This review details a selection of occupational lung diseases, particularly fibrosis (scarring) and tumours that can arise following exposure to mineral dusts. Also described are the sequential repair processes of the lung including oedema, inflammation, epithelial changes and finally scarring. The features by which a dust can be considered bioreactive including shape, size, surface area, durability and surface chemistry is discussed together with the importance of the mass deposited in the lung and particle clearance, particularly through lymphatic drainage. Emphasis is given to the importance of surface chemistry in that crystalline minerals, especially silicas, are often highly bioreactive whereas amorphous silicas or crystalline forms that have aged in the laboratory have lesser activity. Nevertheless, all forms of crystalline silica are particularly hazardous with the long-term ability to produce irreversible disease (fibrosis) when administered to experimental animals.

Experiments were undertaken to determine the toxicity in the lung of dust generated by opencast coal mining. Since it was impractical to collect the large mass of actual opencast respirable dust required for the toxicity experiment, a surrogate dust with the same size distribution was manufactured (PSW). This surrogate dust had the same basic mineralogical composition as mineralogically characterized airborne dust collected from the welsh coal opencast pit at Park Slip West. Diesel exhaust particles (DEP), generated from mining vehicular and mechanical activity, contribute towards opencast particulate matter. Therefore, a second dust comprising of a 50/50 by weight mixture of the surrogate mineral dust and diesel soot was also examined (PSW + DEP). These dusts and DEP (weak biological reactivity) and a-quartz (high biological reactivity) were instilled into the lungs of healthy rats. The animals were sacrificed at 1, 6 and 11 weeks. Assessments of potential toxicity included lung to body weight ratios, acellular protein in lung lavage (markers of lung permeability) and total free cells (marker of inflammation). The surrogate opencast dust with or without DEP caused no significant increases in any of the parameters studied and as such was very similar to the weak biological effects of DEP alone. These effects contrasted sharply with those observed for the bioreactive mineral, quartz that induced rapid increases in permeability and a progressive inflammation. The use of a surrogate is less desirable then the real opencast mine dust, however, if as believed, the surrogate material is a representative mixture of the actual airborne dust around this opencast site, then these particles should show little or no short-term lung toxicity following inhalation.

Airborne dust generated by primary blasting was collected in Taffs Well Quarry, just north of Cardiff, Wales. Collections of airborne particulate matter were also made in the nearby village of Morganstown at the same time as the blasting collections. The explosions were recorded on a motor-driven camera and a digital video camera. These images show that the dust clouds generated by the explosions consist of three distinct components; a reddish-grey dust cloud, followed by a light grey dust cloud, and finally a pale grey cloud that stayed near the blast face. It is believed that the reddish-grey cloud was composed mostly of mineral grains, as evidenced by the chiefly red colour of the dolomitic limestone rock in the quarry. The whiter clouds contained more explosive combustion particles (diesel soot). The samples were studied by analytical scanning electron microscopy, very high-resolution field emission scanning electron microscopy, and image analysis. The two different components (minerals and diesel soot) can be readily seen under high-resolution electron microscopy. Any consideration of the possible adverse health effects or nuisance value of this dust needs to consider both of these components. A size distribution of the quarry particles shows that soot particles dominate the assemblage under 2 mm, whereas the mineral grains are more abundant over 2 mm. This contrasts with the Morganstown particle sizes, where the two components show similar size distributions. The determination of the mineralogy of the quarry dust and Morganstown particles has shown highly complex and heterogeneous mixtures, though some distribution patterns are emerging. It is concluded that much of the dust in Morganstown probably originated from sources other than the quarry, such as other local industries, roads and construction sites.

