AMS dating groundwater

Radiocarbon Determination of Dissolved Organic Carbon (DOC) in Freshwater (salinity≤ 0.5 ppt/psu)

recommended sample size Sample size recommended
  • We recommend sending 1.0 L of sample water. Please contact us before sending samples below the recommended volume.
  • The laboratory will only analyze filtered samples (0.7 µm or less) with a minimum DOC concentration of 5.0 mg C/L (5.0 ppm). Beta Analytic charges separate fees for the DOC extraction.
recommended container Required containers
  • Single-use Amber Glass or Brown Nalgene (HDPE) bottles that allow for as little headspace as possible; bottles with closed-top caps is required.
  • The bottles must be NEW and not previously used for any purpose.
  • Bottle must be pre-acid washed with 10% HCl (aq) and rinsed with DI water to a neutral pH.
lab recommendation
  • NOTE: At this time, we ONLY provide carbon-14 analysis of DOC on freshwater samples. We provide carbon-13 DOC analysis on both fresh (≤ 0.5 ppt, or parts-per-thousand/psu, salinity) and brackish (0.5 – 30 ppt/psu salinity) waters.
  • Please DO NOT pretreat the samples with any chemicals. Note: We cannot accept samples that have been treated with mercury (II) chloride (HgCl2) or sodium azide (NaN3) because we do not have the disposal capabilities for these toxic substances.
  • If your water samples contain salt at a greater concentration than 0.5 ppt/psu, please inform the laboratory.

Note – Fees are inclusive of δ13C 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 fees are charged if oxygen-18 and hydrogen-2 stable isotope measurements are requested.

Sampling Limitations

printed sampleWe are a NATURAL Level carbon-14 testing laboratory and cannot accept water samples that have been collected from any area that is near nuclear power plants, commercial or medical reactors, or industrial/medical waste disposal sites, or from within their drainage areas. The water samples must not be stored or handled in any laboratory or area that uses OR has ever been used in a biomedical facility with artificially labeled carbon-14 at any time.

Should you suspect that your samples may in any way have elevated carbon-14 activities above peak Bomb Carbon levels (~200 pMC / 2.0 F14C), please DO NOT send the samples for testing. Water samples that produce activities above 200 pMC will incur extensive costs related to any cleanup necessary, equipment replacement, and duplicate analyses required for other samples. These costs could easily run into the tens of thousands of dollars, which you will be responsible for as the submitter.

Collecting Samples

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

  2. Nalgene-type bottles may be used for sample collection, but glass is preferable and highly recommended for long-term storage. Regardless of material type, the bottle should be opaque to prevent light exposure of the sample. Chemical reactions that occur with oxygen in the presence of light may alter the DOC signature of the sample. Nalgene and glass bottles must be pre-cleaned in a 10% hydrochloric acid (HCl) bath and rinsed with deionized (DI) water to a neutral pH to remove any possible contaminants. Glass bottles may 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 water at least 3 times before collecting the final sample with the aid of a water filter. Use a filter with pore sizes at 0.7 μm or below. If samples are not filtered, the 14DOC signature is at risk of changing while the samples are in transit.

  4. Fill the bottle with little to no headspace.

  5. If samples are to be stored for any length of time, they must be refrigerated between 3-5 ˚C (37-41˚F). Beware that glass bottles containing the water sample may crack if they are frozen.

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

Other Recommendations

  • Please clearly mark the outside of the bottle and the outer plastic bag with the same sample ID that is listed on the sample in indelible ink or tamper-proof label.
  • It is helpful to measure the pH, salinity, UV Absorbance at λ254 nm, and DOC concentration of your sample 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, such as mercury (II) chloride (HgCl2) or sodium azide (NaN3). If samples are pre-acidified, please contact the laboratory prior to submission.

Samples should be sent chilled or cold (NOT frozen). Long-lasting ice packs (i.e. cooler ice packs, cooler shock, or ice block) work well for this purpose; they will help ensure that the water samples maintain low temperature conditions while in transit to our testing laboratory

Before placing them 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.

Customers must a commercial courier or registered first-class mail when sending samples to the lab. Please send an email with the courier’s 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 (from plants/microbes or 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 changes in the sources and cycling processes of natural waters, both in freshwater and marine water systems when monitored over time (Xue 2015, Xu 2021).

DOC is most useful when combined with additional information, such as δ13C 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 its 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 (Stern 2007).

References:

  1. Beaupré, S. R., Druffel, E. R., & Griffin, S. A low‐blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon. Limnology and Oceanography: Methods, 2007, 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, 2007, 22,1936-1948.
  4. Xue, Y., Ge, T., & Wang, X. 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, 2015, 14(6), 989-993.
  5. Xu, L., et al. Radiocarbon in Dissolved Organic Carbon by UV Oxidation: Procedures and Blanks Characterization at NOSAMS. Radiocarbon, 2021, 63, 357-374

View Beta Analytic’s Publications & Free Webinars

Using environmental tracers to evaluate the preservation of palaeoclimate signals in aquifers of the London Basin, UK (Journal of Hydrology 2023)

Isotopes 101: Dissolved Carbon

Recommended Literature:

Beta Analytic is merely facilitating these literature recommendations as a resource to the community. The company and the services we offer do not have any relationship or endorsement to those research or methods referred to in the recommended literature below.

Heine, F. & Einsiedl, F. Groundwater dating with dissolved organic radiocarbon: A promising approach in carbonate aquifers. Applied Geochemistry, 2021, 125, 104827

Godfrey, L., et al. δ13C and 14C activity of groundwater DOC and DIC in the volcanically active and arid Loa Basin of northern Chile. Journal of Hydrology, 2021, 595, 125987

Page last updated: January 2023