Mine Water Discharge Research Articles

Multi-Decadal Impact of Mine Waters in Przemsza River Basin, Upper Silesian Coal Basin, Southern Poland

Anthropogenic increases in the salinity of surface waters are referred to as secondary salinization. In surface waters, salinity levels can vary significantly due to various natural and anthropogenic influences. This article presents multi-decadal observations of changes in surface water salinity in the highly industrialized region in southern Poland. The case study of the Przemsza River is an example of the significant impacts of industrial, mainly coal mining, activities that have changed the chemical and biological characteristics of water bodies. The presented research revealed that impacts on salinity and water body status due to mining discharges will be difficult or even impossible to restore, considering the process of transition of the coal sector. In the Przemsza river basin, almost 42% less mine water was discharged in 2023 than in 1991. Parallelly, the salinity of mine waters discharged from deeper levels of active coal mines has increased due to the geochemical gradient (the total load of chlorides and sulfates was 534.8 MgCl−+SO42− per day in 1991, while in 2023 the total salinity load was 480.1 MgCl−+SO42− per day). Moreover, of the 19 active mine water discharges in 1991, only 11 remain in 2023, while the observed salinity of surface water in the Przemsza watershed increased rapidly from an average of 2000 µS·cm−1 to 6700 µS·cm−1 due to the significant drought and adverse hydrological conditions, which represent low flows never observed before (three times lower flows in the mouth of the Przemsza River in the period 2021–2023 compared to the previous decades 1991–2020). Impacts on water bodies will continue to occur regardless of mining activities in the area—it should be noted that at the end of exploitation, mine water rebound and flooding do not automatically reduce long-lasting impacts on surface waters. Therefore, salinization is a growing threat that might be amplified by climate change. While industrial and urban impacts on surface water change its characteristics, the future challenge of proper water management with a holistic approach is necessary with proper monitoring data collection and river flow-dependent and surface water salinity-dependent discharge of wastewater in the river basin.

Development of a limestone-based ballasted material for enhanced co-removal of turbidity and fluoride from coal mine water: An efficacy study

The rapid progression of coal mining technology in recent years has resulted to the discharge of mine water with excessively high levels of turbidity and fluoride, presenting a complex contamination issue. This study develop an innovative limestone-based ballasted material, integrating it with ballasted flocculation technology. The synergistic effects of surface flocculation and adsorption have enabled the simultaneous and efficient removal of high concentrations of turbidity and fluoride. The influence of various parameters, including the dosage of the coagulant, flocculant, ballasted material, and the stability under long-term continuous operation, on the performance of this new technology was investigated. Findings indicate that an increase in the dosage of the coagulant, polyaluminum chloride (PAC), positively affects the removal of turbidity and fluoride ions, with an optimal dosage of 60 mg/L. The addition of polyacrylamide (PAM) showed that both conventional and ballasted coagulation techniques exhibit an initial increase followed by a decrease in turbidity removal efficiency, and an ascending trend in fluoride removal efficiency, with an optimal PAM dosage of 1.0 mg/L. The dosage of the new ballasted material was determined based on the initial water turbidity and fluoride concentrations, an increase in its dosage led to a progressive reduction in effluent turbidity and a corresponding increase in fluoride removal. A 30-day continuous operation confirmed the stability of the new process, with a treatment cost of approximately 2.67 $/t. The pseudo-first-order kinetic model and the Langmuir adsorption isotherm equation provided satisfactory fits to the treatment data, suggesting that both conventional and ballasted coagulation involve a combination of surface adsorption and intraparticle diffusion mechanisms for the removal of turbidity and fluoride.

Diagnostics of Acid Sulfate Soils in a Coal Mining Area of the Taiga Zone

Technogenic soils result from the oxidation and hydrolysis of minerals in rocks extracted from mining areas and brought to the surface. Diagnostics of such soils involve a set of detailed tests, which can be both time-consuming and costly. In this study, the pH of sulfate soils in the Kizel Coal Basin (Perm krai, Russia) was determined using hydrogen peroxide. Particularly, the soils affected by runoff from rock dumps, outflow, and mine water discharge were examined. The findings showed pH-H2O2 below 2.5 in certain horizons, indicating the presence of sulfides. Additionally, the soils exhibited significantly higher levels of mobile sulfur and iron, total sulfur, and sulfates, ranging from tens to hundreds of times above the background content. XRD analysis revealed that the soils contained goethite and jarosite, thereby confirming the efficacy of pH determination with hydrogen peroxide for the prompt diagnostics of acid sulfate soils.

