Scottish Universities Environmental Research Centre Research Articles

14C MEASUREMENT OF SAMPLES FOR ENVIRONMENTAL SCIENCE APPLICATIONS AT THE NATIONAL ENVIRONMENTAL ISOTOPE FACILITY (NEIF) RADIOCARBON LABORATORY, SUERC, UK

ABSTRACT The National Environmental Isotope Facility (NEIF) Radiocarbon Laboratory at the Scottish Universities Environmental Research Centre (SUERC) performs radiocarbon measurement of a wide range of sample matrices for applications in environmental research. Radiocarbon is applied to palaeoenvironmental, palaeoceanographic, and palaeoclimatic investigations, as well as work to understand the source, fate, turnover, and age of carbon in the modern carbon cycle. The NEIF Radiocarbon Laboratory supports users in the development and deployment of novel sampling techniques and laboratory approaches. Here, we give an overview of methods and procedures used by the laboratory to support the field collection, laboratory processing, and measurement of samples. This includes in-house development of novel and/or specialized methods and approaches, such as field collection of CO2 and CH4, hydropyrolysis, and ramped oxidation. The sample types covered include organic remains (e.g., plant material, peat, wood, charcoal, proteins), carbonates (e.g., speleothems, foraminifera, mollusc shell, travertine), waters (dissolved organic and inorganic carbon), gases (CO2 and CH4), soils and sediments (including sub-fractions).

Constant 4He Concentration and 190Pt‐4He age of Detrital Pt‐Alloy Grains from the Santiago River, Ecuador: Potential as a 4He Mineral Reference Material

Over the last few decades geo‐ and thermochronological techniques based on the accumulation of radiogenic 4He in minerals have gained popularity. Currently there is no mineral‐based 4He reference material that allows routine screening of gas extraction and measurement procedures. The commonly‐used mineral reference material for (U‐Th)/He thermochronology have variable U and Th contents which result in variable 4He concentrations. Here we demonstrate that native platinum grains (RS‐Pt) from placer deposits in the Santiago River, Ecuador, yield constant 4He contents and may be used as a reference material. Helium concentrations measured at the Scottish Universities Environmental Research Centre (n = 8) and Institute of Precambrian Geology and Geochronology RAS (n = 9) noble gas laboratories yield mean 4He concentrations that overlap at the 95% confidence level. The weighted mean 4He concentration is 215 ± 4 × 1011 at g‐1 (2s) and mean 190Pt‐4He age is 39.6 ± 0.7 Ma (2s). Samples of the Santiago River Pt concentrate are available on request from the SUERC laboratory.

Another 6 years of radiocarbon secondary-standard AMS with two spectrometers

The Scottish Universities Environmental Research Centre (SUERC) has analysed >100,000 individual graphite preparations with two accelerator mass spectrometers. Analysis quality is maintained by a programme of secondary-standards measurement, and annual assessment of the resulting large dataset can provide insight into subtle effects. The same analyses that are used to derive external errors within individual batches of samples, or to monitor inter-batch variance, are also employed in aggregate to determine overall instrument and process performance. The recent 2021 findings are consistent with prior years’, including the apparent contradiction that secondary standard analysis can be both consistent and slightly discordant between the two instruments. However, individual sample radiocarbon measurement on both machines remains accurate and typically 3 ‰ precise.

Advancing dosimetry for Dating Environmental Materials: Development of an ultra-sensitive beta dosimeter system and potential for beta autoradiography

