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The article focuses on the developments leading to the ban on artificial stone in Australia, including the health concerns associated with the material, the regulatory measures taken by the government, and the implications for manufacturers and workers in the industry.

Union activism, medical lobbying and occupational health and safety prosecutions led to a major public health initiative in Australia - the banning from 1 July 2024 of work with engineered/artificial stone, including manufacturing, supplying, processing and installing it. This editorial contextualises within the history of regulation of workers' exposure to risks of contracting silicosis the growing international awareness of the dangers posed by working with engineered stone, particularly in relation to making and installing kitchen and bathroom benchtops made from engineered stone. It argues that the Australian initiative is an important public health decision that has a sound justification, is likely to save many lives and should be emulated internationally. [ABSTRACT FROM AUTHOR]

There is a significant silicosis risk for workers fabricating engineered stone (ES) products containing crystalline silica. The aims of this study by SafeWork NSW were to: (i) assess current worker exposure to respirable dust (RD) and respirable crystalline silica (RCS) following a 5-y awareness and compliance program of inspections in ES workshops and (ii) to identify improvements in work practices from the available evidence base to further reduce exposures. One hundred and twenty-three personal full shift samples taken on as many workers and 34 static samples across 27 workshops fabricating ES were included in the final assessment. The exposure assessment was conducted using Casella Higgins–Dewell cyclones (Casella TSI) placed in the breathing zone of workers attached to SKC Air Check XR 5000 or SKC Chek TOUCH sampling pumps. Sample filters were sent to an ISO (2017) 17025:2017 accredited laboratory for gravimetric analysis for RD and X-Ray Diffraction (XRD) analysis to determine the amount of deposited RCS i.e. alpha-quartz and cristobalite. All workshops used wet methods of fabrication. The geometric mean (GM) of the pooled result for respirable dust (RD) was 0.09 mg/m3 TWA-8 h and 0.034 mg/m3 TWA-8 h for RCS. The highest exposed workers with a GM RCS of 0.062 mg/m3 TWA-8 h were those using pneumatic hand tools for cutting or grinding combined with polishing tasks. Workers operating semiautomated routers and edge polishers had the lowest GM RCS exposures of 0.022 mg/m3 TWA-8 h and 0.018 mg/m3 TWA-8 h respectively. Although ES workers remain exposed to RCS above the workplace exposure limit (WEL) of 0.05 mg/m 3 TWA-8 h, these results point to a very substantial reduction in exposures compared to poorly controlled dry methods of fabrication. Therefore, the wearing of respiratory protection by workers remains necessary until further control measures are more widely adopted across the entire industry e.g. reduction in the crystalline silica content of ES. [ABSTRACT FROM AUTHOR]

An Australian National Dust Disease Taskforce was established to address the re-emergence of occupational lung disease, in particular silicosis. Exposure to respirable crystalline silica (RCS) occurs in various industries in Australia. We asked occupational hygienists about their practical experiences and perspectives on RCS exposure and regulatory action. A total of 105 members of the Australian Institute of Occupational Hygienists completed an anonymous questionnaire, which addressed individual characteristics, experience, perceived level of employer awareness, effectiveness of current regulation, and recommendations for improvement, across three main industrial sectors. Based on professional experience, 71% were concerned about the potential for RCS over-exposure. Barriers to adequate exposure control included lack of management commitment and financial resources. The employment of specialist occupational hygiene inspectors was considered to be the most effective regulatory strategy. Given the large number of exposed workers in the construction industry, with only a moderate awareness, there is the potential for significant cost shifting of the burden of occupational lung disease from employers on to individuals and the public health system. A nationally consistent approach to RCS exposure control across all industrial sectors is now recommended, with an increased focus on measuring and controlling exposure. [ABSTRACT FROM AUTHOR]

