Bernd G. Lottermoser

Ephemeral acid mine drainage at the Montalbion silver mine, north Queensland

Sulfide‐rich materials comprising the waste at the abandoned Montalbion silver mine have undergone extensive oxidation prior to and after mining. Weathering has led to the development of an abundant and varied secondary mineral assemblage throughout the waste material. Post‐mining minerals are dominantly metal and/or alkali (hydrous) sulfates, and generally occur as earthy encrustations or floury dustings on the surface of other mineral grains. The variable solubility of these efflorescences combined with the irregular rainfall controls the chemistry of seepage waters emanating from the waste dumps. Irregular rainfall events dissolve the soluble efflorescences that have built up during dry periods, resulting in ‘first‐flush’ acid (pH 2.6–3.8) waters with elevated sulfate, Fe, Cu and Zn contents. Less‐soluble efflorescences, such as anglesite and plumbojarosite, retain Pb in the waste dump. Metal‐rich (Al, Cd, Co, Cu, Fe, Mn, Ni, Zn) acid mine drainage waters enter the local creek system. Oxygenation and hydrolysis of Fe lead to the formation of Fe‐rich precipitates (schwertmannite, goethite, amorphous Fe compounds) that, through adsorption and coprecipitation, preferentially incorporate As, Sb and In. Furthermore, during dry periods, evaporative precipitation of hydrous alkali and metal sulfate efflorescences occurs on the perimeter of stagnant pools. Flushing of the streambed by neutral pH waters during heavy rainfall events dissolves the efflorescences resulting in remobilisation and transport of sulfate and metals (particularly Cd, Zn) downstream. Thus, in areas of seasonal or irregular rainfall, secondary efflorescent minerals present in waste materials or drainage channels have an important influence on the chemistry of surface waters.

Mobilization of heavy metals from historical smelting slag dumps, north Queensland, Australia

Abstract Slag dumps occur at several historical smelting sites in north Queensland, Australia. The microcrystalline slags contain primary slag phases, relict flux, ore and furnace materials and secondary weathering related minerals. Common primary slag phases are glass, Zn-rich fayalite (± Zn-rich kirschsteinite) and Zn-rich hedenbergite. Other minor minerals include wollastonite, Zn-rich melilite, Zn-rich iscorite (Fe7SiO10), magnetite as well as a number of sulphides (pyrrhotite, galena, bornite, sphalerite, wurtzite), metallic phases (Ag, Cu, Pb, Sb), alloys (Cu3Sn), and unknown metal compounds. The slag materials contain wt.% concentrations of Zn and elevated levels of Ag, As, Cd, Cu, Ni, Pb, Sb and W. Glass, hedenbergite and fayalite/kirschsteinite are the main repositories of Zn, whereas much of the Cu and Pb is hosted by glass, sulphides, Cu3Sn alloys, metallic Cu and Pb, and unknown CuSb, AsSnPb and FeAsCu compounds. The slags are undergoing contemporaneous reaction with air and rainwater. The weathering results in the release of metals and metalloids from primary slag phases, particularly from glass, and the partial immobilization of these metals in secondary soluble and insoluble minerals in the slag heaps. Zinc exhibits pronounced chemical mobility and reports together with elevated Ca and sulphate into surface seepages (up to 10.2 mg l−1 Zn at pH 6.97). The slag dumps represent long-term sources of metal pollutants, particularly of Zn, to local ground and surface waters.

Geochemistry, petrology and origin of Neoproterozoic ironstones in the eastern part of the Adelaide Geosyncline, South Australia

