops of hard rocks are characterized. The tops and upper slopes of local mounts are characterized by the development of soils on the eluvium of granite rocks with a brownish profile: humus petrozems (Skeletic Leptosol) and cryohomogeneous cryozems (Oxyaquic Cryosol). This is a group of acidic soils with a low degree of base saturation. In concave depressions between the mounts, the parent rock is represented by a less acidic fine-grained layer. The soils are developed under the impact of intense cryogenic processes (frost cracking, frost heaving, thermokarst, etc.) and have a higher degree of hydromorphism; they are identified as hydromorphic gleyic cryozems (Reductaquic Cryosols). These soils have a close to neutral reaction and high base saturation, as well as the soils forming on sediments of the ice complex (yedoma) on the continent. Alluvial humus gley soils (Reductaquic Cryosols Fluvic) are developed in the valleys of small creeks under conditions of high hydromorphism. On low sea coasts composed of sand, under a continuous vegetation cover leading to a relatively intensive accumulation of organic matter, acid marsh humus soils (Protic Fluvisols) are described. The total content of Pb, Zn, Cu, Ni, Cd, Co was determined in the samples. The content of these heavy metals directly correlated with the content of the clay fraction (<0.001 mm). An assessment of the specific activity of natural (40K, 238U, 232Th) radionuclides in the soils of the islands was carried out taking into account the soil-geochemical characteristics of the territory. The assessment of the background specific activity of radionuclides in soils did not reveal anomalous zones with increased radioactivity values.