Forum Of European Geological Surveys Research Articles

Direct determination of rare earth elements in natural water and digested sediment samples by inductively coupled plasma quadrupole mass spectrometry using collision cell

The present study is based on the use of a conventional quadrupole ICP-MS for determining directly rare earth elements (REEs) in both fresh or slightly saline waters and digested sediments. The development of a robust method using a collision reaction cell (different collision gases and fluxes have been tested) and kinetic energy discrimination is proposed for the accurate quantification of REEs without any mathematical corrections and preconcentration steps. The choice of He gas over H2 and its flow in the collision reaction cell as well as the isotopes studied are thoroughly discussed with the aim of reducing drastically interferences. The exhaustive list of interferences (argides, chlorides, oxides, hydroxides, hydrides and doubly charged) has been investigated for the first time at different concentration levels, relevant with those found in environmental matrices based on the FORum of European Geological Surveys (FOREGS) database. The interference equivalent concentrations (IECs) have been determined and summarized. Although the impact of barium interferences onto europium and the impossibility to measure Sc have been pointed out, this method has been validated for all the other REEs in aquatic environmental matrices by studying the recoveries of spiked natural waters (5 commercially available mineral waters with dry residues ranging from 22 to 2,513 mg L−1 and a filtrated natural river water from Northern France) with relevant concentrations of REEs. Standard reference materials (i.e. three waters (AQUA-1, SLRS-6 and SLEW-3) and four sediments (BCR-667, HISS-1, Metranal-1 and PACS-3)) were also analysed to ensure the robustness of the method.

A framework for ecological risk assessment of metal mixtures in aquatic systems.

Although metal mixture toxicity has been studied relatively intensely, there is no general consensus yet on how to incorporate metal mixture toxicity into aquatic risk assessment. We combined existing data on chronic metal mixture toxicity at the species level with species sensitivity distribution (SSD)-based in silico metal mixture risk predictions at the community level for mixtures of Ni, Zn, Cu, Cd, and Pb, to develop a tiered risk assessment scheme for metal mixtures in freshwater. Generally, independent action (IA) predicts chronic metal mixture toxicity at the species level most accurately, whereas concentration addition (CA) is the most conservative model. Mixture effects are noninteractive in 69% (IA) and 44% (CA) and antagonistic in 15% (IA) and 51% (CA) of the experiments, whereas synergisms are only observed in 15% (IA) and 5% (CA) of the experiments. At low effect sizes (∼ 10% mixture effect), CA overestimates metal mixture toxicity at the species level by 1.2-fold (i.e., the mixture interaction factor [MIF]; median). Species, metal presence, or number of metals does not significantly affect the MIF. To predict metal mixture risk at the community level, bioavailability-normalization procedures were combined with CA or IA using SSD techniques in 4 different methods, which were compared using environmental monitoring data of a European river basin (the Dommel, The Netherlands). We found that the simplest method, in which CA is directly applied to the SSD (CASSD ), is also the most conservative method. The CASSD has median margins of safety (MoS) of 1.1 and 1.2 respectively for binary mixtures compared with the theoretically more consistent methods of applying CA or IA to the dose-response curve of each species individually prior to estimating the fraction of affected species (CADRC or IADRC ). The MoS increases linearly with an increasing number of metals, up to 1.4 and 1.7 for quinary mixtures (median) compared with CADRC and IADRC , respectively. When our methods were applied to a geochemical baseline database (Forum of European Geological Surveys [FOREGS]), we found that CASSD yielded a considerable number of mixture risk predictions, even when metals were at background levels (8% of the water samples). In contrast, metal mixture risks predicted with the theoretically more consistent methods (e.g., IADRC ) were very limited under natural background metal concentrations (<1% of the water samples). Based on the combined evidence of chronic mixture toxicity predictions at the species level and evidence of in silico risk predictions at the community level, a tiered risk assessment scheme for evaluating metal mixture risks is presented, with CASSD functioning as a first, simple conservative tier. The more complex, but theoretically more consistent and most accurate method, IADRC , can be used in higher tier assessments. Alternatively, the conservatism of CASSD can be accounted for deterministically by incorporating the MoS and MIF in the scheme. Finally, specific guidance is also given related to specific issues, such as how to deal with nondetect data and complex mixtures that include so-called data-poor metals. Environ Toxicol Chem 2018;37:623-642. © 2017 SETAC.

