Acid Mine Drainage

A 24 h investigation of the hydrogeochemistry of baseflow and stormwater in an urban area impacted by mining: Butte, Montana

by Christopher Shope

Hydrogeochemistry and rare earth element behavior in a volcanically acidified watershed in Patagonia, Argentina

by Christopher Shope

Speciation of Arsenic, Chromium, and Vanadium in Red Mud Samples from the Ajka Spill Site, Hungary

by William Mayes

Burke, I.T., Mayes, W.M., Peacock, C.L., Brown, A.P., Jarvis, A.P., Gruiz, K. (2012) Speciation of arsenic, chromium and vanadium in red mud samples from the Ajka spill site, Hungary. Environmental Science and Technology. doi: 10.1021/es3003475.

Results are presented from X-ray absorption spectroscopy based analysis of As, Cr and V speciation within samples of... more Results are presented from X-ray absorption spectroscopy based analysis of As, Cr and V speciation within samples of bauxite ore processing residue (red mud) collected from the spill site at Ajka, Western Hungary. Cr K-edge XANES analysis found that Cr is present as Cr3+ substituted into hematite, consistent with TEM analysis. V K-edge XANES spectra have E½ position and pre-edge features consistent with the presence of V5+ species, possibly associated with Ca-aluminosilicate phases. As K-edge XANES spectra identified As present as As5+. EXAFS analysis reveals arsenate phases in red mud samples. When alkaline leachate from the spill site is neutralised with HCl, 94 % As and 71 % V is removed from solution during the formation of amorphous Al-oxyhydroxide. EXAFS analysis of As in this precipitate reveals the presence of arsenate Al-oxyhydroxide surface complexes. These results suggest that in the circumneutral pH, oxic conditions found in the Torna and Upper Marcal catchments, incorporation and sorption respectively will restrict the environmental mobility of Cr and As. V is inefficiently removed from solution by neutralisation, therefore, the red mud may act as a source of mobile V5+ where the red mud deposits are not removed from affected land.

Microbial community dynamics of a sulfate-reducing bioreactor treating coal generated acid mine drainage

by Liliana Lefticariu

Burns, A.S., Pugh, C.C., Behum, P.T., Segid, Y.T., Lefticariu L., Bender, K.S. (2011) 

The effectiveness of a passive flow sulfate-reducing bioreactor processing acid mine drainage (AMD) generated from an... more The effectiveness of a passive flow sulfate-reducing bioreactor processing acid mine drainage (AMD) generated from an abandoned coal mine in Southern Illinois was evaluated using geochemical and microbial community analysis 10 months post bioreactor construction. The results indicated that the treatment system was successful in both raising the pH of the AMD from 3.09 to 6.56 and in lowering the total iron level by 95.9%. While sulfate levels did decrease by 67.4%, the level post treatment (1153 mg/l) remained above recommended drinking water levels. Stimulation of biological sulfate reduction was indicated by a +2.60‰ increase in δ34S content of the remaining sulfate in the water post-treatment. Bacterial community analysis targeting 16S rRNA and dsrAB genes indicated that the pre-treated samples were dominated by bacteria related to iron-oxidizing Betaproteobacteria, while the post-treated water directly from the reactor outflow was dominated by sequences related to sulfur-oxidizing Epsilonproteobacteria and complex carbon degrading Bacteroidetes and Firmicutes phylums. Analysis of the post-treated water, prior to environmental release, revealed that the community shifted back to predominantly iron-oxidizing Betaproteobacteria. DsrA analysis implied limited diversity in the sulfate-reducing population present in both the bioreactor outflow and oxidation pond samples. These results support the use of passive flow bioreactors to lower the acidity, metal, and sulfate levels present in the AMD at the Tab-Simco mine, but suggest modifications of the system are necessary to both stimulate sulfate-reducing bacteria and inhibit sulfur-oxidizing bacteria.

Mineralogic and sulfur isotopic effects accompanying oxidation of pyrite in millimolar solutions of hydrogen peroxide at temperatures from 4 to 150 C