Beta Dose Rate heterogeneity is a recognized source of uncertainty when applying luminescence dating to heterogeneous samples, such as coarse crystalline rocks and clast-rich sediments. Simulations have shown that a combination of a heterogeneous distribution of minerals and radioactive elements can lead to complex dose distributions, overdispersion and potentially to bias in equivalent dose determinations. However setting realistic conditions for such simulations remains difficult, and there are at present only a few experimental validation cases for such simulated systems. Project ADDEM is investigating means of linking Monte Carlo simulations of dose rate to specific minerals with direct observations using high sensitivity phosphor plates and laser scanning imaging systems in combination with phase mapping. To overcome some of the limitations of autoradiographic imaging of low level beta dose distributions work has been undertaken using Landauer alumina OSL phosphor screens in combination with a laser scanning system developed at the Scottish Universities Environmental Research Centre (SUERC). Preliminary excitation spectra, emission band characterization and time resolved measurements were undertaken, confirming the potential to recording low doses using asynchronous stimulation at 635 nm coupled with blue band detection. Taking advantage of the slow decay of the luminescence signal the scanning equipment has been configured for pulsed stimulation and asynchronous detection to maximise signal to background ratios. Exploratory work was calibrated using a 60Co facility capable of calibrating doses in the μGy to mGy range. A series of powdered granulite/basalt mixtures of known mean activity and dose rate (Dr) have also been used to calibrate the phosphor screens. To reduce background levels during autoradiographic signal accumulation rock slices are being exposed in the Zeplin shield of the STFC Boulby Underground Laboratory, in an environment which is essentially free from cosmic ray muon background.Simulations have been conducted providing preliminary deconvolution parameters in order to either reconstruct the beta dose rate (β Dr) distribution received by the grains in the sample, or retrieve the radioactive element distributions in the minerals of the sample, providing the data required for representative simulations of β Dr.This paper outlines the spectroscopy and sensitivity verification of the autoradiography system, confirming its prospects for measuring spatially resolved β Dr distributions with single pixel lower detection limit of 130 μGy and spatial resolution of 150 μm. Prospects are outlined.

OSL signal resetting in young deposits determined with a pulsed photon-stimulated luminescence (PPSL) unit

Optical Stimulated Luminescence (OSL) is a technique that can be used for dating geological materials deposited within the last half-million years, including sediments transported by air, water or gravity, as well as rocks heated at high temperatures. Recently, several studies have shown that OSL can also provide information on sediment transport. The pulsed photon-stimulated luminescence (PPSL) unit (also known as a portable OSL reader) developed by the Scottish Universities Environmental Research Centre is an instrument designed to read luminescence signals from bulk (untreated) sediment samples comprising poly-mineral and poly-grain fractions. In this contribution, we evaluate the potential of the PPSL unit to assess the degree of OSL signal resetting in 27 young deposits (<2 ka) transported by different geomorphic agents in volcanic, coastal and fluvial depositional settings located in Mexico. Our results are in agreement with previous findings that used the Riso TL/OSL reader, confirming that sediments transported by debrisflows contain the highest inherited luminesce signals. Infrared stimulation (IRSL) values in volcanic ash, lavas, and sand beach and dune deposits exhibit low scatter. However, with blue stimulation (BLSL) these samples reveal a large degree of scattering, attributed to charge transfer in the case of the coastal deposits and to the low sensitivity of quartz in the case of volcanic material. The luminescence signals of fluvial sediments exhibit a highly scattered distribution in both IRSL and BLSL. We conclude that the use of a PPSL unit is a simple approach to assess the degree of OSL signal resetting in deposits sourced from different geological environments. This research contributes to previous studies that have investigated new applications of the PPSL unit to assist in OSL dating of geological materials.

AMS 14C Dating at the Scottish Universities Environmental Research Centre (SUERC) Radiocarbon Dating Laboratory

AbstractThis paper describes all the major procedures adopted by the Scottish Universities Environmental Research Centre (SUERC) Radiocarbon Dating Laboratory. This includes sample pretreatment, graphite production, accelerator mass spectrometry (AMS) measurement, associated stable isotope measurements, data handling, and age calculations, but with the main emphasis being on the chemical pretreatment methods. All of the above enable the laboratory to provide a complete analytical service comprising advice on sample selection, preparation and analysis of samples, and Bayesian analysis of resulting 14C (and other) data. This applies to both our research and commercial activities. The pretreatment methods that we mainly focus on are used to remove contaminant carbon from a range of sample types or to isolate a particular chemical fraction from a sample prior to combustion/hydrolysis, graphitization, and subsequent AMS 14C measurement. The methods described are for bone (collagen extraction, with and without ultrafiltration), cremated bone, tooth enamel, charcoal, grain, carbon residues, shell, wood (including alpha-cellulose isolation), peat, sediments, textiles, fuel/biofuel, and forensic samples.