A comparison of the analysis of respirable crystalline silica direct-on-filter methods using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy was undertaken using 253 real workplace air samples from road construction and tunnelling, coal mining, and kitchen benchtop manufacturing in Australia. Using pure α-quartz standards, XRD and FT-IR direct-on-filter analyses produced identical test results, however, the real workplace samples showed a clear discrepancy between FT-IR and XRD results with on average a 9% positive bias of the FT-IR results. The cause of the positive bias was due to matrix interferences which was confirmed by using synthetic mixture air samples. Approximately a third of the data by direct-on-filter method using FT-IR was assessed to be invalid based on the peak height ratio criterion due to excessive interferences and weight overload limitations. The XRD method showed better results due to less interference from the common matrices. XRD could handle up to twice the sample loading and at higher loadings up to 7 mg when a correction was applied. It was also able to achieve a lower limit of detection of 2 µg filter−1 when a slower scan condition was utilized. [ABSTRACT FROM AUTHOR]

Silicosis is being increasingly reported among young stonemasons in the artificial stone (AS) benchtop fabrication and installation industry. Respiratory health screening, which included a job and exposure history, a chest X-ray (CXR), a respiratory health questionnaire, and gas transfer testing, were offered to stonemasons in Victoria, Australia. Workers typically reported a variety of tasks, including cleaning and labouring, which made exposure assessment complex. We estimated the relative respirable crystalline silica exposure intensity of each job from the proportion of time using AS and the proportion of time doing dry work (work without water suppression). The relative average intensity of exposure for up to five jobs was calculated. Cumulative exposure was calculated as the sum of the duration multiplied by intensity for each job. Installers and factory machinists (other than computer numeric control operators) were the most likely to report dry work with AS, and so had a greater average intensity of exposure. Exposure intensity and cumulative exposure were associated with increased odds of an ILO (International Labour Organisation) CXR profusion major category of ≥1 and with dyspnoea. Exposure duration was also associated with ILO profusion category. In multivariate analyses of health outcomes, only job type was associated with the ILO profusion category. For both most recent and longest-duration job types, when compared to the lowest exposure group, factory machinists were more likely to have an ILO category ≥1. This suggests that intensity of exposure estimated from the proportion of time dry cutting and proportion of time working on AS can predict the risk of adverse respiratory outcomes for workers in this industry. [ABSTRACT FROM AUTHOR]

Objective To determine the frequency of self-reported occupational exposure to silica in SSc patients enrolled in the Australian Scleroderma Cohort Study, and to compare the disease characteristics of the silica-exposed patients with those of the non-exposed patients. Method Data collected over a 12-year period from 1670 SSc patients were analysed. We compared the demographic and clinical characteristics of those who reported occupational silica exposure with those who did not. A subgroup analysis of male patients was performed, as well as a multivariable analysis of correlates of silica exposure. Results Overall, 126 (7.5%) of the cohort reported occupational silica exposure. These individuals were more likely to be male (73 of 231, i.e. 31.6% males exposed) and to have worked in mining and construction industries. Those who reported silica exposure were younger at the onset of SSc skin involvement [odds ratio (OR) 0.9, P  = 0.02], of male gender (OR 14.9, P  < 0.001), have joint contractures (OR 1.8, P  = 0.05) and have higher physical disability as defined by scleroderma HAQ (OR 1.4, P  = 0.01). Conclusion The highest percentage of silica exposure was found in males. These patients were more likely to have the presence of certain clinical manifestations and Scl-70 antibody, which is known to confer a poor prognosis. These findings support the association between occupational silica exposure and the subsequent development of SSc. Further investigation is required to describe the range of clinical manifestations and disease course, including prognosis and treatment response, in those diagnosed with occupationally induced SSc compared with idiopathic SSc. [ABSTRACT FROM AUTHOR]

The article offers information on connective tissue disease due to Silica Exposure and Scleroderma.

