Acid Mine Waste Research Articles

One-stage microwave-assisted activated carbon preparation from Langsat peel raw material for adsorption of iron, manganese and copper from acid mining waste

This study describes the efficacy of microwave technology for the preparation of an activated carbon from Lansium domesticum peel as an adsorbent to adsorb Fe, Cu, and Mn from acid mine waste. In contrast to the conventional pyrolytic carbonization technique, the described method demonstrated several unparalleled advantages, including superior energy efficiency and remarkably rapid processing. The reported microwave irradiation method was able readily to achieve a morphology and extensive surface area similar to that of a sample produced using the traditional pyrolytic carbonization method for 2 hours, and this was accomplished in just 10 minutes. The activated carbon obtained was characterized using SEM-EDX, BET-BJH, and proximate test and applied to adsorb metal ions from acid mine waste to evaluate the isothermal adsorption model. The best power for activated carbon production was 400 watts for 10 minutes, which met the requirements of ASTM D 4607 for determining the iodine value of activated carbon. Optimal mass for adsorbing Fe, Cu, and Mn from acid mine waste was 4 grams with the removal percentages of 94.08%, 83.69%, and 90.67%, respectively. BET surface area was 1367.0385 m2/g along with a BJH cumulative volume and an average pore diameter of 1.112 cm3/g and 2.25 nm, respectively. This suggests that it possesses mesoporous characteristics and adheres to the Langmuir model during the adsorption process, signifying monolayer adsorption. Meanwhile, kinetics followed the pseudo-second-order rate equation.

Formation of Acid Sulfate Soils under the Influence of Acid Mine Waste in the Taiga Zone

Formation of Acid Sulfate Soils under the Influence of Acid Mine Waste in the Taiga Zone

Metal mobility and bioaccessibility from cyanide leaching heaps in a historical mine site

Unlike acidic sulfide mine wastes, where metal/loid mobility and bioaccessibility has been widely studied, less attention has been paid to alkaline cyanide heap leaching wastes. Thus, the main goal of this study is to evaluate the mobility and bioaccessibility of metal/loids in Fe-rich (up to 55%) mine wastes resulting from historical cyanide leaching activities. Wastes are mainly composed of oxides/oxyhydroxides (i.e. goethite and hematite), oxyhydroxisulfates (i.e. jarosite), sulfates (i.e., gypsum, evaporitic sulfate salts), carbonates (i.e., calcite, siderite) and quartz, with noticeable concentrations of metal/loids (e.g., 1453–6943 mg/kg of As, 5216–15,672 mg/kg; of Pb, 308–1094 mg/kg of Sb, 181–1174 mg/kg of Cu, or 97–1517 mg/kg of Zn). The wastes displayed a high reactivity upon rainfall contact associated to the dissolution of secondary minerals such as carbonates, gypsum, and other sulfates, exceeding the threshold values for hazardous wastes in some heap levels for Se, Cu, Zn, As, and sulfate leading to potential significant risks for aquatic life. High concentrations of Fe, Pb, and Al were released during the simulation of digestive ingestion of waste particles, with average values of 4825 mg/kg of Fe, 1672 mg/kg of Pb, and 807 mg/kg of Al. Mineralogy may control the mobility and bioaccessibility of metal/loids under rainfall events. However, in the case of the bioaccessible fractions different associations may be observed: i) the dissolution of gypsum, jarosite and hematite would mainly release Fe, As, Pb, Cu, Se, Sb and Tl; ii) the dissolution of an un-identified mineral (e.g., aluminosilicate or Mn oxide) would lead to the release of Ni, Co, Al and Mn and iii) the acid attack of silicate materials and goethite would enhance the bioaccessibility of V and Cr. This study highlights the hazardousness of wastes from cyanide heap leaching, and the need to adopt restoration measures in historical mine sites.

Rare earth element recovery in hard-rock acid mine drainage and mine waste: A case study in Idaho Springs, Colorado

While the geochemistry of hard-rock generated acid mine drainage (AMD) and waste rock has been extensively studied for environmental and toxicological impacts, their critical metal contents have only recently begun to be characterized. We investigated rare earth element (REE) geochemistry in AMD and waste rock in the Idaho Springs gold district, Colorado. Specifically, we found that two AMD inputs to the Argo Tunnel Wastewater Treatment Plant (ATWTP) contain high dissolved REE concentrations (0.7 and 1.3 mg*L−1), and that REEs could be concentrated using a two-stage pH adjustment. The first stage precipitated iron and removed thorium by adsorption, while the second stage precipitated aluminum, which removed REEs by adsorption. Solids generated were 2670 and 2800 mg*kg−1 for each of the REE-bearing AMD sources, and at 90% REE recovery, the ATWTP could produce nearly 1000 kg of REEs each year with an economically favorable MREE enrichment. REE leaching in waste rock was also investigated, but results indicate that it is unlikely to be a significant source of REEs. More work is needed to characterize both the critical metal content (including other metals besides REEs) and economic feasibility of extraction for mine waste and AMD in hard-rock mining environments.

