Continued emissions of carbon tetrachloride from the United States nearly two decades after its phaseout for dispersive uses

Lei Hu, Stephen A. Montzka, Ben R. Miller, Arlyn E. Andrews, John B. Miller, Scott J. Lehman, Colm Sweeney, Scot M. Miller, Kirk Thoning, Carolina Siso, Elliot L. Atlas, Donald R. Blake, Joost De Gouw, Jessica B. Gilman, Geoff Dutton, James W. Elkins, Bradley Hall, Huilin Chen, Marc L. Fischer, Marikate E. MountainThomas Nehrkorn, Sebastien C. Biraud, Fred L. Moore, Pieter Tans

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


National-scale emissions of carbon tetrachloride (CCl4) are derived based on inverse modeling of atmospheric observations at multiple sites across the United States from the National Oceanic and Atmospheric Administration's flask air sampling network. We estimate an annual average US emission of 4.0 (2.0-6.5) Gg CCl4 y-1 during 2008- 2012, which is almost two orders of magnitude larger than reported to the US Environmental Protection Agency (EPA) Toxics Release Inventory (TRI) (mean of 0.06 Gg y-1) but only 8% (3-22%) of global CCl4 emissions during these years. Emissive regions identified by the observations and consistently shown in all inversion results include the Gulf Coast states, the San Francisco Bay Area in California, and the Denver area in Colorado. Both the observation-derived emissions and the US EPA TRI identified Texas and Louisiana as the largest contributors, accounting for one- to two-thirds of the US national total CCl4 emission during 2008-2012. These results are qualitatively consistent with multiple aircraft and ship surveys conducted in earlier years, which suggested significant enhancements in atmospheric mole fractions measured near Houston and surrounding areas. Furthermore, the emission distribution derived for CCl4 throughout the United States is more consistent with the distribution of industrial activities included in the TRI than with the distribution of other potential CCl4 sources such as uncapped landfills or activities related to population density (e.g., use of chlorine-containing bleach).

Original languageEnglish (US)
Pages (from-to)2880-2885
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number11
StatePublished - Mar 15 2016


  • Carbon tetrachloride
  • Emissions
  • Greenhouse gases
  • Ozone-depleting substances
  • United States

ASJC Scopus subject areas

  • General


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