Гiдрогеохiмiчне моделювання впливу фiльтрацiйних втрат високомiнералiзованих шахтних вод зi ставка-накопичувача у балцi Свистунова (версiя 0.80)

Description

Abstract (English)

The impoundment for highly mineralized mine waters in the Svystunova Gully was constructed in 1976. Over the last two decades, the facility has annually received 10–13 million m³ of mine water from the enterprises of the Kryvyi Rih Iron Ore Basin, with a total mineralization of 28–38 g/L. Subsequently, the accumulated volumes are discharged into the Inhulets River. Concurrently, a portion of the water is inevitably lost through the impoundment bed, infiltrating into the Miocene aquifer. Throughout the operation period of the facility, a massive pollution plume has formed within the surrounding host rocks, leading to significant alterations in the hydrogeological regime and the chemical composition of the aquifer. South of the tailings storage facilities complex and the impoundment, the drinking water resources of the Quaternary and the more confined Neogene aquifers have undergone almost complete degradation. Meanwhile, the actual spatial boundary of the contaminant plume contour remains undetermined to date.

In general, the hydrogeochemical processes occurring with the highly mineralized mine waters of the Kryvbas form a complex conveyor system and can be subdivided into several distinct phases: the mixing of waters of various origins within the hydro-protection systems of mine fields; mixing and partial sedimentation in intermediate surface reservoirs; entry and long-term sedimentation directly within the impoundment; the mixing of seepage losses with local water of the carbonate aquifer; and, ultimately, the mixing of the partially "deactivated" water with the flow of the Inhulets River after the drainage of the aquifer by a network of springs. A separate transit phase of mixing during the period of direct regulated discharge of water from the impoundment is distinguished. Each of these phases is characterized by a unique set of thermodynamic parameters and dominant geochemical reactions. Within the scope of this study, the focus is deliberately narrowed: the object of study is exclusively the transformation phase of seepage losses from the impoundment within the carbonate aquifer.

The problem of the operational activity of the impoundment requires a multi-vector integrated approach, as it combines hydrogeochemical, environmental, engineering, economic, and social factors that interact non-linearly in space and time. This necessitates a profound systemic analysis to adequately assess environmental risks and make well-founded management decisions.

The objective of the presented study is the numerical modeling of the long-term geochemical impact of highly mineralized mine waters on the aquifer confined to limestone deposits. To achieve this objective, a cycle of mathematical modeling of mass transfer processes and a subsequent analysis of the obtained geospatial information were implemented. The primary instrumental method is the calculation of the local thermodynamic equilibrium of dissolved components. Particular attention is paid to the phase equilibria of key carbonate minerals: calcite, aragonite, disordered dolomite, and magnesite. The processes of limestone dissolution and dolomitization under the influence of highly mineralized waters are a fundamental factor causing not only changes in the porosity and hydrodynamic permeability of the strata, but also critically affecting the partitioning of toxic trace elements into mobile (migration-capable) forms.

The empirical basis of the study comprises the results of environmental monitoring (chemical analyses of water samples) collected from the discharge pipe, the impoundment water area, and the network of observation wells during the period of 2012–2021 and in the spring of 2023. Given the probable instrumental and methodological errors of monitoring, it is necessary to emphasize that these datasets constitute the only available factual basis upon which state management decisions currently rely. This renders them a legitimate and unalternative object for the presented study. Separately, it should be noted that the existing configuration of the observation well network does not cover the entire geometry of the impact zone: the data indicate that even at the most remote monitoring points, a state of complete thermodynamic equilibrium between the water mixture and the host limestone massif is not reached.

A critical audit of literature sources revealed a persistent problem of a fundamental-methodological rather than computational nature. The vast majority of environmental assessments of Kryvbas waters rely on methodologies that physically do not function in highly mineralized waters. Classical algorithms for calculating chemical equilibria, which have proven themselves perfectly for freshwaters, are inapplicable to technologically stressed systems. The extreme ionic strength of mine waters requires the involvement of a fundamentally different mathematical apparatus. The extrapolation of basic engineering simplifications to such environments is not merely a rounding error; it is a direct path to erroneous conclusions regarding mineral stability and the toxicity of contaminant plumes. This same conceptual blindness extends to mass transport assessment: multi-year attempts to model filtration using classical hydrodynamics, while ignoring the effects of density-driven convection and gravitational sinking of heavy mineralized waters, inevitably result in the generation of fictitious spatial migration models. Overcoming this methodological inertia, which Nobel laureate Richard Feynman aptly characterized as "Cargo Cult Science", unalternatively requires a return to the rigorous laws of chemical thermodynamics and multiphase flow physics.