Activation of cryptic biosynthetic gene clusters by fungal artificial chromosomes to produce novel secondary metabolites.

In 2017, we reported the discovery of Berkeleylactone A (BPLA), a novel, potent antibiotic produced exclusively in co-culture by two extremophilic fungi, Penicillium fuscum and P. camembertii/clavigerum, which were isolated from the Berkeley Pit, an acid mine waste lake, in Butte, Montana. Neither fungus synthesized BPLA when grown in axenic culture. Recent studies suggest that secondary metabolites (SMs) are often synthesized by enzymes encoded by co-localized genes that form "biosynthetic gene clusters" (BGCs), which might remain silent (inactive) under various fermentation conditions. Fungi may also harbor cryptic BGCs that are not associated with previously characterized molecules. We turned to the tools of Fungal Artificial Chromosomes (FAC)-Next-Gen-Sequencing (NGS) to understand how co-culture activated cryptic biosynthesis of BPLA and several related berkeleylactones and to further investigate the true biosynthetic potential of these two fungi. FAC-NGS enables the capture of BGCs as individual FACs for heterologous expression in a modified strain of Aspergillus nidulans (heterologous host, FAC-AnHH). With this methodology, we created ten BGC-FACs that yielded fourteen different SMs, including strobilurin, which was previously isolated exclusively from basidiomycetes. Eleven of these compounds were not detected in the extracts of the FAC-AnHH. Of this discrete set, only the novel compound citreohybriddional had been isolated from either Penicillium sp. before and only at very low yield. We propose that through heterologous expression, FACs activated these silent BGCs, resulting in the synthesis of new natural products (NPs) with yields as high as 50%-60% of the crude organic extracts.

DECREASE LEVELS OF IRON (Fe) AND MANGANESE (Mn) IN ACID MINING WATER USING ACTIVE CARBON OF EGG SHELL

Acid mine drainage is acidic water that arises as a result of mining activities. Acidic water has a high acidity, which is often characterized by a low pH and contains high levels of heavy metals Fe and Mn. The purpose of this study was to determine the effect of activated carbon on the adsorption process and the effect of mass of activated carbon on eggshells. The method used in this research is the adsorption method using activated carbon of eggshell which is physically and chemically activated. This study used a mass variation of 5, 10, 15 and 20 grams with a contact time of 30 minutes and an adsorbent size of 200 mesh. The parameters studied were heavy metals iron (Fe) and manganese (Mn). The initial concentration of Fe acid mine waste was 29.179 mg/L, and Mn was 7.9692 mg/L. The results showed that the mass of activated carbon had an effect on decreasing the levels of Fe and Mn metals. On physical activation the average decrease in Fe metal was 99.50% and Mn metal was 53.21%, while on chemical activation the average decrease in Fe metal was 97.72% and Mn metal was 97.97%.Keywords: Acid mine water, Fe, Mn, Activated carbon, egg shell

Berkeleylactones and a Citreohybriddione Analogue from Penicillium turbatum.

In 2017 we reported the isolation and characterization of berkeleylactones A-H and A26771B from a coculture of two extremophilic Penicillium sp. isolated from an acid mine waste lake. Berkeleylactone A exhibited potent activity against several strains of multi-drug-resistant Staphylococcus aureus and Bacillus anthracis. A26771B, which is related to the berkeleylactones, also exhibited antibiotic activity. Although the berkeleylactones were novel compounds, A26771B was originally isolated by scientists at Eli Lilly Company from P. turbatum and reported in1977. We recently obtained P. turbatum and grew it in axenic culture. We isolated five new berkeleylactones (2 and 4-7), two berkeley-γ-lactones (8 and 9), and citreohybriddional (10), as well as the known compounds A26771B (1), berkeleylactone E (3), and gliovictin. The structures of the novel compounds were deduced from analysis of spectral data. Compounds 2 and 4 -7 are 16-membered macrolides, while 8 and 9 are γ-lactones that share the hexadecanoic acid skeleton. A26771B (1) and berkeleylactone I (2) were active against several strains of Staphylococcus aureus, including four multi-drug-resistant strains. Berkeleylactone N (8) was active only against Streptococcus pyogenes.