Two new Australian Standard methods to test alkali-silica reactivity (ASR) of aggregates – AS 1141.60.1 accelerated mortar bar test (AMBT) and AS 1141.60.2 concrete prism test (CPT) were published in September 2014. The methods adopted test procedures correspondingly from ASTM C1260 and ASTM C1293 with improved performance limits leading to a new class of slowly reactive aggregates. This paper examines the accuracy of these new testing methods in predicting the ASR of aggregates in field conditions based on international research data. AS 1141.60.1 was found to be a relatively good accelerated test which correctly classified ‘slowly reactive’ and ‘reactive’ aggregates consistent with field performance with few exceptions. It is however a poorer screening test for non-reactive aggregates than ASTM C1260. Both AS 1141.60.2 and ASTM C1293 concrete prism tests were found to be more reliable than AMBT as both correctly classified almost all 64 aggregates against known field performance. [ABSTRACT FROM AUTHOR]

Background: Respirable crystalline silica (RCS) is a biologically active dust that can accumulate in the lung and induce silicosis and lung cancer. Despite occupational exposure being the predominant source, no study has described current occupational RCS exposure on a national scale in Australia. The aim of this study is to estimate the characteristics of those exposed and the circumstances of RCS exposure in Australian workplaces. Methods: A cross-sectional survey of the Australian working population (18-65 years old) was conducted. Information about the respondents' current job and their demographic characteristics was collected in a telephone interview. Occupational exposure to RCS was determined based on preprogrammed decision rules regarding potential levels of exposure associated with self-reported tasks. Results: Overall, 6.4% of respondents were deemed exposed to RCS at work in 2012 (3.3% were exposed at a high level). The exposure varied with sex, state of residence, and socioeconomic status. Miners and construction workers were most likely to be highly exposed to RCS when performing tasks with concrete or cement or working near crushers that create RCS-containing dusts. When extrapolated to the entire Australian working population, 6.6% of Australian workers were exposed to RCS and 3.7% were highly exposed when carrying out tasks at work. Conclusion: This is the first study investigating occupational RCS exposure in an entire national working population. The information about occupational tasks that lead to high level RCS exposure provided by this study will inform the direction of occupational interventions and policies. [ABSTRACT FROM AUTHOR]

Introduction: The aims of this study were to produce a population-based estimate of the prevalence of work-related exposure to formaldehyde, to identify the main circumstances of exposure and to describe the use of workplace control measures designed to decrease those exposures. Methods: The analysis used data from the Australian Workplace Exposures Study, a nationwide telephone survey, which investigated the current prevalence and exposure circumstances of work-related exposure to 38 known or suspected carcinogens, including formaldehyde, among Australian workers aged 18-65 years. Using the web-based tool OccIDEAS, semi-quantitative information was collected about exposures in the current job held by the respondent. Questions were addressed primarily at tasks undertaken rather than about self-reported exposures. Results: Of the 4993 included respondents, 124 (2.5%) were identified as probably being exposed to formaldehyde in the course of their work [extrapolated to 2.6% of the Australian working population-265 000 (95% confidence interval 221 000-316 000) workers]. Most (87.1%) were male. About half worked in technical and trades occupations. In terms of industry, about half worked in the construction industry. The main circumstances of exposure were working with particle board or plywood typically through carpentry work, building maintenance, or sanding prior to painting; with the more common of other exposures circumstances being firefighters involved in fighting fires, fire overhaul, and clean-up or back-burning; and health workers using formaldehyde when sterilizing equipment or in a pathology laboratory setting. The use of control measures was inconsistent. Conclusion: Workers are exposed to formaldehyde in many different occupational circumstances. Information on the exposure circumstances can be used to support decisions on appropriate priorities for intervention and control of occupational exposure to formaldehyde, and estimates of burden of cancer arising from occupational exposure to formaldehyde. [ABSTRACT FROM AUTHOR]

