Cornwall's history as one of the richest metal mining regions in the world has left a legacy of hundreds of kilometres of abandoned mine workings containing millions of cubic metres of water. Despite the growing development of mine water heat schemes in former coal mining areas in the UK, the potential geothermal resource within the flooded mines in Cornwall has yet to be fully recognized. The utilization of this resource presents a few challenges that are different from those met when extracting heat from former coal mines, but it presents readily accessible opportunities for producing sustainable low carbon heating, cooling and thermal storage. There are recorded to be 154 mines in Cornwall that are over 200 m deep. Recent studies have identified the temperature and volumetric resource that may be available in some of the deep mines, together with examples of four mines that show distinctly different types of hydrogeological systems. This has demonstrated the potential and the importance of thoroughly understanding the hydrodynamics of the shafts and underground workings and how these can be best utilized as a low enthalpy heat resource.

ABSTRACT In mineralized regions of the Colorado Rockies, acid rock drainage (ARD) presents an ongoing challenge to water resources. Many watersheds are also experiencing shifts in climate, with linkages to decreasing water quality. Here we examined the Upper Snake River (USR), an ARDimpaired catchment abutting the Continental Divide where one small highly acidic tributary has been proven to be the dominant source of acidity, metals, and rare earth elements (REEs). Longterm research indicates that enhanced weathering and dissolution of metals and REEs is linked to warming summers, drought, and declining baseflows. To better understand these trends, we conducted diel and tracer studies at the confluence of this tributary with the USR. These revealed steady concentrations of ARD solutes over a 24hour period, conservative solute behavior and substantial groundwater input near the confluence. The increased loadings below the confluence suggest strong hyporheic zone connectivity and contributions from an adjacent fen. Our findings underscore the importance of resolving streamflow and solute dynamics to reveal sources, sinks, and/or redox conditions driving downstream fluxes. Studies of the Snake River Watershed continue to offer insight into the hydrological and geochemical controls on ARD, exemplifying the connectivity of mountain hydrology and water quality in a changing world.

Generalized aquifers are widely used in various fields, such as groundwater use, mine water prevention and control, and geothermal energy. This paper presents a transformer-model-based automatic aquifer generalization method using borehole logs in scenarios with scarce experimental parameters. Relying only on basic borehole data, the method used an agent-assisted approach to extract and clean key lithological and coordinate information, which was then fused using a dual embedding mechanism. The model leveraged multi-head self-attention to calculate attention weights between the target stratum and its adjacent strata, capturing the potential contextual correlations in aquifer potential across strata. The resulting deep feature vectors from the transformer’s encoder were fed into a classification head to predict aquifer potential labels. Evaluation results demonstrated a model accuracy of 0.86, significantly outperforming the random classification baseline in precision, recall, the F1-score, and the kappa coefficient.

Mine water discharges pose a significant environmental challenge due to elevated metal concentrations, which can be detrimental to aquatic ecosystems and water quality. In this study, four circumneutral-pH mine water samples were treated with different magnetic nanoparticle (MNP) concentrations (0.1 g L-1, 1 g L-1, and 5 g L-1) to assess their efficacy for Zn removal. Sorption of Zn to all MNP systems tested, occurred within 48 hours. At 5 g L-1, MNPs removed Zn from all mine waters tested, reducing concentrations to 0.09, 0.66, 0.0 and 0.0 mg L-1 for the River Ystwyth, Cwmystwyth adit, River Nent and Haggs adit respectively. A clear positive correlation was recorded for Zn removal as a function of MNP dose, with MNP concentrations >1 g L-1 required for Zn removal to below trace concentrations. Analysis of competing ions (e.g., Ca2+, Mg2+, Na+) showed that a decrease in concentration followed the order Zn > Na+> Ca2+ > Mg2+. These findings confirm that MNPs are effective for the removal of Zn from real mine water samples even when applied at low dosages, suggesting that they are a highly promising water treatment technology for such applications.

Distinguishing natural from mining-related metal sources by including streambank groundwater data in a stream mass loading study.