Composition and structure of soil fauna communities and their relationships with environmental factors in copper mine waste rock after re-vegetation

The re-vegetation of acid mine waste rock from the Dexing copper (Cu) mine in Shuilong mountain has been conducted for more than 10 years. However, few studies have assessed the composition of soil fauna communities in this restored ecosystem. Here, we investigated the relationship between the soil fauna communities and soil environmental factors in this area using two re-vegetation restoration types (shrub-dominated and herb-dominated vegetation types) and in one area without re-vegetation (control) and modified Tullgren and Baermann methods. The 3558 soil fauna individuals collected belonged to five classes, 13 orders, three suborders, and 29 families. The number of individuals and taxa of small- and medium-sized soil fauna were significantly influenced by the different re-vegetation types (P < 0.05). Soil temperature, organic carbon, total nitrogen, carbon-nitrogen ratio, total phosphorus, available phosphorus, as well as the number of individuals and taxa of soil fauna were higher in the shrub-dominated re-vegetated plots than in the herb-dominated re-vegetated plots. The number of taxa was significantly and positively correlated with soil available phosphorus (P < 0.05), and the number of taxa, diversity, and richness of the soil fauna were significantly and positively correlated with the content of cadmium (Cd) in the soil (P < 0.05). Redundancy analysis revealed that the effects exerted by soil temperature, total nitrogen, and carbon-nitrogen ratio on the main taxa of soil fauna were the most important (P < 0.05). Among the various heavy metals in the soil, Cd, lead, zinc, and Cu exerted the most significant effects on the main soil fauna taxa (P < 0.05). Our results showed that the re-vegetation types significantly influenced the community composition and diversity of soil fauna in the waste rock dump of the Dexing Cu mine in Shuilong mountain, and that soil properties and soil heavy metal content influenced soil fauna community structure.

Native plants facilitate vegetation succession on amended and unamended mine tailings

Facilitating the establishment of native pioneer plant species on mine tailings with inherent metal and/or acid tolerance is important to speed up natural succession at minimal cost, especially in remote areas where phytoremediation can be labor intensive. We investigated vegetation community dynamics after ∼48 years of succession along two legacy Ni–Cu mine tailings and waste rock deposits in the Sudbury Basin, Ontario, Canada with and without various site amendments (i.e. liming and fertilization) and planting. Metal/acid tolerant pioneer plants (Betula papyrifera, Populus tremuloides, Pohlia nutans) appeared to facilitate the establishment of less tolerant species. Conifers and nitrogen-fixers less tolerant to site conditions were planted at the fully amended (limed, fertilized, planted) mine tailings site in the 1970s, but conifers were not propagating at the site or facilitating understory succession. The planted nitrogen-fixing leguminous species Lotus corniculatus was, however, associated with increased diversity. These findings have implications for long-term reclamation strategies in acidic mine waste deposits utilizing native species, as primary colonizing tree species are only recently emerging as candidates for phytoremediation. Novelty statement The potential for native species to act as facilitators for vegetation colonization has rarely been investigated on tailings, despite wide use in remediation of less toxic sites. This study provides a retrospective of over 40 years of plant growth following initial treatment of toxic tailings. We observed that regardless of tailings geochemical conditions, acid/metal tolerant pioneer plants were facilitating ecological succession on acidic Ni-Cu mine tailings sites.

Molybdenum sulphide modified chelating resin for toxic metal adsorption from acid mine wastewater

Acid mine wastewater from mining industries leads to serious environmental problems due to its acidic nature and high levels of hazardous heavy metal ions. Thus, it is important to develop novel adsorbent materials for selective removing heavy metal ions. In this work, an amorphous molybdenum sulphide functionalized dipicolyamine exchanger were prepared and ultilised to scavenge toxic heavy metal ions from both synthetic and real acid mine waste water (copper mining industry). This new exchanger combines the advantages of exceptional heavy metal affinities from molybdenum sulphide and engineered macroporous structure from dipicolylamine resin. The results of batch and fixed-bed column tests suggest high selectivity towards heavy metals, fast adsorption kinetics, good reusability and excellent adsorption capacities in the sequence of Hg(II)≫Cd(II) > Cu(II). The metal adsorption mechanism has been demonstrated by X-ray Photoelectron Spectroscopy (XPS). Our findings support the potential practical application of this new material for scavenging heavy metal ions in mining wastewater.

Characteristics of an Iron-Reducing, Moderately Acidophilic Actinobacterium Isolated from Pyritic Mine Waste, and Its Potential Role in Mitigating Mineral Dissolution in Mineral Tailings Deposits.

