Humus state of buried soils of different age archaeological monuments on the territory of Ufa (Russia, Republic of Bashkortostan)

Abstract

The paper studies the humus state of buried soils on the territory of archaeological monuments: the New–Ufa Burial Ground (early Iron Age) and the Settlement Ufa–II (early Middle Ages), located in the urban district of Ufa (Russia, Republic of Bashkortostan). The soil cover of archaeological monuments is represented by Greyzemic Phaeozem over Grayzemic Phaeozem (gz–PH over gz–PH). The humus content in buried horizons is 2.06–5.26%, which is 2–4 times less in comparison with the native soil. There are two types of humus such as humate and humate–fulvate. Among humic acids, the fraction associated with calcium (HAs–2) predominates. The spectral curves of humic acids HAs–2 at different wavelengths for the buried humus–accumulative horizon of the New–Ufa Burial Ground have a steeper character and lower optical density values compared to the background soil. The spectral curves of the buried horizons of the Settlement Ufa–II have flatter disposition and, in terms of optical density, are close to the values of the native soil. Obtained results make it possible to estimate the transformation of organic matter in the soils after their burial in comparison with the modern native soil Greyzemic Phaeozem (gz–PH) of the city park.