The eastern part of the Adelaide Geosyncline contains well preserved glaciomarine sequences of the Sturtian glaciation (:750‐700 Ma) including calcareous or dolomitic siltstone, manganiferous siltstone, dolostone and diamictite units and the associated Braemar ironstone facies. The ironstone facies occurs as matrix to diamictites and as massive to laminated ironstones and comprises abundant Fe oxides (hematite, magnetite) and quartz, minor silicates (muscovite, chlorite, biotite, plagioclase, tourmaline), carbonate and apatite, and detrital mineral grains and lithic clasts. Micro-textures indicate that magnetite and hematite are of metamorphic origin. They are intergrown with silicates and carbonates, with the mineral assemblage indicative of greenschist facies (biotite grade) metamorphism. Chemical compositions of ironstones vary greatly and reflect changes from silica-, alumina-poor ironstones formed by predominantly chemical precipitation processes to silica-, alumina-rich examples with a significant detrital component. Silica-, alumina-poor ironstones are characterised by low concentrations of transition metals and large ion lithophile and high field strength elements and display REE signatures of modern coastal seawater. The Braemar facies accumulated in a marine basin along the border of a continental glaciated highland and a low-lying weathered landmass. Wet-based glaciers originated from the Palaeoproterozoic to Mesoproterozoic metamorphic basement and debouched into a fault-controlled depocentre, the Baratta Trough. The intimate association of dolostones, manganiferous siltstones, ironstones and diamictites can be explained by a transgressive event during a postglacial period. Hydrothermal exhalations added significant amounts of Fe and other metals to Neoproterozoic seawater. Melting of floating ice led to an influx of clastic detritus and deposition of glaciomarine sediments from wet-based glaciers and to oxygenation of ferriferous (9manganiferous), carbonate and CO2 charged coastal waters. Release of CO2 to the atmosphere from the oxygenated waters resulted in the precipitation of carbonate as dolostones and oxygenation of ferriferous (9manganiferous) waters led to the precipitation of Fe 3 oxides as laminated ironstones and as matrix of diamictic ironstones. Further increases in Eh conditions led to the precipitation of Mn oxides or carbonates and their incorporation in clastic sediments. Thus the Braemar ironstone facies is the result of chemical precipitation of dissolved Fe (and Mn) during a postglacial, transgressive period and formed in a near-coastal environment under

Fertilizer-Derived Uranium and its Threat to Human Health

P fertilization remains the main source of uranium contamination of agricultural land, primarily due to impurities in the phosphate rock used for fertilizer manufacture. In particular, long-term application of uranium-bearing fertilizers can significantly elevate the uranium concentration in fertilized soils. The magnitude of uranium enrichment of cultivated soils varies, depending on phosphate fertilizer application rate, uranium content of applied fertilizer, soil type and prevailing climate. In Germany, the use of phosphate fertilizer from 1951 to 2011 has resulted in a cumulative application of approximately 14 000 t of uranium on agricultural land, corresponding to an average cumulative loading of 1 kg of uranium per hectare. Fertilizer-derived uranium in soils is prone to leaching because uranium is mobile in surface soils as uranyl complex depending on prevailing pH and Eh conditions. Alternatively, uranium can be immobilized in subsurface materials by sorption or coprecipitation mechanisms. The fate of uranium in soil and subsurface environment is therefore influenced by a delicate balance of U association between immobile and mobile phases. Yet, uranium is highly soluble as uranyl (U) complex under oxidizing conditions. Consequently, mobility of fertilizerderived uranium from agricultural soils into ground and surface waters has been recognized in agricultural catchments and, numerous studies have established the transfer of fertilizerderived uranium from soils into ground, surface and marine coastal waters. For example in Germany, rivers and streams of agricultural catchments have 10 times higher uranium concentrations (0.08 versus 0.8 μg/L U) than those dominated by forestry. Significantly enriched uranium concentrations (>2 μg/L U) were detected in heavily cultivated catchments. Moreover, unconfined aquifers below agricultural land, groundwater has 3 to 17 times higher uranium concentrations than that below forested regions. Generally, there is a concurrent and strong correlation of dissolved uranium concentrations in groundwater with those of other highly mobile and fertilizerderived elements such as boron, magnesium, and potassium as well as nitrate. The likely reason for the strong uranium-nitrate correlation in groundwater could be due to (a) increased fertilization of agricultural land using NP and NPK fertilizers; (b) significant mobility of fertilizer-derived uranium as uranylcarbonate complex and transfer into the underlying aquifer; and (c) pronounced solubility of uranium as uranyl−nitrate complex into groundwater. In northern Germany, unmineralized groundwater used as drinking water supply contains variable uranium contents, with one-quarter to two-thirds likely impacted by fertilizer-derived uranium. Thus, agricultural soils and nearby land and water resources are becoming increasingly contaminated by uranium due to fertilizer use. Fertilizer-derived uranium has entered German drinking water supplies. Principal route of exposure of humans to uranium occurs via ingestion, skin contact, and inhalation. In particular, naturally mineralized groundwaters and bottled mineral waters can contribute significantly to uranium uptake. In Germany, more than 2 million people currently receive drinking water that contains >10 μg/L uranium. Here, a carnivore with a skewed taste for offal, shellfish, and bottled mineral water can achieve the highest uranium uptake. A considerable body of evidence suggests that overexposure to uranium in drinking water may cause significant health effects in both humans and animals. Reported health effects of uranium derive from experimental animal studies and human epidemiology. Uranium may damage biological systems through its chemical toxicity as well as its radioactivity, with the chemical toxicity perceived as the primary health hazard and the effects from uranium’s ionizing radiation being of secondary concern. The main health concerns with respect to uranium are renal, developmental, reproductive, diminished bone growth, as well as DNA and brain damage. In humans uranium is particularly known for its nephrotoxic nature, with short-term and long-term exposure to uranium through drinking water leading to renal effects. The information available on the chronic health effects caused by the exposure to uranium in drinking water points to the fact that regions with elevated groundwater uranium concentrations and more groundwater use have an increased incidence of certain diseases. For example, increasing incidence in chronic kidney disease in Sri Lankan nationals has been related to the low-level fertilizer-