Reactive pyritic mine tailings can be populated by chemolithotrophic prokaryotes that enhance the solubilities of many metals, though iron-reducing heterotrophic microorganisms can inhibit the environmental risk posed by tailings by promoting processes that are the reverse of those carried out by pyrite-oxidising autotrophic bacteria. A strain (IT2) of Curtobacterium ammoniigenes, a bacterium not previously identified as being associated with acidic mine wastes, was isolated from pyritic mine tailings and partially characterized. Strain IT2 was able to reduce ferric iron under anaerobic conditions, but was not found to catalyse the oxidation of ferrous iron or elemental (zero-valent) sulfur, and was an obligate heterotrophic. It metabolized monosaccharides and required small amounts of yeast extract for growth. Isolate IT2 is a mesophilic bacterium, with a temperature growth optimum of 30 °C and is moderately acidophilic, growing optimally at pH 4.0 and between pH 2.7 and 5.0. The isolate tolerated elevated concentrations of many transition metals, and was able to grow in the cell-free spent medium of the acidophilic autotroph Acidithiobacillus ferrooxidans, supporting the hypothesis that it can proliferate in acidic mine tailings. Its potential role in mitigating the production of acidic, metal-rich drainage waters from mine wastes is discussed.

Estuarine foraminifera from South West England: impact of metal pollution in a mining heritage area

The southern coastline of SW England is characterized by a number of drowned river valleys (known locally as rias) that contain a range of important estuarine environments including saltmarsh, mud flats, sea grass meadows and open marine sands. All of these ‘rias’ drain catchments with Devonian and Carboniferous rocks that were intruded by granite during the Variscan Orogeny and which were mineralized at that time. The Cornwall and West Devon Mining Heritage UNESCO World Heritage Site records the exploitation of these minerals since Roman times, though mining ceased in the twentieth century. All these mineralized rocks, mining waste and the occasional ‘flood’ of old mine workings have contaminated the estuaries with Cu, Zn, Sn, As, Cr, Hg, Ag, etc., which, in many places, may have left a record of foraminifera with test abnormalities. Since 1973, in a series of student-led projects, the estuaries of the region have been studied for their foraminiferal assemblages, sometimes including sampling strategies that meant monthly, or 3-monthly, suites of samples being collected. The Fal Estuary is one of the largest and most complex of the ‘rias’ and, while draining mineralized areas, also suffered a major release of acidic mine waste during a flood in January 1992. Recovery from that ‘event’ showed that the total absence of foraminifera began to recover within 2 years and assemblages have now returned to pre-incident levels, though still recording malformed individuals. This re-colonization is probably the result of propagule dispersion from more open waters of the Fal Estuary.

Biochar aided aromatic grass [Cymbopogon martini (Roxb.) Wats.] vegetation: A sustainable method for stabilization of highly acidic mine waste

Dumping of acidic mine waste poses severe threats to the ecosystem due to high acidity, nutrient deficiency and mobility of toxic metals. The present study has been undertaken on phytoremediation by amending the acidic soil/mine waste with biochar (BC) and plantation of palmarosa (Cymbopogon martini (Roxb.) Wats. A greenhouse experiment in different combinations of biochar and acidic mine waste was conducted to assess the phytoremediation efficiency of palmarosa by BC amendments. Results indicate that the palmarosa tolerates multiple stresses effectively with a 54 % metal tolerance index (MTI) and capable of reducing acid production from the acidic mine waste alone. BC incorporation in the mine waste and soil treatments significantly enhanced the palmarosa biomass (1.11–3.3 times) and oil content by liming the acid, immobilization of metals and improving the soil quality. BC addition in highly acidic mine waste amplified the phytoremediation efficiency and mitigates abiotic oxidative stress on plants (MTI 84 % to >100 %). BC aided palmarosa plantation shifted the soil from high-risk assessment code (RAC) to low RAC for vegetation. Biochar amendments along with palmarosa plantation offer a sustainable technology for phytostabilization of highly acidic mine waste along with the production of industrially important essential oil.

Bioreduction in the development of new mineral technology

Reductive dissolution is like “biomining in reverse gear”. Selected sulfur reducing bacteria (SRB) can be used under anaerobic conditions – as in bioleaching – for metal recovery from oxide minerals and laterite. General assumptions of the BioSulphide® and Ferredox processes for nickel recovery from laterite ores and copper from acid mine drainage or waste water were presented.