Work was undertaken in 1997 as part of a UK government programme to monitor air quality in the Cornish china clay area. These studies showed that concentrations of airborne particulate matter with an aerodynamic diameter <10 μm (PM10) did not exceed UK National Air Quality Strategy (NAQS, 1995) guidelines but were, however, greater than those normally associated with rural areas. Subsequently, in the summer of 2000, airborne dust sampling was conducted at three sites around the IMERYS (formerly ECCI) Kernick mica dam, a potential source of resuspended airborne particulates from china clay waste minerals. Analytical scanning electron microscopy examination of the collected material suggested that up to 61% of the airborne PM10 monitored next to the mica dam could be associated with china clay extraction compared with 46% 2 km to the south. Results showed the presence of substantial percentages of respirable kaolinite, muscovite and quartz; the major components of china clay waste. The health effects of the particular mineral dust emissions associated with china clay mining are reviewed.

The PM10 (airborne particulate matter with aerodynamic diameter <10 mm) in Beijing has a distinct seasonality, with industrial, domestic and natural sources providing a heterogeneous cocktail of airborne particulate matter (PM). Collections were made during late winter, summer and high wind dust storms to determine composition and probable sources of this PM. The concentration of the PM during winter (174 μg m–3) was approximately four times higher than summer (37 μg m–3) with dust storms raising the concentration further (200 μg m–3). During the winter the PM was dominated by combustion products (66% filter area). During the summer combustion products and loess contributed ~35% to the filter area each, but during elevated wind speeds (>10 mph) loess completely dominated the collections (96% filter area). The majority of the PM10 collected was in the respirable (PM2.5) size range (winter 99.7%, summer 96.6%, dust storms 82.3%). The loess in Beijing comprises quartz, feldspar, calcite, chlorite and mica and is in the coarse silt to sand (20–60 mm) size range. The collections are therefore likely to be made up of finer silt and clay, primarily derived from of the erosion of cultivated land. Using a plasmid assay, the Beijing particulate matter was found to have little or no surface free radical activity.

The Chernobyl accident in 1986 resulted in the widespread identification of the post-accident presence of radioactive (or ‘hot’) particles across large areas of Eastern and Central Europe. Such particles arise from direct deposition and also from condensation and interactions on particle surfaces during and following the deposition of soluble fallout. Identification of the presence and nature of hot particles is necessary in order to determine the long-term ecological impact of radioactive fallout. This paper describes several techniques for the identification and characterization of hot particles in soil samples from Belarus. In addition to new results from the use of gamma spectrometry, we include two novel instrumentation approaches that have been developed and applied to Chernobyl fallout-contaminated soils. The first, ‘differential’ autoradiography, utilizes a photographic film sandwich to characterize the nature of the ionizing radiation emitted from samples. In this paper we show that differential autoradiography can not only identify hot particle presence in soil, but can also determine the dominant radionuclide in that particle. The second approach, sector field ICP-MS (ICP-SFMS), can provide rapid, high-precision determination of the actinides, including the transuranic actinides, that characteristically occur in hot particles originating from weapons fallout or fuel matrices. Here, ICP-SFMS is shown to yield sufficiently low detection limits for plutonium isotopes (with the exception of 238Pu) to enable us to confirm negligible presence of plutonium in areas outside the Chernobyl exclusion zone, but with high levels of fission-product contamination.

Heavy metal-bearing sediment particles enter river systems by discharge of mine or processing waste, tailings dam failures, remobilization of mining-contaminated alluvium and mine drainage. The mineralogy and geochemistry of these particles is dependent upon the original ore mineralogy, and on processes that have occurred in the source areas, during transport and deposition and during postdepositional early diagenesis. This paper reviews the research carried out to date on the sources, mineralogy, chemistry and fate of heavy metal-bearing particles in mining-affected river systems, and identifies six important avenues for further investigation.

Computer-controlled scanning electron microscopy (CCSEM) has been assessed for the determination of form and size distribution of heavy metals in urban contaminated soils. Metal distributions within individual particles were determined using X-ray element mapping. The sites selected for study were (1) around a landfill site, previously a colliery in Wolverhampton, UK and (2) a private garden adjacent to a railway in Nottingham, UK. Backscattered thresholding techniques were used to isolate the Pb-containing categories. The classification results for both Wolverhampton and Nottingham soils were generally similar but more Pb-containing classes were observed for the Nottingham samples when a comparison was made between results of the same size fractions. However, difficulties with the technique arose when particles showing chemically similar weathering crusts were assigned to the same class, despite having different internal compositions. The CCSEM data therefore need to be interpreted with caution and their application limited to situations in which particle internal complexity is not an issue.

