Kruglaya

Created: 2015-11-11 13:34:50
Modified: 2015-11-11 13:42:46

The grid “Cape Kruglaya”, 100x100 m, is located on Lower-Anadyr (Nizhneanadyrskaya) Lowland at the south-east coast of Onemen bay (Gniloy ugol) - 64°38¢ North and 176°58¢ East. Relief of the area is lake bog basin with altitudes 1.5 to 2.5 m above the water level in the Bay. CALM grid is set at the flat bottom lake-marsh basin. The surface is represented by typical hummocky-moss tundra and sedge marsh. Hummocks are formed of cotton grass (Erioophorum vaginatum) dominating on dry area. Hummock height is 10-15 cm. Here they occupy 40 to 50% of the surface, the rest occupied by inter-hummock depressions filled sedge, green and bog mosses (Sphagnum sp.sp.) with participation low shrub. In south-east part of the grid wide-spread bush of the osier (Salix glauca, S. tschuktschorum), with lower tier from moss, sedge and gramineae. Coverage of the bush tundra within the grid is 10-15 %; coverage of moss-sedge bog tundra is 20-30 % and of hummocky-moss tundra  - 70 to 55%. Main producer of ground-level phytomass is cotton grass and sedge.

The grid is located in the area of transition from moderately-continental to marine climate subzone of the Sub-Arctic climatic zone. Mean annual air temperature at Anadyr weather station (30 km from the grid) is -7.7oС, mean annual precipitation is 312 mm.

The hydrochemical conditions of the grid in many respects are instituted by closeness of marine coast. The type of atmospheric precipitation here is transitional from maritime to continental. Rain and thawed snow water are of chloride-hydrocarbon-sodium type with mineralization up to 45 mg/l. At inflow of thawed and rain waters into the active layer, they get saturated by ions of calcium, magnesium and hydrocarbonate, the mineralization rise up to 80-88 mg/l.

The grid is located in the continuous permafrost area. Taliks of hydrogenous type are found only below the Onemen Bay and large lakes. Mean annual ground temperature is about –5oC, the permafrost thickness is up to 150 m. Frost cracks and ice-wedge, and spot-medallion formation are periglacial features developed within the grid. At the adjacent area, the coastal processes are spread: coastal thermoerosion, thermocircues connected with massive ground ice occurrence. Cryolithological structure of permafrost is variable. Immediately beneath the active layer modern ice wedges are lying, up to 1 m wide and up to 2 m high.

SAMPLING DESIGN AND METHOD:

Permanent 100x100 m grids have been established, with 10-m intervals between grid nodes. Thaw depths were determined at each grid node (121) using a steel rod. The measurements of the active-layer thickness were performed according to the CALM procedure from 2010 to present.