Introduction: Gosses Bluff is a ~24 km diameter complex impact structure in central Australia, located 160 km WSW of Alice Springs. The impact age is poorly constrained at between 383-165 Ma [1,2,3]. Target rocks are near horizontal Late Proterozoic to Devonian sedimentary units of the Amadeus Basin [4]. An eroded expression of the ~4.5 km diameter central uplift forms well-preserved ridges that stand ~180-240 m above the surrounding plains [4,5]. The impact structure is well represented with gravity data, showing a ~3 km diameter low over the central uplift, with a gradient corresponding to the ~24 km diameter crater rim [6,7]. While shocked quartz, shatter cones, impact melt, impact breccias and impact glass have all been reported at Gosses Bluff [5], no accessory mineral microstructural studies have previously been done. An anomalous topographic high, called Mt Pyroclast, is located ~3 km south of the central uplift. Mt Pyroclast predominantly consists of tan and pale grey with black-coloured polymict lithic impact breccia and impact melt-bearing breccia [4]. Fieldwork in 2017 identified dark red polymict lithic breccia dykes ranging from 2 cm to 3 m in width that cross-cut the tan-coloured polymict lithic impact breccia; the red dykes are the focus of this study. Methods: A microscopic analysis of thin sections of the largest identified (3 m-wide) dark red polymict breccia dyke, which cross-cuts the polymict lithic impact breccia at Mt Pyroclast, was analysed in this study. Scanning electron microscopy (SEM) with backscatter electron (BSE), energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) were used. Analysis was done using the Tescan Mira3 FESEM with Oxford Instruments Symmetry EBSD detector and AZtec Symmetry software, and a Tescan integrated mineral analyzer (TIMA) with four EDS detectors at the John de Laeter Centre (JDLC), Curtin University. Results and discussion: The red breccia is matrix supported (60% matrix, 40% clasts) and includes clasts of varying sedimentary compositions, the largest of which (up to 1 cm) is predominantly a porous carbonate which contains a mixture of calcite, dolomite, lechatelierite and other amorphous silica. The clasts are very angular and show very little evidence of reworking. Other than lechatelierite no conspicuous melt particles were observed. TIMA analysis of one thin section identified 85 zircon grains larger than 10 µm. These grains display a multitude of different microstructures, including: granular neoblastic zircons, many of which preserve crystallographic orientation microstructures that indicate former reidite in granular neoblastic (FRIGN) zircon; grains with evidence of localised dissociation of zircon to zirconia (ZrO2) and silica (SiO2) within granular domains along grain margins; grains with {112} deformation twins; and grains with planar deformation bands (PDB). Reidite was identified in several zircon grains, both as lamellae within subhedral non-granular grains, and as granular neoblasts coexisting with zircon within FRIGN zircon. This presence of reidite in non-granular grains, FRIGN zircon, FRIGN zircon with preserved reidite domains, {112} twins, PDBs, and dissociation textures, all within this section, represents nearly the full spectrum of pressure and temperature conditions reported for zircon from impact environments [8]. Such a wide variety of zircon microstructural responses suggests that the red breccia dykes contain material sampled from a variety of environments within the impact structure, and thus are not necessarily a remobilized/modified version of the dyke host rocks. Ongoing work is focused on determining the nature of the enigmatic dykes, including if the matrix contains evidence of fusion or is entirely clastic. FRIGN zircon grains in the red dyke are appropriate for U-Pb dating and will be targeted for analysis to further constrain the age of Gosses Bluff impact. [ABSTRACT FROM AUTHOR]

Abstract: The long-term cleaning needs and response to different cleaning approaches of a portable capacitive deionisation (CDI) prototype unit were investigated at two Australian locations: Wilora, a remote community in the Northern Territory (NT), and Mawson Lakes, an urban area in South Australia (SA). The high levels of calcium, magnesium and silica at Wilora had a limited effect on long-term CDI operation; Wilora's groundwater had a low level of dissolved organics, causing no observed fouling. The current CDI technology proved suitable for direct application for brackish water desalination in this location. For comparison, ground water containing a higher level of dissolved organics was studied in Mawson Lakes, SA. A reduction in the salinity removal ability of the CDI cells was observed due to organic fouling. However, a relatively mild cleaning solution (0.01M citric acid for calcium and magnesium scaling and 0.01M sodium hydroxide for the organic fouling) restored the desalination capacity of the CDI unit to its initial level. This unit thus represents a viable alternative for brackish water treatment, especially in remote locations where building and operating reverse osmosis (RO) treatment plants is not practical. These findings can be used to guide on-site maintenance of CDI technology. [Copyright &y& Elsevier]

