Soil Reference Material Data Sheets : BGS110 to BGS119

The British Geological Survey (BGS) has produced a suite of 10 new soil Reference Materials, BGS110 to BGS119. They are intended for use as quality control samples for the determination of total elemental concentrations in soils. The Reference Materials contain a wide range of concentrations to cater for different analytical needs, interests and industries, e.g. agriculture, geochemical exploration, contaminated land. Data sheets for each of these materials are available on the BGS website https://www.bgs.ac.uk/sciencefacilities/laboratories/geochemistry/igf/Services/referenceMaterials.html

Validation report for the determination of non-purgeable organic carbon by TOC-V analyser

This report describes the validation of Technical Procedure AGN 2.3.8, Determination of Non- Purgeable Organic Carbon (NPOC), in preparation for accreditation of the analytical method by the United Kingdom Accreditation Service (UKAS)

Validation for the transition of SPSS QI Analyst to the SPC for Excel program for quality control charting

The statistical process control charting software utilised by the Inorganic Geochemistry team, SPSS QI Analyst version 3.5, (1998, (QIA)), was no longer viable because it was incompatible with operating system requirements for networked computers. Therefore, an alternative program, SPC for Excel version 5, (2017, (SPC)), has been validated to replace the legacy version of QIA. The benefits of using SPC include but are not limited to the following: Conformity with accredited QC processes according to the Inorganic Geochemistry Analytical Quality Control Operating Procedure (AGN 1.7) Ease of transferring results from the analytical software Program is accessible to computers connected to the network Control charting and recording QC checks are all accomplished using Excel alone User friendly with moderate Excel skills Lower cost per licence than the latest version of the existing software The following document provides evidence to satisfy the requirements of UKAS accredited Standard ISO17025 by validating the new software system against the existing QIA software according to a validation plan using two complementary approaches. Specifically, this validation document comprises: Tests with a synthetic dataset, which confirms that QIA and SPC for Excel produce the same result against the criteria specified by Analytical Quality Control procedures (AGN 1.7) Tests with standards run during a recent large stream water analysis programme, which confirms that QIA and SPC for Excel control charts are able to perform the same quality control checks for analytes in “real” control sample data A comparative table of terminology differences between QIA and SPC for Excel A companion document “SPC for Excel Instruction manual v2_WORKING VERSION”, provides working guidance on the operation of SPC for Excel version 5 2017, located in Appendix 5

Natural and anthropogenic influences on atmospheric Pb-210 deposition and activity in sediments : a review

The determination of the age of a sediment layer is invaluable for understanding geochemical processes and their time-scales. The application of Pb-210 as a radiometric chronometer has been extensively researched in recent years, being applied to a variety of freshwater, estuarine and marine environments worldwide. The estimation of sedimentation rate changes using Pb-210 dating can also provide valuable information on possible causes for variation in a water body’s physiochemical and biological characteristics; making the technique relevant to environmental remediation. However, to reliably draw conclusions based on Pb-210 dating; a comprehensive understanding of the influence that other natural and anthropogenic variables have on Pb-210 is essential. This literature review summarises the key factors which may influence both unsupported Pb-210 deposition from the atmosphere and the unsupported Pb-210 activity found in sediments. The deposition of unsupported Pb-210 is shown to be predominantly via the rain-out mechanism (within-cloud scavenging) as opposed to wash-out (below cloud), and the suppression or release of Rn-222 exhalation from sediments may also be controlled by surface air temperatures and pressures, which consequently will result in seasonal variations in atmospheric Pb-210 concentrations and Pb-210 deposition. Organic matter (OM), silt and clay content also have an influence on the sediment unsupported Pb-210 activity; thus leading to a general consensus of positive correlation between unsupported Pb-210 activity and the OM, silt or clay content as a result of greater adsorption affinity for Pb-210 and an enhanced specific surface area relative to sand and larger particles. Bioturbation will also impact the unsupported Pb-210 activity in sediments, however mathematical models used to estimate this influence still require further refinement to accurately represent activity variation associated with different species’ burrowing techniques and different soil porosities. Anthropogenic influences on sediment unsupported Pb-210 activity may also have been observed i.e. additional Pb-210 from the anthropogenic source, though research on these are limited and further research is advised in assessing the impact of anthropogenic activities such as farming, mining and fossil fuel combustion

