How to Prevent Contamination of Core Samples Stored for Future Radiocarbon Dating

There can be problems encountered when radiocarbon dating cores (organic sediment fraction) that have been stored for long periods of time depending on the storage conditions.

When cores are stored damp, contaminants like mold, mildew and other fungus can thrive and grow in the cores thereby introducing new carbon. Sometimes these mold, mildew and fungus get there carbon solely from:

(1) the organic substances in the cores
(2) from the atmosphere only, and
(3) from both the organic substances in the core and the CO2 in the atmosphere.

In situations 2 & 3, the radiocarbon ages can be biased in the more recent direction by some unknown amount.

If radiocarbon dating is being performed on forams, shells or other carbonates found in the core, then core drying or freezing is not a requirement as any mold, mildew or fungus won’t affect the age of the shells. This is also true for larger chunks of wood, plant or charcoal as the lab can aggressively pretreat them before analysis.

Storage Tips

The best way to store cores is to immediately dry them out so that mold, mildew and fungus will not grow. If this is not possible, then the cores should be covered in plastic wrap with all of the air removed. The wrapped core should then be kept solidly frozen in a sub-zero freezer.

Please note however that such storage conditions do not 100% inhibit the growth of these contaminants. The best situation is to always collect the core and perform radiocarbon dating immediately.

Carbon Dating Services for Sediment Cores

ISO 17025-accredited Beta Analytic provides two services for carbon dating sediment cores: 

• AMS Standard – results are reported in 14 business days or less
• AMS Priority – 6 business days or less

Fees are inclusive of δ13C analyses if sample size permits, quality assurance reports, calendar calibration when applicable, and 24/7 web access to past results and pending analyses.

You may find these topics interesting:
* Sample Collection Best Practices video in our Radiocarbon Dating Sediments page
* Recommendations for Preparing & Collecting Sediment for Analysis (PNG)
* Free Sediments Webinar: C14 Dating, U-Th Dating, Sr Analysis

Radiocarbon Dating Prices

Please use this contact form for price inquiries or estimate/quotation requests. Let us know how many samples you plan to analyze, the service requested (AMS Standard or AMS Priority), and the billing information of the paying institution.

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