Environmental relevance monitoring and assessment of ochreous precipitates, hydrochemistry and water sources from abandoned coal mine drainage

This study investigated the mineralogical and chemical characteristics of ochreous precipitates and mine water samples from abandoned Upper Carboniferous hard coal mines in an extensive former mining area in western Germany. Mine water characteristics have been monitored and assessed using a multi-methodological approach. Thirteen mine water discharge locations were sampled for hydrochemical analysis, with a total of 46 water samples seasonally collected in the whole study area for stable isotopic analyses. Mineralogical composition of 13 ochreous precipitates was identified by a combination of powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM/EDS). Results showed that abandoned mine drainage was characterized by circumneutral pH, Eh values ranging from 163 to 269 mV, relatively low concentrations of Fe and Mn, and was dominated by HCO3− > SO42− > Cl− > NO3− and Na+ > Ca2+ > Mg2+ > K+. Goethite and ferrihydrite were the dominant precipitated Fe minerals, with traces of quartz, dolomite, and clay minerals. Some metal and metalloid elements (Mn, Al, Si, and Ti) were found in the ochreous sediments. The role of bacteria in the formation of secondary minerals was assessed with the detection of Leptothrix ochracea. The δ18O and δ2H values of mine water plotted on and close to the GMWL and LMWLs indicated local derivation from meteoric water and represented the annual mean precipitation isotopic composition. Results might help to develop strategies for the management of water resources, contaminated mine water, and public health.

Experimental study on the scaling law of the heat exchange tube surface in the process of low-temperature single-effect distillation of high-mineralized mine water

High-mineralized mine water, due to its characteristics such as high mineralization degree, will have scaling phenomena on the surface of the heat exchange tube during the desalination treatment process, resulting in a reduction in the water production efficiency of the equipment and affecting the normal operation. To reduce the cost of water production and improve the service life of distillation equipment, this paper independently designs and builds a low-temperature single-effect distillation high-mineralized mine water experimental system to study the influence of operating parameters (temperature, spray density, concentration ratio, and system pressure) on the scaling law on the surface of the heat exchange tube. The distribution and characteristics of scale deposits on the surface of the heat exchange tube are analyzed through the growth rate and microscopic morphology of the scale deposit. The results indicate that the scaling on the surface of the titanium plate is mainly in the needle-like and rod-like morphology of CaCO3 aragonite, and a small amount of CaSO4 and calcite are generated with the increase of temperature. It was found that within the range of spray density from 0.0509 kg/(m·s) to 0.0625 kg/(m·s), concentration ratio from 2.3 to 2.7, and system pressure at 36.3 kPa, it is beneficial to the evaporation heat transfer of the heat exchange tube and the reduction of scaling generation. At the same time, it is found that the scaling of the first row of heat exchange tubes is mainly within the range of circumferential angle from 0 to 100 degrees, and the scaling of the second row and the third row of heat exchange tubes is mainly within the range of circumferential angle from 110 to 170 degrees. The research results of this paper provide support for the design and operation of the low-temperature multi-effect treatment system for mine water in engineering, promote the process of zero discharge of high-mineralized mine water in Xinjiang, China, and improve the resource utilization rate of high-mineralized mine water.

Saline mine water influences eukaryote life in shallow groundwater of a tropical sandy stream

Eukaryotic communities in groundwater may be particularly sensitive to disturbance because they are adapted to stable environmental conditions and often have narrow spatial distributions. Traditional methods for characterising these communities, focussing on groundwater-inhabiting macro- and meiofauna (stygofauna), are challenging because of limited taxonomic knowledge and expertise (particularly in less-explored regions), and the time and expense of morphological identification. The primary objective of this study was to evaluate the vulnerability of eukaryote communities in shallow groundwater to mine water discharge containing elevated concentrations of magnesium (Mg) and sulfate (SO4). The study was undertaken in a shallow sand bed aquifer within a wet-dry tropical setting. The aquifer, featuring a saline mine water gradient primarily composed of elevated Mg and SO4, was sampled from piezometers in the creek channel upstream and downstream of the mine water influence during the dry season when only subsurface water flow was present. Groundwater communities were characterised using both morphological assessments of stygofauna from net samples and environmental DNA (eDNA) targeting the 18S rDNA and COI mtDNA genes. eDNA data revealed significant shifts in community composition in response to mine waters, contrasting with findings from traditional morphological composition data. Changes in communities determined using eDNA data were notably associated with concentrations of SO42−, Mg2+ and Na+, and water levels in the piezometers. This underscores the importance of incorporating molecular approaches in impact assessments, as relying solely on traditional stygofauna sampling methods in similar environments may lead to inaccurate conclusions about the responses of the assemblage to studied impacts.