Evaporative mineral precipitates from a historical smelting slag dump, Río Tinto, Spain

This work reports the chemistry and mineralogy of mineral efflorescences associated with slag deposits at the historical Rio Tinto smelter site, southwest Spain. The slags have been subject to weathering since dumping in the 19 th and 20 th century, and a series of evaporative mineral efflorescences has been observed. The efflorescences commonly occur as powdery or cemented salt precipitates at seepage points at the base of the slag dump and as solid aggregates in protected overhangs facing the Tinto river. The mineral salt types include Ca and Mg sulfates (gypsum, epsomite, hexahydrite, bloedite) as well as mixed Fe2+ – Fe3+ hydrated sulfates (copiapite, roemerite). The salt mixtures have variable metal concentrations, including major (> 1 wt %) concentrations of Zn, minor Cu (> 1000 ppm), sub-minor (100–1000 ppm) to traces (< 100 ppm) of As and Co as well as traces (< 100 ppm) of Ag, Bi, Cd, Mo, Ni, Pb, Sb, Sn, Tl and W. Copiapite-rich samples exhibit the highest As, Cd and Cu, epsomite–hexahydrite rich samples have the highest Zn, and the gypsum-rich samples show the lowest metal and metalloid concentrations. Dissolution experiments show that all salt mixtures are acid generating due to Fe and Al hydrolysis and resultant pH decrease in the solution. Thus, weathering and leaching of metalliferous smelting slags are accompanied by the mobilisation of metals, metalloids, alkali earth elements and sulfate into pore and seepage waters. Evaporation of seepage waters emanating from the slag dump causes the precipitation of mobilised elements and compounds and leads to their temporary fixation in secondary soluble minerals. Dissolution of the efflorescences during the next rainfall and flushing event and associated Al3+ and Fe3+ hydrolysis contribute to the acidification and metal and sulfate contamination of Rio Tinto waters.

MAGHEMITE FORMATION IN BURNT PLANT LITTER AT EAST TRINITY, NORTH QUEENSLAND, AUSTRALIA

Evidence for the formation of maghemite from goethite due to a bushfire on acid sulfate soil at East Trinity, Australia, is presented. Oxidation of pyrite-bearing acid sulfate soils led to precipitation of goethite-impregnated leaf litter. During a major bushfire, goethite with a crystal size calculated from broadening of the 110 reflection of ∼9 nm was converted to microcrystalline maghemite (size 12 nm, 220 reflection) and hematite (17 nm, 104 reflection) in a matrix of partly combusted plant litter. Replication of this natural formation of maghemite from goethite was achieved in the laboratory by burning goethite-impregnated leaf litter.

