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Storb MB, Bussell AM, Caldwell Eldridge SL, Hirsch RM, Schmidt TS. Growth of Coal Mining Operations in the Elk River Valley (Canada) Linked to Increasing Solute Transport of Se, NO 3-, and SO 42- into the Transboundary Koocanusa Reservoir (USA-Canada). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:17465-17480. [PMID: 37922122 PMCID: PMC10653222 DOI: 10.1021/acs.est.3c05090] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 11/05/2023]
Abstract
Koocanusa Reservoir (KOC) is a waterbody that spans the United States (U.S.) and Canadian border. Increasing concentrations of total selenium (Se), nitrate + nitrite (NO3-, nitrite is insignificant or not present), and sulfate (SO42-) in KOC and downstream in the Kootenai River (Kootenay River in Canada) are tied to expanding coal mining operations in the Elk River Watershed, Canada. Using a paired watershed approach, trends in flow-normalized concentrations and loads were evaluated for Se, NO3-, and SO42- for the two largest tributaries, the Kootenay and Elk Rivers, Canada. Increases in concentration (SO42- 120%, Se 581%, NO3- 784%) and load (SO42- 129%, Se 443%, NO3- 697%) in the Elk River (1979-2022 for NO3-, 1984-2022 for Se and SO42-) are among the largest documented increases in the primary literature, while only a small magnitude increase in SO42- (7.7% concentration) and decreases in Se (-10%) and NO3- (-8.5%) were observed in the Kootenay River. Between 2009 and 2019, the Elk River contributed, on average, 29% of the combined flow, 95% of the Se, 76% of the NO3-, and 38% of the SO42- entering the reservoir from these two major tributaries. The largest increase in solute concentrations occurred during baseflows, indicating a change in solute transport and delivery dynamics in the Elk River Watershed, which may be attributable to altered landscapes from coal mining operations including altered groundwater flow paths and increased chemical weathering in waste rock dumps. More recently there is evidence of surface water treatment operations providing some reduction in concentrations during low flow times of year; however, these appear to have a limited effect on annual loads entering KOC. These findings imply that current mine water treatment, which is focused on surface waters, may not sufficiently reduce the influence of mine-waste-derived solutes in the Elk River to allow constituent concentrations in KOC to meet U.S. water-quality standards.
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Affiliation(s)
- Meryl B. Storb
- U.S.
Geological Survey WY-MT Water Science Center, 3162 Bozeman Avenue, Helena, Montana 59601, United States
- Department
of Land Resources and Environmental Sciences, Montana State University, Bozeman, Montana 59717, United States
| | - Ashley M. Bussell
- U.S.
Geological Survey WY-MT Water Science Center, 3162 Bozeman Avenue, Helena, Montana 59601, United States
| | - Sara L. Caldwell Eldridge
- U.S.
Geological Survey WY-MT Water Science Center, 3162 Bozeman Avenue, Helena, Montana 59601, United States
| | - Robert M. Hirsch
- U.S.
Geological Survey Water Mission Area, 12201 Sunrise Valley Drive, Reston, Virginia 20192, United States
| | - Travis S. Schmidt
- U.S.