by Liliana Lefticariu

Liliana Lefticariu, Lisa M. Pratt and Edward M. Ripley

Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA

Oxidation of pyrite by hydrogen peroxide (H2O2) at millimolar levels has been studied from 4 to 150 °C in order to... more Oxidation of pyrite by hydrogen peroxide (H2O2) at millimolar levels has been studied from 4 to 150 °C in order to evaluate isotopic effects potentially associated with radiolytic oxidation of pyrite. Gaseous, aqueous, and solid phases were collected and measured following sealed-tube experiments that lasted from 1 to 14 days. The dominant gaseous product was molecular oxygen. No volatile sulfur species were recovered from any experiment. Sulfate was the only aqueous sulfur species detected in solution, with sulfite and thiosulfate below the detection limits. X-ray diffraction patterns and images from scanning electron microscopy reveal solid residues composed primarily of hydrated ferric iron sulfates and sporadic ferric–ferrous iron sulfates. Hematite was detected only in solid residue produced during high temperature experiments. Elemental sulfur and/or polysulfides are inferred to be form on reacting pyrite surface based on extraction with organic solvents. Pyrite oxidation by H2O2 increases in rate with increasing H2O2concentration, pyrite surface area, and temperature. Rates measured in sealed-tube experiments at 25°C, for H2O2 concentration of 2 × 10−3 M are 8.8 × 10−9 M/m2/sec, which are higher than previous estimates. A combination of reactive oxygen species from H2O2 decomposition products and reactive iron species from pyrite dissolution is inferred to aggressively oxidize the receding pyrite surface. Competing oxidants with temperature-dependent oxidation efficiencies results in multiple reaction mechanisms for different temperatures and surface conditions. Sulfur isotope values of remaining pyrite were unchanged during the experiments, but showed distinct enrichment of 34S in produced sulfate and depletion in elemental sulfur. The Δsulfate–pyrite and Δelemental sulfur–pyrite was +0.5 to +1.5‰ and was −0.2 to −1‰, respectively. Isotope data from high-temperature experiments indicate an additional 34S-depleted sulfur fraction, with up to 4‰ depletion of 34S, in the hematite. Sulfur isotope trends were not influenced by H2O2 concentration, temperature, or reaction time. Results of this study indicate that radiolytically produced oxidants, such as hydrogen peroxide and hydroxyl radicals, could efficiently oxidize pyrite in an otherwise oxygen-limited environment. Although H2O2 is generally regarded as being of minor geochemical significance on Earth, the H2O2 molecule plays a pivotal role in Martian atmospheric and soil chemistry. Additional experimental and field studies are needed to characterize sulfur and oxygen isotope systematics during radiolytical oxidation of metallic sulfides and elemental sulfur.

Identifying diffuse sources of inorganic pollutants in post-industrial catchments

by William Mayes

Basin-scale fluxes of metals from historically mined orefields in the UK

by William Mayes

Seasonal and spatial variation of diffuse (non-point) source zinc pollution in a historically metal mined river catchment, UK

by William Mayes

Application of a new methodology for assessing the priorities for abandoned mine water pollution remediation at a national scale: Results and implications from …

by William Mayes

Assessing the importance of diffuse mine water pollution: a case study from County Durham, UK.

by William Mayes

ABSTRACT
In the UK and Europe mine water management has, to date, focused almost exclusively on addressing point... more ABSTRACT
In the UK and Europe mine water management has, to date, focused almost exclusively on addressing point sources of pollution. However, with the introduction of the EU Water Framework Directive (2000/60/EC), there is a need to address mine water pollution from a catchment management perspective. For this reason it is necessary to investigate diffuse sources of mining pollution. This paper relates the outcomes of a study of the River Gaunless catchment in County Durham, UK. These studies have shown that up to 45% of the iron load to the River Gaunless may be due to diffuse sources during dry weather conditions, and over 95% of the iron in the river may be attributable to diffuse sources during wet weather conditions. Identification and quantification of the most important diffuse sources (e.g. surface runoff from spoil, re-suspension of ochre from streambeds) is ongoing. This paper describes the results of the investigation to date in detail, and also discusses preliminary
results of a 12 month investigation to identify the exact diffuse sources of iron pollution to the River Gaunless. The implications of the study for future mine water management are discussed.

Treatment of zinc-rich acid mine water in low residence time bioreactors incorporating waste shells and methanol dosing

by William Mayes

Journal of Hazardous Materials

Bioreactors utilising bacterially mediated sulphate reduction (BSR) have been widely tested for treating metal-rich... more Bioreactors utilising bacterially mediated sulphate reduction (BSR) have been widely tested for treating metal-rich waters, but sustained treatment of mobile metals (e.g. Zn) can be difficult to achieve in short residence time systems. Data are presented providing an assessment of alkalinity generating media (shells or limestone) and modes of metal removal in bioreactors receiving a synthetic acidic metal mine discharge (pH 2.7, Zn 15 mg/L, SO42− 200 mg/L, net acidity 103 mg/L as CaCO3) subject to methanol dosing. In addition to alkalinity generating media (50%, v.v.), the columns comprised an organic matrix of softwood chippings (30%), manure (10%) and anaerobic digested sludge (10%). The column tests showed sustained alkalinity generation, which was significantly better in shell treatments. The first column in each treatment was effective throughout the 422 days in removing >99% of the dissolved Pb and Cu, and effective for four months in removing 99% of the dissolved Zn (residence time: 12–14 h). Methanol was added to the feedstock after Zn breakthrough and prompted almost complete removal of dissolved Zn alongside improved alkalinity generation and sulphate attenuation. While there was geochemical evidence for BSR, sequential extraction of substrates suggests that the bulk (67–80%) of removed Zn was associated with Fe–Mn oxide fractions.

