Toxicity of vapor-gas flows from technogenic substance

The relevance. Vapor-gas flows from technogenic substances (storage wastes of the mining industry), carrying a high amount of potentially toxic elements, are a big problem for the environment and the population, because metals and metalloids in the composition of emanations are in an easily digestible bioavailable forms and are able to easily penetrate into living organisms. The main aim of this study is an assessment of toxicity for living organisms of air mixtures containing gaseous products emitted by a surfaces of mine tailings freely located near settlements and under the influence of climatic factors and microorganisms. Methods. Carrying out experiments with white rats male Wistar, analysis of organs for the content of a wide range of elements by ICP-MS on a NexION 300D mass spectrometer (PerkinElmer, USA) (PNL  GGC IShPR TPU). In the experiment, a pooled sample of the waste substance was used. The sample was analyzed for the content of oxides of the silicate group by XRF using X-ray fluorescence spectrometer ARL-9900-XP (Thermo Electron Corporation, Switzerland) at the Laboratory of X-ray Spectral Analysis Methods of the IGM SB RAS; elemental analysis was carried out by ICP-MS using an ELAN-9000 DRC-e instrument Perkin Elmer, USA (HAC Plasma). Results. Under the influence of vapor-gas emanations from the substance of arsenide tailings of the Tuvacobalt plant on a group of rats male Wistar, pathological changes occurred in the experimental group. Small foci of hemorrhages formed in the lungs, the tissues became edematous and inflamed. The liver of all animals increased, the share structure became sharply expressed, the color became light beige. Single hemorrhages were found in the kidneys. The vessels of the meninges are dilated, petechial hemorrhages are observed. The synthetic function of cells and the stability of cellular and intracellular membranes were disrupted, first of all, the endothelium of blood vessels was affected, the physiological functioning of organs and tissues was disrupted with the accumulation of intermediate products of biochemical reactions, determined macroscopically. Also, dystrophy of internal organs was determined, in particular, the liver, lungs, kidneys, and brain. Elemental analysis of animal organs showed the accumulation of toxic elements in comparison with the control group. The most characteristic elements, the excess of which was recorded in most cases, are mercury and arsenic. They were unevenly distributed throughout the organs. Mercury accumulated mainly in the lungs, kidneys and liver, while arsenic accumulated mainly in the liver and brain. This may indicate the entry of mercury and arsenic ions in a biologically available form into the bloodstream by inhalation, and local irritating and toxic effects on the lungs were not prevailing, and the liver was the most damaged organ according to the results of toxicochemical and morphological studies. The homeostasis of micro and macro elements is finely regulated, and any concentration imbalance in the form of a deficiency leads to a progressive decrease and disruption of normal biological function, to severe physiological and clinical outcomes, which we observed from the results of the experiment. The data obtained proved the acute toxic effect of vapor-gas flows on living organisms, and also confirmed the possibility of the removal of many chemical elements in easily accessible and assimilable forms

Modeling the Process of Thawing of Tailings Dam Base Soils by Technological Waters

The storage of wastes from mining and mineral processing plants in the tailing dumps in regions with cold climates has a number of environmental consequences. Interactions of water with tailings in cold climates often lead to the thawing of permafrost soils, formation of technogenic thawing zones, and leakage of drainage waters. In the case of fault zones development in these areas, technogenic solutions are often filtered outside the tailing dump, promoting further development of filtration channels. In order to prevent leakage of solution from tailing dumps over time, it is necessary to determine the thawing zones and prevent the formation of filtration channels. In the case of the formation of a filtration channel, it is necessary to know what rate of rock thawing occurred near the formed filtration channel. In this study, for the tailing dump of a diamond mining factory, we calculated two exothermic effects: (1) due to physical heating of dump rock by filtering industrial water with temperatures from 2 to 15 °C through the rock; and (2) due to the chemical interaction of industrial water with the dam base rock. The amount of energy transferred by the water to the frozen and thawed rock over 10 years was calculated using thermophysical modeling and was 207.8 GJ and 8.39 GJ respectively. The amount of energy that the rock received during the ten-year period due to dissolution of the limestones and equilibration of solutions was calculated using thermodynamic modeling and was 0.37 GJ, which is 4.4% of the average amount of energy, expended on heating the thawed rock (8.39 GJ)

Chemical Treatment of Highly Toxic Acid Mine Drainage at A Gold Mining Site in Southwestern Siberia, Russia

The critical environmental situation in the region of southwestern Siberia (Komsomolsk settlement, Kemerovo region) is the result of the intentional displacement of mine tailings with high sulfide concentrations. During storage, ponds of acidic water with incredibly high arsenic (up to 4 g/L) and metals formed on the tailings. The application of chemical methods to treat these extremely toxic waters is implemented: milk of lime Ca(OH)2, sodium sulfide Na2S, and sodium hydroxide NaOH. Field experiments were carried out by sequential adding pre-weighed reagents to the solutions with control of the physicochemical parameters and element concentrations for each solution/reagent ratio. In the experiment with Ca(OH)2, the pH increased to neutral values most slowly, which is contrary to the results from the experiment with NaOH. When neutralizing solutions with NaOH, arsenic-containing phases are formed most actively, arsenate chalcophyllite Cu18Al2(AsO4)4(SO4)3(OH)24·36H2O, a hydrated iron arsenate scorodite, kaatialaite FeAs3O9·8H2O and Mg(H2AsO4)2. A common specificity of the neutralization processes is the rapid precipitation of Fe hydroxides and gypsum, then the reverse release of pollutants under alkaline conditions. The chemistry of the processes is described using thermodynamic modeling. The main species of arsenic in the solutions are iron-arsenate complexes; at the end of the experiments with Ca(OH)2, Na2S, and NaOH, the main species of arsenic is CaAsO4−, the most toxic acid H3AsO3 and AsO43−, respectively. It is recommended that full-scale experiments should use NaOH in the first stages and then Ca(OH)2 for the subsequent neutralization