Scyphozoan jellyfish provide short-term reproductive habitat for hyperiid amphipods in a temperate near-shore environment

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 510:229-240 (2014) - DOI: https://doi.org/10.3354/meps10896 Scyphozoan jellyfish provide short-term reproductive habitat for hyperiid amphipods in a temperate near-shore environment Nicholas E. C. Fleming1,2,*, Chris Harrod1,3,4, Donal C. Griffin1, Jason Newton5, Jonathan D. R. Houghton1,2 1School of Biological Sciences, Queen’s University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK 2Queen’s University Belfast Marine Laboratory, 12-13 The Strand, Portaferry, Co. Down, BT22 1PF, UK 3Instituto de Ciencias Naturales Alexander Von Humboldt, Universidad de Antofagasta, Avenida Angamos 601, Antofagasta, Chile 4School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK 5NERC Life Sciences Mass Spectrometry Facility, Scottish Universities Environmental Research Centre, Scottish Enterprise, Technology Park, East Kilbride G75 0QF, UK *Corresponding author: nfleming05@qub.ac.uk ABSTRACT: Hyperiid amphipods (Order Amphipoda, Suborder Hyperiidea) are known to infest gelatinous zooplankton. However, the temporal backdrop to these associations is less clear, given that data are often gathered during discrete sampling events rather than over time. In general, hyperiids are considered to be pelagic: however, for individuals associated with metagenic jellyfishes in temperate shallow shelf seas, this may not always be the case, as the majority of their gelatinous hosts are present in the water column from spring to the onset of autumn. Here, we explored the temporal patterns of colonisation and overall duration of the association between Hyperia galba and 3 scyphozoan jellyfish species (Aurelia aurita, Cyanea capillata and C. lamarckii) in a temperate coastal system (Strangford Lough, Northern Ireland) during 2010 and 2012. Concomitantly, we used carbon and nitrogen stable isotope ratios to examine whether hyperiid infestation represented a permanent association with their host or was part of a more complex life history. We found that jellyfish were colonised by H. galba ca. 2 mo after they are first observed in the lough and that H. galba reached 100% prevalence in the different jellyfish species shortly before the medusae of each species disappeared from the water column. It is possible that some jellyfish overwintered in deeper water, prolonging the association between H. galba and their hosts. However, all the medusae sampled during the spring and early summer (whether they were newly emerged or had overwintered from the previous season) were not infected with hyperiids, suggesting that such behaviour was uncommon or that individuals had become dissociated from their host during the winter. Further evidence of temporary association came from stable isotope data, where δ13C and δ15N isotope ratios were indicative of feeding outside of their host prior to jellyfish colonisation. In combination, these findings suggest alternating habitat associations for H. galba, with the amphipods spending the majority of the year outside of the 3 scyphozoan species considered here. KEY WORDS: Hyperiid amphipod · Scyphozoan · Medusae · Stable isotope analysis · Diet composition · Bayesian analysis Full text in pdf format Supplementary material PreviousNextCite this article as: Fleming NEC, Harrod C, Griffin DC, Newton J, Houghton JDR (2014) Scyphozoan jellyfish provide short-term reproductive habitat for hyperiid amphipods in a temperate near-shore environment. Mar Ecol Prog Ser 510:229-240. https://doi.org/10.3354/meps10896 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 510. Online publication date: September 09, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Argon extraction from geological samples by CO 2 scanning laser step-heating