Novel approach to zinc removal from circum-neutral mine waters using pelletised recovered hydrous ferric oxide

by William Mayes

Journal of Hazardous Materials

Data are presented which evaluate the performance of a pilot-scale treatment system using pelletised hydrous ferric... more Data are presented which evaluate the performance of a pilot-scale treatment system using pelletised hydrous ferric oxide (HFO; a waste stream from coal mine water treatment) as a high surface area sorbent for removing zinc (Zn) from a metal mine water discharge in the North Pennines Orefield, UK. Over a 10-month period the system removed Zn at mean area- and volume-adjusted removal rates of 3.7 and 8.1 g m−3 day−1, respectively, with a mean treatment efficiency of 32% at a low mean residence time of 49 min. There were seasonal effects in Zn removal owing to establishment and dieback of algae in the treatment tank. This led to increased Zn uptake in early summer months followed by slight Zn release upon algae senescence. In addition to these biosorptive processes, the principal sinks for Zn appear to be (1) sorption onto the HFO surface, and (2) precipitation with calcite-dominated secondary minerals. The latter were formed as a product of dissolution of portlandite in the cement binder and calcium recarbonation. Further optimisation of the HFO pelletisation process holds the possibility for providing a low-cost, low footprint treatment option for metal rich mine waters, in addition to a valuable after-use for recovered HFO from coal mine water treatment facilities.

Quantifying the importance of diffuse minewater pollution in a historically heavily coal mined catchment

by William Mayes

Environmental Pollution

There has been considerable progress in developing treatment systems for point sources of minewater pollution in... more There has been considerable progress in developing treatment systems for point sources of minewater pollution in recent years; however, there remains a knowledge gap in the characterisation and remediation of diffuse minewater sources. Data are presented from the River Gaunless catchment, a historically heavily coal mined catchment in the northeast of England. Instream iron (Fe) loadings were monitored alongside loadings arising from point minewater discharges over a 12-month period to assess the dynamic importance of diffuse sources of minewater pollution. In low flow, diffuse sources account for around 50% of instream loading, a proportion which increases to 98% in high flow conditions. The low flow sources appear to be dominated by direct discharge of contaminated groundwater to surface waters in lower reaches of the catchment. In high flow, resuspended Fe-rich sediments, which are both naturally occurring and derived from historic mining, become the dominant diffuse source of Fe in the water column.

Wetland treatment at extremes of pH: A review

by William Mayes

Science of the Total Environment

Constructed wetlands are an established treatment technology for a diverse range of polluted effluents. There is a... more Constructed wetlands are an established treatment technology for a diverse range of polluted effluents. There is a long history of using wetlands as a unit process in treating acid mine drainage, while recent research has highlighted the potential for wetlands to buffer highly alkaline (pH > 12) drainage. This paper reviews recent evidence on this topic, looking at wetlands treating acidic mine drainage, and highly alkaline leachates associated with drainage from lime-rich industrial by-products or where such residues are used as filter media in constructed wetlands for wastewater treatment. The limiting factors to the success of wetlands treating highly acidic waters are discussed with regard to design practice for the emerging application of wetlands to treat highly alkaline industrial discharges. While empirically derived guidelines (with area-adjusted contaminant removal rates typically quoted at 10 g Fe m2/day for influent waters pH > 5.5; and 3.5–7 g acidity/m2/day for pH > 4 to < 5.5) for informing sizing of mine drainage treatmentwetlands have generally been proved robust (probably due to conservatism), such data exhibit large variability within and between sites. Key areas highlighted for future research efforts include: (1) wider collation of mine drainage wetland performance data in regionalised datasets to improve empirically-derived design guidelines and (2) obtaining an improved understanding of nature of the extremophile microbial communities, microbially-mediated pollutant attenuation and rhizospheral processes in wetlands at extremes of pH. An enhanced knowledge of these (through multi-scale laboratory and field studies), will inform engineering design of treatmentwetlands and assist in the move from the empirically-derived conservative sizing estimates that currently prevail to process-based optimal design guidance that could reduce costs and enhance the performance and longevity of wetlands for treating acidic and highly alkaline drainage waters.