Effects of deep coal mining on groundwater hydrodynamic and hydrochemical processes in a multi-aquifer system: Insights from a long-term study of mining areas in ecologically fragile western China

The groundwater hydrodynamic and hydrochemical process of the multi-aquifer system will experience complicated and serious influence under deep coal mining disturbance. There is relatively little research that has integrated hydrodynamic and hydrochemical properties of groundwater to investigate the spatiotemporal distribution characteristics and evolution patterns of hydrogeochemistry and hydrodynamic information in deep multi-aquifer systems. The study of the groundwater hydrodynamic and hydrochemical spatiotemporal coupling response of multi-aquifer systems under the deep and special thick coal seam mining-motivated effect in ecologically fragile western mining areas is of great significance for the safe mining of coal resources and ecological environment protection. In this research, the hydrochemical analysis data composed of 218 groundwater samples from Tangjiahui coalfield, Northwest China with 1526 measurements and a 6-year (2016–2021) sampling period were collected for studying the hydrogeochemical spatiotemporal evolution process and governing mechanism of the multi-aquifer system using hierarchical cluster analysis, ion-ratio method, saturation index and multidimensional statistical analysis. Additionally, wavelet analysis and cross-wavelet coherence analysis were implemented to quantitatively recognize the spatiotemporal variation characteristics of hydrodynamic information and analyze the coherence relationships between time series. The results demonstrate that the hydrochemical characteristics exhibit significant spatial differences, while the temporal variation of hydrochemical characteristics in the Permian Shanxi Formation fractured sandstone aquifer (PSFFA), mine water (MW), and Ordovician karst limestone aquifer (OKA) is not significant. The water-rock interaction is the predominant control mechanism for the spatial evolution of hydrogeochemistry in the research area. Moreover, the large-scale mining of deep coal seams controls the type and degree of water-rock interactions by damaging the structure of aquifers and altering the hydrodynamic conditions of groundwater. The period from 2016 to 2021 exhibits multi-time scale characteristics in time series of precipitation, mine water discharge, and the water level of PSFFA and OKA. The mine water discharge has a positive correlation with the water level of PSFFA and OKA, whereas the significant period of precipitation and the water level of PSFFA coherence is not obvious. The research findings not only provide in-depth insights to protect the groundwater resources in water-shortage mining areas but also promote the secure mining of deep coal resources.

Developing plant functional groups to identify changes in functional composition and diversity in a dryland river experiencing artificially sustained flows

Land use and climate changes are driving significant shifts in the magnitude and persistence of dryland stream surface flows. The impact of these shifts on ecological functioning is largely unknown, particularly where streams have become wetter rather than drier. This study investigated relationships between hydrologic regime (including surface water persistence, differences in groundwater depth and altered flooding dynamics) with plant traits and riverine vegetation functional composition. Our study system was a previously ephemeral creek in semi-arid northwest Australia that has received groundwater discharge from nearby mining operations for >15 years; surface flows are now persistent for ∼27 km downstream of the discharge point. We aimed to (i) identify plant functional groups (FGs) associated with the creek and adjacent floodplain; and (ii) assess their distribution across hydrological gradients to predict shifts in ecological functioning in response to changing flow regimes. Seven FGs were identified using hierarchical clustering of 40 woody perennial plant species based on morphometric, phenological and physiologic traits. We then investigated how FG abundance (projective foliar cover), functional composition, and functional and taxonomic richness varied along a 14 km gradient from persistent to ephemeral flows, varying groundwater depths, and distances from the stream channel. Dominant FGs were (i) drought avoidant mesic trees that are fluvial stress tolerant, or (ii) drought tolerant xeric tall shrubs that are fluvial stress intolerant. The drought avoidant mesic tree FG was associated with shallow groundwater but exhibited lower cover in riparian areas closer to the discharge (persistent surface flows). However, there were more FGs and higher species richness closer to the discharge point, particularly on the floodplain. Our findings demonstrate that quantifying FG distribution and diversity is a significant step in both assessing the impacts of mine water discharge on riverine ecosystems and for planning for post-mining restoration.

