Sunlight Induces the Production of Atmospheric Volatile Organic Compounds (VOCs) from Thermokarst Ponds

• Published in: Environmental Science & Technology
• Main Authors: Wang, Tao, Kalalian, Carmen, Fillion, Daniel, Perrier, Sébastien, Chen, Jianmin, Domine, Florent, Zhang, Liwu, George, Christian
• Other Authors: Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval Québec (ULaval)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: photochemistry; [SDE]Environmental Sciences; permafrost; Thermokarst
• Online Access: https://hal.science/hal-04308300; https://hal.science/hal-04308300/document; https://hal.science/hal-04308300/file/Manuscript.pdf; https://doi.org/10.1021/acs.est.3c03303

Ground subsidence caused by permafrost thawingcauses the formation of thermokarst ponds, where organiccompounds from eroding permafrost accumulate. We photolyzedwater samples from two such ponds in Northern Quebec anddiscovered the emission of volatile organic compounds (VOCs)using mass spectrometry. One pond near peat-covered permafrostmounds was organic-rich, while the other near sandy mounds wasorganic-poor. Compounds up to C10 were detected, comprisingthe atoms of O, N, and S. The main compounds were methanol,acetaldehyde, and acetone. Hourly VOC fluxes under actinic fluxessimilar 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 pondwere greater than those from the organic-rich pond. We suggestthat different segregations of organics at the air/water interface may partly explain this observation. This study indicates that sunlitthermokarst ponds are a significant source of atmospheric VOCs, which may affect the environment and climate via ozone andaerosol formation. Further work is required for understanding the relationship between the pond’s organic composition and VOCemission fluxes.