Acidity in organic horizons of arctic soils on the Barents Sea coast

Parameters of water and KCl extracts from organic horizons of arctic soils on the coast of Khaipudyr Bay of the Barents Sea, in which the values of pH are 3.8–4.3 and 2.7–3.5, respectively, have been compared. It has been found that the content of water-extractable organic carbon is 0.2–0.5 g/dm3; the contents of low-molecular-weight carbohydrates and acids are 1–24 and 6 mg/dm3, respectively, and the content of Fe3+ ions is 1–4 mmol/dm3. The increase in the ionic strength of solution reduces the extraction efficiency of total organic carbon in 1.2 times and that of acids and carbohydrates in 3 times on the average at the simultaneous increase in the content of iron ions in the liquid phase in 7–15 times. It has been shown that organic acids and iron compounds are the main sources of acidity in salt extracts from organic soil horizons. The low contents of Ca2+ and Mg2+, which participate in the neutralization of acids, favor the high acidity of the studied horizons.