Abstract: Independent dating evidence and dune morphology indicate great stability of the Australian dunefields. Most dunefields have seen only minor superficial modification since they were formed, up to 1 million years ago, despite quite large changes in climate conditions. This stability may be partly due to the relatively dense vegetation cover on Australian dunes under the marginally arid climate. But new studies, supported by many older observations, suggest that ‘sticky’ dunes (where sand grains are bonded or cemented) may form under a broader range of wind climates than widely thought and have greater resistance to reworking. New mapping of the Australian continental dunefields from satellite imagery shows a previously unrecognised diversity of dune morphologies. Dune orientation, continuity, connectedness, crest planform, crest sharpness, spacing and setting all show patterns of variation over the continent. These are consistent with the overall low sand supply and variable wind climate that contribute to the dominance of longitudinal dunes but also with only superficial modification of the dunes after their initial formation. The longevity of the dunes is likely also partly due to the stabilisation of dune sand by pedogenesis: the bonding of sand by pedogenic calcium carbonate, gypsum, silica and translocated clays. The extremely low mobility of the sand dunes has led to preservation of dunes of great age, with stacked accretionary units and multiple palaeosols. [Copyright &y& Elsevier]

Abstract: Protistan species composition and abundance in the Sub-Antarctic Zone (SAZ) and Polar Front Zone (PFZ) south of Tasmania were determined by microscopy and pigment analysis from samples collected during the Sub-Antarctic Zone—Sensitivity of the sub-Antarctic Zone to Environmental Change (SAZ-Sense) voyage, in January and February of 2007. A primary goal of this voyage was to determine the potential effects of climate change-induced natural iron fertilisation of the SAZ on the protistan community by exploring differences between communities in waters west of Tasmania, which are low in iron, and eastern waters, which are fertilised by continental iron input and mixing across the subtropical front. The SAZ is a sink for anthropogenic CO2 in spring, but the magnitude of this may vary depending on seasonal changes in protistan abundance, composition and trophodynamics. Protistan species composition and abundance in the western Sub-Antarctic Zone at process station 1 (P1) showed a community in which low carbon biomass was dominated by a Thalassiosira sp., which was very weakly silicified under strong silica limitation. Protistan cell carbon was dominated by diatoms and nano-picoflagellates at process station 2 (P2) in the Polar Front Zone (PFZ), while dinoflagellates dominated in the iron-enriched waters of eastern SAZ at station 3 (P3). Iron enrichment enhanced production and favoured proliferation of small flagellates during summer in the silica-depleted eastern SAZ rather than large diatoms, though the effect this may have on the vertical export of particulate organic carbon (POC) is still unclear. [Copyright &y& Elsevier]

An unexpected result of ground-penetrating radar (GPR) surveys in the Great Victoria Desert (South Australia) was the lack of returning signal in what appeared to be a favorable environment for GPR, with dry silica sand and calcrete aggregates in the near surface. We found that the dielectric response of the dry sand samples had much higher dielectric losses than comparable sands from Western Australia and that the dielectric losses are controlled by the presence of iron oxide minerals, although iron concentrations themselves are only around 0.4%. The samples contained over 90% quartz, with subsidiary amounts of carbonates, kaolin, and smectite occurring with the iron oxide minerals as a coating on the quartz grains. An acid washing procedure removed the reducible iron oxide minerals from the clay coating but left the clays substantially unaltered. Subsequent dielectric and magnetic analysis of the samples indicates that the iron oxide minerals removed during the washing process are responsible for the reduction of GPR penetration at 250 MHz from approximately 10 m to only 1 m. [ABSTRACT FROM AUTHOR]