Rare earth elements in French stream waters — Revisiting the geochemical continental cycle using FOREGS dataset

The geochemical behavior of rare earth elements (REEs) has been investigated mainly in geological systems where these elements represent the best proxies of processes involving the occurrence of an interface between different media. This behavior is assessed according to REE concentrations recorded along the REE series normalized with respect to upper continental crust. In this study based on a field approach, the geochemical behavior of REE was investigated in French stream waters. This study is based on FOREGS (Forum of European Geological Surveys) Geochemical dataset that consists on a sampling at regular mesh on all Europe. In France, 119 stream water samples were extracted in drainage basins <100km2. The aim of the study is that of describing the spatial variation of REEs and finding the hydro-topo-geochemical factors that affect their distribution by means of a Multivariate Factorial Kriging.On the basis of their atomic number and of the results of a preliminary Principal Component Analysis three REEs have been selected (La, Eu and Lu) and five physicochemical properties (pH, organic carbon, carbonates, Fe, Mn). A cokriging has been applied that shows a similar spatial organization of REEs: higher values are especially observed in the Aquitaine basin. In order to investigate more deeply on the different sources of variation acting in the study area, a factorial cokriging is applied. The first 2 regionalized factors have been estimated to give a synthetic description of the studied process at the different selected spatial scales. At higher spatial scales (250km) environmental parameters like Fe, carbonates, and pH, supposed to be ascribed to the rock's nature or to other geological larger scale processes (i.e., hydrographic network and topography), have shown to affect REE distribution. At short range, only Eu and Mn weigh more, which are ascribed to the process of liberation of Mn oxides in rivers that also release the REEs sorbed onto these oxides.

The FOREGS repository: Modelling variability in stream water on a continental scale revising classical diagrams from CoDA (compositional data analysis) perspective

The investigation of variability that characterises stream water composition is a very important item since the role of the weathering processes that have acted during geological time can be recognised. Several methods are often used to achieve this aim, starting from bivariate diagrams towards more complicated multivariate or inverse procedure approaches. In the first case, several examples are known like the Gibbs's diagram or other diagrams with molar ratios sharing a common denominator or tri-linear plots. In all cases, the basic idea is to identify compositions related to the dominance of specific geochemical processes (rock weathering, evaporation, dilution by precipitation and runoff, pollution) to be then used as reference terms to interpret the meaning of new data when located in the same framework. For this reason, the diagrams were derived from experimental data, but considering information on a very wide scale, continental or worldwide. The chemical data of the most important rivers of the world were thus often considered. In this context, the use of information about water collected in monogenetic basins, characterised by a well-defined lithology has improved the use of these tools, thus clearly characterising the chemistry of water interacting with silicates or carbonates or other type of material. However, the use of binary diagrams may be highly compromised when compositional data are analysed, due to their constrained nature and positivity. In particular, because of their construction, it is not possible to apply statistical analysis correctly on the Gibbs's diagram or on diagrams with coordinates given by molar ratios, since they represent non-orthogonal directions, thus limiting the modelling phase.In this paper, a revision of the Gibbs's diagram is presented proposing an approach coherent with the nature of compositional data, thus obtaining a simple tool to be used in a statistical sense, going beyond the descriptive approach. The chemical composition of the European stream water samples derived from the FOREGS (Forum of European Geological Surveys) repository is used to verify the proposed method, and to evidence the processes affecting the aqueous solutions on such a continent-wide scale, thus giving a convenient tool that can be also used to compare statistically the chemistry of new data.

