PHYSICO-CHEMICAL PROPERTIES OF PEAT DEPOSITS AS INDICATORS OF GEOCHEMICAL PROCESS INTENSITY IN INDUSTRIAL EXTRACTION

Abstract

Peat deposits are natural geochemical accumulators of heavy metals and naturally occurring radionuclides, the stability of which fundamentally depends on the maintenance of waterlogged reducing conditions. Industrial peat extraction, for which drainage is an indispensable first stage, initiates a cascade of interrelated geochemical transformations whose intensity is determined primarily by the physico-chemical properties of the peat itself. This paper substantiates the concept of geochemical predictors – a system of standard deposit characteristics (ash content, degree of decomposition, type of organic matter, moisture content, depth to the water table) that allow quantitative pre-extraction assessment of the expected intensity of four key geochemical pressure processes: heavy metal mobilisation due to changes in redox potential and pH; pyrite oxidation with acid drainage formation; aerobic mineralisation of organic matter with dissolved organic carbon (DOC), ammonium nitrogen and trace metal release; and mechanical destruction of peat during milling generating metal-enriched particulate matter. The terms “indicator” and “predictor” are used as functionally close in this paper; however, the term “predictor” emphasises the prognostic nature of the assessment – i.e. the capacity of a parameter to forecast the intensity of a process before its onset. Based on a systematic analysis of peer-reviewed scientific literature, functional relationships between each predictor and the corresponding pressure process are established, and threshold values of elevated risk are defined for each parameter with explicit reference to their sources in the scientific literature. The results are formalised as an analytical predictor matrix suitable for direct application in Environmental Impact Assessment (EIA) report preparation. It is demonstrated that the intensity of geochemical pressure processes is differentiated by deposit type: poorly decomposed deposits with low ash content pose greater risks to surface water quality through DOC emission, while well-decomposed deposits with elevated ash content are more hazardous for groundwater and soils through heavy metal mobilisation and dust migration. The proposed predictor system provides a tool for overcoming the systemic gap between geological survey data and geochemical risk assessment in current EIA practice, and aligns with the new regulatory framework outlined in the draft Cabinet of Ministers of Ukraine Resolution on the special legal regime for peatland land use.