This paper presents X-ray diffraction and SEM evidence for the formation of alunite, and possibly small quantities of natroalunite, within opal-A stalactites formed on quartz sandstone near Sydney in south-eastern, Australia. Alunite has been reported as a speleogenetic mineral from sediments within a number of caves around the world, but this is believed to be the first report of speleothemic alunite in opaline silica speleothems. Individual alunite crystals have not been visually identified, but SEM X-ray element mapping suggests the alunite has formed amongst kaolinite clay. Sedimentary alunite and natroalunite formation is usually associated with the reaction of sulphuric acid on illite, smectite and kaolinite clay materials. In this location groundwater sulphate levels are not high, but evaporative concentration of stalactite drip-water containing small amounts of sulphuric acid generated by oxidization of pyrite might lower the pH to a level sufficiently acidic for conversion of kaolinite or illite to alunite. The ferrolysis of hydrous Fe2+-oxides, or the biochemical activities of bacteria or other micro-organisms, also provide conceivable pathways for the generation of pH sufficiently low to contribute to alunite formation. The occurrence of alunite in these silica stalactites, whilst unusual, is consistent with the normal silica stalactite-forming process in this region, and in accord with observations of the authigenic formation of alunite and groundwater opal in weathering profiles elsewhere. INSET: 1. [ABSTRACT FROM AUTHOR]

Abstract: Extensive Paleozoic sinter deposits occur at the surface associated with sub-surface quartz veining and epithermal Au mineralisation in the Drummond Basin, Australia. We investigated the trace element composition of the sinter deposits and quartz veins in an attempt to develop a new geochemical exploration guide for geological resources. The Drummond Basin hydrothermal silica deposits are unique in having anomalously enriched incompatible element (Cs, Li, Be, U, Th and REE) concentrations in comparison to hydrothermal quartz veins from various granitic-pegmatitic systems elsewhere. The development of relative Ce deficiencies (Ce/Ce*norm <1) in silica deposits indicate preferential mobilisation of REE over Ce from source rocks by oxidised hydrothermal fluids, leading to relative Ce enrichment in the source material (e.g., rhyolite intrusions). Sinters and quartz veins and some volcanic source rocks show a conspicuous positive Y anomaly relative to REE. This is interpreted in terms of Y fractionation due to fluorine complexation with REE during hydrothermal activity. The majority of sinter and quartz samples within or near the Au mineralisation zone are more enriched in mobile elements (Cs, Li, Rb and Be) than the silica deposits from areas distal to the mineralised area. Normalised Y–REE patterns of the sinter deposits, quartz veins, and wall rocks provide important information on the physico-chemical environment of epithermal mineral deposition in geothermal systems. Trace element systematics as revealed in the current study, particularly in relation to the alkali element mobility, have significant implications for finding new prospect areas and evaluating the potential of existing prospect areas for epithermal metal deposits and active geothermal fields. [ABSTRACT FROM AUTHOR]

The dehydration of an opal specimen was investigated by thermogravimetric analysis (TG) in powder and bulk forms. The change in geometry resulted in a significant difference in the temperature range in which dehydration occurred with peak temperatures in the differential TG (DTG) curve for the hand ground opal at 203°C and for the bulk opal at 340°C. This difference was attributed to time taken for diffusion of free water in the bulk opal to the specimen surface prior to evolution as a registered mass loss. A model was proposed to account for the diffusion of water and was used to estimate the diffusion coefficient. [ABSTRACT FROM AUTHOR]

The dehydration of samples of a Coober Pedy, South Australian sedimentary white opal, displaying play of colour, was investigated using TMA by heating the samples of the specimen to a range of temperatures between room temperature and 1000 at 200°C intervals followed by cooling to room temperature. Etched fracture surfaces of the samples were then examined using SEM. The samples showed the typical expansion at low temperature up to 210°C before contraction was observed. The contraction of the opals was ascribed to both sintering, supported by morphological change observed in the SEM micrographs, and dehydroxylation of the silanol groups producing silicon-oxygen-silicon bridges resulting in a more dense silica network. [ABSTRACT FROM AUTHOR]