At the time of the study, there are no mentions in the public academic space regarding the application of equilibrium thermodynamics methods to groundwaters within the impact zone of the impoundment in the Svystunova Gully. Given the narrow distribution of computational complexes of the PHREEQC class among domestic specialists, it can be stated that such calculations were either not performed at all or remain isolated within closed corporate reports. Consequently, the presented monograph serves as a precedent for an open, reproducible, and transparent computational analysis of a geochemical system of this scale.

Unlike traditional descriptive hydrochemistry, the methodology of this work focuses on hidden thermodynamic factors: the potential solubility of mineral phases, saturation index gradients, and competitive complexation of trace elements. Within the scope of this study, the author proposes a conceptual innovation: to consider the aquifer degradation process as a full-fledged geochemical analog of infiltration metasomatism. This approach allows moving beyond the primitive diffusion paradigm (the mechanical "spreading" of salts) and treating infiltration as active mineralogical replacement of the mineral matrix. The contaminant plume emerges as a complexly organized macro-system in which reaction fronts, zones of mobilization/immobilization of chemical elements, and barriers of secondary mineral formation are shaped. The impoundment's impact zone acts as a dynamic metasomatic belt that irreversibly transforms the state of the rock massif.

Relying on these principles, the author proposes a new thermodynamic criterion for establishing the boundaries of the anthropogenic impact zone. In contrast to the obsolete practice of searching for "background concentrations", the proposed approach is based on mapping the zones of phase equilibrium disruption with calcite. The destruction of the natural buffering equilibrium is the earliest and most rigorous indicator of the contaminant plume's advancement. Accordingly, the true boundary of environmental impact lies not where concentrations visually "return to normal", but where the system restores thermodynamic balance with the host rock massif.

A special place in the architecture of the study is allocated to advanced spatial data visualization. In the context of multidimensional hydrogeochemical modeling, graphical representation is not merely an illustration but an independent heuristic tool. The visualization of multidimensional data enables the rapid identification of hidden spatiotemporal patterns, diagnostically significant clusters, and geochemical anomalies, ensuring reliable verification of mathematical results.

The modeled processes convincingly demonstrate that the contaminant plume has formed a two-tier zonal structure, the components of which are linked by a positive feedback loop. Such a geochemical configuration implies the self-reinforcement of the massif's degradation. Consequently, the purely engineering elimination of water losses from the impoundment, without performing geochemical remediation of the entire "affected" zone of the aquifer, is no longer capable of stopping the initiated process of limestone destruction.

The study was deliberately carried out at the intersection of hydrogeochemistry, data science, geoinformatics, and classical ore formation theory. The author is aware that such a cross-disciplinary lens may seem unorthodox to narrow-specialized geological schools. However, it is precisely the hybridization of methods that provides the highest explanatory power for natural-technogenic systems of this level of complexity. Possessing a prognostic character, the proposed spatial interpretations are open to further field verification, and their value lies in creating a fundamentally new systemic framework for understanding the problem of the impoundment and the contaminated aquifer. Hence, geochemistry (physical chemistry) is considered in the monograph as an unalternative basis for any subsequent engineering, environmental, or economic risk assessments.

The bibliographic and source base of the monograph was formed through a classical, deep examination of primary sources. Despite the technical availability of modern generative AI models for mass literature aggregation, the author deliberately chose the path of direct hermeneutic analysis of scientific works. This guarantees the absence of contextual hallucinations and ensures the rigorous relevance of every involved theoretical concept to the specific features of the object under study.

Ultimately, despite the absence of a prior serial academic publication record in this narrow niche, this monograph represents the quintessence of long-term computational and analytical work implemented in the status of a fully independent researcher—without an external institutional umbrella, targeted grants, or administrative resources. The chosen structure, style of presentation, and architecture of argumentation constitute a deliberate attempt to break down and rethink the classical academic format of a monograph, adapting it to the dynamic realities of open science and independent research initiatives.

The fact that following the publication of earlier preprints of this work (starting with version 0.72 on the Zenodo platform), a sudden activation of relevant organizations has been observed—which for decades had ignored the thermodynamic aspect of the impoundment problem in the Svystunova Gully—serves as the best indicator of its impact. Within the open science paradigm, the emergence of alternative expert assessments or attempts to replicate these calculations should be viewed not as competition, but as undeniable proof that independent research has successfully broken the environmental problem out of its deadlock.