Physical dispersion of radioactive mine waste at the rehabilitated Radium Hill uranium mine site, South Australia

The Radium Hill uranium deposit, in semiarid eastern South Australia, was discovered in 1906 and mined for radium between 1906 and 1931 and for uranium between 1954 and 1961 (production of 969 300 t of davidite ore averaging 0.12% U3O8). Rehabilitation was limited to removal of mine facilities, sealing of underground workings and capping of selected waste repositories. In 2002, gamma-ray data and samples of tailings, uncrushed and crushed waste rock, stream sediment, topsoil and vegetation were collected to assist in examining the current environmental status of the mine site. The data indicate that capping of tailings storage facilities did not ensure the long-term containment of the low-level radioactive wastes due to the erosion of sides of the impoundments. Moreover, wind erosion of waste fines (phyllosilicates, ore minerals) from various, physically unstable waste repositories has caused increasing radiochemical (from a background dose of 35 – 70 nSv/h to max. 0.94 μSv/h) and geochemical (Ce, Cr, La, Lu, Rb, Sc, Th, U, V, Y, Yb) impacts on local soils. Plants (saltbush, pepper tree) growing on waste dumps display evidence of biological uptake of lithophile elements, with values being up to 1 – 2 orders of magnitude above values for plants of the same species at background sites. However, radiation doses associated with the mine and processing site average 0.67 μSv/h; hence, visitors to the Radium Hill site will not be exposed to excessive radiation levels. Although rehabilitation procedures have been partly successful in reducing dispersion of U and related elements into the surrounding environment, it is apparent that 20 years after rehabilitation, there is significant physical and limited chemical mobility, including transfer into plants. Additional capping and landform design of the crushed waste and tailings repositories are required in order to minimise erosion and impacts on surrounding soils and sediments.

Phosphate stabilization of polyminerallic mine wastes

Abstract Polyminerallic, sulphidic mine wastes were treated with KH2PO4-H2O2 solutions to determine whether the formation of solid phosphate coatings inhibits sulphide oxidation and metal and metalloid mobility. The waste rocks were metal (PbZnCu) and metalloid (AsSb) rich and consisted of major quartz, dickite, illite and sulphide minerals (e.g. galena, chalcopyrite, tetrahedrite, sphalerite, pyrite, arsenopyrite) as well as minor to trace amounts of pre- and post-mining oxidation products (e.g. oxides, hydroxides, arsenates and sulphates). Scanning electron microscopy observations of the waste material treated with KH2PO4-H2O2 solutions showed that metal, metal-alkali and alkali phosphate precipitates formed and coatings developed on all sulphides (with the exception of tetrahedrite). The abundance of phosphate phases was dependant on the availability of metal and alkali cations in solution. In turn, the release of cations was dependent on the amount of sulphide oxidation induced during the experiment or the presence of soluble oxidation products. Lead and to a lesser degree Cu and Zn phosphate coatings remained stable during H2O2 leaching, preventing acid generation and metal release. In contrast, the lack of phosphate coating on tetrahedrite and arsenopyrite allowed oxidation and leaching of As and Sb to proceed and mobilized As and Sb did not form phosphate phases. As a result, As and Sb displayed the greatest release from the coated waste. Thus, the application of KH2PO4-H2O2 solutions to partly oxidized, polyminerallic mine wastes suppresses sulphide oxidation and is most effective in inhibiting Pb (Cu and Zn) release. However, the technique appears ineffective in preventing metalloid (As, Sb) leaching from tetrahedrite- and arsenopyrite-bearing wastes.

Petrogenesis of rare-element pegmatites in the Olary Block, South Australia, part 1. Mineralogy and chemical evolution