Geological Survey WY-MT Water Science Center, 3162 Bozeman Avenue, Helena, Montana 59601, United States
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Petryshen W. Spatial distribution of selenium and other potentially toxic elements surrounding mountaintop coal mines in the Elk Valley, British Columbia, Canada. Heliyon 2023; 9:e17242. [PMID: 37415941 PMCID: PMC10320305 DOI: 10.1016/j.heliyon.2023.e17242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 07/08/2023] Open
Abstract
Despite the extensive use of mountaintop coal mining in the Elk Valley, British Columbia, Canada's largest metallurgical coal-producing region, little is known about the transport and deposition of fugitive dust emissions within its mountain landscape. This study aimed to assess the extent and spatial distribution of selenium and other potentially toxic elements (PTEs) near the town of Sparwood originating from fugitive dust emitted from two mountaintop coal mines. To achieve these objectives concentrations of 47 elements within moss tissues of Hylocomium splendens, Pleurozium schreberi, and Ptilium crista-castrensis were analyzed from 19 locations between May 29 to June 1, 2022. Contamination factors were then calculated to identify areas of contamination, along with generalized additive models to assess the relationship between selenium and the mines. Finally, Pearson correlation coefficients were calculated between selenium and other PTEs to determine which exhibited similar behaviour. This study found that selenium concentrations are a function of proximity to mountaintop mines, and the region's topographic features and prevailing wind patterns play a role in the transport and deposition of fugitive dust. Contamination is highest immediately surrounding mines and decreases at increasing distances, with the region's steep mountain ridges shielding the deposition of some fugitive dust when acting as a geographic barrier between adjacent valleys. Furthermore, silver, germanium, nickel, uranium, vanadium, and zirconium were identified as other PTEs of concern. The implications of this study are significant as it demonstrated the extent and spatial distribution of contaminants originating from fugitive dust emissions surrounding mountaintop mines and some of the controls to its distribution in mountain regions. As Canada and other mining jurisdictions look to expand critical mineral development, it will be important for proper risk assessment and mitigation in mountain regions to limit community and environmental exposure to contaminants within fugitive dust.
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Sen P, Mehta R, Mehta P. Water quality assessment of Banas River, eastern-south region of Rajasthan, using water quality index. PROCEEDINGS OF THE INDIAN NATIONAL SCIENCE ACADEMY 2022. [DOI: 10.1007/s43538-022-00145-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Welch C, Barbour SL, Hendry MJ. The geochemistry and hydrology of coal waste rock dumps: A systematic global review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 795:148798. [PMID: 34247080 DOI: 10.1016/j.scitotenv.2021.148798] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 06/08/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
Coal has been a major global resource for at least the past 250 years. The major waste product of coal mining is waste rock, which is stored in dumps of various sizes. Although the adverse effects of coal waste rock dumps on ecosystems and human health are widely recognised, there is little information on their internal hydrological and geochemical processes in the peer-reviewed literature. Coal and conventional waste rock dumps share many similarities, but coal waste rock dumps differ in structure, organic matter content, and size, which can affect the timing and rate of aqueous chemical release. In this global systematic review, we identify limited links to climate setting and dump construction, and inconsistent reporting of sampling and monitoring approaches, as limitations to the generalisation of findings. Furthermore, sources of aqueous constituents of interest (COIs) are not routinely or adequately identified, which can lead to incorrect assumptions regarding COI availability and geochemical mobility. Water flow regimes within dumps are dominated by matrix and/or preferential flow, depending on dump texture; these flow mechanisms exert a primary control on patterns of aqueous COI release. The inability to successfully transfer COI release rates from laboratory or field scale trials to operational scale dumps is primarily due to limitations of testing methods and fundamental characteristics of scale. Prediction of future release rates is hampered by a lack of long-term studies that fully characterise geochemistry (e.g., source and COI production rates) as well as dump hydrology (e.g., water balance, water migration). Five critical elements to include in best practice investigations are climate setting, dump physical characteristics, geochemical processes, water regime, and environmental load over time, as aqueous release of COIs from coal waste rock dumps occurs over decades to centuries. Key considerations are identified for each of these elements to guide best practice.
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Affiliation(s)
- Chani Welch
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
| | - S Lee Barbour
- Department of Civil, Environmental and Geological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
| | - M Jim Hendry
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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Huang M, Barbour SL, Hendry MJ. Simulating nitrate release from an unsaturated coal waste rock dump. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 779:146429. [PMID: 33743462 DOI: 10.1016/j.scitotenv.2021.146429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/08/2021] [Accepted: 03/08/2021] [Indexed: 06/12/2023]
Abstract
Knowledge of the controls affecting the release of contaminants from waste rock dumps is critical for developing strategies to mitigate downstream impacts on water quality. In this study, a three-dimensional model of a large coal waste rock dump constructed in the Elk Valley, British Columbia, Canada was developed to capture the impact of construction history (1981-2012) and solute transport on nitrate (NO3-) release over a 100-year timeframe. The model consisted of 21, one-dimensional finite element models that represented the temporal evolution of the dump. Nitrate, derived from undetonated blast products, was assumed to be present at the time of waste rock placement and was simulated as a conservative species. The simulated pattern of NO3- release to the surface water receptor occurred approximately 8 years before its measured arrival. This time lag is attributed to displacement of the water within a basal alluvial aquifer by dump effluent. The simulated patterns of historic releases corrected for the 8-year time lag, compare favourably with monitoring data and suggest the dominant hydrogeological and geochemical mechanisms are captured in the model. The model indicated the flushing of NO3- from the dump should be complete by about 2042 with a peak effluent concentration of NO3- in 2008. The addition of reclamation covers to the model resulted in an immediate decrease in the annual NO3- loading rate but extended the time frame for NO3- release from the dump relative to the no cover case. The model also showed that the timing of cover placement had little impact on NO3- release relative to the no cover case due to long duration of waste rock placement (~30 years) over a relatively large footprint.
