In the Earth’s lithosphere, fungi are of fundamental importance as decomposer organisms, animal and plant pathogens and symbionts (e.g. lichens and mycorrhizas), being ubiquitous in sub-aerial and subsoil environments. The ability of fungi to interact with minerals, metals, metalloids and organic compounds through biomechanical and biochemical processes, makes them ideally suited as biological weathering agents of rock and building stone. They also play a fundamental role in biogeochemical cycling of nutrients, (e.g. C, N, P and S) and metals (e.g. Na, Mg, Ca, Mn, Fe, Cu, Zn, Co and Ni) essential for the growth of living organisms in the biosphere. In addition they play an integral role in the mobilization and immobilization of non-essential metals (e.g. Cs, Al, Cd, Hg and Pb). Most studies on mineral-microbe interactions and microbial involvement in geological processes have concentrated on bacteria and archaea (Prokaryota): fungi (Eukaryota) have, to a certain extent, been neglected. This article addresses the role of fungi in geomicrobiological processes, emphasizing their deteriorative potential on rock, building stone and mineral surfaces and involvement in the formation of secondary mycogenic minerals. Such roles of fungi are also of importance for the global carbon reservoir and have potential biotechnological applications, e.g. in the bioremediation of xenobiotic-, metal- and/or radionuclide-contaminated soils and wastes, and metal/radionuclide recovery.

This paper presents the results of a laboratory study on the influence of heterotrophic bacteria on dissolution of a silicate mineral (K-feldspar) under a variety of growth conditions. Twenty seven strains of heterotrophic bacteria were isolated from a feldspar-rich soil (Shap, NW England). Liquid and solid minimal aerobic media (C/N-sufficient, K-limited, Fe-limited, N-limited and glucose/NH4Cl only) at 26ºC were used for isolation of the bacteria. The media selected bacterial isolates that were fastgrowing aerobic heterotrophs able to use glucose as the sole source of carbon and energy. The extent of mineral dissolution (in the presence of the isolates) was assessed after 48 h of incubation by measuring the release of Al from the K-feldspar by ICP-AES. More detailed dissolution experiments were carried out with one of the strains, Serratia marcescens, an isolate that was very effective in enhancing feldspar dissolution. The main conclusions of this study are: (1) the degree of enhancement of K-feldspar dissolution varied with bacterial isolate and growth conditions; (2) enhancement of dissolution began during stationary phase growth; (3) the production of chelating compounds (exopolymers, siderophores, pigments) during the stationary phase might be a possible mechanism for bacterially enhanced K-feldspar dissolution; (4) the frequent sub-culturing of isolates can have a significant effect on their physiological characteristics and may possibly influence their capacity to enhance mineral dissolution.

We have imaged the spatially-preserved microtexture of biogenic apatite, retained together with its collagen template, in non-demineralized human bone using high-resolution transmission electron microscopy. Using ion-beam thinning, a specimen preparation method generally employed for inorganic minerals rather than for biological materials, we have imaged a composite nanostructure of bone not previously reported, and we propose a model for this nano-architecture that involves a boxconstruction of apatite plates and apatite sheets. This observation provides a new understanding of bone strength at the nanometre scale and suggests how post mortem enhancement of this texture by recrystallization probably accounts for the durability of ancient bone. Modern sheep bone (a close analogue for recently dead human bone) imaged in the same way also shows evidence of this composite architecture.

Knowledge of the solid-phase speciation of As in Bengali sediments associated with hazardous As-rich groundwaters is crucial to understanding the processes controlling As release. The local coordination environment of As in such a sediment has been probed using K-edge As EXAFS. This revealed that As exists predominantly in its oxidized form, As(V), probably adsorbed as bidentate arsenate tetrahedra on metal (Fe and/or Al) oxide/hydroxide surfaces, although incorporation of As into a metal oxide structure cannot be ruled out. Arsenic was found to occur in several different coordination environments and this, together with the low concentration (<10 μg g–1) of As in the sediment prevented the unambiguous assignment of the second coordination sphere. The EXAFS analysis of the sediment after incubation under anaerobic conditions in the presence of added electron donor for metal reduction indicated changes in the relative concentrations of different solid-phase As species, providing circumstantial evidence for differential susceptibility to microbial action.

