The AEL AMS Laboratory Webinar Series
As a means to reach a broader research community and disseminate information about our laboratory, its technical capabilities, and the wide range of applications in AMS, the A. E. Lalonde AMS Laboratory will be hosting a series of webinars starting in February 2021.
The series will feature our specialized analytical facilities, expert staff, and guest speakers from a variety of fields. The webinars will offer users the opportunity to learn about new AMS techniques, explore applications in their field of interest, and connect with other users in the Canadian research community. We hope that these webinars will inspire new research initiatives that can take advantage of our world class facility.
The AEL AMS Webinar Series will resume Fall 2021. Missed a webinar? Check out the Webinar Archive for recordings and transcripts.
The interpretation in a climate context of synoptic tracer 129I sections across the Arctic Ocean
Guest speaker: Dr. John Smith, Bedford Institute of Oceanography
During the 1990s, discharges of 129I from European nuclear fuel reprocessing plants increased by an order of magnitude resulting in a large, well resolved, tracer spike whose passage through the Arctic and North Atlantic Oceans via the “Arctic Loop Current” has been followed by time series measurements over the past 25 years. This robust and rapidly changing tracer signal has been used in conjunction with other gas (e.g. CFC-11, SF6) and radionuclide tracers (e.g. 137Cs, 236U) to calculate transit time distributions (TTDs), provide time scales for biogeochmical processes and constrain water circulation and mixing time scales for a wide range of high latitude water masses.
Radioactive Waste Regulation, Safety Case, and the Role of Iodine-129
Guest speaker: Dr. Matthew Herod, Canadian Nuclear Safety Commission
The Canadian Nuclear Safety Commission (CNSC) is Canada’s nuclear regulator, responsible for licensing and compliance of all nuclear facilities in Canada. This includes radioactive waste storage and disposal facilities. In the future, the CNSC will evaluate the safety of a potential deep geological repository (DGR) for Canada’s used nuclear fuel when a licence application is submitted. Natural analogues for DGR’s enable investigation of the key safety features of DGR’s in the natural world and assess their performance over geologic time. This experience is then applicable to assessing the ability of similar natural and engineered barriers in a proposed DGR. One of these projects is investigating the production and transport of iodine-129 in the world famous Cigar Lake natural analogue as 129I is the key isotope of concern in DGR safety assessments as it is a mobile fission product found in used nuclear fuel.
Environmental Radiation Surveillance at Health Canada’s Radiation Protection Bureau
Guest speaker: Dr. Kurt Ungar, Head, Verification and Incident, Health Canada
Environmental radiation monitoring at Health Canada’s Radiation Protection Bureau (RPB) has evolved considerably since 1995, first through a program of rationalization including improvements to reliability of the national network field sampling; then to incorporation of a powerful global network providing daily air sample measurements of radioactive aerosols and radioxenon in support of Comprehensive Nuclear-Test-Ban Treaty Verification; and finally through establishment of a network of real-time spectroscopic dosimeters, configured nationally and regionally to improve incident response capability after the September 11, 2001 terrorist attacks on the USA.
Integration of high-performance atmospheric transport and dispersion modelling from Environment and Climate Change Canada allows a multi-scaled use of environmental data from all these networks for effective operational assessments of major incidents releasing radioactivity and assessment of the general radiological situation nationally and abroad. The approach includes a standard characterization of the radiological situation at the network station site but extends RPB’s capability to characterization of emission sources and their influence where measurement data is unavailable.
Lalonde AMS Capabilities for Monitoring of Radioactive Materials in the Environment
Guest speaker: Dr. Liam Kieser, Director, André E. Lalonde AMS Laboratory
The analytical requirements of organizations such as Health Canada’s Radiation Protection Bureau (HC-RPB) can make use of the services of a number of the operational units at the Lalonde Laboratory: Noble Gas, Actinides and Fission Products and Radiohalides – as well as the accelerator system. This presentation will review the capabilities and details of these units, indicating how the design of the 3 MV accelerator system makes high measurement sensitivity possible. To finish, an example of atmospheric monitoring of radioactivity on air filters provided by HC-RPB will be described, as well as the use of those data in air-mass back-trajectory calculations.
How to date a pescatarian: Calibrating radiocarbon dates from mixed marine-terrestrial consumers
Guest speaker: Dr. Alison Harris, SSHRC Post-doctoral Fellow, Department of Archaeology, Memorial University
Humans and animals with mixed marine-terrestrial diets have long posed a problem for radiocarbon dating in archaeology. The global oceans are depleted in 14C which produces an average offset of 400 years between contemporaneous marine and terrestrial radiocarbon-dated samples. When working with the hard tissues of marine organisms, calibration is relatively straightforward, but the situation is more complicated when working with organisms that live in the terrestrial environment, but consume marine resources. In this case, atmospheric and marine carbon, which differ in the abundance of 14C, are both incorporated into skeletal tissues. This presentation will demonstrate an effective strategy for dealing with samples of bone collagen from individuals with mixed diets. Using examples from North Atlantic archaeology, this presentation will show how stable carbon and nitrogen isotope analysis can be combined with statistical dietary modeling to facilitate a weighted calibration against the marine and atmospheric curves.