A review of acid recovery from acidic mining waste solutions using solvent extraction

AbstractThe minerals industry is increasingly being forced by regulatory and cost pressures to reduce the amount of liquid acidic waste they produce. This requires a strong focus on waste reduction by recycling, regeneration and reuse. Four mineral acids were examined for recovery from waste acidic solutions including H2SO4, HNO3, HCl, and H3PO4. The selection of the optimal extractant for acid recovery was based on extraction, stripping and scrubbing efficiencies. The extractants suitable for the recovery of H2SO4 and HCl are in the order of TEHA &gt; Cyanex 923 &gt; TBP &gt; Alamine 336. TEHA has the highest degree of acid extraction and stripping compared with Cyanex 923 and almost 99% of the acid can be stripped. Alamine 336 can extract higher acid (for H2SO4 and HCl systems) than Cyanex 923 and TBP. However loaded acid for Alamine 336 system cannot be stripped using water at 60°C. For the recovery of nitric and phosphoric acids from acidic waste effluents, TBP was the best option. This work clearly demonstrates that extractant suitable for acid extraction may not be suitable for its recovery. However such extractant may be applied for the removal of acid from any waste acidic solution sacrificing the back extraction of the loaded acid. The effective implementation of options for acid recovery was examined to improve sustainability in the mineral industry. © 2018 Society of Chemical Industry

English

Sulfate reducing bacteria (SRB) was successfully isolated from Estuary Dam in Suwung Denpasar, Indonesia. This estuary catches highly polluted water from Badung River which runs across and hence carries pollution due to waste disposal from Denpasar City. SRB was studied in detail for their ability to reduce sulfate to sulfide with organic material as an oxidizing agent. SRB exploration of the estuary ecosystem of the contaminated dam was accomplished through isolation, selection and characterization of the isolates obtained. The result of this study found superior SRB named DPS 1711, DPS 1705 and DPS 1703. The bacteria have the ability to grow at pH 3, room temperature and uses compost as organic substrate. This ability is an important factor for the application of isolates in the treatment of acid mine waste. Isolates have optimum optical density under the pH range of 4 to 7 and the best at pH 5 have a growth rate profile at a temperature range of 25 to 40&deg;C. The isolates observed were Gram-negative stem, motile bacteria which only grow in anaerobic condition. Physiological-biochemical characterization showed the three isolates, namely DPS 1703, DPS 1705 and DPS 1711 were SRB groups identified as Desulfotomaculum orientis. Key words: Sulfate reducing bacteria, polluted waters, estuary dam ecosystem. &nbsp

