210Pb, 137Cs, 241Am dating and Gamma-ray Spectrometry
Internal UW clients, please contact the EIL for information.
Analytical Fees
| Analysis | Minimum | Recommended | Pricing $CAD | CAN Gov/CAN Academic $CAD |
|---|---|---|---|---|
| 210Pb Gamma Ray Analysis | 1g (dry weight) | 5g (dry weight) | $190 | $175 |
| Loss on ignition (LOI) and pre-weighing | $10 | $10 | ||
| Freeze drying | $5 | $5 | ||
| Age Model Report (including activity data of 210Pb, 226Ra, 137Cs, 241Am, 238U, 232Th, 40K) | $100 per core | $100 per core | ||
Additional Information
With four co-axial HPGe well detectors (ORTEC GWL-120-15-XLB-AWT), optimized for high detector efficiency of small samples (1-4cc), the Environmental Isotope Laboratory (EIL) is well-equipped to handle multiple sediment core dating cores and projects simultaneously. Gamma-ray spectrometry typically uses 1-5g dry wt samples for analysis. While more mass generally gives better data quality, though near the top of a sediment core, available sample mass is likely to be low but is generally well compensated for by more far 210Pb activity being present in the recent most sediment intervals. Gamma-ray spectrometry is also a non-destructive analysis so sample mass may be recovered afterwards and be repurposed to any task that can use freeze dried sediment.
With 20 years of 210Pb dating experience, we have built upon success and can offer flexible needs providing 210Pb dating model results (with reported uncertainties) for CRS (recommended), CF:CS (aka linear) CIC age models with 137Cs and 241Am-based dating models as well as using these fallout isotopes to help verify 210Pb age models. The CRS age model also comes with a variable sedimentation rate over time, and with LOI.
As part of our standard approach, we include activity data of those isotopes required for dating of recent sediment (last ~150 yrs): total 210Pb, supported 210Pb (= 226Ra activity from the weighted average of 214Pb and 214Bi activity [3 gamma peaks]), 137Cs and 241Am. We also report activity data of other normally encountered radioisotopes: 40K, 238U, 232Th. If the cores are collected and delivered to use promptly, we may also be able to measure cosmogenic 7Be (t½ =53 days) in the top core slice, indicative of a clean capture of the sediment-water interface.
We use a multi-standard detector efficiency calibration approach, a moving wall of machine blanks to fully account for background so we can produce precise and accurate measurements. Furthermore, we participate in IAEA-TERC (International Atomic Energy Association, Terrestrial Environmental Radiochemistry Laboratory) interlaboratory comparison tests to regularly verify and improve our gamma spectrometry methodologies where appropriate.
Sample submission:
Please contact us to discuss a full core analytical approach with more site-specific information. Our technical staff can provide guidance as to the recommended core length and sediment interval sizes based on project scope, sedimentation rates, and other considerations.