Soil profiles developed in different climates and physical settings are highly variable in structure, in mineralogy, in the local biosphere and in the compositions of the soil gas and water phases. Discussion of metals in ‘the weathering environment’ needs to acknowledge and address this diversity.

The thermochemical methods developed by Pourbaix (1949) and Garrels and Christ (1965) remain useful predictors of metal speciation and solubility but the approach is valid only for processes involving carbonates, sulphides, hydroxides and similar minerals in soils and sediments. Almost no primary silicates are thermodynamically stable: they spontaneously decompose to non-equilibrium solid products with metal release determined by kinetics.

Hydrolysis constants for aquo-complexes are useful indicators of metal speciation, mobility and availability. Recent work on soluble soil organic matter confirms that the active ligands are overwhelmingly oxygen based: phenols, carboxylic acids, alcohols. Many of these molecules compete very effectively with aquo-complexes to form strong metal chelates and appear to be responsible for substantial Al and Fe mobilization within and translocation down soil profiles.

It is important to note also that strong clay mineral/organic matter associations (clay-organic complex) will fix metals as a consequence of the same chelation reactions (in this case removing them from solution - retardation).

Understanding the biogeochemical behaviour of arsenic in the weathering and shallow subsurface environment depends critically upon determining the nature and distribution of the chemical species present in natural waters. To this end, coupled ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) is widely used, though species fractionation during ultrasonic nebulization, and matrix-dependent ionization in the plasma are analytical issues that need to be addressed. Hexapole collision cell technology is shown to be effective in suppressing chloride-based polyatomic interferences. Irrespective of the analytical technique used, As(III)/As(V) ratios of natural waters may change substantially during storage due to (1) differential adsorption of arsenic species on hydrated ferric oxides (HFOs); and (2) microbial activity. A wide range of apparently contradictory speciation changes observed by various workers can be rationalized in terms of the differences of microbial consortia present in different water samples. Arsenic speciation in certain water types can be stabilized for days or even weeks by combined filtration, acidification and refrigeration whilst the addition of EDTA and the use of 0.1 mm filters is indicated for iron-rich waters and waters with high activities of redox-active bacteria, respectively. Although the use of hydrochloric acid has been reported elsewhere as resulting in the apparent oxidation of As(III), we show that for certain water types it acts as an extremely effective preservative of arsenic speciation.

The soluble metal sulphate salts melanterite, rozenite, rhomboclase, szomolnokite, copiapite, coquimbite, hexahydrite and halotrichite, together with gypsum, have been identified, some for the first time, on the banks of the Rio Tinto, SW Spain. Secondary Fe-sulphate minerals can form directly from evaporating, acid, sulphate-rich solutions as a result of pyrite oxidation. Chemical analyses of mixtures of these salt minerals indicate concentrations of Fe (up to 31 wt.%), Mg (up to 4 wt.%), Cu (up to 2 wt.%) and Zn (up to 1 wt.%). These minerals are shown to act as transient storage for metals and can store on average up to 10% (9.5 — 11%) and 22% (20—23%), Zn and Cu respectively, of the total discharge of the Rio Tinto during the summer period.

Melanterite and rozenite precipitates at Rio Tinto are only found in association with very acidic drainage waters (pH <1.0) draining directly from pyritic waste piles. Copiapite precipitates abundantly on the banks of the Rio Tinto by (1) direct evaporation of the river water; or (2) as part of a paragenetic sequence with the inclusion of minor halotrichite, indicating natural dehydration and decomposition. The natural occurrences are comparable with the process of paragenesis from the evaporation of Rio Tinto river water under laboratory experiments resulting in the formation of aluminocopiapite, halotrichite, coquimbite, voltaite and gypsum.

