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Jorquera C.O.,Imperial College London | Oates C.J.,Applied Geochemistry Solutions | Plant J.A.,Imperial College London | Kyser K.,Kingston University | And 2 more authors.
Geochemistry: Exploration, Environment, Analysis | Year: 2015

Geochemistry is a key tool in identifying sources of elements for both mineral exploration and environmental purposes. This study evaluates the first systematic regional hydrogeochemical survey for environmental assessments of the classic Andean copper mineral province and the Andina–Los Bronces mining district of Central Chile. One hundred and fortyfive water samples were collected systematically in the Valparaíso and Metropolitana Regions of Central Chile, including the capital, Santiago. The concentrations of more than 70 elements and compounds were determined using inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) along with the stable isotopes (δD, δ18O, δ34S, δ18OSO4, δ15N and δ18ONO3) and used to define the geochemical baselines in the area and distinguish between different sources. The geochemistry demonstrates the potential to distinguish between natural (bedrock, hydrothermal alteration and mineralization) and anthropogenic (agriculture, sewage and urban) sources of elements. The distribution patterns of many chemicals show a strong correlation with the presence of evaporitic components (Ca, SO4 2-, Sr, K, Rb, total dissolved solids (TDS)), hydrothermal alteration and sulphide mineralization (Cu, Zn, Ni, Cd, Co and REEs). High concentrations of nitrate, phosphate and alkalinity occur downstream of agricultural areas and reflect pollution from fertilizers. Overall, the catchment areas affected by mining activities are relatively small and highly localized compared to those affected by agriculture and urban centres. © 2014 AAG/The Geological Society of London.

van Geffen P.W.G.,Kingston University | Kurt Kyser T.,Kingston University | Oates C.J.,Applied Geochemistry Solutions | Ihlenfeld C.,Anglo American
Geochemistry: Exploration, Environment, Analysis | Year: 2015

Eleven partial extraction methods were assessed for their exploration utility on 15 soil samples from a one-kilometre transect over the Palaeoproterozoic Talbot VMS occurrence that is hosted by metamorphic sequences of the Flin Flon-Snow Lake terrane and overlain by 100 m of Palaeozoic dolomites and up to 2 m of Quaternary glacial sediments. Student’s t-test statistics and t-distribution probabilities (Pt) were calculated to evaluate the magnitude and spatial accuracy of anomalies in each dataset. In the surface soil that was analysed, Zn anomalies have the greatest contrast by most methods, followed by P and Cd, albeit mostly restricted to a strong anomaly at a fault zone that is laterally offset c. 100 m from the projection of mineralization. Extraction methods with significant anomaly contrast in decreasing order of exploration utility are Enzyme Leach, deionized water, sodium pyrophosphate, MMI, and ammonium acetate at pH 7. Weaker leaches generate anomalies with greater contrast than stronger acid digests of the soils, which tend to dissolve the sample matrix and overwhelm the secondary signal from adsorbed species of ore indicator elements. Aqua regia digestions on the clay fraction extracted from the soil also have greater contrast than most soil digestions for ore-indicator elements. Continuous-leach ICP-MS analysis of the Talbot soil provides detailed phase relationships that indicate the presence of labile Zn present as organic complexes in anomalous soil over the fault, and the absence of such secondary Zn species in background soil, in which most Zn is released from carbonate dissolution. © 2014 AAG/The Geological Society of London.

van Geffen P.W.G.,Queens University | Kyser T.K.,Queens University | Oatea C.J.,Applied Geochemistry Solutions | Ihlenfeld C.,Anglo American
Geochemistry: Exploration, Environment, Analysis | Year: 2013

Two size fractions of till, <250 μm and <2 μm, humus, moss and black spruce bark, as well as sulphides, host rocks and Palaeozoic cover dolostone from drill cores were sampled at the Talbot Lake volcanogenic massive sulphide (VMS) prospect in the Flin Flon-Snow Lake terrane, Manitoba, Canada. Lead isotope-ratios in organic surface media indicate significant input of anthropogenic Pb from the Flin Flon smelter at 160 km distance to the northwest, with 206Pb/204Pb between 16.5 and 18.2, whereas background till and upper dolostone range between 21.6 and 23.1. At deeper levels, the influx of Pb from Proterozoic mineralization from greater than 100 m depth is recognized. Strontium isotope ratios in these media indicate enhanced vertical fluid flow in the till cover at a fault zone, coincident with the Pb isotope anomaly, as well as relative contributions of Sr from carbonates, silicates and vegetation to the till profile. In humus, sphagnum moss and black spruce bark, the Pb isotope ratios are progressively more similar to that of the feed of the Flin Flon smelter. Measurements of Pb and Sr isotope ratios reveal that Pb from Proterozoic mineralization situated beneath 100 m of Palaeozoic dolostone can be distinguished from Pb contributed by anthropogenic and other geogenic sources. © 2013 AAG/Geological Society of London.