The interaction of the {104} cleavage surface of calcite with Hg(CH3COO)2 aqueous solutions with concentration of 5 mM Hg(II) (pH ≈3.5), was investigated using microscopic and spectroscopic techniques. In situ atomic force microscopy experiments showed that surface microtopography changes significantly as a result of the interaction, and that the initial rhombic etch pits induced by H2O dissolution are rapidly transformed to deeper etch pits exhibiting an unusual triangular shape. The growth of these etch pits is strongly anisotropic, moving faster along the [21] direction than along the [010] direction (with step-retreat velocities of ∼12 nm s –1 and ∼4 nm s–1, respectively). The modified etch pits are due to Hg(II) sorption in the surface, rather than due to the effect of the acetate anion. The sorption (adsorption and probably absorption also) of Hg(II), in the first minutes of the interaction, is shown by X-ray photoelectron spectroscopy. After ∼2 h, the triangular etch pits are interconnected to form larger hexagonal etch pits, while Hg(II)-bearing phases (confirmed later by SEM-EDS) grow onto the surface through a heterogeneous nucleation process. The crystal growth of orthorhombic (montroydite-type) hydrated Hg(II) oxide (HgO·nH2O) on the surface of calcite was confirmed by XRD patterns and FT-IR spectra from samples exposed for longer times to Hg(CH3COO)2 solution.

Oxidative dissolution of a primary Mn-silicate phase (rhodonite) was studied via synchrotron X-ray techniques. The study was designed to combine the element-specific chemical technique of Glancing Incidence X-ray Absorption Spectroscopy (GIXAS) with the surface structural technique of X-ray scattering in order to produce the first depth resolved study of Mn-silicate low-temperature reactivity. A chemo-mechanically polished polycrystalline rhodonite sample was characterized and then reacted with pH 3.5 nitric acid. The surface originally had a mosaic structure and 15.5 (±1) Å r.m.s. roughness. Surface composition was not measurably different from bulk rhodonite before reaction, indicating that the surface preparation regimen had not produced an altered surface. After 1 h of reaction, the roughness of the mineral surface decreased and reflectivity oscillations developed, resulting from the formation of a leached layer. This layer was 74.7 (±2) Å thick with an electron density equal to 72% of that of bulk rhodonite (equal to the loss of ~1 in 2 Mn atoms). Both the primary and the buried interfaces had similar roughnesses; 4.9 and 4.5 (±1.0) Å , respectively. Diffuse scatter indicated that the correlation length between surface features also decreased. The GIXAS analysis showed that the Mn remaining in the surface had become oxidized, with the degree of oxidation decreasing as a function of depth. Oxidation penetrated at least 140 Å into the structure. A further 2.5 h of reaction at pH 3.5 caused dissolution of the leached layer and reduced the thickness of this altered region to 16.0 (±2) Å , while surface roughness increased slightly to 6.2 (±1.0) Å . Depletion of Mn in this region increased only slightly relative to the first reaction step; the electron density was 67% that of bulk rhodonite, equivalent to the loss of 2 in 3 Mn atoms. The thickness of the oxidized region however, persisted. Analysis by XPS on the same specimen corroborates the X-ray results.

An epidemiological and environmental study of the area around Biancavilla (CT, Italy) was prompted by a significant incidence of malignant pleural mesothelioma, which was not related to a specific occupational activity. An environmental dispersion of fibres was found and attributed to local quarry activities, whose extracted volcanic products also contained fibrous amphiboles and had been used extensively in the local building industry, especially in the period 1960–1970.

Abundant yellowish and grey-whitish asbestiform amphiboles with strongly asymmetric morphology were identified in this study, intimately associated with albitic feldspar, hematite and very minor orthopyroxene. These minerals fill the pores of the altered volcanic host rock (metasomatized benmoreitic lavas and pyroclastic rocks). The Rietveld method allowed a quantitative mineralogical analysis of the mineral mixture (24% amphiboles-asbestos, 73% feldspar and 3% hematite).

The crystal size and morphology of the grey-whitish amphibole fibres do not allow quantitative microprobe analyses; semi-quantitative EDS-SEM analyses of a prismatic mineral known to be fluoroedenite and the unknown fibrous crystals studied here suggest that they are the same mineral, although the fibres are generally depleted in Ca and Mg. The F content is the same in both occurrences. Unitcell parameters of the fibres are: a = 9.815(1), b = 17.992(3), c = 5.2733(6) Å , β = 104.547(9)º, V = 901.4(3)Å3, and the refractive indices are in the range 1.60 –1.63. Optical, chemical and Rietveld analyses of the fibres confirm their similarity with the yellow prismatic fluoro-edenite previously analysed.