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Affiliation(s)
- Mingbin Huang
- The State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi Province 712100, PR China; Department of Civil, Geological and Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada; CAS Center for Excellence in Quaternary Science and Global Change, Xian, Shaanxi 710061, China
| | - S Lee Barbour
- Department of Civil, Geological and Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada.
| | - M Jim Hendry
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada
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Biogeochemical Controls on the Potential for Long-Term Contaminant Leaching from Soils Developing on Historic Coal Mine Spoil. SOIL SYSTEMS 2020. [DOI: 10.3390/soilsystems5010003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Coal mine spoil is widespread in US coal mining regions, and the potential long-term leaching of toxic metal(loid)s is a significant and underappreciated issue. This study aimed to determine the flux of contaminants from historic mine coal spoil at a field site located in Appalachian Ohio (USA) and link pore water composition and solid-phase composition to the weathering reaction stages within the soils. The overall mineralogical and microbial community composition indicates that despite very different soil formation pathways, soils developing on historic coal mine spoil and an undisturbed soil are currently dominated by similar mineral weathering reactions. Both soils contained pyrite coated with clays and secondary oxide minerals. However, mine spoil soil contained abundant residual coal, with abundant Fe- and Mn- (oxy)hydroxides. These secondary phases likely control and mitigate trace metal (Cu, Ni, and Zn) transport from the soils. While Mn was highly mobile in Mn-enriched soils, Fe and Al mobility may be more controlled by dissolved organic carbon dynamics than mineral abundance. There is also likely an underappreciated risk of Mn transport from coal mine spoil, and that mine spoil soils could become a major source of metals if local biogeochemical conditions change.
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Zhang X, Tian J, Hu Y, Han H, Luo X, Sun W, Yue T, Wang L, Cao X, Zhou H. Selective sulfide precipitation of copper ions from arsenic wastewater using monoclinic pyrrhotite. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 705:135816. [PMID: 31972947 DOI: 10.1016/j.scitotenv.2019.135816] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 11/25/2019] [Accepted: 11/26/2019] [Indexed: 06/10/2023]
Abstract
Pyrrhotite is a potential source of S2- for the sulfide precipitation of nonferrous metal ions in hydrometallurgy and waste water treatment. In this study, different pyrrhotite crystals were prepared using zero-valent iron and sulfur to determine the effects of the pyrrhotite's structure on the sulfide precipitation of copper ions. The results indicate that the sulfide precipitation of copper ions highly depends on the crystal structure and crystallinity of pyrrhotite. Monoclinic pyrrhotite was found to be the most effective for copper sulfide precipitation, which can be used for the selective precipitation of copper ions from arsenic wastewater. More than 96% copper ions were removed with little loss of arsenic, contributing to a copper product of 20.2% Cu and 0.7% As, which can serve as raw materials of copper metallurgy. X-ray diffraction analysis showed the presence of CuS and (CuxFe1-x)S, indicating that most copper ions precipitated as CuS and some copper ions entered the FeS lattice by a lattice substitution reaction. Therefore, monoclinic pyrrhotite may provide an alternative solution for the selective precipitation of copper from arsenic wastewater.