Formation of secondary nonsulfide zinc ore in Cho Dien Pb-Zn deposits

In Viet Nam, non-sulfide zinc ore in the Cho Dien deposit has been exploited for a long time. Up to the present, zinc ore remains the major exploited ore in Cho Dien. There are numerous studies of Pb-Zn ore in Cho Dien. However, most of the studies have dedicated only to description of mineralogical and chemical composition of Pb-Zn ore. There has been no publication on this non-sulfide zinc ore. Based on the mineralogical studies, the content of Pb and Zn in groundwater determined by reflective microscope, SEM, EPMA and ICP-MS methods, the study explained the formation of secondary non-sulfide zinc ore in the Cho Dien deposit. Strong weathering process makes the upper part of ore bodies completely oxidized. Difference in geochemical behavior of lead (Pb) and zinc (Zn) in the oxidation process of Pb-Zn ore is the reason to form non-sulfide zinc ore in the Cho Dien deposit. Oxidation of primary Pb-Zn ore is mainly sphalerite, pyrite, galena minerals which creates a low pH environment and transforms of zinc from immobile (sphalerite - ZnS) to mobile (Zn2+) and retained in solution under acid pH conditions whereas lead has the tendency to form soluble minerals (anglesite, cerussite). The acid neutralization actions of the surrounding rocks make zinc precipitate, to form secondary non-sulfide zinc minerals.ReferencesAndreas Nuspl, 2009. Genesis of nonsulfide zinc deposits and their future utilization (www.geo.tu-frei berg.de/oberseminar/OS_09/Andreas_Nuspl.pdf.Boland M.B., et al., 2003. The Shaimerden supergene zinc deposit, Kazakhstan: Economic Geology, 98(4), 787-795.Chau N.D., Jadwiga P., Adam P., D.V. Hao, L.K. Phon, J. Paweł, 2017. General characteristics of rare earth and radioactive elements in Dong Pao deposit, Lai Chau, Vietnam, Vietnam J. Earth Sci., 39(1), 14-26.Dao Thai Bac, 2012. Characteristics and distribution law of lead-zinc metallogenic fomations in Viet Bac region. Doctoral thesis.Heyl A.V., Bozion C.N., 1962. Oxidized zinc deposits of the United States, Part 1. General Geology: U.S. Geological Survey Bulletin 1135-A.Hoa T.T., et al., 2010. By-products in lead-zinc and copper ores of Northeast Vietnam. J. Sci. of the Earth, 289-298 (in Vietnamese).Hoang Minh Thao, Tran Thi Hien, Dao Duy Anh, Pham Thi Nga, 2017. Mineralogical characteristics of graphite ore from Bao Ha deposit, Lao Cai Province and proposing a wise use. Vietnam J. Earth Sci., 39(4), 324-336.Jurjovec J., et al., 2002. Acid neutralization mechanisms and metal release in mine tailings: A laboratory column experiment: Geochimica et Cosmochimica Acta, 66, 1511-1523.Large D., 2001. The geology of non-sulphide zinc Deposits - an Overview: Erzmetall, 54(5), 264-276.Maria Boni, 2003. Nonsulfide Zinc Deposits: a new - (old) type of economic mineralization. Society for geology applied to mineral deposits (SGA) News, Number 15. https://www.e-sga.org/fileadmin/sga/newsletter/news15/art01.html.McPhail D.C., et al., 2003, The geochemistry and mobility of zinc in the regolith: in Roach, I.C., ed., Advances in Regolith, 287-291.Murray W. Hitzman, et al., 2003. Classification, genesis, and exploration guides for non-sulfide zinc deposits: Economic Geology, 98(4), 685-714.Nguyen V.P., 2013. Wet tropical wethering in Viet Nam. Natural Science and Technology Publisher.Nicola Mondillo, 2013. Supergene Nonsulfide Zinc-Lead Deposits: The Examples of Jabali (Yemen) and Yanque (Peru). Doctoral thesis.Nordstrom D.K., Alpers C.N., 1999. Geochemistry of acid mine waste. Review in Economic Geology, the environmental geochemistry of ore deposits/Eds. G.S.Plumlee, M.J. Logsdon. Part A: Processes, techniques, and health issues, 6A, 133-160.Reynolds N.A., et al., 2003. The Padaeng Supergene Nonsulfide Zinc Deposit, Mae Sod, Thailand. Economic Geology, 98(4), 773-785.Sangameshwar S.R., Barnes H.L., 1983. Supergene Processes in Zinc-Lead-Silver Sulfide Ores in Carbonates: Economic Geology, 78, 1379-1397.Stumm W., Morgan J.J., 1996. Aquatic Chemistry, Third Edition. John Wiley &amp; Sons, New York, NY.Takahashi T., 1960. Supergene alteration of zinc and lead deposits in limestone: Economic Geology, 55, 1083-1115.Thornber M.R. and Taylor G.F., 1992. The mechanisms of sulphide oxidation and gossan formation, in: Butt, C.R.M., and Zeegers H., (Eds.)., Regolith exploration geochemistry in tropical and subtropical terrains, in Govett G.J.S., ed., Handbook of exploration geochemistry: Amsterdam, Elsevier, 4, 119-138.Tran Trong Hoa, 2005. Potential assessment of By- products in lead-zinc and copper deposits of Northeast Vietnam. Final report.Tran Tuan Anh, 2010. Studying accompanying component in the types of potential deposits of basic metals and precious - rare metals of north Viet Nam to improve the efficiency of mining and environmental protection. Final report. KC.08.24/06-10.Tran Tuan Anh, et al., 2011. Mineralogical and geochemical characteristics and forming conditions of lead - zinc deposits in Lo Gam structure, northern Vietnam. J. Sci. of the Earth, 33(3DB), 393-408 ( in Vietnamese).Vito Coppola et al., 2009. Nonsulfide zinc deposits in the Silesia - Cracow district, Southern Poland. Springer Link, 44, 559-580.Vito Coppola, et al., 2007. Non-sulfide zinc deposits in Upper Silesia, Southern Poland. Proceeding of the Ninth Biennial SGA Meeting, Dublin, 1401-1404.Williams P.A., 1990. Oxide zone geochemistry: Ellis Horwood Ltd., Chichester, UK, 286p.

Novel Microbial Assemblages Dominate Weathered Sulfide-Bearing Rock from Copper-Nickel Deposits in the Duluth Complex, Minnesota, USA.