SummaryRare-element pegmatites within the Proterozoic Olary Block are of the berylcolumbite-phosphate type and probably related to the crystallisation of syn- to posttectonic peraluminous, S-type granitoids. The pegmatites are typically zoned and possess an inner quartz core, or a series of cores, an asymmetrical intermediate zone of coarse-grained muscovite, quartz, microcline and minor plagioclase, and an outer border zone of fine- to medium-grained microcline, quartz, plagioclase and muscovite. The zones contain abundant beryl and F-apatite, with additional species such as tourmaline, ferrocolumbite, samarskite, Nb-rutile and triplite-zwieselite nodules. These rare-element minerals occur preferentially at the contact between the intermediate zone and the quartz core. Hydrothermal alteration of triplite-zwieselite led to the development of secondary, microcrystalline bermanite, leucophosphite and phosphoferrite-kryzhanovskite. Paragenetic relationships of these phosphates suggest a sequence of hydrothermal transformations in an oxidising, low-temperature environment (< 250°C). A prominent feature of this succession is the decrease in Mg and Ca, and an increase in Fe3+/Fe2+, Mn3+/Mn2+, and H2O. High aHF, low pH and Al mobility occurred during the development of the secondary phosphates as shown by associated fluorite, sellaite and thomsenolite/pachnolite. Increasing Ca activities at a late hydrothermal stage led to the replacement of prexisting triplitezwieselite by additional F-apatite. Finally, weathering-related cyrilovite, lipscombite and crandallite-group minerals were formed by percolating meteoric waters under increasing fo2ZusammenfassungSeltenelementpegmatite im Proterozoischen Olary Block sind vom Beryl-Columbit-Phosphat Typ und stehen wahrscheinlich mit der Kristallisation von syn- bis spättektonischen, peraluminen, S-Typ Graniten in Verbindung. Die Pegmatite sind zoniert und besitzen einen inneren Quarzkern, oder eine Reihe von Kernen, eine asymmetrische Zwischenzone aus grobkörnigem Muskovit, Quarz, Mikroklin und Plagioklas, und eine äussere Randzone aus fein- bis mittelkörnigem Mikroklin, Quarz, Plagioklas und Muskovit. Die Zonen enthalten häufig Beryll, Fluorapatit, Turmalin, Ferrocolumbit, Samarskit, Niobrutil und Triplit-Zwieselit Nester. Diese Seltenelement Minerale finden sich überweigend am Kontakt der Zwischenzone und dem Quarzkern. Hydrothermale Alteration des Triplit-Zwieselit führte zu der Bildung von sekundärem, mikrokristallinen Bermanit, Leukophosphit und Phosphoferrit-Kryzhanovskit. Paragenetische Beziehungen dieser Phosphate weisen auf eine Abfolge von hydrothermalen Umwandlungen in einem oxidierenden, niedrig-Temperatur Milieu hin. Ein wesentlicher Bestandteil dieser Abfolge ist eine Abnahme von Mg und Ca und eine Zunahme von Fe3+/Fe2+, Mn3+/Mn2+ und H2O. Die Assoziation mit Fluorit, Sellait und Thomsenolit/Pachnolit zeigt hohen aHF, geringen pH and Al Mobilität während der Bildung der sekundären Phosphate an. Während des hydrothermalen Endstadiums führten erhöhte Ca Aktivitäten zu der Verdrängung von bereits vorhandenem TriplitZwieselit durch zusätzlichen Fluorapatit. Schliesslich wurden während der Verwitterung Cyrilovit, Lipscombit und Crandallit-Minerale durch meteorische Wässer unter erhöhtem fO2 gebildet.

Exposure Assessment of Naturally Metal Enriched Topsoils, Port Macquarie, Australia

An exposure assessment was conducted on naturally metal enriched topsoils of the city of Port Macquarie in order to establish whether the soils pose any threat to human health. Surface soils (0–10 cm depth, <2 mm) were investigated for their total, bioavailable and leachable Cr and Ni concentrations. Total metal concentrations ranged from 145 to 4540 mg Cr kg−1 and 20 to 2030 mg Ni kg−1, whereas soil extractions revealed low leachable contaminant concentrations (EDTA extraction: <0.1–0.2 mg Cr L−1 and <0.1–4.7 mg Ni L−1; acetic acid extraction: <0.1 mg L−1 Cr and Ni). Thus the bioavailability of Cr and Ni to plants is low, the leaching of metals into ground and surface waters is insignificant and the pathways of these metal pollutants from topsoils into residents are limited to the inadvertent ingestion, inhalation and skin adsorption of soil metals. Simulated gastric experiments, using hydrochloric acid, indicated that less than 0.01% of the total Cr and 0.1–2.4% of the total Ni ingested are soluble and available, for uptake into the human body. Critical receptors, such as small children would have to ingest considerable soil quantities (> 11.8 g per day) over long periods of time to experience an appreciable risk of deleterious effects. Thus, although Cr and Ni are present in high concentrations, the effective uptake of Cr and Ni from soil by the majority of residents is insignificant. The possibility that the Ni enriched topsoil induces allergic contact dermatitis in sensitised individuals remains to be evaluated.