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Affiliation(s)
- Xingfei Zhang
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China
| | - Jia Tian
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China
| | - Yuehua Hu
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China
| | - Haisheng Han
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China.
| | - Xianping Luo
- Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
| | - Wei Sun
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China
| | - Tong Yue
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China
| | - Li Wang
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China
| | - Xuefeng Cao
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China
| | - Hepeng Zhou
- Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
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8
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Abstract
Coal mine spoils have the potential to create environmental impacts, such as salt load to surrounding environments, particularly when exposed to weathering processes. This study was conducted to understand the effect of physical and chemical weathering on the magnitude, rate, and dynamics of salt release from different coal mine spoils. Five spoil samples from three mines in Queensland were sieved to three different particle size fractions (<2 mm, 2–6 mm, and >6 mm). Two samples were dispersive spoils, and three samples were nondispersive spoils. The spoils were subjected to seven wet–dry cycles, where the samples were periodically leached with deionised water. The rate, magnitude, and dynamics of solutes released from spoils were spoil specific. One set of spoils did not show any evidence of weathering, but initially had higher accumulation of salts. In contrast, broad oxidative weathering occurred in another set of spoils; this led to acid generation and resulted in physical weathering, promoting adsorption–desorption and dissolution and, thus, a greater release of salts. This study indicated that the rate and magnitude of salt release decreased with increasing particle size. Nevertheless, when the spoil is dispersive, the degree of weathering manages salt release irrespective of initial particle size. This study revealed that the long-term salt release from spoils is not only governed by geochemistry, weathering degree, and particle size but also controlled by the water/rock ratio and hydrological conditions of spoils.
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9
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Wang P, McKenna BA, Menzies NW, Li C, Glover CJ, Zhao FJ, Kopittke PM. Minimizing experimental artefacts in synchrotron-based X-ray analyses of Fe speciation in tissues of rice plants. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:1272-1279. [PMID: 31274454 DOI: 10.1107/s1600577519004351] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/30/2019] [Indexed: 06/09/2023]
Abstract
Iron (Fe) plays an important role within environmental systems. Synchrotron-based X-ray approaches, including X-ray absorption spectroscopy (XAS), provide powerful tools for in situ analyses of Fe speciation, but beam damage during analysis may alter Fe speciation during its measurement. XAS was used to examine whether experimental conditions affect the analysis of Fe speciation in plant tissues. Even when analyzed in a cryostat at 12 K, it was found that FeIII can rapidly (within 0.5-1 min) photoreduce to FeII, although the magnitude of photoreduction varied depending upon the hydration of the sample, the coordination chemistry of the Fe, as well as other properties. For example, photoreduction of FeIII was considerably higher for aqueous standard compounds than for hydrated plant-root tissues. The use of freeze-dried samples in the cryostat (12 K) markedly reduced the magnitude of this FeIII photoreduction, and there was no evidence that the freeze-drying process itself resulted in experimental artefacts under the current experimental conditions, such as through the oxidation of FeII, although some comparatively small differences were observed when comparing spectra of hydrated and freeze-dried FeII compounds. The results of this study have demonstrated that FeIII photoreduction can occur during X-ray analysis, and provides suitable conditions to preserve Fe speciation to minimize the extent of beam damage when analyzing environmental samples. All studies utilizing XAS are encouraged to include a preliminary experiment to determine if beam damage is occurring, and, where appropriate, to take the necessary steps (such as freeze drying) to overcome these issues.
