Lake Physical and Geochemical Traits Impact CH4 and CO2 Concentrations

Abstract:

Spatiotemporal variability combined with few lake measurements have resulted in a large amount of uncertainty regarding the emission potential of lakes. Both the amount of methane (CH₄) emitted and controls on this emission vary spatially and temporally. A positive correlation has been shown between lake water/sediment temperature and the amount of CH₄ emitted from lakes. Lack of data available on how other lake characteristics affect the emission of greenhouse gasses, specifically CH₄ and carbon dioxide (CO₂), indicate the need for measurements across a diversity of lake types to be able to accurately predict emissions in the future.

This study focused on answering the question of how lake physical and geochemical traits impact emission potential in lake waters. Twenty subarctic lakes located in the Stordalen area, Abisko, Sweden (68°21’N, 18°49’E) were sampled for dissolved CH_4, CO₂ (as dissolved inorganic carbon (DIC)), DOC, particulate organic carbon (POC), water temperature, dissolved oxygen (DO), conductivity, and pH. Qualitative characteristics of shoreline vegetation and lake bottom structure were also noted. Data analysis included analysis of variance (ANOVA) and multiple linear regression analysis to determine the differences and predictability of emission potential based on the observed lake characteristics. The strongest correlation between CH₄ concentrations and temperature occurred in lakes with algae and sediment bottom types with the lowest occurrences in rock and peat bottom types. Methane concentrations were highest in lakes with shore types composed of Carex spp., peat/ Carex spp. and rock/ Carex spp..