The Duluth Complex in northeastern Minnesota hosts economically significant deposits of copper, nickel, and platinum group elements (PGEs). The primary sulfide mineralogy of these deposits includes the minerals pyrrhotite, chalcopyrite, pentlandite, and cubanite, and weathering experiments show that most sulfide-bearing rock from the Duluth Complex generates moderately acidic leachate (pH 4 to 6). Microorganisms are important catalysts for metal sulfide oxidation and could influence the quality of water from mines in the Duluth Complex. Nevertheless, compared with that of extremely acidic environments, much less is known about the microbial ecology of moderately acidic sulfide-bearing mine waste, and so existing information may have little relevance to those microorganisms catalyzing oxidation reactions in the Duluth Complex. Here, we characterized the microbial communities in decade-long weathering experiments (kinetic tests) conducted on crushed rock and tailings from the Duluth Complex. Analyses of 16S rRNA genes and transcripts showed that differences among microbial communities correspond to pH, rock type, and experimental treatment. Moreover, microbial communities from the weathered Duluth Complex rock were dominated by taxa that are not typically associated with acidic mine waste. The most abundant operational taxonomic units (OTUs) were from the genera Meiothermus and Sulfuriferula, as well as from diverse clades of uncultivated Chloroflexi, Acidobacteria, and Betaproteobacteria Specific taxa, including putative sulfur-oxidizing Sulfuriferula spp., appeared to be primarily associated with Duluth Complex rock, but not pyrite-bearing rocks subjected to the same experimental treatment. We discuss the implications of these results for the microbial ecology of moderately acidic mine waste with low sulfide content, as well as for kinetic testing of mine waste.IMPORTANCE Economic sulfide mineral deposits in the Duluth Complex may represent the largest undeveloped source of copper and nickel on Earth. Microorganisms are important catalysts for sulfide mineral oxidation, and research on extreme acidophiles has improved our ability to manage and remediate mine wastes. We found that the microbial assemblages associated with weathered rock from the Duluth Complex are dominated by organisms not widely associated with mine waste or mining-impacted environments, and we describe geochemical and experimental influences on community composition. This report will be a useful foundation for understanding the microbial biogeochemistry of moderately acidic mine waste from these and similar deposits.

Assessment of heavy metal pollution in abandoned Giap Lai pyrite mine (Phu Tho Province)