An improved approach to characterize potash-bearing evaporite deposits, evidenced in North Yorkshire, United Kingdom

Traditionally, potash mineral deposits have been characterized using downhole geophysical logging in tandem with geochemical analysis of core samples to establish the critical potassium (% K2O) content. These techniques have been employed in a recent exploration study of the Permian evaporite succession of North Yorkshire, United Kingdom, but the characterization of these complex deposits has been led by mineralogical analysis, using quantitative X-ray diffraction (QXRD). The novel QXRD approach provides data on K content with the level of confidence needed for reliable reporting of resources and also identifies and quantifies more precisely the nature of the K-bearing minerals. Errors have also been identified when employing traditional geochemical approaches for this deposit, which would have resulted in underestimated potash grades. QXRD analysis has consistently identified polyhalite (K2Ca2Mg(SO4)4·2(H2O) in the Fordon (Evaporite) Formation and sylvite (KCl) in the Boulby Potash and Sneaton Potash members as the principal K-bearing host minerals in North Yorkshire. However, other K hosts, including kalistrontite (K2Sr(SO4)2) a first recorded occurrence in the UK, and a range of boron-bearing minerals have also been detected. Application of the QXRD-led characterization program across the evaporitic basin has helped to produce a descriptive, empirical model for the deposits, including the polyhalite-bearing Shelf and Basin seams and two, newly discovered sylvite-bearing bittern salt horizons, the Pasture Beck and Gough seams. The characterization program has enabled a polyhalite mineral inventory in excess of 2.5 billion metric tons (Bt) to be identified, suggesting that this region possesses the world’s largest known resource of polyhalite. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed

Developments in Pb-210 methodologies to provide chronologies for environmental change

Chronologies generated from core profiles to apply dates to environmental changes commonly use the measurement of the activity of radionuclides deposited and stratified with physical environmental material. The most commonly reported nuclide to define chronologies covering the last 150 years is Pb-210, for which accepted data processing methodologies in the literature have focussed on the constant rate of supply (CRS) model and the more recently published Bayesian Plum model. This short communication describes a validation approach using defined sediment layers referred to as ‘varve’ counting, which provide known points of reference to account for uncertainty between generated dates from each model using published Pb-210 measurements. A significant improvement in the chronologies was observed when applying reference date corrections to the models. This was shown to be essential in providing confidence in reported datasets and accuracy of predicted chronologies, which will better inform the interpretation of environmental change, e.g. sedimentation rates, climate change, pollution pathways and land degradation. Generated chronologies from both the CRS and Plum methods showed good agreement with the established varve dates (typically < 4-year difference)

UK Geoenergy Observatories, Glasgow environmental baseline soil chemistry dataset

This report describes the environmental baseline topsoil chemistry dataset collected in February-March 2018 (03-18) as part of the United Kingdom Geoenergy Observatories (UKGEOS) project. Ninety, samples were collected from the shallow coal-mine Glasgow Geothermal Energy Research Field Site (GGERFS). The report accompanies the GGERFS Soil Chemistry03-18 dataset. It provides valuable information on soil chemistry prior to installation of the GGERFS-facility boreholes, against which any future change during the development/ running of the facility can be assessed. This information is necessary to help understand and de-risk similar shallow geothermal schemes in the future, provide public reassurance, and inform sustainable energy policy

The validation of the detemination of trace elements by energy dispersive polarised X-ray fluorescence spectrometry

This report describes the validation of method AGN 2.1.6 Analysis of Pressed Powder Pellets by Energy Dispersive Polarised X-Ray Fluorescence Spectrometry for its accreditation under UKAS. It includes additional validation carried out on soil samples undertaken to meet the requirements of the MCERTS Standard for submission of data to the Environment Agency

Mineralogical investigations of the interaction between iron corrosion products and bentonite from the NF-PRO experiments (Phase 2)