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Affiliation(s)
- Peng Wang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Brigid A McKenna
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Neal W Menzies
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Cui Li
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Chris J Glover
- Australian Synchrotron ANSTO, Clayton, Victoria 3168, Australia
| | - Fang Jie Zhao
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Peter M Kopittke
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
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Hendry MJ, Wassenaar LI, Barbour SL, Schabert MS, Birkham TK, Fedec T, Schmeling EE. Assessing the fate of explosives derived nitrate in mine waste rock dumps using the stable isotopes of oxygen and nitrogen. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 640-641:127-137. [PMID: 29859430 DOI: 10.1016/j.scitotenv.2018.05.275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 05/21/2018] [Accepted: 05/22/2018] [Indexed: 06/08/2023]
Abstract
Ammonium nitrate (NH4NO3) mixed with fuel oil is a common blasting agent used to fragment rock into workable size fractions at mines throughout the world. The decomposition and oxidation of undetonated explosives can result in high NO3- concentrations in waters emanating from waste rock dumps. We used the stable isotopic composition of NO3- (δ15N- and δ18O-NO3-) to define and quantify the controls on NO3- composition in waste rock dumps by studying water-unsaturated and saturated conditions at nine coal waste rock dumps located in the Elk Valley, British Columbia, Canada. Estimates of the extent of nitrification of NH4NO3 in oxic zones in the dumps, initial NO3- concentrations prior to denitrification, and the extent of NO3- removal by denitrification in sub-oxic to anoxic zones are provided. δ15N data from unsaturated waste rock dumps confirm NO3- is derived from blasting. δ15N- and δ18O-NO3- data show extensive denitrification can occur in saturated waste rock and in localized zones of elevated water saturation and low oxygen concentrations in unsaturated waste rock. At the mine dump scale, the extent of denitrification in the unsaturated waste rock was inferred from water samples collected from underlying rock drains.
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Affiliation(s)
- M Jim Hendry
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada.
| | - Leonard I Wassenaar
- International Atomic Energy Agency, Vienna, International Centre, 1400 Vienna, Austria
| | - S Lee Barbour
- Department of Civil and Geological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | - Marcie S Schabert
- SRK Consulting (Canada) Inc., 1066 W Hastings St., Vancouver, BC V6E 3X2, Canada
| | - Tyler K Birkham
- O'Kane Consultants Inc., 905C Industrial Road 2, Cranbrook, BC V1C 4C9, Canada
| | - Tony Fedec
- Teck Coal Ltd., P.O. Box 3000, Sparwood, BC V0B 2G1, Canada
| | - Erin E Schmeling
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada
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Mahmood FN, Barbour SL, Kennedy C, Hendry MJ. Nitrate release from waste rock dumps in the Elk Valley, British Columbia, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 605-606:915-928. [PMID: 28693108 DOI: 10.1016/j.scitotenv.2017.05.253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/26/2017] [Accepted: 05/27/2017] [Indexed: 06/07/2023]
Abstract
The origin, distribution and leaching of nitrate (NO3-) from coal waste rock dumps in the Elk Valley, British Columbia, Canada were defined using chemical and NO3- isotope analyses (δ15N- and δ18O-NO3-) of solids samples of pre- and post-blast waste rock and from thick (up to 180m) unsaturated waste rock dump profiles constructed between 1982 and 2012 as well as water samples collected from a rock drain located at the base of one dump and effluent from humidity cell (HC) and leach pad (LP) tests on waste rock. δ15N- and δ18O-NO3- values and NO3- concentrations of waste rock and rock drain waters confirmed the source of NO3- in the waste rock to be explosives and that limited to no denitrification occurs in the dump. The average mass of N released during blasting was estimated to be about 3-6% of the N in the explosives. NO3- concentrations in the fresh-blast waste rock and recently placed waste rock used for the HC and LP experiments were highly variable, ranging from below detection to 241mg/kg. The mean and median concentrations of these samples ranged from 10-30mg/kg. In this range of concentrations, the initial aqueous concentration of fresh-blasted waste rock could range from approximately 200-600mg NO3--N/L. Flushing of NO3- from the HCs, LPs and a deep field profile was simulated using a scale dependent leaching efficiency (f) where f ranged from 5-15% for HCs, to 35-80% for the LPs, to 80-90% for the field profile. Our findings show aqueous phase NO3- from blasting residuals is present at highly variable initial concentrations in waste rock and the majority of this NO3- (>75%) should be flushed by recharging water during displacement of the first stored water volume.
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Affiliation(s)
- Fazilatun N Mahmood
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada.
| | - S Lee Barbour
- Department of Civil, Geological and Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada.
| | - C Kennedy
- SRK Consulting (Canada) Inc., 22nd Floor, 1066 West Hastings Street, Vancouver, BC V6E 3X2, Canada.
| | - M Jim Hendry
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada.
