Inland aquatic systems, especially freshwater lakes, are known to contribute significantly to terrestrial greenhouse gas emissions through organic carbon processing. However, studies on carbon emission in saline, alkaline lakes are scarce, despite their total global water volume being comparable to that of freshwater lakes. Alkaline lakes are biogeochemically distinctive from freshwater habitats because of their high pH conditions. This leads to the direct conversion of dissolved atmospheric CO₂ to bicarbonate and carbonate, causing CO₂ removal from the atmosphere. However, alkaline lakes are also hotspots for terrestrial and macrophyte-derived organic carbon processing, which can result in greenhouse gas emissions. The FizzingSoda project aimed to gather seasonal gas emission data from alkaline lakes by conducting direct emission measurements on 12 distinct sites, alongside water chemical characterization and meta-omic investigations to understand the role of the resident microbiome in relation to atmospheric emissions. The results of the seasonal measurement campaigns showed that saline-alkaline lakes can substantially differ in their daily overall carbon trends. Carbon fluxes ranged from carbon dioxide sinks to substantial emitters (-181 mg C/m²/day to 3600 mg C/m²/day), with surprisingly high CH₄ fluxes detected for all soda lakes. The FizzingSoda project findings highlight the need for more research on carbon cycling in alkaline lakes, given their significance in the global water system and potential contribution to greenhouse gas emissions and removal.

Primary Presenter: Attila Szabo, Centre for Ecological Research (attila.szabo.ttk@gmail.com)

Authors:

Attila Szabo, Institute of Aquatic Ecology, Centre for Ecological Research  (attila.szabo.ttk@gmail.com)

Andras Hidas, Institute of Aquatic Ecology, Centre for Ecological Research  (hidas.andras@ecolres.hu)

Jan Fiedler, Swedish University of Agricultural Sciences  (jan.fiedler@slu.se)

Dora Anda, Institute of Aquatic Ecology, Centre for Ecological Research  (andadora1989@gmail.com)

Xiao Yi Chen, Institute of Aquatic Ecology, Centre for Ecological Research  (chen.ani@ecolres.hu)

Sofia Amanda Abad Sojos, Institute of Aquatic Ecology, Centre for Ecological Research  (sufiabad@gmail.com)

Peter Dobosy, Institute of Aquatic Ecology, Centre for Ecological Research  (dobosy.peter@ecolres.hu)

Tamas Felfoldi, Institute of Aquatic Ecology, Centre for Ecological Research  (tamas.felfoldi@gmail.com)

David Bastviken, Linköping University  (david.bastviken@liu.se)

Stefan Bertilsson, Swedish University of Agricultural Sciences  (stefan.bertilsson@slu.se)

Anna Szekely, Swedish University of Agricultural Sciences  (anna.szekely@slu.se)