Giap Lai pyrite mine had been exploited in the period 1975 - 1999, and abandoned after the mine became closed. This work is conducted with the aim to evaluate the impacts of the abandoned mine to the environment. 23 surface water, 15 ground water and 20 soil samples from the mining area were collected for experiments. Acid production potential and metal leaching of waste materials from tailings were tested. Results show that acid rock drainage (ARD) in the old mining area still occurs, with sulfide-rich tailings and waste rocks being sources of ARD, causing elevated metal concentrations in downstream water bodies. Surface water shows significant pollution of Fe, Mn, Ni and partially As. In the rainy season, the percentage of surface water samples having low pH values as well as metal contents in samples is higher than in the dry season. Metal concentrations in ground water are generally low, but many samples have low pH values, indicating the influence of the ARD. The geo-accumulation index reveals that soil from mining area is moderately contaminated with Ni, Cu, Hg and partially As. Most of the polluted samples are located near old mining pits, waste dumps and tailing ponds. The study also shows that negative effect of Giap Lai pyrite mine on the surrounding water and soil has been ongoing. However, no post-closure remediation measures have been applied at the mine, so there must be appropriate solutions for the acid mine drainage treatment before its being discharged to the environment. Given the facts revealed by this study, it is recommended that the Environmental Protection Law should be fully implemented at mining sites not only during the exploitation but also after their closures.References AMIRA, 2002. ARD Test Handbook. Project P387A Prediction &amp; Kinetic Control of Acid Mine Drainage. AMIRA international May 2002, 42p. Çevik, F., Göksu, M. Z. L., Derici, O. B., Fındık, Ö., 2009. An assessment of metal pollution in surface sediments of Seyhan dam by using enrichment factor, geoaccumulation index and statistical analyses. Environmental Monitoring and Assessment 152, 309-317. EPA, 2000. Abandoned mine site characterization and cleanup hand book, 129p, (https://yosemite.epa.gov/r10/amscch.pdf). Ghrefat, H.A., Abu-Rukah, Y., Rosen, M.A., 2011. Application of geoaccumulation index and enrichment factor for assessing metal contamination in the sediments of Kafrain Dam, Jordan. Environmental Monitoring and Assessment 178, 95-109. IAEA, 2000. Reference Sheet, reference material. Trace elements in soil. (https://nucleus.iaea.org/rpst/Documents/rs_iaea-soil-7.pdf). INAP, 2009. Global Acid Rock Drainage Guide. International Network for Acid Prevention. (http://www.gardguide.com/index.php/Main_Page). Loska, K., Wiechula, D., Korus, I. 2004. Metal contamination of farming soils affected by industry. Environment International, 30(2), 159-165. MCMPR/MCA, 2010. Strategic Framework for Managing Abandoned Mines in the Minerals Industry, http://www.industry.gov.au/resource/Mining/Documents/StrategicFrameworkforManagingAbandonedMines.pdf. Mhlongo, S.E. and Amponsah-Dacosta, F., 2015. A review of problems and solutions of abandoned mines in South Africa, International Journal of Mining, Reclamation and Environment, DOI: 10.1080/17480930.2015.1044046. Müller, G., 1969. Index of geoaccumulation in sediments of the Rhine River. Geojournal 2, 108-118. Newton, G., et al, 2000. California’s Abandoned Mines. A Report on the Magnitude and Scope of the Issue in the State, Vol.1, 60p. Http://www.conservation.ca.gov/omr/abandoned_mine_lands/AML_Report/Documents/volume1textonly.pdf Nordstrom, D.K., Alpers, C.N., 1999. Geochemistry of acid mine waste. In “Review in Economic Geology, the environmental geochemistry of ore deposits”/Eds. G.S.Plumlee, M.J. Logsdon. Part A: Processes, techniques, and health issues Vol.6A, 133-160. Nowrouzi, M. and Pourkhabbaz, A., 2014. Application of geoaccumulation index and enrichment factor for assessing metal contamination in the sediments of Hara Biosphere Reserve, Iran. Chemical Speciation and Bioavailability, 26(2),99-105. Pham Tich Xuan, Nguyen Van Pho, Hoang Tuyet Nga, Doan Thi Thu Tra, Cai Van Truong, Nguyen Van Thu, Vu Manh Long, 2010. Heavy metal pollution in some metal mines in the Northern Vietnam. Procceding of Conference in commemoration of the 35th day of Establish of VAST. Environment and Energy, Hanoi, 236-244 (in Vietnamese with English abstract). Sobek, A.A., Schuller, W.A., Freeman, J.R. and Smith, R.M., 1978. Field and laboratory methods applicable to overburden and minesoils. Report EPA 600/2-78-054, US Environmental Protection Agency, 204p. Tarras-Wahlberg N.H, Lan T. Nguyen, 2008. Environmental regulatory failure and metal contamination at the Giap Lai pyrite mine, Northern Vietnam. Journal of Environmental Management, 86(4), 712-720. Tran Xuan Toan, 1963. Some characteristics of pyrite mineralization in the Giap Lai deposit, Phu Thọ. Geology 10, 18-24, Hanoi (in Vietnamese). Wei, Z., Wang, D., Zhou, H., Qi, Z., 2011. Assessment of Soil Heavy Metal Pollution with Principal Component Analysis and Geoaccumulation Index. Procedia Environmental Sciences, 10, 1946 -1952. Zawadzki, J and P. Fabijan´czyk, P., 2013. Geostatistical evaluation of lead and zinc concentration in soils of an old mining area with complex land management. Int. J. Environ. Sci. Technol. 10, 729-742. Ziemkiewicz, P., J. Renton and T. Rymer, 1991. Prediction and Control of Acid Mine Drainage: Effect of Rock Type and Amendment. Proceedings Twelfth Annual West Virginia Surface Mine Drainage Task Force Symposium, April 3-4, Morgantown, West Virginia, Vol.1, 51-54.

Mapping acidic mine waste with seasonal airborne hyperspectral imagery at varying spatial scales

Airborne imaging spectrometer (also known as hyperspectral) remote sensing has been widely used to characterize mineralogy on mine waste surfaces, which is useful for predicting potential sources of acidity and metal leaching. The most successful applications employ fine spatial resolution—20-m pixels or smaller. Future satellite imaging spectrometer sensors are proposed to provide coarser spatial resolution—30- to 60-m pixels. This study examined the ability to map minerals related to acid mine drainage with visible to shortwave infrared hyperspectral imagery at varying spatial scales (2-, 15-, 30-, 60-m pixels) at the Leviathan mine Superfund site, located in the Eastern Sierra Nevada. Mineral maps were produced using spectral angle mapper and matched filtering algorithms. The 15-m images provided comparable maps to the 2-m images. The 30- and 60-m images lost the ability to identify smaller features; however, they were still able to identify high- and low-priority remediation zones at least 75 m in width. Based on our results, we believe 30-m spatial resolution on a satellite hyperspectral sensor will be sufficient for identifying hazardous surfaces at larger mine waste sites and provide important reconnaissance information that can help prioritize detailed ground-based studies.