Ce, La and Y concentrations in agricultural and grazing-land soils of Europe

Ce, La and Y from agricultural (Ap) and grazing land (Gr) soils of Europe have been investigated using new geochemical data produced by the GEMAS (Geochemical mapping of agricultural and grazing land soils) project. Interpolated maps showing Ce, La, and Y distributions in Ap and Gr were generated using ArcView and classified with the concentration — area (CA) fractal method. The median values of the investigated elements show similar concentrations in Ap and Gr soils, while the median values obtained by XRF-total analyses are generally higher than those obtained by aqua regia extraction, ICP-MS (aqua regia). In general, high pH alkaline soils have higher REE concentrations while specific anomalies can often be correlated with known phosphate and REE mineralizations. The GEMAS and the topsoils media from the FOREGS (Forum of European Geological Surveys) Project databases are compared. FOREGS geochemical data shows larger extended anomalies, such as the European wide north–south division, which are difficult to attribute to local processes, while the GEMAS anomalies are spatially more restricted, and can be related to a number of more local factors (e.g., climate, geology, pH, clay content and presence of till).

Rare earth element distribution and mineralization in Sweden: An application of principal component analysis to FOREGS soil geochemistry

This paper presents results of statistical analyses and spatial interpretations of distributions of rare earth elements (REEs) in Sweden using the Forum of European Geological Surveys (FOREGS) geochemical database of topsoil, subsoil and stream sediment compositions. Raster maps depicting spatial distributions of individual REEs were created by interpolation of uni-element data and then principal component (PC) analysis was carried out on the REE data to identify geochemical anomalies associated with bedrock lithology and known mineralizations. The spatial distributions of REEs in Sweden are studied using only the Swedish data subset and the entire European data set. The light rare earth elements (LREEs) La, Ce, Nd and Sm show good correlations among each other but not with Eu. The heavy rare earth elements (HREEs) including Tb, Dy, Ho, Er, Tm, Yb and Lu also show good correlations among each other but not necessarily with the LREE. La, Ce and Nd are the most abundant REEs in all the studied media (topsoils, subsoils and stream sediments), with average median concentrations of 25.3mg/kg, 53.6mg/kg and 23.9mg/kg, respectively. The total explained variances of the first two PCs of each of the REE dataset for topsoils, subsoils, and stream sediments are 95.4%, 95.8% and 95.2%, respectively. Biplots of the first two PCs of each of the REE dataset for topsoils, subsoils, and stream sediments commonly reveal two distinct groupings – HREEs and LREEs – whereas biplots of PC1 versus PC3 of these datasets commonly reveal three distinct groupings – Eu, Ce and other REEs. The main difference between the distribution patterns of LREE and HREE is likely due to enrichment of the LREEs in the Archean bedrock underlying northern Sweden. HREE concentrations in the Archean to Paleoproterozoic metasediments are rather low. Color composites of PC maps produced from the topsoil and subsoil datasets clearly reflect the Archean rocks in northern Sweden and outline the second phase of the Svecokarelian orogen.

Mapping geochemical patterns at regional to continental scales using composite samples to reduce the analytical costs

The use of composite samples to reduce the time and cost of chemical analysis is discussed. It is shown when composite samples can be used without affecting predefined project objectives. Furthermore, it is also demonstrated when they should not be used, and also how much information is lost due to their use.The study presents a comparison of data concentrations of some major (Al2O3, CaO, Fe2O3, K2O, P2O5, TiO2) and trace elements (Cd, Co, Cr, La, Rb, Sr, Th, Tl, U, Zn) in European topsoil and subsoil produced by FOREGS (Forum of European Geological Surveys) and two other data sets derived by compositing the five individual samples in each 160×160km cell of the Global Terrestrial Network (GTN); the first by physically compositing the samples, and analysing the composites, and the second by artificially compositing the samples in each GTN cell.The three soil databases were compared statistically and spatially to quantify the significance of the differences. The results of this study clearly demonstrate that composite samples can be used effectively to show broad continental-scale element distribution patterns; their use may not be effective if the goal is to highlight local geochemical anomalies. It is concluded that compositing samples for continental-scale surveys is a time- and cost-effective procedure, especially for reducing the costs for chemical analysis.