Evidence of Volatility Metals and Metalloids at Environment Conditions

Tailings represent a significant risk to the environment globally, but very little is known about the composition of the near-surface air. We conducted laboratory experiments to determine the sizes of the particles and the chemical composition of the flow above the mine waste. A condensate of vapor–gas flow was collected in parallel with particle control by an aerosol diffusion spectrometer (ADS). We reveal that there were no aerosol particles bigger than 3 nm in the flow. The collected condensate contained chemical elements, ions of sulfates, chlorides, phosphates, and formates and a wide range of sulfur-, selenium-, and carbon-containing gases. The main findings of the study are the presence of the metals Zn, Cu, Fe, Al, Cd, Ni, and Ba and the metalloids As, Sb, Se, Ag, Co, Ti, and V in the true-gas phase or in the form of particles smaller than 3 nm in the air above the mine tailings. The surprising fact is that the migration of metals and metalloids in a true-gas form or in ultrafine particles (<3 nm) is possible, which opens up a new research direction on the volatile forms of chemical elements in various climatic conditions and their bioavailability and toxicity

Determination of Arsenic Species Distribution in Arsenide Tailings and Leakage Using Geochemical and Geophysical Methods

This study describes the distribution of arsenic mobile species in the tailings of Cu–Co–Ni–arsenide using the sequential extraction and determining the contents of arsenate (AsV) and arsenite (AsIII). The object of this study is the tailings ponds of the Tuvakobalt plant, which contains waste from the hydrometallurgical arsenide ore processing of the Khovu-Aksy deposit (Republic of Tuva, Russia). A procedure of sequential extraction for arsenic was applied, and it includes the extraction of the following forms: water-soluble, potentially water-soluble and exchangeable, easily sorbed on the surface of carbonates, associated with Fe/Mn oxides/hydroxides, associated with easily oxidized minerals, and accounted for by non-oxidized arsenic minerals. This procedure, which takes into account the peculiarities of the physical and chemical composition of the waste, was supplemented by the analytical determination of the arsenite and arsenate content by using the methods of inductively coupled plasma atomic emission spectrometry (ICP-AES) combined with the hydride generation technique (HG-ICP-AES). The content of the most mobile forms of arsenic, which are water-soluble, potentially water-soluble, and exchangeable species, is equal to 56% of the total arsenic content, 23% and 33% of which are arsenite and arsenate, respectively. Unlike arsenic, the mobile forms of metals have been determined in small quantities. The largest proportion of water-soluble and exchangeable forms is formed by Mg, Ca, and Sr at 11, 9.4, and 20%, respectively (residual and redeposited carbonates). The proportion of water-soluble forms of other metals (Cu, Zn, Co, and Ni) is < 1% or 0. The main part of the metals is adsorbed on the surface of Fe and Mn hydroxides, enclosed in easily and hardly oxidized minerals. In addition to geochemical studies, the presence of leaks from the tailing ponds into ground waters was determined by using electrical resistivity tomography. The data obtained indicate a high environmental hazard of tailings and the possibility of water-soluble and highly toxic arsenic compounds entering ground waters and aquifers

NMR-relaxometry laboratory study of fluids taken from boreholes

The relevance. Timely diagnostics of the fluid, taken from a borehole, allows determining the rise of flooding and destruction of the bottom-hole zone at the initial stage of well operation. Now diagnostics of a liquid phase is carried out by means of hydrochemical analysis of water samples in laboratory conditions. This method provides meaningful data on ionic-salt and microcomponent composition of the studied liquid. Diagnostics operativeness is very important in the most of cases, that is why it is important to find alternative methods and approaches for reservoir fluids express studying. This method is NMR-relaxometry. It allows typifying effectively the fluid taken from a borehole in combination with the hydrochemical data. The aim of the research is to develop the NMR-relaxometry method as applied to diagnostics of the fluid taken from a borehole, based on the dependence of transverse relaxation time on concentration of paramagnetic ions. The methods used: expanded hydrochemical analysis including the determination of ion-salt and microcomponent composition and laboratory methods of pulsed NMR-relaxometry aimed at determining transverse relaxation time. The results. Using the laboratory hydrochemical analysis data on ionic-salt and microcomponent composition of the fluid taken from a borehole and based on the conducted NMR-investigations, the authors have experimentally confirmed the considerable dependence of transverse relaxation time on change in concentration of paramagnetic metal ions. The authors determined the dependence of the transverse relaxation time on the content of calcium and sodium ions. The latter provide a basis for distinguishing technogeneous and formation water, subsequent to the results of hydrochemical analysis, which is the basis for prompt typification of the fluid taken from a borehole by NMR-data. This dependence allows distinguishing exactly the technogeneous water characterizing by high content of metal paramagnetic ions