In the world practice, the organic carbon content (C_org) in the soils containing carbonates is measured in different ways. We have analyzed the methods for solving this problem including the state-of-the-art approaches, such as thermogravimetry, differential scanning calorimetry, and spectroscopy. As is shown, the presence of CaCO₃ does not prevent the C_org measurement with dichromatometric method (Tyurin and Walkley–Black variants). The disadvantages of this method comprise the laborious analysis, constant presence of operator, incomplete oxidation of organic compounds, and environmental pollution. The measurement of soil weight loss-on-ignition (LOI) is economical and rapid but overestimates C_org content because of inadequacy of the conversion factor of 1.724, the presence of adsorbed and chemically bound water, as well as mineral components decomposing at T = 105–550°C. The most relevant solution for assaying the C_org content in carbonate soils is to use an analyzer and a calcimeter although the accuracy of C_org measurements in the presence of carbonates is significantly reduced because the errors of two methods are quadratically summed. A high cost of the device, maintenance, verification, and repair limit its widespread use in soil laboratories. The content of soil carbonates can be measured using both gravimetric (LOI) and volumetric (calcimeter) methods. The latter method is preferable for the soils with the prevalence of CaCO₃ in carbonates. The preliminary removal of carbonates from soil samples is labor-intensive and can cause a partial loss of C_org via acid extraction. A high cost of the instruments and the absence of the libraries of soil spectra hinder the development of Vis-NIR and MIR spectroscopy as an alternative to wet chemistry methods. Further comparative studies will give a deeper insight into the spatial patterns in the distribution of soil organic carbon.

The content of soil organic matter (SOM) is a fundamental characteristic of the humus status of soils. The dichromatometric method based on a significant variety of measurement approaches is actively used in world practice to assess the SOM content. The unification of methods for determining the SOM content and other soil parameters is an international communication tool, which enables the interaction of specialists for the creation of databases on soils of the world and for inventory and monitoring of soil resources. The given data show that some modifications of Tyurin’s method may include procedures, which reduce the accuracy of the SOM measurement. The staff of the Institute of Biology has developed and certified a new modification of the method by Tyurin, excluding these procedures. The correctness of the introduction of a correction factor f = 1.15 into the calculation of the SOM content to account for incomplete oxidation of carbon of organic compounds has been experimentally determined. The f factor used in case, when the measurement error does exceed 20%, provides the results, which are consistent with the methods by Walkley-Black and high-temperature combustion of organic carbon on an analyzer.

Landscapes of the northern part of the Bolshoi Paipudynskii Ridge (the Polar Urals) served as a key site to study the taxonomic diversity of soils on calcareous rocks as related to both bioclimatic and geogenic (relief, thickness of eluvial and colluvial derivatives of calcareous rocks) factors. Soils of the postlithogenic trunk of the new Russian soil classification system are developed under different plant communities. They are classified within several soil orders: cryometamorphic soils (Mollic Calcaric Stagnosols), lithozems (Folic Mollic Calcaric Leptosols), organo-accumulative soils (Molic Leptic Calcaric Stagnosols), and gley soils (Folic Calcaric Gleysols). These soils compose either small individual areas, or occur in soil associations. The mass of carbon and nitrogen in the aboveground phytomass ranges within 40–49 and 0.9–2.3%, respectively. The storage of aboveground phytomass (fresh weight) varies from 20 to 1600 g/m². In each soil profile, the surface horizons have a maximum content of organic carbon and nitrogen (up to 40 and 2.5%, respectively). The C_org and N_org patterns in soils depend on the productivity of plant communities, the composition of falloff, and the conditions for its decomposition. In all soil profiles, the inorganic carbon content (C_inorg) increases down the soil profile reaching 12%. The mineral nitrogen content does not exceed 1%. The contents of N-\({\text{NH}}_{4}^{ + }\) and N-\({\text{NO}}_{3}^{ - }\) have their maximums reaching 140 and 30 mg/kg, respectively, in the surface soil horizons.

Concentrations of total carbon and nitrogen were measured by gas chromatography method, and the carbon content of inorganic compounds was determined by the volumetric method in soils of...

Soils and vegetation of the coastal zone of the Khaipudyr Bay of the Barents Sea have been examined and compared with analogous objects in the Karelian coastal zone of the White Sea. The...