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AMS dating groundwater

Radiocarbon Dating Dissolved Organic Carbon (DOC) in Freshwater

Sample size recommended 
1 L (please contact the lab before sending samples)
The lab will only accept filtered samples (0.7 microns or less) with a minimum DOC concentration of 5.0 mg/L. If you don’t know the DOC concentration, please inform the lab.
Please contact us before sending samples lesser than the recommended volume.
Service available
AMS Standard – results reported in 30 business days
Recommended container
Amber glass bottle that allows for as little headspace as possible; narrow-mouth amber glass bottles with closed-top caps are recommended.
NOTE: At this time, we ONLY provide 14C analysis of DOC on freshwater samples. We provide 13C DOC analysis on fresh and brackish waters.
Please DO NOT pretreat the samples with any chemicals.

Note – Fees are inclusive of d13C measurements, quality assurance reports, and 24/7 web access to past results and pending analyses. DOC extraction fee applies in addition to the standard price. Additional fee is charged if Oxygen-18 and Deuterium stable isotope measurements are requested.

Please let us know if your water samples contain salt or have been in the proximity of any location using labeled 14C (artificial 14C).

The collection and/or shipping containers must be new and were not previously used for any purpose.

Beta Analytic cannot accept samples that have been treated with mercuric chloride (HgCl2) or sodium azide (NaN3). We do not have the disposal capabilities for these toxic substances.

Collecting Samples

  1. Be sure to collect water samples at the depth you would like to be studying.

  2. Nalgene-type bottles may be used for sample collection but glass is preferable and highly recommended for long-term storage.

    Both plastic and glass bottles must be pre-cleaned in a 10% hydrochloric acid (HCl) bath and rinsed with deionized (DI) water to remove any possible contaminants. Glass bottles should also be heated at 450˚C for 6 hours to further ensure that there are no contaminants present.

  3. Thoroughly flush the bottle with the sample at least 2 times before collecting the final sample with the aid of a water filter. Use a filter with pore sizes between 0.2-0.7 μm. If samples are not filtered, the DOC signature is at risk of changing while the samples are in transit.

  4. Fill the bottle with as little headspace as possible.

  5. If samples are to be stored for any length of time, they must be refrigerated between 3-5˚C (37-41˚F).

  6. Seal the space between the bottle and the cap with tape to prevent carbon dioxide (CO2) exchange with the atmosphere during shipment.

Other Recommendations

  • Please clearly mark the outside of the bottle with the sample identifier in indelible ink or tamper-proof label.
  • It is helpful to measure the pH, salinity, and DOC concentration prior to shipment but this is not required.
  • Do not add any chemicals to the water samples upon collection, including acids or common sample-preservation compounds.

If possible, samples should be sent chilled or cold (NOT frozen). First-aid ice packs work well for this purpose; they will ensure that samples do not heat up too much while in transit.

Before placing into a cooler or cardboard box, the bottles should be placed inside a plastic bag and sealed. Please use shipping containers with enough packing material to prevent breakage.
NOTE: Beta Analytic WILL NOT return water samples, bottles or coolers.

We recommend commercial courier or ​registered ​first-class mail when sending the samples to the lab. Please email the courier name and tracking number so we can monitor your package.

Dissolved organic carbon (DOC) is the largest pool of organic matter and reduced carbon in the oceans, roughly equal in size to CO2 in the atmosphere (Beaupré 2007). DOC is also found in terrestrial ecosystems and plays an important role in the global carbon cycle, partially due to its ability to transport carbon between different pools in the ecosystem (Kolka 2008). DOC can be sourced from outside the ecosystem (atmospheric carbon, long distance transport) or within the ecosystem (plants/microbial or from soils/sediments), and higher levels of organic material are not uncommon in environments with lower oxygen levels such as swamps (Bruckner 2016).

The measurement of radiocarbon in DOC is a useful tool for identifying the sources and cycling processes of DOC in natural waters, both in freshwater and marine (Xue 2015). While the absolute ages alone can provide information on the sources of the carbon contained in the DOC, it is most useful when combined with additional information, such as 13C measurements or other stable isotope measurements from nutrients such as phosphate or nitrate. This is due to the role of DOC in nutrient cycling and availability in ecosystems.

Along with other nutrients present in the ecosystem, radiocarbon and stable isotope measurements of DOC allow for a more complete picture of an ecosystem’s health. When samples are collected along a transect in a watershed, agricultural area, etc., the data can be used to quantify contributions to the DOC pool from both old and modern carbon sources, determine water quality, and ultimately determine the impact on a particular ecosystem. As an example, a pristine, low-impacted area in the Florida Everglades will have a modern or near-modern radiocarbon age, indicating a relatively low contribution from “old” carbon sources like peat deposits and high contributions from modern sources, primarily CO2 uptake by native wetland C3-plants of atmospheric CO2 (Stern 2007).

References:

  1. Beaupré, S. R., Druffel, E. R., & Griffin, S. (2007). A low‐blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon. Limnology and Oceanography: Methods, 5(6), 174-184.
  2. Kolka, Randall, Peter Weishampel, and Mats Fröberg. Measurement and importance of dissolved organic carbon. Field measurements for forest carbon monitoring. Springer, Dordrecht, 2008. 171-176.
  3. Stern, J., et al. Distribution and turnover of carbon in natural and constructed wetlands in the Florida Everglades. Applied Geochemistry 22.9 (2007): 1936-1948.
  4. Xue, Y., Ge, T., & Wang, X. (2015). An effective method of UV-oxidation of dissolved organic carbon in natural waters for radiocarbon analysis by accelerator mass spectrometry. Journal of Ocean University of China, 14(6), 989-993.
  5. Monica Z. Bruckner (2016). Measuring Dissolved and Particulate Organic Carbon (DOC and POC) (accessed September 2019)