Comparison of results analyzed by Chinese and European laboratories for FOREGS geochemical baselines mapping samples

Geochemical subsoil data obtained from China and European laboratories have been compared in this study. 787 C horizon subsoil samples from FOREGS (Forum of European Geological Surveys) geochemical baselines mapping project were sent to China’s IGGE (Institute of Geophysical and Geochemical Exploration) laboratory and composited to 190 samples according to the 160 km × 160 km GNT (Global Terrestrial Network) cells. In addition to the FOREGS elemental analysis package, Au, Pt, Pd, B, Ge, Br, Cl, Se, N, Li and F were also analyzed by using the IGGE’s 76 element analytical scheme. Geochemical data statistics, scatter plotting, and geochemical map compilation techniques have been employed to investigate differences between FOREGS and IGGE analytical results. The results of two datasets, the IGGE’s analysis data for composited samples, and the FOREGS average data of samples in each GNT cell, agree extremely well for about 23 elements, viz: SiO 2, Sr, Al 2O 3, Zr, Ba, Fe 2O 3, Ti, Rb, Mn, Gd, CaO, Ga, MgO, P, Pb, Na 2O, Y, Th, As, U Sc, Cr, and Co. There are slight differences between-laboratory biases shown as proportional errors between the datasets for Ni, K 2O, Tb, Tl, Cu, S, Sm, La, Ce, Pr, Nd, Eu, Ho, Er, Tm, Yb, Lu, Ta, Nb, Hf, and Dy. For Cd, Cs, Be, Sb, In, Mo, I, Sn, and Te, the correlation of the two datasets and the similarity of the geochemical maps are fairly good, but obvious biases exist between the two datasets at values near detection limits. Sensitivities of FOREGS analytical methods for W, Bi, Sn, Te, Be, and I are insufficient to produce reportable values in at least 80% of the samples. Although the detection limits of Ag for both FOREGS and IGGE are sufficient to provide reportable values, a large bias was found between the two datasets. This study demonstrates that consistent analytical data for certain elements of global geochemical mapping samples can be achieved by different qualified laboratories, such as China’s IGGE laboratory and some European laboratories. For some elements, such as Ag, further research on the selection of the proper analytical methods and on the development of quality control methods should be undertaken — with final recommendations adhered to by all participants of the global geochemical mapping program.

The rare earth element distribution over Europe: geogenic and anthropogenic sources

The distribution of rare earth elements (REE) in Europe has been investigated using new geochemical data prepared by the Forum of European Geological Surveys (FOREGS), to estimate baseline values and to identify anomalous levels attributable to anthropogenic sources. Interpolated maps showing REE distributions in subsoils were generated using ArcView™ and classified with the new concentration–area (CA) fractal method available in the software GeoDAS™; they identify three broad ranges for baseline REE levels that are related to regional geological/geomorphological features. A combination of REE spider diagrams and interpolated maps showing REE distributions in floodplain and stream sediments was used to investigate anthropogenic sources of REE in Europe. It is concluded that the large-scale distribution patterns of REE over Europe are entirely attributable to geology. No evidence has been found of REE contamination from likely anthropogenic sources such as the electronics or nuclear industry. Three component colour maps of REE ratios (Gd/Lu, Eu/Eu* and La/Y) were used to identify the major plates of the Variscan orogeny and Variscan granites caught up in Alpine nappes in Italy.

Application of factorial kriging analysis to the FOREGS European topsoil geochemistry database

Concern about increasing levels of trace elements in the environment has led to the development and implementation of a global programme to determine the current baseline levels of these chemicals in the Earth’s surface. The FORum of European Geological Surveys (FOREGS) has recently published a geochemical database for Europe, while progress on similar databases is continuing in other major regions of the world. The FOREGS database comprises multimedia samples collected at a resolution of approximately 72 × 72 km from 26 European countries. This enables the investigation of the factors governing geochemical variation on a continental scale, potentially allowing contributions of natural processes to be appreciated prior to setting environmental quality standards. This paper investigates the variation in European topsoil geochemistry using factorial kriging analysis, which performs principal components analysis at different spatial scales. The results are interpreted with the aid of a GIS database. Four spatial scales were identified: a nugget component representing variation over a range less than the sampling density; a ‘short’ scale component with a range of 296 km; an ‘intermediate’ scale component (875 km); and a ‘long’ scale component (1750 km). The first three principal components (PCs) of the nugget covariance matrix explained 22.2% of the overall variance, representing local variation in geology, land use, weathering and organic matter content. The first two PCs of the short range structure explained 12.6% of the variance, representing variation according to the major structural divisions of Europe, and to carbonate content. The first PC of the intermediate structure explained 7.2% of the variance and was found to relate to glacial history and Quaternary deposition. Finally, the first three PCs of the long range structure explained 29.6% of the variance and represented variation due to mineralisation, soil texture, climate and possibly anthropogenic contamination.

