Christian Ihlenfeld

Cadmium levels in Europe: implications for human health

In this study we used the Forum of European Geological Surveys geochemical baseline data to examine the distribution of cadmium (Cd) in Europe, with a particular reference to the international soil and water guideline values. The highest cadmium levels were found to occur in topsoil and to follow closely the distribution of P2O5, suggesting that the contamination was from the use of rock phosphate fertilizer in intensive arable agriculture. In terms of human health impacts, food (up to several hundred μg/day) was found as the only major route of exposure to Cd for the non-smoking general population. It appeared that low levels of chronic exposure to Cd resulted in completely different human health impacts than those high levels that had caused the ‘itai–itai’ disease. Some correlations were suggested between cadmium levels and the age-adjusted prostate or breast cancer rates distributed in the European countries under study.

Till and vegetation geochemistry at the Talbot VMS Cu-Zn prospect, Manitoba, Canada: implications for mineral exploration

The Proterozoic Talbot VMS occurrence in the Flin Flon-Snow Lake terrane is buried under more than 100 m of Palaeozoic dolomites and Quaternary glacial till. Structurally controlled anomalies of Zn, Cu, Ag, Pb, Au, Mn, Hg, Cd, Co, Bi and Se in the clay fraction of till depth-profiles indicate upward element migration from the buried volcanogenic massive sulphide mineralisation and near-surface chemostratigraphic deposition. Principal component analysis and molar element ratios indicate that separation of the <2 µm clay fraction reduces chemical heterogeneity and increases trace-element yield relative to the <250 µm fraction of the till. The greatest anomalies occur at or below 30 cm depth and over faults, suggesting that elements were deposited in the till after upward migration through structures. The ratio Zn/Al in the <250 µm fraction can be used as a proxy for Zn in the clay fraction, producing high-contrast anomalies. Carbon isotopic compositions indicate that these anomalies are related to organic carbon in the clay fraction. Humus, moss and black spruce bark are of limited use for exploration in this environment, because they accumulate atmospheric Pb and Cd, most likely from the Flin Flon smelter at 160 km NW. Black spruce tree rings that formed before smelter operations commenced indicate Zn and Mn anomalies in an uncontaminated sampling material. Much of the initial vertical migration of elements to the surface at the Talbot prospect was driven by upward advection of groundwater through fractures in the dolomite, resulting from a combination of subsurface karst collapse and remnant hydrostatic pressure during glacial retreat.

Screening and prioritisation of chemical risks from metal mining operations, identifying exposure media of concern

Metals have been central to the development of human civilisation from the Bronze Age to modern times, although in the past, metal mining and smelting have been the cause of serious environmental pollution with the potential to harm human health. Despite problems from artisanal mining in some developing countries, modern mining to Western standards now uses the best available mining technology combined with environmental monitoring, mitigation and remediation measures to limit emissions to the environment. This paper develops risk screening and prioritisation methods previously used for contaminated land on military and civilian sites and engineering systems for the analysis and prioritisation of chemical risks from modern metal mining operations. It uses hierarchical holographic modelling and multi-criteria decision making to analyse and prioritise the risks from potentially hazardous inorganic chemical substances released by mining operations. A case study of an active platinum group metals mine in South Africa is used to demonstrate the potential of the method. This risk-based methodology for identifying, filtering and ranking mining-related environmental and human health risks can be used to identify exposure media of greatest concern to inform risk management. It also provides a practical decision-making tool for mine acquisition and helps to communicate risk to all members of mining operation teams.

Evaluation of partial digestions for soils to detect a deeply buried VMS Cu-Zn prospect in boreal forests

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.

Lead isotope ratios in till and vegetation over a VMS occurrence under significant allochthonous cover

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.

Inorganic substances screening and prioritization (ISSP) in risk assessment for mining operations

Abstract Metals have been central to the development of human civilization from the Bronze Age to the present although historically, mining and smelting have been the cause of local environmental pollution with the potential to harm human health. Despite problems from artisanal mining in some developing countries, modern mining for Western standards now uses the best available mining technology combined with environmental monitoring, mitigation and remediation measures to control emissions to the environment. The relocation and removal of large quantities of mineral and waste could also release chemicals into the environment including surface water, ground water and soil during the mining life cycle. There are only few published methods available for prioritizing hazardous chemicals. These fail to recognize differences between organic and inorganic chemicals make it necessary to develop separate screening and prioritization procedures for those two different classes of chemicals. In this study, we focus on the development of screening and prioritization procedure in risk assessment for inorganic chemicals with particular reference to those used, generated and released in mining operations.

Regional hydrogeochemical mapping in Central Chile: natural and anthropogenic sources of elements and compounds

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 forty-five 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, SO42-, 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. Supplementary material: A list of anomalously high element concentrations and specific isotopic compositions associated by source is available at: http://www.geolsoc.org.uk/SUP18799