Optimization of mine water discharge with the river hydrograph. Case study Samara River in Western Donbas

The paper deals with modeling salt transport in surface watercourses affected by mine water discharge taking into account the river hydrograph, hydrogeological, and climatic data. The developed model enables optimizing the discharge parameters; thus, minimizing the mineralization of river water throughout the year. As the case study, we considered the section of the Samara River in the Western Donbas where mine water is discharged from three storage ponds located in the ravines of Kosminna, Taranova, and Svidovok. Taking into account the pond capacities, it is proposed to discharge at least 60% of mine water from all ponds in December-April, with more than 88% of the most mineralized waters from the pond in the Svidovok ravine. The increase of the river water mineralization at the exit from the coal mining area does not exceed 0.22 g/dm3 on average per year, with a maximum of 0.36 g/dm3 during the low water season. The model novelty is coupling natural and man-made factors forming the water and salt balance in the surface watercourse throughout the year with the optimization methods. The proposed technique can be used to optimize the mode of mine water discharge.

Mine Wastewater Effect on the Aquatic Diversity and the Ecological Status of the Watercourses in Southern Poland

Coal mining activity contributes to energy security and employment occupation, but is associated with environmental deterioration. Coal combustion leads to GHG emissions, while coal mining results in the generation of saline effluents. These effluents are discharged in inland surface waters, applying significant pressure on their quality, with a negative impact on aquatic life and the economy of a region. This study includes water samples that were analyzed in order to investigate the organic compounds, heavy metals, and other physicochemical parameters. Biological monitoring was done according to the Water Framework Directive methodology. The results from an aquatic area in Southern Poland, which indirectly receives coal mine effluents, indicate elevated salinity with excessive chlorides, sulfates, and sodium ions. The water quality of another non-polluted aquatic area was also assessed to examine the impact of indirect coal mine wastewater discharge on this area. The high salinity levels hinder the use of river water for drinking, agricultural, or industrial purposes. The results obtained show high pressure on the ecological status of streams and rivers that receive mine effluents, and on the density and diversity of aquatic invertebrates. This pressure is clearly visible in the structure of benthic communities and in invertebrate diversity. It also contributes to the appearance of invasive species and increasing water salinity. Limiting discharges of mine water transporting large loads of saline substances would reduce the negative impact on the quality of river waters and biological life.

Research on CeO2 Activated Carbon Electrode Capacitance Method for Sulfate Removal from Mine Water

Sulfate is a typical characteristic pollutant in mine water. Because of its high concentration and large discharge of mine water, it has become a difficult problem in mineral exploitation. Capacitive deionization (CDI) is an innovative and economical removal technology. There are few reports on the use of CDI to remove SO42− from mine water. In this study, a CeO2 activated carbon electrode with good wettability, excellent electrochemical performance, and suitable pore structure was prepared by the sol-gel method. The application of the CeO2 activated carbon electrode to the capacitive method for treating high SO42− mine water was investigated using simulated wastewater and actual mine water. The study structure shows that CeO2:activated carbon (AC) has the best wettability, the highest specific capacitance, and the lowest electrical conductivity when the mass ratio of CeO2 is 5%. At 100 mg/L, the electrode has the maximum SO42− ion specific adsorption capacity (SAC). At 1 V and 20 mL/min, this value is measured. The electrode has a SAC value of 9.36 mg/g, far higher than the AC electrode’s 4.1 mg/g. The effect of CDI process factors such the voltage, flow rate, and initial concentration was studied to find the best treatment method. SAC retention is 91% after 10 adsorption–desorption cycles, demonstrating outstanding electrode performance. Under the best CDI process (1.4 volts, 30 mL/min), mine water was treated. After 20 cycles of treatment, the concentration of SO42− in mine water decreased from 1170 mg/L to 276.46 mg/L, and the removal rate was 76.37%. This study proved that the CeO2 modified activated carbon electrode capacitance method can effectively remove sulfate ions and other ions from mine water.