Chemicals in the environment: implications for global sustainability

The impact of chemicals on the environment and human health is a cause of increasing concern. Although many studies continue to be carried out on this subject, most address only individual chemicals or particular groups of chemicals, such as metals or radioactive substances. In this paper, we consider the availability of data and knowledge about potentially harmful chemicals from the national to international scale and suggest a strategy to help prevent chemical pollution or deficiencies damaging global sustainability into the 21st century. The main groups of chemicals considered are:(i) Potentially harmful inorganic elements such as As, Cd, Hg and Pb known to have adverse physiological effects at low levels, and elements and species such as Se, I and NOx that can be essential or harmful depending on their concentration, speciation and bioavailability. Chemical elements such as Ga, In and the PGEs that are increasingly used in the development of new materials, including nanotechnology applications, are also discussed briefly.(ii) Radioactive substances, including naturally occurring radioisotopes, such as 238U and its decay products 226Ra and 222Rn, and processed materials, such as depleted uranium (DU), which affect the environment and human health because of their radiological and chemical toxicity. Data on isotopes from the nuclear industry, such as the relatively short-lived isotopes 137Cs and 90Sr, are also discussed, including from accidental releases such as Chernobyl in 1986. Isotopes with longer half-lives such as 243Am and 240Pu, which are important in the development of nuclear waste management strategies are also considered.(iii) Persistent organic pollutants (POPs) including many synthetic chemicals such as dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), flame retardants and their metabolites, which are characterised by their persistence, bioaccumulation (lipophilicity) and toxicity (PBT) properties. Other synthetic chemicals such as perfluorooctane sulphonate (PFOS), which have different bioaccumulation properties, are considered briefly.(iv) Human and veterinary pharmaceuticals, of which there is increasing evidence of their presence in the environment. These substances are of particular concern because many are designed to target specific biological receptors and hence can have potentially deleterious effects at exceptionally low concentrations.All these groups of chemicals include endocrine disrupting chemicals (EDCs), capable of disrupting animal and human hormone systems (including sex and thyroid).Geochemical databases such as those prepared by the Forum of European Geological Surveys (FOREGS) and the British Geological Survey (BGS) provide systematic information on levels of inorganic chemicals in the environment. Similarly, airborne radiometric databases provide systematic information on the distribution of radioactive substances. Examples of such data are used to demonstrate how the distribution of chemicals in the environment can be mapped, and how modelling and monitoring systems derived from them are of strategic importance in understanding the impact of chemicals on ecosystems and human health from the national to global scale. There is concern, however, about the lack of such systematic data for organic chemicals. It is argued that such systematic data for all chemicals is crucial for sustaining the Earth's life-support systems into the 21st century.

The distribution of uranium over Europe: geological and environmental significance

The variation of baseline levels of uranium in soil and stream sediments over Europe is described, based on new data prepared by the Forum of European Geological Surveys (FOREGS). The samples have been collected and analysed according to the protocols established for the International Union of Geological Sciences/International Association of Geochemistry and Cosmochemistry (IUGS/IAGC) Working Group on Global Geochemical Baselines. The baseline levels of U vary between 0·21 to 53 mg kg-1 in topsoils, 0·19 to 30 mg kg-1 in subsoils and < 1 to 59 mg kg-1 in stream sediments. There is generally good agreement between the levels of U in the three sample types, and the median concentration in all three media is approximately 2 mg kg-1. The most anomalous baseline levels occur over the Variscan orogen, especially areas into which late postorogenic radiothermal high heat production (HHP) granites were emplaced. Spiderdiagrams based on trace element levels and rare earth element (REE) plots, confirm the association between the highest U anomalies and evolved radiothermal granites. High values are also associated with parts of the Alpine terrain especially in Slovenia, where there are historical U workings, and Southern Italy, where high values of U reflect contemporary volcanism. In contrast, much of the Caledonides of North West Europe and the Precambrian of the Baltic Shield and East European craton and its overlying sedimentary cover have very low values, generally < 4 mg kg-1. The results suggest that the main concern for the environment and human health from U, and the Th and K with which it is generally associated, is the naturally occurring total gamma radiation and radon potential associated with radiothermal granites. This is likely to be especially important where the granites are mineralised and have been worked historically, for example in the North West of the Iberian Peninsula where U and its decay products are likely to be more dispersed in the surface environment. The study also indicates the value of multielement data in distinguishing between anthropogenic and naturally occurring anomalies.

