Soil salinization of the Baer Mounds in the Volga River delta

Abstract

The Baer Mounds are elongated hills arranged in parallel rows stretched from the east to the west in the Astrakhan steppe. The distance between the mounds varies from 200 to 1500 m (300 m on the average). The width of the mounds is about 250 m and their length is from 450 m to 4.5–5 km long (sometimes, up to 15–20 km). The height of the mounds varies from 7 to 10 m and increases in the southward direction. The mounds are composed of clayey sand; loamy sand; light loam; and, sometimes, loam. Their top (1–3 m) parts consist of clayey sand and loamy sand with thin interlayers of loam, clay, and argillite pebbles. The upper horizons of the brown semidesert soils are not saline. Soluble salts are leached off from them into deeper horizons. On the slopes, the deep soil horizons are saline, and salts are transported from the deep soil layers into the upper layers. This can be explained by the regular flooding of the foots of the mounds with floodwater and the capillary rise of water. Alternation of salinization and desalinization processes is responsible for the nonuniform distribution of salts in the soil profiles and along the soil catena.