Sunlight Induces the Production of Atmospheric Volatile Organic Compounds (VOCs) from Thermokarst Ponds
Résumé
Ground subsidence caused by permafrost thawing
causes the formation of thermokarst ponds, where organic
compounds from eroding permafrost accumulate. We photolyzed
water samples from two such ponds in Northern Quebec and
discovered the emission of volatile organic compounds (VOCs)
using mass spectrometry. One pond near peat-covered permafrost
mounds was organic-rich, while the other near sandy mounds was
organic-poor. Compounds up to C10 were detected, comprising
the atoms of O, N, and S. The main compounds were methanol,
acetaldehyde, and acetone. Hourly VOC fluxes under actinic fluxes
similar to local solar fluxes might reach up to 1.7 nmol C m−2 s−1.
Unexpectedly, the fluxes of VOCs from the organic-poor pond
were greater than those from the organic-rich pond. We suggest
that different segregations of organics at the air/water interface may partly explain this observation. This study indicates that sunlit
thermokarst ponds are a significant source of atmospheric VOCs, which may affect the environment and climate via ozone and
aerosol formation. Further work is required for understanding the relationship between the pond’s organic composition and VOC
emission fluxes.
Domaines
Sciences de l'environnementOrigine | Fichiers produits par l'(les) auteur(s) |
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