Biancavilla is the first occurrence of amphibole fibres in a volcanic context (the Etnean volcanic complex). These fibres have a very anomalous composition (high ANa, IVAl and O3F contents) in comparison to other known oncogenic minerals.

The tropospheric dust loading in Upper Silesia (Poland) shows a steady, annually averaged supply of minerals from natural and anthropogenic sources, industrial dust emitters, domestic heating, transportation, but with superimposed seasonal changes for some dust types. Samples of airborne and deposited particles were collected at monthly intervals between 1996 and 2001 in several cities of Upper Silesia. Dust samples were examined by X-ray powder diffraction, analytical transmission electron microscopy, analytical scanning electron microscopy, and electron microprobe microanalysis. The most common dust included quartz, gypsum, coke, soot, hematite, magnetite, wüstite, bassanite, graphite and various K-, Fe- and Mg-bearing aluminosilicates, in order of decreasing abundance. Minor phases included α-iron, sulphur, sphalerite, halite, sylvite, hercynite, franklinite, baryte, dolomite, ankerite, apatite, olivine and feldspars. Quartz, and specific industrial minerals, e.g. spinels, sphalerite, olivine and iron, occurred throughout the year in almost constant abundances. The amounts of all other dust components show seasonal variations; gypsum, baryte and other sulphates are particularly abundant in winter. In general, minerals related to low-emission sources are abundant in the winter time, while both natural dusts and dust from high-emission sources are predominant during the summer.

Small domestic cooking furnaces are widely used in China. These cooking furnaces release SO2 gas and dust into the atmosphere and cause serious air pollution. Experiments were conducted to investigate the effects of vermiculite, limestone or CaCO3, and combustion temperature and time on desulphurization and dust removal during briquette combustion in small domestic cooking furnaces. Additives used in the coal are vermiculite, CaCO3 and bentonite. Vermiculite is used for its expansion property to improve the contact between CaCO3 and SO2 and to convey O2 into the interior of briquette; CaCO3 is used as a chemical reactant to react with SO2 to form CaSO4; and bentonite is used to develop briquette strength. Expansion of vermiculite develops loose interior structures, such as pores or cracks, inside the briquette, and thus brings enough oxygen for combustion and sulphation reaction. Effective combustion of the original carbon reduces amounts of dust in the fly ash. X-ray diffraction, optical microscopy, and scanning electron microscopy with energy dispersive X-ray analysis show that S exists in the ash only as anhydrite CaSO4, a product of SO2 reacting with CaCO3 and O2. The formation of CaSO4 effectively reduces or eliminates SO2 emission from coal combustion. The major factors controlling S retention are vermiculite, CaCO3 and combustion temperature. The S retention ratio increases with increasing vermiculite amount at 950°C. The S retention ratio also increases with increasing Ca/S molar ratio, and the best Ca/S ratio is 2-3 for most combustion. With 12 g of the original coal, 1 to 2 g of vermiculite, a molar Ca/S ratio of 2.55 by adding CaCO3, and some bentonite, a S retention ratio >65% can be readily achieved. The highest S retention ratio of 97.9% is achieved at 950°C with addition of 2 g of vermiculite, a Ca/S ratio of 2.55 and bentonite.

Structural transformations between the different hydration states of three vermiculite samples from Sta. Olalla (Huelva, Spain), Paulistana (Piaui, Brasil) and West China, have been observed by X-ray diffraction at atmospheric pressure, P = 1.4 x 10–2 mbar and P = 2.4 x 10–4 mbar. The samples were studied in flake and powder forms. The effect of vacuum has been proven to be the same as that of temperature, i.e. it causes dehydration of vermiculite, but with a different evolution through the different hydration states. In fact, under vacuum, the process seems to be inhibited at a one-water layer hydration state (1-WLHS), without a further dehydration of samples to a zero-water layer hydration state (0-WLHS).

Furthermore, the dehydration process has been shown to occur through different interstratified states in each vermiculite. This result has been related to the interlayer Mg-cation content, due to its affinity to water molecules. The interstratified states have been analysed by the direct Fourier-transform method. The vermiculite from Sta. Olalla exhibits the most complex process, with formation of three different interstratified phases: two phases characterized by an interstratification of interplanar distances, d = 11.5 –13.8 Å and d = 9.6 –11.5 Å , respectively, and a practically segregated phase characterized by d = 13.8 Å . For the vermiculite from China, an interstratified phase not previously reported has been found, with an interplanar distance of 12.10 Å.

