Greenhouse Gas Dynamics of Saline Lakes: A Study on the Impacts of Environmental Change

Date

2024-10-03

Author

Yılmaz, Gültekin

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Saline lakes, increasingly impacted by climate change and land use, play an important role in the global carbon and nitrogen cycles. This thesis study examined the complex factors influencing greenhouse gas (GHG) emissions from a diverse array of saline lakes, with a particular focus on those situated in semi-arid regions and experiencing increasing salinization pressures. Employing a combined approach of literature review, remote sensing methods, predictive models, field surveys, and controlled mesocosm experiments, we examined the interplay between salinity, temperature, climate effects and eutrophication on methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) emissions. Our findings reveal that saline lakes, particularly inland ones, are significant sources of CH4 and N2O, with ebullition emerging as a minor, but potentially significant emission pathway. Salinity exerted the primary inhibitory effect on CH4 emissions, and the current salinization trend can further reduce CH4 emissions from these ecosystems. However, organic matter availability partially counteracts the reducing impact of salinity. Temperature emerged as a primary driver of GHG emissions, tapping several biogeochemical pathways involved in GHG production and exhange, particularly stimulating ebullition, yet its influence varied across study sites, implicating the role of site specific factors. While temperature directly stimulated GHG production through enhanced microbial activity, it also altered ecosystem metabolism and nutrient cycling, which likely contributed to the observed variability. Unlike CH4, which is strongly influenced by salinity, N2O and CO2 emissions are anticipated to increase in a likely future characterized by increased salinization, eutrophication, significant lake surface area losses, and frequent dry outs. This potentially mitigates the climate forcing benefit caused by the reduction of CH4 emissions. This study underscores the vulnerability of saline lakes to land and water use changes, and emphasizes the interconnectedness of GHG emissions and ecological state of the ecosystem. Effective GHG mitigation strategies must address the underlying causes of ecosystem degradation, as increased emissions are symptomatic of broader environmental challenges.

Subject Keywords

Saline lakes, freshwater salinization, eutrophication, climate change, anthropogenic pressures

URI

https://hdl.handle.net/11511/111471

Collections

Graduate School of Marine Sciences, Thesis