AbstractLasers are fundamental tools for sampling in geochemical studies and have found wide application in mass spectrometric sample introduction systems. Here we describe an isotope extraction method for 40Ar/39Ar geochronology using a new scanning CO2 laser system. This method can partially un-mix radiogenic (40Ar*) from trapped argon components and provides an alternative to furnace step-heating methods. A key advantage of the laser scanning method developed at the Scottish Universities Environmental Research Centre (SUERC) is the ability to step-heat samples as large as 100 mg to fusion using low raster speeds, although care must be taken to avoid self-shielding of grains and proper laser targeting. The scanning laser extraction system has the potential for lower overall blanks and the ability to run blanks and calibrations between steps of a heating sequence. This provides better control on system performance and characterization during sample measurement and can result in improved data quality.Supplementary material:Ar/Ar data presented in Figures 6a–c and 7 (obsidian) is available at http://www.geolsoc.org.uk/SUP18694.

Chronology of tectonic, geomorphic, and volcanic interactions and the tempo of fault slip near Little Lake, California

Research Article| July 01, 2013 Chronology of tectonic, geomorphic, and volcanic interactions and the tempo of fault slip near Little Lake, California Colin B. Amos; Colin B. Amos † 1Geology Department, Western Washington University, Bellingham, Washington 98225, USA †E-mail:Colin.Amos@wwu.edu Search for other works by this author on: GSW Google Scholar Sarah J. Brownlee; Sarah J. Brownlee 2Department of Geology, Wayne State University, Detroit, Michigan 48202, USA Search for other works by this author on: GSW Google Scholar Dylan H. Rood; Dylan H. Rood 3Accelerator Mass Spectrometry Laboratory, Scottish Universities Environmental Research Centre (SUERC), East Kilbride G75 0QF, UK4Earth Research Institute, University of California, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar G. Burch Fisher; G. Burch Fisher 5Department of Earth Science, University of California, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar Roland Bürgmann; Roland Bürgmann 6Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Paul R. Renne; Paul R. Renne 7Berkeley Geochronology Center, Berkeley, California 94709, USA Search for other works by this author on: GSW Google Scholar Angela S. Jayko Angela S. Jayko 8U.S. Geological Survey, U.C. White Mountain Research Station, Bishop, California 93514, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2013) 125 (7-8): 1187–1202. https://doi.org/10.1130/B30803.1 Article history received: 06 Oct 2012 rev-recd: 05 Mar 2013 accepted: 30 Mar 2013 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Colin B. Amos, Sarah J. Brownlee, Dylan H. Rood, G. Burch Fisher, Roland Bürgmann, Paul R. Renne, Angela S. Jayko; Chronology of tectonic, geomorphic, and volcanic interactions and the tempo of fault slip near Little Lake, California. GSA Bulletin 2013;; 125 (7-8): 1187–1202. doi: https://doi.org/10.1130/B30803.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract New geochronologic and geomorphic constraints on the Little Lake fault in the Eastern California shear zone reveal steady, modest rates of dextral slip during and since the mid-to-late Pleistocene. We focus on a suite of offset fluvial landforms in the Pleistocene Owens River channel that formed in response to periodic interaction with nearby basalt flows, thereby recording displacement over multiple time intervals. Overlap between 40Ar/39Ar ages for the youngest intracanyon basalt flow and 10Be surface exposure dating of downstream terrace surfaces suggests widespread channel incision during a prominent outburst flood through the Little Lake channel at ca. 64 ka. Older basalt flows flanking the upper and lower canyon margins indicate localization of the Owens River in its current position between 212 ± 14 and 197 ± 11 ka. Coupled with terrestrial light detection and ranging (lidar) and digital topographic measurements of dextral offset, the revised Little Lake chronology indicates average dextral slip rates of at least ∼0.6–0.7 mm/yr and <1.3 mm/yr over intervals ranging from ∼104 to 105 yr. Despite previous geodetic observations of relatively rapid interseismic strain along the Little Lake fault, we find no evidence for sustained temporal fluctuations in slip rates over multiple earthquake cycles. Instead, our results indicate that accelerated fault loading may be transient over much shorter periods (∼101 yr) and perhaps indicative of time-dependent seismic hazard associated with Eastern California shear zone faults. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Assessment of Infinite-Age Bones from the Upper Thames Valley, UK, as 14C Background Standards