Toxic trace elements present an environmental hazard in the vicinity of mining and smelting activities. However, the processes of transfer of these elements to groundwater and to plants are not always clear. Tharsis mine, in the Iberian pyrite belt (SW Spain), has been exploited since 2500 BC, with extensive smelting taking place from the 1850s until the 1920s. Sixty four soil (mainly topsoils) and vegetation samples were collected in February 2001 and analysed by ICP-AES for 23 elements. Concentrations are 6—6300 mg kg-1 As and 14—24800 mg kg-1 Pb in soils, and 0.20—9 mg kg-1 As and 2—195 mg kg-1 Pb in vegetation. Trace element concentrations decrease rapidly away from the mine, with As and Pb concentrations in the range 6—1850 mg kg—1 (median 22 mg kg—1) and 14—31 mg kg—1 (median 43 mg kg—1), respectively, 1 km away from the mine. These concentrations are low when compared to other well-studied mining and smelting areas (e.g. 600 mg kg—1 As at 8 km from Yellowknife smelter, Canada; >100 mg kg—1 Pb over 270 km2 around the Pb-Zn Port Pirie smelter, South Australia; mean of 1419 mg kg—1 Pb around Aberystwyth smelter, Wales, UK). The high metal content of the vegetation and the low soil pH (mean pH 4.93) indicate the potential for trace element mobility which could explain the relatively low concentration of metals in Tharsis topsoils and cause threats to plans to redevelop the Tharsis area as an orange plantation.

The dispersion and sediment-water partitioning of Pb and Zn have been studied in the Conwy River, North Wales. Analysis included major and trace element water chemistry and concentrations of sediment-hosted Pb and Zn. In situ solution pH, Eh, temperature and conductivity were also measured. Sediments were characterized via SEM, XRD, nitric acid leaching and sequential chemical extraction to quantify metal distribution and sediment phase associations. Dissolved and sediment-bound Pb and Zn within river and estuary waters and sediments have been used to calculate whole sediment- and phase-specific apparent partition coefficients.

Weathering of galena and sphalerite, associated with the Llanrwst Mining Field, provide point sources of elevated dissolved and sedimentary Pb and Zn in the upper catchment. Dissolved Pb is actively adsorbed onto sedimentary surface coatings of Fe-Mn (hydr)oxides and organics whilst Fe-Mn (hydr)oxides, organics and carbonates were the main hosts for Zn. Systematic changes in metal sorption are evident between the estuary and the upper catchment, with organic matter becoming progressively more important upstream. This change is ascribed to the sorptive properties of sedimentary organic material. Solution pH, [Cl] and aqueous metal speciation are the dominant solution controls on metal partitioning. Laboratory sorption experiments parallel Pb sorption behaviour in the natural system.

Tidal mudflats are locally enriched in heavy metals at the head of Strangford Lough in Northern Ireland, where drainage from the hinterland enters the sea lough via a tidal canal in an urban area. To characterize the metallic contaminants and investigate their provenance, heavy particles separated from stream, canal and estuarine sediments were analysed by electron microprobe and laser Raman microspectroscopic methods. Potential metal sources are mineralization in the catchment area and industrial or domestic pollution. Anthropogenic particles include metallic grains, alloys and compounds of Pb, Zn, Cu, Fe, Cr and Sn. Alteration of metallic particles includes de-zincification of brass in freshwater sediment and replacement of Cu wire by covellite in brackish to marine sediment. Mobility of Cu, Fe and S in canal and estuarine sediments is indicated by the authigenic growth of framboidal Fe sulphide on oxide substrates and of chalcopyrite rims on covellite. Intricate colloform and platy crystalline textures suggest a cyclical deposition of covellite and chalcopyrite under conditions of varying redox and salinity. Lead and Cr mobility in the contaminated estuarine sediment is shown by the authigenic formation on Pb-rich substrates of heterogeneous Pb- and Cr-rich sulphate-phosphate compounds and Pb-oxychlorides.

