Data on the soilscape and vegetation properties at the key site in the NW Caspian sea coast, Russia

Research on the environment in recent soils is important to understand geochemical processes in coastal landscapes and the rate of pedogenesis. In this article, we present original data on Gleyic Solonchaks (Loamic) and vegetation described at the eastern part of the Terek-Kuma lowland (Northern Dagestan, Russia). At the key site of 45 × 30 m released from water 293±13 years calBP, we described vegetation at 345 plots of 2 × 2 m (4 m²) and soil properties in 58 auger holes and 2 pedons, the latter characterizing a typical microhigh with Tamarix and a microlow with saltworts. The flora of the sites amounts to 32 species (predominantly, halophytes) belonging to 11 families. Shrubs represented by tamarixes are the dominant. Under their crowns, dense herb and grass microcommunities with a predominance of tall Puccinellia gigantea occur. Sparse stunted halophytic plants (Petrosimonia, Frankenia, Puccinellia) occupy open habitats between shrubs. In soil water extracts from auger holes (696 samples in total), we measured electrical conductivity (EC) and pH. In 49 soil samples from pedons, we described particle size distribution, total concentration of macro elements (Al, Ca, Fe, K, as well as Mg, Mn, P, Ti, and Si) and trace elements (As, Co, Cr, Cu, Ni, Pb, Sr, and Zn), EC, pH, basicity (HCO₃ ^- and CO₃ ^2-) as well as the content of cations (Ca²⁺, Mg²⁺, Na⁺, and K ⁺) and anions (SO₄ ^2- and Cl^-) in soil water extracts. Gleyic Solonchaks (Loamic) with bulk density of 1.35±0.12 g/cm³ (mean and standard deviation) contain SiO₂ 69±8%> Al₂O₃ 11.8 ± 3.5 and CaO 7.5 ± 2.5%, Fe₂O₃ 3.6 ± 1.4%, K₂O 2.0 ± 0.3 and MgO 1.9 ± 0.4%> TiO₂ 0.62±0.25%> P₂O₅ 0.14±0.06% and MnO 713±268 mg/kg> Sr 481±262 mg/kg > Cr 79±9 mg/kg > V 76±36, Zn 68±31, Cu 62±10, and Ni 50±17 mg/kg, Co 32±6 mg/kg> Pb 11±6 mg/kg> As 5.6 ± 1.4 mg/kg. The particle-size distribution is (WRB system,%): clay 13±5, fine silt 34±12, coarse silt 30±18, as well as very fine sand 11±10, fine sand 7.3 ± 10.5, medium sand 3.5 ± 5.8, coarse sand 0.9 ± 3.2, and very coarse sand 0.08±0.31 (n = 38). Soil water extract has EC 9.4 ± 4.1 dSm/m (soils: water ratio of 1:2.5, n = 713), contains Na⁺ 15.9 ± 7.0 > Ca²⁺7.3 ± 5.0 and Mg²⁺ 7.3 ± 3.1 > K ⁺ 0.30±0.20 cmol(eq)/kg, as well as Cl^- 15.7 ± 7.3 and SO₄ ^2- 14.6 ± 7.9 > HCO₃ ^- 0.55±0.15 > CO₃ ^{2 -}< 0.01 cmol(eq)/kg, and has pH 7.9 ± 0.3 (soils: water ratio of 1:5, n = 21). In soil paste, pH is 8.3 ± 0.2 (n = 461). Data obtained can be used for more confident identification of pollution sources and pollutants' migration routes and more effective conservation and remediation of human-affected soils at the Caspian Sea coast.