It is becoming increasingly clear that in order to generate accurate radiocarbon dates for bone collagen samples it is important to determine a sample-specific background correction to account for the greater complexity and higher number of steps in the pretreatment chemistry of this material. To provide suitable samples for the14C community, 7 bone samples were obtained from contexts within British gravel quarries, which according to other dating techniques or stratigraphic information, should be of infinite age with respect to14C. The bones were analyzed at the Oxford Radiocarbon Accelerator Unit (ORAU) and the Scottish Universities Environmental Research Centre (SUERC) to determine their suitability. In this paper, we show that 6 of the samples were indistinguishable from background. Both institutions measured finite ages for sample 387 from Oxey Mead that were statistically indistinguishable. Further work is required to establish whether this is because the bone was intrusive and of a younger age than expected or whether it is contaminated either postdepositionally or in the laboratory. We favor the former explanation because (1) the 2 chemistry laboratories use very different pretreatment schemes, (2) collagen yields were high, and (3) the laboratories produced ages that are in good agreement. The 6 “greater than” age samples will be made available to14C laboratories to be used as background standards.

Assessment of Infinite-Age Bones from the Upper Thames Valley, UK, as 14C Background Standards

It is becoming increasingly clear that in order to generate accurate radiocarbon dates for bone collagen samples it is important to determine a sample-specific background correction to account for the greater complexity and higher number of steps in the pretreatment chemistry of this material. To provide suitable samples for the 14C community, 7 bone samples were obtained from contexts within British gravel quarries, which according to other dating techniques or stratigraphic information, should be of infinite age with respect to 14C. The bones were analyzed at the Oxford Radiocarbon Accelerator Unit (ORAU) and the Scottish Universities Environmental Research Centre (SUERC) to determine their suitability. In this paper, we show that 6 of the samples were indistinguishable from background. Both institutions measured finite ages for sample 387 from Oxey Mead that were statistically indistinguishable. Further work is required to establish whether this is because the bone was intrusive and of a younger age than expected or whether it is contaminated either postdepositionally or in the laboratory. We favor the former explanation because (1) the 2 chemistry laboratories use very different pretreatment schemes, (2) collagen yields were high, and (3) the laboratories produced ages that are in good agreement. The 6 “greater than” age samples will be made available to 14C laboratories to be used as background standards.

Interpreting luminescence data from a portable OSL reader: three case studies in fluvial settings

AbstractOptically stimulated luminescence (OSL) is a technique that has been applied from the mid‐1980s, mainly for sediment dating. The OSL technique is based on sample stimulation by light to determine the luminescence signal that is stored in the crystal lattices of sediment grains after deposition, burial by later sediment and subsequent exposure to ionizing radiation from radioactive elements in the surrounding sediment. In such sediment dating, two parameters are required: the equivalent dose (i.e. the luminescence signal stored in the grains), and the dose rate (i.e. the ionizing energy from α, β and γ radiation emitted by naturally occurring radioisotopes in the deposit, plus the effects of cosmic radiation). In this research, the OSL technique is not used for dating. The study goal is to analyse only the luminescence signals (the total photon counts) in polymineral samples obtained after light stimulation in the blue (BLSL) and infrared (IRSL) wavelengths using a portable OSL reader designed and built at the Scottish Universities Environmental Research Centre (SUERC). Three fluvial case studies – from Cambodia, Australia and Mexico – are used to illustrate the geomorphological interpretations possible with the portable OSL reader data from sediments resulting from a range of different depositional processes. The case studies show that aspects of sediment's transport and depositional processes can be inferred from the portable OSL reader data, providing valuable insights into geomorphological history. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Comparison of 41Ca analysis on 0.5 MV and 5 MV-AMS systems