Stream sediment geochemistry provides an innovative method of assessing the basinal history of the Caledonian slate belts. Despite glaciation, the stream sediment geochemical patterns spatially mimic the outcrop of underlying bedrock lithologies. However, erosion from rock to sediment by fluvial processes may either increase or reduce an element’s abundance depending on the nature of its mineral host. An element held in heavy, resistate minerals will be concentrated, whereas one residing in unstable ferromagnesian minerals, which readily break down to clays during weathering, may be preferentially removed. Examples are provided from the Cr-Ni-V-Mg, base metal and Rb-Sr element suites. Primary and secondary bedrock patterns are recognized in the stream sediments. Primary patterns follow the original composition of the source bedrock, with steep gradients in the element distribution coinciding with lithostratigraphical boundaries. Such patterns also reveal subtle divisions within the established geological units for which the main compositional control was the nature of the ancient sedimentary provenance. Secondary patterns reflect remobilization of elements within the bedrock and so may cut across lithostratigraphical boundaries. These patterns (or their absence) are influenced by the thermal histories of the Caledonian basins, and so are indicative of the geotectonic regime in which the sedimentary sequences were originally deposited.

The profile of the supergene zone of the Zapadno-Ozernoe massive sulphide Cu-Zn deposit differs from the classic model (Emmons, 1917) in that it includes a prominent dark sooty subzone rich in secondary sulphides. This subzone is situated above residual pyrite sands, which overlie the massive sulphide body and below quartz-baryte leached sands. It contains a diverse mineral assemblage which consists of secondary sulphides such as galena, sphalerite, metacinnabar, Se-bearing pyrite—dhzarkenite series, tiemannite, native Au, native S and native Se, and unidentified sulphosalts of Ag and Hg. The very light S isotope composition of the secondary sulphides (lowest values δ34S = —17.2‰ (VCDt) in comparison with primary pyrite ∼0‰ and baryte +18.4‰ is indicative of bacterial sulphate reduction. The overlying oxidized part of the supergene column contains minerals of the jarosite-beudantite- segnitite series. The maximum concentrations of Au, up to 150 ppm, occur in the lower part of the profile. The atypical structure, mineral assemblage and S isotope composition of the secondary sulphides in the dark layer of the supergene profile are indicative of particular geochemical conditions due to the existence of a stagnant water body that gave rise to intense bacterial activity, in turn controlled by fluctuations in the redox boundary.

Supergene Fe sulpho-selenides (pyrite, dzharkenite and their intermediate compositions) were discovered in the oxidation zone of the Zapadno-Ozernoe copper-zinc massive sulphide deposit, South Urals, in association with other rare supergene sulphides, such as galena, tetrahedrite, metacinnabarite, tiemannite, Pb sulpharsenides of the jordanite group, undetermined sulphosalts of Hg and Ag, and native elements, such as S, Au and Se. This is the second known occurrence of dzharkenite. The results of the investigation of Fe sulpho-selenides using electron microprobe analysis, X-ray diffraction (XRD) and reflected light microscopy show the existence of a limited solid-solution series between pyrite and dzharkenite, which has not been described before.

Efflorescences in the geothermal field of SE Melos, Greece, contain significant amounts of hydrated Al sulphate, alunogen, which could represent the Melian alumen exploited in Roman times and commended by Pliny. The efflorescences at subaerial fumaroles are explained as follows: Sulphur crystallizes on oxidation of H2S emanating from depth. Weathering produces sulphuric acid enhancing groundwater alteration of volcanic rocks. The high geothermal gradient and arid climate stimulate efflorescences. Salts are recycled during wet and dry weather leading to Al-enrichment on loss of Fe(II,III) and other cations. δ34S‰ V-CDT values for sulphur in fumarole sublimates, solfatara soils and ‘veins’ range from —0.3 to 6.4‰, mean 3.8‰ (n = 8) while Al, Ca and Mg-sulphates in diverse settings range from —4.1 to 6.8‰ (n = 16). The values for sulphur indicate that the initial H2S had an igneous source and the signature is largely inherited by the sulphates.

This study aims to underpin research into the exploitation of industrial minerals in the Roman period. When searching for early alumen workings, areas with evidence of acid sulphate alteration (white rocks) and sulphurous fumarole activity should be investigated.