This study aims to evaluate the actual sump capacity in accommodating mine water discharge, design a sump that fits field conditions, and determine the optimal pump capacity and system at PT Satria Alam Manunggal, Telen Orbit Prima Site. The research methods include field data collection (sump condition, water discharge, and pump capacity) and supporting data (rainfall, geological maps, and pump specifications). The design rainfall was calculated using the Gumbel method with a five-year return period, while water discharge was estimated from runoff, rainfall, and groundwater inflow. The results indicate that the existing sump, with a capacity of 508 m³, is insufficient to accommodate an inflow of 1.210 m³/s. Therefore, two new sumps were designed: the West Sump with a capacity of 38,400 m³ and the East Sump with 78,281 m³. Each sump employs a DnD 150-4H pump with a discharge rate of 480 m³/hour. The West Sump pump can drain water within approximately three days, while the East Sump requires about seven days. The trapezoidal sump design was chosen for its efficiency, structural stability, and effectiveness in sediment (TSS) deposition control, maintaining levels within safe limits. In conclusion, the design of the West and East sumps is considered optimal in accommodating mine water discharge and improving the overall effectiveness of the mine drainage system.

Characterization and modeling approach for planning restoration strategies in a complex basin affected by acid mine drainage.

Microbial communities serve as critical bioindicators and functional drivers of soil restoration processes, particularly in mining-impacted ecosystems undergoing remediation. However, systematic insights into microbial dynamics during clean water restoration of contaminated paddy soils remain limited. This study systematically investigated, by means of column experiments, the temporo-spatial dynamics of microbial community structure and metal speciation in acid mine drainage (AMD)-contaminated paddy soil from the Dabaoshan mining area. The soil was subjected to constant flooding with clean water, including experiments with artificial AMD as a control, for 176 days. The heavy metal fractions present in the soil were determined by sequential extraction. The bacterial community was analyzed at 7 time points and 5 depths using high-throughput 16S rRNA gene amplicon sequencing of the V5-V7 region. Long-term flooding increased the dominance of Firmicutes, Acidobacteria, and Proteobacteria, with limited overlap in significantly enriched taxa during restoration, indicating specialized microbial adaptation or microbial selection. The metal mobility increased as a result of flooding, most strongly in the mobile fractions of Cd at 5 cm depth (FM increased from 62.6% to 68.7%) and Cu at 20 cm depth (FM increased from 16.2% to 21.6%). This was accompanied by a substantial reduction in the residual total reducible-phase Cu (the sum of Fe/Mn oxide-bound fraction F3 and the organic-matter-bound fraction F4) was reduced from 188.4 to 30.8 mg kg-1. Likewise, residual easily migratable Cd (the sum of exchangeable fraction F1 and carbonate-bound fraction F2) was reduced from 5.8 to 0.3 mg kg-1. Such increased mobility might present an increased environmental risk. Canonical correspondence analysis identified the pH, Cu/Cd concentrations, and SO42- as primary environmental drivers (cumulative explanation: 72.3%) governing microbial community restructuring. Complementary LEfSe analysis further elucidated potential microbial interaction networks underlying the rehabilitation process. The identified microbial-metal dynamics highlight the importance of integrating biological indicators with geochemical parameters when assessing the rehabilitation efficacy in heavy metal-contaminated agricultural systems.

Dispersed alkaline substrate passive treatment technology for highly contaminated acid mine drainage: 20 years of successful application.

Temporal and spatial distribution, sources and health risk assessment of trace elements in a typical karst river basin in Southwest China: Influence of acid mine drainage from abandoned coal mines.

Sustainable preparation of battery-grade FePO4·2H2O from acid mine drainage through a precipitation-purification pathway

Synergistic effects of sulfate, magnesium, and bicarbonate ions in mine water on the hydration, microstructure, and long-term durability of Portland cement paste

Microbial consortia in mine water bioremediation: principles, design and practical applications.

Study on the effect of Ca2+ concentration in mine water on the wettability of lignite

The suitability of fermenter liquor from MSW as an electron donor for hypersaline sulfate reduction.

A novel approach based on iron-manganese bio-oxidation process for acid mine drainage treatment: Performance and mechanism

Composite low-carbon biopolymer-amended bentonite in geosynthetic clay liners for containing acid mine drainage leachate

The contribution of physical-chemical effects of abandoned mine water to the deterioration of Mode-I Fracture Toughness- Based on CT-DEM integrated modeling

Calcium-phosphate mediated green remediation of uranium mine water: sulfur-fixing ash enhanced phosphorus leaching from phosphogypsum for targeted uranium mineralization

Efficiency of Fe and Zn metal adsorption in post-tin mining water using Fe3O4/activated carbon composite coffee grounds waste