The Forum of European Geological Surveys Geochemistry Task Group inventory 1994–1996

The Forum of European Geological Surveys (FOREGS) includes representatives from 33 European countries and is responsible for co-ordinating Geological Survey activities in Europe. The FOREGS Geochemistry Task Group was established in 1994 to develop a strategy for the preparation of European geochemical maps following the recommendations of the International Geological Correlation Programme (IGCP) Project 259 ‘International Geochemical Mapping’ (now the International Union of Geological Sciences (IUGS) /International Association of Geochemistry and Cosmochemistry (IAGC) Working Group on Global Geochemical Baselines). The FOREGS geochemistry programme is aimed at preparing a standardised European geochemical baseline to IGCP-259 standards. The principal aims of this dataset will be for environmental purposes, as a baseline for the assessment of the extent and distribution of contaminated land in the context of variations in the natural geochemical background, but it will also have applications in resource assessment and for the development of policy for the sustainable management of metalliferous mineral and other resources. The first phase of the programme was the compilation of an inventory of geochemical data based on the results of a questionnaire completed by Geological Surveys and related organisations throughout the FOREGS community. The results show that the sample types which have been used most extensively are stream sediment (26% coverage), surface water (19% coverage) and soil (11% coverage). Stream sediments have been collected using a narrow range of mesh sizes (< 150–< 200 μm), but soil samples have been collected according to two different conventions: some surveys used a similar mesh size range to that used for stream sediments while others employed the < 1000 or < 2000 μm fractions traditionally used by soil surveys. Sample densities range from 1 sample per 0.5 km 2 to 1 per 3500 km 2. Various analytical methods have been used, but most of the available data have been calibrated using international reference materials, and data for the most important of the potentially harmful elements (PHEs) are available for most datasets. Systematic radiometric data are available for only a small proportion of Europe, a situation which compares very unfavourably with that in Australia, North America, the former Soviet Union and many developing countries. Recommendations are made for increasing the compatibility of geochemical methods between national geochemical surveys as a basis for the preparation of a series of European geochemical maps. The next stage of the FOREGS Geochemistry Task Group will be the collection of the Global Reference Network of samples against which to standardise national datasets according to the methods recommended in the final report of the IGCP 259 programme.

Regional geochemical mapping of Western Europe towards the year 2000

The Directors of the Western European Geological Surveys (WEGS, presently the Forum of European Geological Surveys, FOREGS) created in 1985 a Working Group on “Regional Geochemical Mapping” for the study of different aspects of regional geochemical surveys. The Working Group proposed to the Directors a systematic low sampling density regional geochemical mapping project to obtain baseline data. Following this proposal for a systematic low sampling density regional geochemical mapping programme of Western Europe a three-year (1988–1990) Pilot Project was carried out. Its objectives were (1) to prepare an inventory of regional geochemical mapping already completed in Western Europe, and (2) to assess the scope and limitations in the use of overbank and stream sediment as sample media in wide-spaced regional geochemical mapping. Based on the results obtained in the Pilot Project, the Directors decided that more research was required before taking a final decision. The Working Group was asked to carry out further research and to submit its final report in 1993. The WEGS Working Group collected and evaluated a substantial amount of information during the pilot and research projects. This paper summarises the main results of the research work carried out from 1986 to 1992.