Legacy coal mining impacts downstream ecosystems for decades in the Canadian Rockies

Mountaintop removal coal mining leaves a legacy of disturbed landscapes and abandoned infrastructure with clear impacts on water resources; however, the intensity and persistence of this water pollution remains poorly characterized. Here we examined the downstream impacts of over a century of coal mining in the Crowsnest Pass (Alberta, Canada). Water samples were collected downstream of two historical coal mines: Tent Mountain and Grassy Mountain. Tent Mountain hosts a partially reclaimed surface mine that closed in 1983. Selenium concentrations downstream of Tent Mountain reached 185 μg/L in a lake below the mine spoil pile, and up to 23 μg/L in Crowsnest Creek, which drains the lake and the mine property. Further downstream, a well-dated sediment core from Crowsnest Lake records increases in sediment, selenium, lead, carbon, nitrogen, and polycyclic aromatic compounds that closely tracked the history of mining at Tent Mountain. In contrast, episodic discharge of mine water from abandoned underground adits at Grassy Mountain drive periodic (but short-term) increases in iron, various metals, and suspended sediment. These results underscore the lasting downstream impacts of abandoned and even reclaimed coal mines.

Evaluation of physical and heavy metal contamination and their distribution in waters around Maddhapara Granite Mine, Bangladesh

The Maddhapara Granite Mine is a significant contributor to Bangladesh's economy, causing considerable environmental concern due to the discharge of untreated mine water. This water presents possible hazards to local ecosystems, agriculture, and public health. For this investigation, we obtained water samples from 15 distinct places in the vicinity of the granite mine. A comprehensive analysis of the physicochemical properties was conducted including pH, turbidity, electrical conductivity (EC), total dissolved solids (TDS), and dissolved oxygen (DO) and an Atomic Absorption Spectrometer to quantify the heavy metals’ levels, specifically Ni, Zn, Fe, Pb, Cu, and Cr, following the requirements set by the World Health Organization (WHO), Food and Agriculture Organization (FAO), and Department of Energy (DoE) in Bangladesh. The study was carried out on various pollution indices i.e., Heavy Metal Pollution Index (HPI), Heavy Metal Evaluation Index (HEI), and Degree of Contamination (Cd). The pH of the samples varied from 6.27 to 8.86. Furthermore, the samples’ TDS and EC ranged from 36 mg/l to 392.56 mg/l and 102.78 μS/cm to 611.51 μS/cm, respectively. The HPI values exhibited substantial variation, with the highest HPI-a (WHO) measuring 52215.6, indicating a severe level of heavy metal contamination. Similarly, the HEI-a (WHO) reached a maximum value of 1252.45, while the highest contamination degree (Cd-a, WHO) was 1248.45 and these results are beyond the acceptable limits for human consumption and ecological balance. Immediate actions are required to develop treatment technologies and management strategies to prevent the potential health risks associated with using untreated mine wastewater.

Effects of mine water discharge on river sediments: metal fate and behaviour, Upper Silesian Coal Basin

The study aims to characterise the changes in elemental composition in the river sediments of streams influenced by mine waters enriched with radionuclides. The study took place in the vicinity of Ostrava, a city located in a coal mining region in the Czech Republic, namely the Upper Silesian Coal Basin. River sediments and waters of the Karvinský potok and Stružka streams were investigated. Field measurements were made for ambient dose equivalent rate (ADER). Laboratory gamma spectrometry and X-ray fluorescence were used to determine the content of radionuclides and elemental composition in river sediments. Water samples were analysed for the content of major ions and radionuclides. The field ADER measurement proved elevated content of radionuclides with values exceeding 1,000 nSv/h in both streams. The discharged mine waters were Na–Cl type, containing an 226Ra (0.68–0.70 Bq/l) as a dominant radionuclide. Laboratory measurements of radionuclides in bottom sediments proved that the prevailing source of radiation are 226Ra and 232Th in both streams. The calculated enrichment factors showed extreme values for Sr, Cr, Pb, Zn, Cu, and Mo. The precipitation reactions forming Ca-minerals (calcite and aragonite), Fe-bearing minerals (hematite, goethite and amorphous Fe(OH)3) and hausmannite were found to be the primary geochemical process underway in the studied riverine systems. The correlation between elements and radionuclides demonstrated the significant role of geochemical barriers that lead to the precipitation of radionuclides from solution. The results show that the precipitation takes place preferentially in places where other waters enter the stream, or where recent organic matter is present.

