LONG CHAIN N-ALKANES IN LAKE SEDIMENT TRACK DIFFERENCES IN ADJACENT LAND VEGETATION

We analyzed n-alkanes, lignin-derived phenols, and other sediment markers from 19 lakes across four Saskatchewan ecoregions, from Prairie Grassland to Boreal Upland, to establish ecoregion-specific signatures and assess their correlation with catchment land cover (trees vs. herbaceous plants). Significant correlations were found between the n-alkane ratios C₃₁/(C₂₇ + C₃₁) and C₃₁/(C₂₇ + C₂₉ + C₃₁) and the herbaceous-to-tree ratio in catchments, indicating their potential for reconstructing historical land cover from sediment records. The C₃₁/(C₂₇ + C₃₁) ratio also varied significantly among ecoregions, particularly distinguishing Prairie Grassland from forested regions. No correlations were observed between sediment n-alkane ratios and chlorophyll-a in lake water, confirming these ratios reflect terrestrial land cover rather than algal production. The C/N ratio and δ¹³C were not effective for distinguishing ecoregions or land cover, likely due to confounding influences from algal production and agricultural activities. In contrast, lignin-derived phenols appeared to be influenced by other factors such as mean annual temperature, soil type, and decomposition processes before depositing into the lake. Overall, our research highlights the potential of n-alkanes as biomarkers for tracking distinct land cover types and enhancing the accuracy of estimating surface vegetation composition, due to their positive correlation with the proportion of grasses and trees.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Bowen Xiao, University of Ottawa (bxiao049@uottawa.ca)

Authors:

Bowen Xiao, University of Ottawa  (bxiao049@uottawa.ca)

Dënë Cheecham-Uhrich, Clearwater River Dënë Nation  (dcheecham-uhrich@iegconsulting.com)

David Eickmeyer, University of Ottawa  (deickmey@uottawa.ca)

Linda Kimpe, University of Ottawa  (linda.kimpe@uottawa.ca)

Vilmantas Prėskienis, Université du Québec à Chicoutimi  (vpreskie@uqac.ca)

Henriikka Kivilae, Université du Québec à Chicoutimi  (henriikka.kivila@gmail.com)

Meiling Man, University of Toronto at Scarborough  (meiling.man@utoronto.ca)

Myrna Simpson, University of Toronto at Scarborough, Toronto  (myrna.simpson@utoronto.ca)

Irena Creed, University of Toronto at Scarborough, Toronto  (irena.creed@usask.ca)

Milla Rautio, Université du Québec à Chicoutimi  (Milla.Rautio@uqac.ca)

Jules Blais, University of Ottawa  (Jules.Blais@uottawa.ca)