Occupational exposure to respirable crystalline silica (RCS) is common in a range of industries, including mining, and has been associated with adverse health effects such as silicosis, lung cancer, and non-malignant respiratory diseases. This study used a large population database of 6,563 mine workers from Western Australia who were examined for personal exposure to RCS between 2001 and 2012. A standardized respiratory questionnaire was also administered to collect information related to their respiratory health. Logistic regression analyses were performed to ascertain the association between RCS concentrations and the prevalence of respiratory symptoms among mine workers. The estimated exposure levels of RCS (geometric mean 0.008mg/m 3 , GSD 4.151) declined over the study period ( p < 0.001) and were below the exposure standard of 0.05 mg/m 3 . Miners exposed to RCS had a significantly higher prevalence of phlegm ( p = 0.017) and any respiratory symptom ( p = 0.013), even at concentrations within the exposure limit. Miners are susceptible to adverse respiratory health effects at low levels of RCS exposure. More stringent prevention strategies are therefore recommended to protect mine workers from RCS exposures., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Rumchev, Hoang and Lee.)

The composition and structure of the surface layers of a series of silica particles (10-20 mu m across), embedded in a bituminous coal from the Whybrow seam, Sydney Basin, Australia, have been characterized in situ using time-of-flight secondary ion mass spectrometry (TOFSIMS), ion imaging, and depth profiling. The silica particles investigated are typically encased in a multilayered shell, the composition of which differs from average composition of both the silica and the bulk coal. The analysis directly demonstrates the presence of a silanol-rich (Si-OH) interfacial layer 3 nm in thickness. This silanol-rich region separates the bulk silica and a complex non-silica layer encasing the particles. The interfacial region also shows significant lithium enrichment (approximately fivefold over bulk) which implies diffusion and precipitation of lithium-containing species during the authigenetic formation of the surface layers of the silica grains. The outer layer encasing the silica particles is 10 nm in thickness and is composed of clays and carbonates, and, in some cases, includes organic material. The elemental constituents of this layer include aluminium, sodium, potassium, magnesium, iron, and lesser amounts of titanium and copper. The variation in the aluminium concentration from the outermost surface to the deeper layers is less than that of other non-silica species. A relatively high amount of calcium is found associated with the silica bulk. Although only nonrespirable-sized silica particles are examined in this work, the methods of analysis developed have potential in providing an insight into the surface composition of respirable particles and in further studies of the surface bioavailability of silica species. [ABSTRACT FROM AUTHOR]

We have developed a simple mechanistic model, which simulates the temporal and spatial variability of concentrations of the diatom Aulacoseira granulata in the River Murray, NSW Australia, over large distances under different flow conditions. The model incorporates a simple growth function determined by the availabilities of silica and light, and by temperature. It also includes losses due to sinking and downstream advection. The model is tested against weekly measurements for the period 1981-1990, at three sites separated by 1100 km. The seasonal cycle of Aulacoseira concentrations along the river is well represented by the model. During times of high flow, the concentrations of Aulacoseira remain fairly uniform along the river as the diatoms have insufficient time to grow before being advected downstream. [ABSTRACT FROM PUBLISHER]