A comparative study was made between the compact AMS system at the PSI/ETH Laboratory of Ion Beam Physics in Zurich with 0.5 MV terminal voltage and the 5 MV-AMS system at the Scottish Universities Environmental Research Centre (SUERC), Glasgow. Overall 34 urinary samples with 41Ca/ 40Ca ratios in the range from 4 × 10 −11 to 3 × 10 −10 were processed to CaF 2 and aliquots of the same material were measured on both instruments. Measurements on the compact AMS system were performed in charge state 3+ achieving a transmission of 4% at 1.7 MeV beam energy. Under these conditions a suppression of the interference 41K is virtually impossible. However, samples with an excess of potassium can be identified by a shift of the 41Ca/ 41K peak in the Δ E − E histogram of the gas ionization detector employed and a criterion for data rejection can be defined. An overall precision of ∼4% and a 41Ca/ 40Ca background level of 5 × 10 −12 have been reached. For studies with higher demands on the detection limit AMS systems like the one at SUERC are attractive: in charge state 5+ and using a gas stripper beam energy of 27 MeV, a transmission of 5%, a 41K suppression factor of ∼500 and a 41Ca/ 40Ca background level of 3 × 10 −14 are achieved. We demonstrate that both systems are well suited for large-scale 41Ca biomedical applications.

SUERC AMS ion detection

In a short time Be, C, Al, Cl, Ca and I accelerator mass spectrometry (AMS) have been established on the National Electrostatics Corporation (NEC) 5MV pelletron system at the Scottish Universities Environmental Research Centre (SUERC). While summarising the present performance of the system, this report will focus on the details of ion detection, which sample materials are used and the analytical procedures employed for each individual species during routine analysis.All rare isotope detection is with a single flexible detector and ion event analysis system, but switching of analysed species typically requires a detector reconfiguration. Configurations for routine 10Be, 14C, 26Al, 36Cl, 41Ca and 129I detection have been established and will be presented here. Notably, there has proven to be sufficient suppression of the isobaric interferences of 36Cl and 41Ca in the 5+ charge state using an argon gas stripper at a terminal voltage of 5.0MV to allow for routine analysis of these isotopes.

Progress in AMS Target Production of Sub-Milligram Samples at the NERC Radiocarbon Laboratory

Recent progress in graphite target production for sub-milligram environmental samples in our facility is presented. We describe an optimized hydrolysis procedure now routinely used for the preparation of CO2 from inorganic samples, a new high-vacuum line dedicated to small sample processing (combining sample distillation and graphitization units), as well as a modified graphitization procedure. Although measurements of graphite targets as small as 35 μg C have been achieved, system background and measurement uncertainties increase significantly below 150 μg C. As target lifetime can become critically short for targets &lt;150 μg C, the facility currently only processes inorganic samples down to 150 μg C. All radiocarbon measurements are made at the Scottish Universities Environmental Research Centre (SUERC) accelerator mass spectrometry (AMS) facility. Sample processing and analysis are labor-intensive, taking approximately 3 times longer than samples ≥ 500 μg C. The technical details of the new system, graphitization yield, fractionation introduced during the process, and the system blank are discussed in detail.

Capabilities of the New SUERC 5MV AMS Facility for 14C Dating

A new National Electrostatic Corporation (NEC) 5MV accelerator mass spectrometer became operational at the Scottish Universities Environmental Research Centre (SUERC) in July 2002. It has 2 Cs sputter negative ion sources: a 134-sample source (S1) for the routine measurement of all species, and a hybrid source (S2) with 40 spaces for radiocarbon measurements with either graphite or CO2 samples. A number of performance tests on graphite samples have been carried out on both sources. A precison of better than 0.3% is feasible for modern samples on a routine basis. The 14C background of the machine and the graphite preparation process blank are 0.04 ± 0.01 and 0.16 ± 0.05 pMC, respectively, indicating that 14C dating back to ~50 kyr BP is possible. The normalized 14C values for a series of reference materials agree well with the IAEA, TIRI, and FIRI consensus values. Routine measurement of 14C has been underway since May 2003. Preliminary results of performance tests on the CO2 gas ion source are also reported.