Assessing the Effect of Sterilization on the Radiocarbon Signature of Freshwater Dissolved Organic Carbon

Radiocarbon analysis of freshwater dissolved organic carbon (DOC) involves substantial sample pretreatment, including an initial rotary evaporation stage necessary to concentrate large volumes of freshwater sample. This may lead to a health risk from the exposure to pathogens, and there is the additional concern that the warm conditions during the rotary evaporation stage may provide ideal growing conditions for some pathogens. To remove any pathogen risk in water samples, boiling or autoclaving can be undertaken. However, to date, no studies have been undertaken to investigate whether boiling will alter the 14 C signature of dissolved organic carbon. Here, we analyze the effect of sterilization on 9 contrasting river water samples. Comparing filtered, filtered and boiled, and filtered and sterilized dissolved organic matter, we observe that both boiling and autoclaving increases the uncertainty associated with the 14 C and 13 C of DOC, that the 14 C and 13 C changes are not unidirectional, and that they are not related to original DOC composition. Neither sterilization method is recommended unless essential, in which instance we recommend a 3σ uncertainty on 14 C and that the 13 C is not considered representative of the original sample

Boiling · Dissolved organic carbon · Organic matter · Radiocarbon dating · Total organic carbon · Chemistry · Environmental Science · Groundwater and Isotope Geochemistry · Isotope Analysis in Ecology · Marine and coastal ecosystems · Environmental Chemistry · Geology

• Plumbing the Global Carbon Cycle

  Open Access•J J Cole, Yves T Prairie et al.•Ecosystems•2007

  Add to list

• The Effect of Storage on the Radiocarbon, Stable Carbon and Nitrogen Isotopic Signatures and Concentrations of Riverine DOM

  Open Access•P Gulliver, S Waldron et al.•Radiocarbon•2010

  Add to list