Details

Autor(en) / Beteiligte

• Karavanova, E. I.
• Astaykina, A. A.

Titel

Properties of Water-Soluble Organic Substances Isolated from Soils Using Centrifugation and Vacuum Filtration

Ist Teil von

• Moscow University soil science bulletin, 2022, Vol.77 (1), p.23-29

Ort / Verlag

Moscow: Pleiades Publishing

Erscheinungsjahr

2022

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• This paper examines the composition and properties of water-soluble organic substances in relation to their localization in different parts of soil pore space, which determines the organic matter’s susceptibility to biodegradation. Water-soluble organic substances contained in the sod and humus horizons of a Mollic Gleysol were extracted from pores more and less than 30 μm in diameter using sequential centrifugation of soil samples saturated to the full moisture capacity. The obtained solutions do not differ statistically significantly in the total concentration of carbon and phenolic compounds or in their absorption and fluorescence spectra; however, a strong variation in parameter values (the maximum and minimum values differ by 4–15 times) indicates that the composition of extracted substances is heterogeneous. Concentrations of simple phenolcarboxylic acids (PCAs) in solutions extracted from large pores in the humus horizon are 4–8 times higher in comparison with those extracted from smaller pores. Salicylic, benzoic, and cinnamic acids predominate in large pores (75% of the total amount); while p -hydroxybenzoic and benzoic acids predominate in small pores (67% of the total amount). Dissolved organic matter present in the ELBTg horizon of a podzolic soil was isolated from pores more and less than 14.7 μm in diameter at a soil moisture level of 22% using tension lysimeters. Dissolved organic matter extracted from large pores contains more C, N, and phenolic compounds; based on the absorption spectra, it has a larger molecular weight and a higher aromaticity degree. Organic matter contained in small pores is more hydrophobic, and its C : N ratio varies in a wider range (i.e., it is more resistant to decomposition). Phenolic compounds are predominantly confined to large pores; this ensures their preservation in soil due to the transportation to lower horizons with water flows and subsequent chemical stabilization in the form of organomineral compounds.