An improved method for atmospheric 14CO measurements

Details

• Journal Title:
  Atmospheric Measurement Techniques
• Personal Author:
  Petrenko, Vasilii V. ; Smith, Andrew M. ; Crosier, Edward M. ; Kazemi, Roxana ; Place, Philip ; Colton, Aidan ; Yang, Bin ; Hua, Quan ; Murray, Lee T.
• NOAA Program & Office:
  ESRL (Earth System Research Laboratory) ; OAR (Oceanic and Atmospheric Research)
• Description:
  Important uncertainties remain in our understanding of the spatial and temporal variability of atmospheric hydroxyl radical concentration ([OH]). Carbon-14-containing carbon monoxide (14CO) is a useful tracer that can help in the characterization of [OH] variability. Prior measurements of atmospheric 14CO concentration ([14CO] are limited in both their spatial and temporal extent, partly due to the very large air sample volumes that have been required for measurements (500–1000 L at standard temperature and pressure, L STP) and the difficulty and expense associated with the collection, shipment, and processing of such samples. Here we present a new method that reduces the air sample volume requirement to ≈90 L STP while allowing for [14CO] measurement uncertainties that are on par with or better than prior work (≈3 % or better, 1σ). The method also for the first time includes accurate characterization of the overall procedural [14CO] blank associated with individual samples, which is a key improvement over prior atmospheric 14CO work. The method was used to make measurements of [14CO] at the NOAA Mauna Loa Observatory, Hawaii, USA, between November 2017 and November 2018. The measurements show the expected [14CO] seasonal cycle (lowest in summer) and are in good agreement with prior [14CO] results from another low-latitude site in the Northern Hemisphere. The lowest overall [14CO] uncertainties (2.1 %, 1σ) are achieved for samples that are directly accompanied by procedural blanks and whose mass is increased to ≈50 µgC (micrograms of carbon) prior to the 14C measurement via dilution with a high-CO 14C-depleted gas.
• Keywords:
  Atmospheric Science
• Source:
  Atmospheric Measurement Techniques, 14(3), 2055-2063
• DOI:
  https://doi.org/10.5194/amt-14-2055-2021
• ISSN:
  1867-8548
• Format:
  PDF
• Publisher:
  Copernicus GmbH
• Document Type:
  Journal Article
• License:
  https://creativecommons.org/licenses/by/4.0/
• Rights Information:
  CC BY
• Compliance:
  Library
• Main Document Checksum:
  urn:sha-512:a9d73f62769e855e0b50fe8cf7fd2bb59f710250e7b043680c1a8540b7b884fde8f2a442048a629b57855e79d1fde82e56da57c45edfb715605bed3d13266a81
• Download URL:
  https://repository.library.noaa.gov/view/noaa/64293/noaa_64293_DS1.pdf
• File Type:
  [PDF - 750.68 KB ]