Migration of microelements in river system in impact zone of acid mine water discharge in the Kizel Coal Basin

Migration of microelements in river system in impact zone of acid mine water discharge in the Kizel Coal Basin

Hydrochemical Characteristics and Controlling Factors in Wudu River Basin of Guizhou Province

TheWudu River is a typical mining-type watershed in the karst mountainous area of western Guizhou Province. Based on the collection of the main stream, tributaries, spring water, and mine water samples in Wudu River Basin, the hydrochemical characteristics and control factors of Wudu River Basin were studied using Gibbs diagram, Piper diagram, and mathematical statistics analysis, and the solute contribution rate of different sources was calculated. The results revealed that the pH value of the water in the Wudu River Basin ranged from 7.87 to 8.52, with an average of 8.14. The TDS values ranged from 135 to 243 mg·L-1, with an average of 191.7 mg·L-1. The major cations in natural river and spring water were Ca2+ and Mg2+, the major anion was HCO3-, and the hydrochemical type was HCO3-Ca. However, owing to the influence of mining activities, the major cations in some tributaries were Ca2+ and Na+, and the hydrochemical types transitioned to HCO3·SO4-Ca and HCO3·SO4-Ca·Na. The ion components of river water in Wudu River Basin were affected by mine water discharge and cation exchange, carbonate rock weathering, silicate rock weathering, and agricultural fertilization. The high concentration of SO42- and Na+in mine water was the primary source of SO42- and Na+in the tributaries of the Wudu River. The method for calculating chemical material balance showed that the contribution rate of carbonate rock weathering ranged from 44.12% to 86.92%, with an average of 74.32%. The contribution rate of mining activities ranged from 3.28% to 37.07%, with an average of 11.61%. Carbonate rock weathering was the main controlling factor of hydrochemical components in the Wudu River Basin; meanwhile, mining activities also had a certain impact on river water chemistry but they showed spatial heterogeneity. The average contribution rates of atmospheric precipitation, silicate rock weathering, agricultural activities, and domestic sewage were 3.75%, 4.67%, 2.85%, and 2.81%, respectively, which had a limited impact on the hydrochemical components of the basin.

Synoptic water isotope surveys to understand the hydrology of large intensively managed catchments

Understanding the hydrology of large catchments has always been a major challenge due to the spatial heterogeneity of climate, geology, topography, soils and land use. However, precise knowledge of water cycling, storage and losses across large scale catchments is required to sustainably meet growing water demands and adjust water management strategies. This study used four large-scale, seasonal synoptic surveys in 2021 to characterize the spatio-temporal patterns of water isotopes (stable water isotopes and radioisotope tritium at natural abundance) to better understand the complex hydrology of the intensively managed 10,000 km2 catchment of the River Spree in Germany. Apart from the upper headwaters, the hydrology of the Spree is heavily regulated by reservoir releases, pumped minewater discharges, extensive wetlands and lakes, water abstractions and urban drainage. Moreover, the catchment is drought-sensitive with potential evapotranspiration (∼800 mm a year) often exceeding annual rainfall (∼600 mm). This is reflected in the isotopic composition of river water: In the steeper, upper headwaters, the river has a “flashy” rainfall-runoff response, with isotopes plotting close to the Global Meteoric Water Line (GMWL) consistent with dominant groundwater sources, but showing more influence by rainfall in winter. However, flows in the midstream parts are complex due to artificially enhanced baseflows and attenuated high flows from extensive reservoir releases and pumped groundwater releases from dewatering of mines. The reservoir waters are isotopically heavier and reflect the effects of open water evaporation. Fractionation effects strengthen downstream as managed wetland areas in the Spreewald and natural lakes further enhance evaporation and attenuate flows. Water abstractions for drinking water and to sustain the Oder-Spree canal reduce flows further. In Berlin, sources of urban runoff and waste water discharges reduce the effects of fractionation, though samples still plot below the meteoric water line. Seasonally, the effects of evaporation in the lower river network are strongest in summer and autumn, though they remain in winter and spring, indicating a large memory effect due to long mean travel times within the river system. Tritium variability along the river reflects inputs of younger and older water in different parts of the river system; though the influence of pumped groundwater means that the mean age of stream water (i.e., time elapsed since rainfall) in the lower river is likely to be >50 years. Climate change, together with increased population and economic growth in Berlin, is likely to increase pressures on the Spree system in future. In the coming years, the anticipated termination of the lignite mining will lead to a reduction in artificial inputs into surface water, which in turn may exacerbate water stress. We demonstrated that longer-term, synoptic isotope studies are valuable in better understanding the hydrology of such complex, large-scale, heavily modified river systems in terms of insights into water sources and mixing processes; thus, providing an evidence base for more sustainable management in the future.