A national strategy for identification, prioritisation and management of pollution from abandoned non-coal mine sites in England and Wales. I.:: Methodology …

by William Mayes

Science of the Total Environment

In regions affected by historic non-coal (principally metal) mining activity, government agencies are often faced with... more In regions affected by historic non-coal (principally metal) mining activity, government agencies are often faced with the challenge of deploying limited remedial resources at abandoned mine sites to achieve maximum improvements in the chemical and ecological quality of impacted ground and surface waters. As such, strategies for the defensible allocation of public funds require comprehensive and systematic frameworks by which to identify and prioritise polluting sites for remediation. This paper describes the development and initial findings of such a national initiative in England and Wales which allies catchment-scale environmental impact assessments using existing public archive data, with recognition of the uncertainty in impact appraisals arising from disparities in data availability between sites and regions. The methodology identifies polluting sites and takes account not only of the chemical and ecological impacts of mine water discharges on receiving watercourses, but also of socio-economic factors such as conservation and heritage concerns, which can both impede or complement efforts to remediate mine sites. Using a Geographic Information System database and a suite of spatial analyses employing Boolean operators, both the extent of the pollution problem from abandoned non-coal mines in England and Wales (6% of 7815 surface water bodies are affected nationally) and the insight that can be gleaned from systematic analyses of existing archive data are highlighted. The results of the nationwide survey can be used as a dynamic database to inform future remedial planning, in terms of prioritising impacted river basins and abandoned non-coal mine sites themselves for either remediation or future monitoring efforts. As the assessment framework is built upon existing water quality and ecological data and mine site/geological data, there is considerable scope for the approach to be applied elsewhere where the legacy of historic mining persists through the widespread pollution of the aquatic environment.

Inventory of aquatic contaminant flux arising from historical metal mining in England and Wales

by William Mayes

The impact of discharges from abandoned metal and ironstone mines has been a much studied form of aquatic pollution in... more The impact of discharges from abandoned metal and ironstone mines has been a much studied form of aquatic pollution in recent decades. Few attempts however, have been made to accurately determine the overall contaminant mass flux arising from abandoned mine sites at scales above catchment level. Such assessments are critical to determine the significance of former mining to national, regional and ultimately global trace metal flux. This paper presents the most comprehensive national survey to date across England and Wales of the total pollution burden discharged at source from abandoned non-coal mine sites. 338 discharges have been identified (from 4923 known abandoned metal mines) and while concurrent flow and contaminant concentration records are only available for around 30% of these, significant quantities of metals (and As) have been quantified to be discharged. A minimum of 193 tonnes of Zn, 18.5 tonnes of Pb, 0.64 tonnes Cd, 19.1 tonnes of Cu, 551 tonnes Fe, 72 tonnes Mn and 5.1 tonnes As are released in water discharges from abandoned non-coal mines to the surface water environment of England and Wales each year. Precautionary extrapolation of mass fluxes based on the frequency distribution of measured concentration and flow data, for discharges with absent data, suggests that the actual total mass flux for these contaminants could be up to 41% higher. The mass flux of Pb released from mines exceeds that of all currently permitted discharges (e.g. active industrial sites and wastewater treatment works) to surface waters across England and Wales, while those of As, Cd and Zn are of a similar magnitude. These data put into context the enduring legacy of historic mining on the water environment, highlighting its significance relative to more highly regulated polluting sites. Comparison of the figures with estimates of global trace metal flux suggests that the national total identified here is significant on a global scale.

Mine water management at the catchment scale: case studies from north-east England

by William Mayes

Recent implementation of the EU Water Framework Directive
necessitates addressing water quality issues at the... more Recent implementation of the EU Water Framework Directive
necessitates addressing water quality issues at the catchment scale. In this study, contaminant loading of all point discharges have been measured, establishing the overall impact of mine waters within the catchments, and allowing the derivation
of contributions of diffuse mine water pollution to these totals. The results of two ongoing case studies of mine-impacted river catchments in the north-east of England are presented. The Allen catchment, Northumberland, is impacted by discharges from abandoned Pb/Zn mines with up to 6 mg/l Zn and 0.2 mg/l Pb, which significantly exceed European ecotoxicological standards by up to a factor of 75 and 20 respectively. The Gaunless catchment, County Durham, receives uncontrolled discharges of coal mine waters with up to 8 mg/l Fe. Preliminary
findings show that during both low and high flow conditions diffuse iron pollution contributes significantly to in-stream iron loadings. Probable pathways include direct groundwater input and remobilisation due to scouring of streambed sediments.

Prediction of acid mine generating potential: Validation using mineralogy

by Hassan Bouzahzah

BOUZAHZAH, H., BENZAAZOUA, M., PLANTE, B., BUSSIÈRE, B., PIRARD, E.

24th International Applied Geochemistry Symposium (IAGS), 1-4 June 2009, Fredericton, Canada.

Suppression of pyrite oxidation in acidic aqueous environments using lipids having two hydrophobic tails

by Martin Schoonen

A vibrational spectroscopic study of the oxidation of pyrite by ferric iron

by Martin Schoonen