This study aims at focusing on the geo-chemical reactions of caprock upon injection of supercritical CO 2 (ScCO 2) under deep saline aquifer's conditions. The caprock samples were obtained at a depth of 979 m in the DMP Harvey-2 well, which is recognized as mudstone in the Lesueur Formation of the South-west Hub geo-sequestration project located 120 kilometres south of Perth in Australia. Geo-chemical reactions were conducted in a reaction chamber to determine the chemical reactivity of brine-saturated caprock under actual reservoir conditions (40 °C, 10 MPa and salinity 4.5%). The reaction was conducted at 10 MPa ScCO 2 pressure and allowed for 37 weeks. The reacted fluid samples were subjected to several chemical analyses, including alkalinity tests, pH measurements and inductively-coupled plasma optical emission spectrometry (ICP-OES) tests. The solid minerals were tested using X-ray Diffraction (XRD), Scanning electron microscopy (SEM) and Energy-Dispersive X-ray (EDX) to obtain a better understanding related to of their chemical characterization of the caprock. Finally, a geochemical model (PHREEQC) was developed to forecast mineral dissolution/precipitation equilibrium and redox reactions. Fluid chemistry showed that the concentration of major elements such as Ca, Mg and K increased with time due to the dissolution of minerals such as K-feldspar, anorthite, and chlorite. On the other hand, the release concentration of Si, Fe and Al ions decreased with time due to the precipitation of secondary minerals such as kaolinite, gibbsite, amorphous silica and Fe(OH) 3. Accordingly, the dissolution of minerals is very significant compared to precipitation of secondary minerals in the short term which can increase the pore volume of the caprock. • Chemical reactivity tests conducted for mudstone providing reservoir conditions. • Conducted mineral-brine analysis for 37 weeks including geo-chemical modelling. • Dissolution of minerals such as K-feldspar, anorthite, and chlorite. • Precipitation of minerals such as kaolinite, gibbsite, amorphous silica and Fe(OH) 3. • Dissolution of minerals is significant which can increase pore volume of caprock. [ABSTRACT FROM AUTHOR]

Global climate change may increase invasions of exotic plant species by directly promoting the success of invasive/exotic species or by reducing the competitive abilities of native species. Changes in plant chemistry, leading to altered susceptibility to stress, could mediate these effects. Grasses are hyper-accumulators of silicon, which play a crucial function in the alleviation of diverse biotic and abiotic stresses. It is unknown how predicted increases in atmospheric carbon dioxide (CO 2 ) and air temperature affect silicon accumulation in grasses, especially in relation to primary and secondary metabolites. We tested how elevated CO 2 (eCO 2 ) (+240 ppm) and temperature (eT) (+4°C) affected chemical composition (silicon, phenolics, carbon and nitrogen) and plant growth in eight grass species, either native or exotic to Australia. eCO 2 increased phenolic concentrations by 11%, but caused silicon accumulation to decline by 12%. Moreover, declines in silicon occurred mainly in native species (-19%), but remained largely unchanged in exotic species. Conversely, eT increased silicon accumulation in native species (+19%) but decreased silicon accumulation in exotic species (-10%). Silicon and phenolic concentrations were negatively correlated with each other, potentially reflecting a defensive trade-off. Moreover, both defences were negatively correlated with plant mass, compatible with a growth-defence trade-off. Grasses responded in a species-specific manner, suggesting that the relative susceptibility of different species may differ under future climates compared to current species rankings of resource quality. For example, the native Microlaena stipoides was less well defended under eCO 2 in terms of both phenolics and silicon, and thus could suffer greater vulnerability to herbivores. To our knowledge, this is the first demonstration of the impacts of eCO 2 and eT on silicon accumulation in grasses. We speculate that the greater plasticity in silicon uptake shown by Australian native grasses may be partly a consequence of evolving in a low nutrient and seasonally arid environment., (© 2017 John Wiley & Sons Ltd.)

Abstract: Systemic sclerosis (SSc) is a rare and potentially severe connective-tissue disease, characterized by skin fibrosis and involvement of internal organs. Because of its rarity and heterogeneous clinical presentation, reliable epidemiological studies on SSc have been particularly difficult to carry out. SSc prevalence is estimated between 3 and 24 per 100,000 population and appears to be higher in North America and Australia as compared to Europe and Japan. Incidence estimates have significantly increased between the fifties and the eighties, but this could result from greater physician awareness of the disease and more reliable ascertainment methods. Risk factors for SSc include female sex and African origin. Reports of sporadic clusters of higher prevalence also suggest environmental risk factors. In particular, silica and solvents exposure has been associated with SSc by several rigorous case–control studies. The ten-year cumulative survival of SSc has improved significantly from 50% in the seventies to over 70% at the present time. Pulmonary fibrosis and pulmonary arterial hypertension are now the two main causes of death. Diffuse cutaneous forms, as well as cardiac, pulmonary, and renal involvement are independent risk factors for SSc-related mortality. [Copyright &y& Elsevier]