Efficiency of acid sulphate soils reclamation in coal mining areas

During the development of coal deposits, acid mine waters flowing to the surface cause the formation of acid sulphate soils. We study the effectiveness of soil reclamation by agrochemical and geochemical methods at the site of acid mine water discharge in the Kizel Coal Basin, carried out in 2005 using alkaline waste from soda production and activated sludge. A technosol with a stable phytocenosis was detected on the reclaimed site, and soddy-podzolic soil buried under the technogenic soil layer with no vegetation on the non-reclaimed site. The buried soddy-podzolic soil retains a strong acid рН concentration Н2О = 3. A high content of organic matter (8-1.5 %) is caused by carbonaceous particles; the presence of sulphide minerals reaches a depth of 40 cm. Technosol has a slightly acid pH reaction H2O = 5.5, the content of organic matter due to the use of activated sludge is 19-65 %, the presence of sulphide minerals reaches a depth of 20-40 cm. The total iron content in the upper layers of the technosol did not change (190-200 g/kg), the excess over the background reaches 15 times. There is no contamination with heavy metals and trace elements, single elevated concentrations of Li, Se, B and V are found.

Evaluation and refinement of a fish movement model for a tropical Australian stream subject to mine contaminant egress

The impacts of mine contaminants on ecological connectivity in rivers and streams are poorly documented globally. We used acoustic telemetry to evaluate and refine conceptual models of fish movement in Magela Creek, a stream in the wet-dry tropics of Australia. This creek receives wastewater discharge from a nearby uranium mine, and a secondary objective was to describe behavioural responses of fish to one such discharge event. Of 55 fish (black bream Hephaestus fuliginosus, saratoga Scleropages jardinii, sharp-nose grunter Syncomistes butleri) tagged in dry season refuge pools 18 km upstream of the mine lease area (RPA [Ranger Project Area]), 16 (29%) moved downstream after the first wet season flows, using the RPA as habitat for 3–5 months before moving upstream to their previous locations as flows receded. Of 39 fish (spangled perch Leiopotherapon unicolor, barred grunter Amniataba percoides, black catfish Neosilurus ater) tagged ~ 8–12 km downstream of the RPA in the late wet season, only two were subsequently detected in the RPA. Direct and camera-based observations of 12 species of upstream-migrating fish during mine-water discharge in the late wet season showed no evidence of mine-water avoidance. Our results demonstrate that Magela Creek provides wet season habitat for fish within the RPA and acts as a migration pathway that connects lowland reaches and floodplains to upstream dry season refuges. Use by fish of waterbodies within the RPA highlights the need to manage the site to ensure that future contaminant egress and water quality do not adversely affect fish migration and habitat suitability.

Assessment of the Impact of Industrial and Municipal Discharges on the Surface Water Body Status (Poland)

Due to potential pressure from industrial and municipal activities, urban water bodies are at risk of not achieving the environmental objectives of the Water Framework Directive (WFD) by 2027. This study comprised the quality assessment of water body “Kłodnica do Promnej (bez)” under a strong anthropogenic influence. The main potential sources of pollution in the catchment were identified and the related characteristic contaminants were analysed. The obtained values of pollutants were compared with the limit values for surface waters from Regulation (Journal of Laws 2021, item 1475). The results confirmed that the analysed water body located in highly urbanized area is characterized by poor water quality and chemical status below the good status. The main threat to the aquatic environment is high salinity associated with the presence of mine water discharges. Moreover, the priority substances, such as Cd, Ni and Pb, exceeded the environmental quality standards values (EQS) in most of the designated measurement points. Due to the fact that water ecosystems do not constitute stand-alone structures, but are included in a wider socio-ecological system, the implementation of an integrated approach to characterizing the existing status of the water bodies and estimating the risk posed to the aquatic ecosystem is a crucial element of the catchment management process in the context of the provisions of the WFD.