Minor impacts of rain on methane flux from hemiboreal, boreal, and subarctic lakes

Anna Katarzyna Sieczko; Jonathan Schenk; David Rudberg; Nguyen Thanh Duc; Gustav Pajala; Henrique O Sawakuchi; David Bastviken

doi:10.1016/j.scitotenv.2023.164849

Minor impacts of rain on methane flux from hemiboreal, boreal, and subarctic lakes

Sci Total Environ. 2023 Oct 15:895:164849. doi: 10.1016/j.scitotenv.2023.164849. Epub 2023 Jun 16.

Authors

Anna Katarzyna Sieczko¹, Jonathan Schenk², David Rudberg², Nguyen Thanh Duc², Gustav Pajala², Henrique O Sawakuchi², David Bastviken²

Affiliations

¹ Department of Thematic Studies - Environmental Change, Linköping University, 58183 Linköping, Sweden. Electronic address: anna.katarzyna.sieczko@liu.se.
² Department of Thematic Studies - Environmental Change, Linköping University, 58183 Linköping, Sweden.

PMID: 37331406
DOI: 10.1016/j.scitotenv.2023.164849

Abstract

Methane (CH₄) emissions (F_CH4) from northern freshwater lakes are not only significant but also highly variable in time and one driver variable suggested to be important is precipitation. Rain can have various, potentially large effects on F_CH4 across multiple time frames, and verifying the impact of rain on lake F_CH4 is key to understand both contemporary flux regulation, and to predict future F_CH4 related to possible changes in frequency and intensity of rainfall from climate change. The main objective of this study was to assess the short-term impact of typically occurring rain events with different intensity on F_CH4 from various lake types located in hemiboreal, boreal, and subarctic Sweden. In spite of high time resolution automated flux measurements across different depth zones and covering numerous commonly types of rain events in northern areas, in general, no strong impact on F_CH4 during and within 24 h after the rainfall could be observed. Only in deeper lake areas and during longer rain events F_CH4 was weakly related to rain (R² = 0.29, p < 0.05), where a minor F_CH4 decrease during the rain was identified, suggesting that direct rainwater input, during greater rainfall, may decrease F_CH4 by dilution of surface water CH₄. Overall, this study indicates that typical rain events in the studied regions have minor direct short-term effects on F_CH4 from northern lakes and do not enhance F_CH4 from shallow and deeper parts of lakes during and up to 24-h after the rainfall. Instead, other factors such as wind speed, water temperature and pressure changes were more strongly correlated with lake F_CH4.

Keywords: Lakes; Methane; Precipitation.