Radiocarbon dating marine shell: Implications for archaeological interpretation
Guest speaker: Marisa Dusseault, MA/MSc candidate, Physics and Archaeology, Memorial University
Understanding chronologies of coastal settlement through the Holocene era is frequently based on the radiocarbon analysis of marine shells recovered from archaeological sites. Interpreting radiocarbon measurements from marine bivalve mollusk shells depends heavily on our ability to confidently calculate local marine reservoir effects and to detect diagenesis in aragonitic shells. This in turn has consequences for how we understand intra-shell radiocarbon variability and how we use these radiocarbon measurements to build and interpret chronologies in archaeological sites. This presentation uses examples from the Pacific Northwest Coast of Canada to show how we can build greater confidence in radiocarbon dates from marine shell.
Analytical capabilities at the A.E. Lalonde AMS Laboratory in support of archaeological research
Guest speaker: Carley Crann, MSc, Research Scientist, AEL AMS Laboratory
Since installation of the 3MV accelerator mass spectrometer (AMS) at the A.E. Lalonde AMS Laboratory in 2014, the radiocarbon lab has processed over 15,000 samples. The first status report, Crann et al. (2017), outlines the standard pretreatment protocols for archaeological samples falling into broad categories: organics (wood, charcoal, seeds), collagen (bone, teeth, ivory), and carbonates (shell, and now calcined bone). Solvent treatment for pieces that have undergone conservation or tissues that contain fats are also employed. Various qualitative and quantitative observations at each step in the process (physical pretreatment, chemical pretreatment, CO2 extraction, graphitization, pressing, AMS analysis, results) give our skilled technical staff indicators about the quality of the sample, and this information is included in the final report along with radiocarbon results given in both uncalibrated and calibrated units. Stable isotopes (δ13C, δ15N) are important quality indicators for collagen and are now run on all collagen extractions. With the forthcoming installation of a new, carbon dedicated AMS called a MICADAS, the capability to analyze small samples (<400 ugC) will be developed. For archaeologists, this presents the opportunity obtain precise radiocarbon dates on samples that were previously thought to be too small such as individual seeds or forams, or microsamples from museum pieces.
Feedback, collaborative projects, and technique development ideas from our user community are valuable ways to help the radiocarbon lab continue to expand the analytical capabilities and continue to serve the archaeological community at the highest standards. We encourage group virtual tours and other initiatives to engage with our technical and research staff. Even though we can’t currently have visitors to the lab, our motto, “Our doors are always open” is still true!
Re-establishing tritium as a modern tracer for groundwater age-dating in southern Ontario
Guest speaker: Guest speaker: Dr. Elizabeth Priebe, Hydrogeologist, Ontario Geological Survey
The 1963 thermonuclear tritium peak in precipitation was a key hydrogeological time marker, making it possible to estimate groundwater age using a simple exponential decay equation. Today, the tritium peak has since been assimilated by decay and dispersion, and in its absence, age-dating can only be performed with tritium if groundwater samples are also analyzed for its daughter product, 3He. To re-establish tritium as a simple tracer in the present day, the initial tritium input to groundwater as precipitation or recharge must be known. Long-term monthly tritium precipitation values for Ottawa show that annually-averaged concentrations have been constant since the early 1990’s. Unlike Ottawa, tritium concentrations in precipitation in areas proximal to nuclear power plants in Ontario have been observed to fluctuate significantly with time.
In this investigation, we establish an initial tritium input value for any location in southern Ontario by interpolating tritium concentrations in recently recharged, shallow groundwaters. The tritium data and well details are taken from the Ontario Geological Survey (OGS), Ambient Groundwater Geochemistry dataset. Since 2007, the OGS Ambient Groundwater Geochemistry program has collected samples from 2,561 wells across southern Ontario, offering an excellent sample density for interpolation. Our tritium interpolation enables once again, groundwater age estimates with a simple decay equation.
Analytical techniques for tritium analysis at the A.E. Lalonde AMS Laboratory
Guest speaker: Anthony Lapp, Noble Gas Laboratory Manager, AEL AMS
Analytical techniques for tritium performed by AEL and their applications will be discussed including: AMS, liquid scintillation counting, electrolytic enrichment, and 3He-ingrowth. After the atmospheric nuclear weapons test ban and subsequent loss of tritium in the environment, tritium analysis requires us to reach lower and lower detection limits. Nevertheless, tritium remains a valuable tool in hydrological monitoring and will always be relevant when discussing nuclear related activities.