This report describes the findings of a second programme of work (Phase 2) undertaken by the British Geological Survey (BGS) on behalf of Svensk Kärnbränslehantering AB (SKB), to characterise the mineralogical alteration of samples of compacted bentonite from experiments that SKB have co-funded in a study by Serco Assurance (Culham Laboratory, Oxfordshire, United Kingdom) to investigate the interaction of iron and bentonite, within the EU Framework 6 NFPRO Project (Smart et al., 2006). Reacted bentonite residues from four NF-PRO Experiments – NFC1, NFC4, NFC7 and NFC13 were examined by BGS using; X-ray diffraction analysis (XRD); petrographical analysis with backscattered scanning electron microscopy (BSEM) with energy-dispersive X-ray microanalysis (EDXA) techniques, cation exchange capacity (CEC) and exchangeable cation analysis; and sequential chemical extraction. In addition, background chemical analysis of altered and background bentonite were also obtained by X-ray fluorescence spectrometry (XRFS). Bentonite immediately adjacent to corroding steel wires was found to have interacted with Fe released from the corroding metal. This resulted in the formation of narrow haloes of altered bentonite around the corroding steel wires, in which the clay matrix was significantly enriched in Fe. Similar observations were observed in bentonite around corroded iron coupons (observed in experiments NFC4 and NFC7 only), although the alteration zones were not as well developed in comparison to those around corroded steel wires. Detailed petrographical observation found no evidence for the formation discrete iron oxide or iron oxyhydroxide phases within the clay matrix but appeared to show that the clay particles themselves had become enriched in Fe. However, data from sequential chemical extraction suggests that a significant proportion (26 to 68 %) of the iron in the altered bentonite is present as amorphous iron oxide or crystalline iron oxides (15 to 33 % of the total iron). Some of the crystalline iron is present as primary magnetite and ilmenite present from the original MX-80 bentonite but part of this will also probably be secondary magnetite formed as a corrosion product of the steel. Nevertheless, sequential chemical extraction analyses also suggest that a large proportion of the iron (11-38 %) may be present within the silicate/clay mineral lattice. The implication of this would be that there has been significant conversion of the original montmorillonite to an Fe-rich clay mineral within these alteration haloes. Although XRD does not detect very much change in clay mineralogy, and suggests that the smectite in the altered bentonite is dioctahedral, it is likely that the subsampling for XRD analysis was on too coarse a scale to be able to resolve the alteration within these very narrow reaction zones around the corroded wires. The alteration observed around the corroded steel wires in experiments NFC4, NFC7 and NFC13 is more complex than that in NFC1 or earlier experiments studied in Phase 1 (Milodowski et al., 2007) or previously by Smart et al. (2006). The reacted bentonite from these experiments exhibited the formation of a Mg-Fe-rich clay mineral or aluminosilicate alteration product. This was formed within the Fe-enriched alteration halo but appears to have formed relatively early and was subsequently partially overprinted or replaced by more Fe-rich aluminosilicate. EDXA microchemical mapping did suggest some slight Mg enhancement in the reacted bentonite from NFC1 but no discrete Mg-rich phase was detected. Whilst Mg may potentially have been derived from the “Allard” reference water used in experiment NFC4, in the case of NFC7 and NFC13 it could only have been derived from the breakdown of the bentonite itself since the porefluid only contained NaCl in these two experiments. XRD observations indicated a slight increase in d002/d003 peak ratio, which could possibly be accounted for by a small amount of substitution of Fe into the octahedral layers of the smectite. This is not supported by exchangeable cation analyses, which show very little exchangeable Fe to be present within the altered bentonite. The cation exchange capacity (CEC) and exchangeable cation chemistry of the bentonite show very little difference in properties between reacted and background bentonite. However, it is also possible that the subsampling for exchangeable cation analysis was also on too coarse a scale to be able to resolve such changes within the fine alteration haloes. Fe released from the corroding steel was also observed to displace Ca2+ from the interlayer cation sites in the montmorillonite component. This was manifested by the marked concentration of Ca at the interface with the corroding metal and along the leading edges of ‘fronts’ of Fe diffusing into the bentonite matrix. The displaced Ca was seen to have reprecipitated as aragonite. The petrographical observations show that the bentonite within the alteration zone, that has reacted with and is enriched by Fe, has a tendency to show significantly reduced shrinkage on sample drying than the unaltered bentonite. Conversely, this would suggest that the reacted and altered clay will also have less ability to swell on hydration with water. This behaviour might be consistent with the partial conversion of the montmorillonite to an iron rich dioctahedral smectite such as nontronite. If this is the case, then this may have important implications for the longterm behaviour of bentonite seals around radioactive waste canisters made of iron or steel