The inhibition of dehydration at 1-WLHS, as observed, could be used in applications such as adsorption and separation technology of gases and liquids, or in heterogeneous catalysis processes.

Lead, zinc and arsenic mobilization/attenuation processes during interactions between smelter slag and water show differences depending on the origin of the slag. The studied samples, waste from ore and car-battery processing, were submitted to long-term (365 days) batch leaching at two different initial pH values. The leachate analyses were input to the EQ3NR speciation-solubility code to speciate the solutions and determine the degree of saturation with respect to different phases, and a mineralogical investigation was made of the newly formed phases. An ‘oxidizing’ scenario can be proposed for slag waste disposal, considering that cerussite (PbCO3) at pH >6 becomes a major solubility-controlling phase for Pb, and newly formed hydrous ferric oxides (HFO – common secondary phases under oxidizing conditions) efficiently adsorb As. No efficient scavenging mechanism was found for Zn, which was progressively leached from the slag and in particular from the ore-processing slag. Quenched glass-rich slag from old car-battery processing was found to release significant amounts of Pb, especially in acidic environments. Neither slag would therefore be suitable for recycling for civil engineering purposes. Conversely, extremely low releases of Pb, Zn and As were observed for recent car-battery processing slag, which could therefore be considered for road construction.

In bioreactor systems for the treatment of metal-contaminated water, pretreatment with zerovalent Fe can be exploited for oxygen consumption and H2 production. In this study, a column experiment is used to investigate the changes in surface chemistry and solid phase products that result from the reaction of a Zn-sulphate-lactate solution with zerovalent Fe filings. The results of this study indicate that zerovalent Fe is very effective in immobilizing dissolved Zn with a porewater residence time of 1.3 –3.1 days. A combination of X-ray diffractometry, X-ray photoelectron spectroscopy, and mineral equilibria calculations indicates that Zn precipitates as Zn(OH)2 and zincite at pH 9 –10. At pH ≈6, Zn primarily adsorbs to abundant ferric oxyhydroxides, although incorporation in green rust is also considered. During the course of the experiment, the surface mineralogy changes from magnetitelepidocrocite- goethite to green rust-akaganéite-goethite. The results suggest that the zerovalent Fe surface becomes passivated by a surface film of ferric oxyhydroxides, green rust and organic material, so that the rate of electron transfer and proton consuming reactions (i.e. oxygen consumption, H2 generation) declines, resulting in a decrease in solution pH.

The development of protocols for the identification of metal phosphates in phosphate-treated, metalcontaminated soils is a necessary yet problematical step in the validation of remediation schemes involving immobilization of metals as phosphate phases. The potential for Raman spectroscopy to be applied to the identification of these phosphates in soils has yet to be fully explored. With this in mind, a range of synthetic mixed-metal hydroxylapatites has been characterized and added to soils at known concentrations for analysis using both bulk X-ray powder diffraction (XRD) and Raman spectroscopy.

Mixed-metal hydroxylapatites in the binary series Ca –Cd, Ca –Pb, Ca –Sr and Cd –Pb synthesized in the presence of acetate and carbonate ions, were characterized using a range of analytical techniques including XRD, analytical scanning electron microscopy (SEM), infrared spectroscopy (IR), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and Raman spectroscopy. Only the Ca –Cd series displays complete solid solution, although under the synthesis conditions of this study the Cd5(PO4)3OH end member could not be synthesized as a pure phase. Within the Ca –Cd series the cell parameters, IR active modes and Raman active bands vary linearly as a function of Cd content. X-ray diffraction and extended X-ray absorption fine structure spectroscopy (EXAFS) suggest that the Cd is distributed across both the Ca(1) and Ca(2) sites, even at low Cd concentrations.

In order to explore the likely detection limits for mixed-metal phosphates in soils for XRD and Raman spectroscopy, soils doped with mixed-metal hydroxylapatites at concentrations of 5, 1 and 0.5 wt.% were then studied. X-ray diffraction could not confirm unambiguously the presence or identity of mixed-metal phosphates in soils at concentrations below 5 wt.%. Raman spectroscopy proved a far more sensitive method for the identification of mixed-metal hydroxylapatites in soils, which could positively identify the presence of such phases in soils at all the dopant concentrations used in this study. Moreover, Raman spectroscopy could also provide an accurate assessment of the degree of chemical substitution in the hydroxylapatites even when present in soils at concentrations as low as 0.1%.