Kaveh F.,Kingston University | Oates C.J.,Applied Geochemistry Solutions | Beauchemin D.,Kingston University
Geochemistry: Exploration, Environment, Analysis | Year: 2014

A fast method for the direct analysis of soils, namely solid sampling (SS) electrothermal vapourization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES), was validated through the accurate analysis of a soil standard reference material (SRM) using another soil SRM as a calibration standard and an Ar emission line as internal standard to compensate for sample loading effects on the plasma. Good agreement was obtained between the measured concentrations and certified values according to a Student’s t-test. The validated method was applied to the determination of the distribution of elements in depth profile soil samples from across the Talbot Lake VMS Cu-Zn prospect, in the Flin Flon-Snow Lake terrane, Manitoba, Canada. These profiles revealed that: Zn, P and Ag had anomalously high concentrations at 20–50 cm depth at 400 m, above where the easternmost part of the ore deposit is located along a 0–1000 m sampling line; Cu, Al, Ba, Pb and Hg were concentrated on the surface and at 40-cm depth mostly between 500 and 600 m; and Cl, Br and I were concentrated at depth at 400 m and over all depths at 600 m. As the geochemical anomaly is known to lie from 400 to 600 m, all these elements could be used to locate the ore. Good agreement was obtained with results by ICP mass spectrometry (ICP-MS) following aqua regia (AR) digestion, for those elements that could be determined by ICP-MS. In fact, not only is sample dissolution unnecessary but qualitative analysis by SS-ETV-ICP-AES is sufficient to obtain depth profiles, including for elements like Cl, which cannot be determined when AR is used for digestion. © 2014, Geochemistry: Exploration, Environment, Analysis, All rights Reserved.

Singh K.,Imperial College London | Ihlenfeld C.,Anglo American | Oates C.,Applied Geochemistry Solutions | Plant J.,Imperial College London | Voulvoulis N.,Imperial College London
International Journal of Mineral Processing | Year: 2011

There is increasing scientific and public concern about the use of synthetic chemicals which may enter the environment especially if they pose a risk to human health. Recent chemical legislation, requires industry to assess the hazards and risks of all chemical substances used in their operations, with increasing financial and legal implications. Chemicals are used intensively in chemical processing industries, agriculture and cleaning, and less intensively, in engineering, welding and woodwork. The mining industry relies heavily on the use of chemicals in most of its operations and it is now required to comply with specific chemical legislation, such as the REACH (Registration, Evaluation, Authorisation and restriction of Chemicals) regulation, introduced by the European Union in 2007. Here we consider the state of the art of understanding the hazards and risks to human health and the environment associated with the use of synthetic chemicals as a basis for developing a risk assessment procedure for the mining industry. Several screening and risk assessment procedures, some used by chemical process industries are evaluated to determine their appropriateness for focusing on hazard identification and exposure estimation. Most of the procedures considered are for single substance assessments, or specific exposure scenarios, and these are used to develop a new framework for risk assessment for synthetic chemicals used in the mining industry, for which the following factors are important: i) the selection of hazardous property categories; ii) the method for scoring hazardous properties of the chemicals considered; iii) the assessment of data quality; iv) the identification of data gaps; and v) the reduction in the number of chemicals that need to be screened. It is important that the method developed must combine aspects of several of the available procedures if the needs of the mining industry in terms of accommodating the range of volumes, exposure scenarios, different uses, unknown mixtures, range of disposal routes and disparities in chemical housekeeping, are to be met. The final system developed, requires a systematic approach to identify which chemicals and ingredients in product formulations are on priority lists, or are likely to be so in the future, as a result of their hazardous or physicochemical properties. Moreover, the system developed must screen situations in which the chemicals are used, in order to determine the most high risk scenarios, so that appropriate measures to prevent and reduce accidents can be taken. © 2011 Elsevier B.V. All rights reserved.

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