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Villeneuve SA, Barbour SL, Hendry MJ, Carey SK. Estimates of water and solute release from a coal waste rock dump in the Elk Valley, British Columbia, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 601-602:543-555. [PMID: 28575832 DOI: 10.1016/j.scitotenv.2017.05.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 05/03/2017] [Accepted: 05/04/2017] [Indexed: 06/07/2023]
Abstract
Long term (1999 to 2014) flow and water quality data from a rock drain located at the base of a coal waste rock dump constructed in the Elk Valley, British Columbia was used to characterize the release of three solutes (NO3-, Cl- and SO42-) from the dump and obtain whole dump estimates of net percolation (NP). The concentrations of dump derived solutes in the rock drain water were diluted by snowmelt waters from the adjacent natural watershed during the spring freshet and reached a maximum concentration during the winter baseflow period. Historical peak baseflow concentrations of conservative ions (NO3- and Cl-) increased until 2006/07 after which they decreased. This decrease was attributed to completion of the flushing of the first pore volume of water stored within the dump. The baseflow SO42- concentrations increased proportionally with NO3- and Cl- to 2007, but then continued to slowly increase as NO3- and Cl- concentrations decreased. This was attributed to ongoing production of SO42- due to oxidation of sulfide minerals within the dump. Based on partitioning of the annual volume of water discharged from the rock drain to waste rock effluent (NP) and water entering the rock drain laterally from the natural watershed, the mean NP values were estimated to be 446±50mm/a (area normalized net percolation/year) for the dump and 172±71mm/a for the natural watershed. The difference was attributed to greater rates of recharge in the dump from summer precipitation compared to the natural watershed where rainfall interception and enhanced evapotranspiration will increase water losses. These estimates included water moving through subsurface pathways. However, given the limitations in quantifying these flows the estimated NP rates for both the natural watershed and the waste rock dump are considered to be low, and could be much higher (e.g. ~450mm/a and ~800mm/a).
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Affiliation(s)
- S A Villeneuve
- Department of Civil and Geological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada.
| | - S L Barbour
- Department of Civil and Geological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada.
| | - M J Hendry
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada.
| | - S K Carey
- School of Geography and Earth Sciences, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.
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Das S, Lindsay MBJ, Essilfie-Dughan J, Hendry MJ. Dissolved Selenium(VI) Removal by Zero-Valent Iron under Oxic Conditions: Influence of Sulfate and Nitrate. ACS OMEGA 2017; 2:1513-1522. [PMID: 31457519 PMCID: PMC6640955 DOI: 10.1021/acsomega.6b00382] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 04/04/2017] [Indexed: 06/01/2023]
Abstract
Dissolved Se(VI) removal by three commercially available zero-valent irons (ZVIs) was examined in oxic batch experiments under circumneutral pH conditions in the presence and absence of NO3 - and SO4 2-. Environmentally relevant Se(VI) (1 mg L-1), NO3 - ([NO3-N] = 15 mg L-1), and SO4 2- (1800 mg L-1) were employed to simulate mining-impacted waters. Ninety percent of Se(VI) removal was achieved within 4-8 h in the absence of SO4 2- and NO3 -. A similar Se(VI) removal rate was observed after 10-32 h in the presence of NO3 -. Dissolved Se(VI) removal rates exhibited the highest decrease in the presence of SO4 2-; 90% of Se(VI) removal was measured after 50-191 h for SO4 2- and after 150-194 h for SO4 2- plus NO3 - depending on the ZVI tested. Despite differences in removal rates among batches and ZVI materials, Se(VI) removal consistently followed first-order reaction kinetics. Scanning electron microscopy, Raman spectroscopy, and X-ray diffraction analyses of reacted solids showed that Fe(0) present in ZVI undergoes oxidation to magnetite [Fe3O4], wüstite [FeO], lepidocrocite [γ-FeOOH], and goethite [α-FeOOH] over time. X-ray absorption near-edge structure spectroscopy indicated that Se(VI) was reduced to Se(IV) and Se(0) during removal. These results demonstrate that ZVI can be effectively used to control Se(VI) concentrations in mining-impacted waters.
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Affiliation(s)
- Soumya Das
- E-mail: . Tel: 306-966-4664. Fax: 306-966-8593
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