Discriminating sources and preservation of organic matter in surface sediments from five Antarctic lakes in the Fildes Peninsula (King George Island) by lipid biomarkers and compound-specific isotopic analysis

• Published in: Science of The Total Environment
• Main Authors: Carrizo, Daniel, Sánchez-García, Laura, Menes, Rodrigo Javier, García-Rodríguez, Felipe
• Other Authors: Instituto Antártico Uruguayo, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España)
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2019
• Subjects: Lipids biomarkers; Lakes; Organic matter; Maritime Antarctica; Isotopes; Antarctic; King George Island; Uruguay; Fildes; Fildes peninsula; Toledo; Correa; Sarmiento; Artigas; Collins Glacier; Carrizo; Artigas Base; Kitezh; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10261/376783; https://doi.org/10.1016/j.scitotenv.2019.03.459

Lakes are important paleoenvironmental archives retaining abundant information due to their typical high sedimentation rates and susceptibility to environmental changes. Here, we scrutinize the organic matter (OM) composition, origin and preservation state in surface sediments from five lakes in a remote, warming-sensitive, and poorly explored region partially covered by the retreating Collins Glacier in King George Island (Antarctica), the Fildes Peninsula. Lipid biomarkers of terrestrial origin (i.e. high-molecular weight n-alkanes, n-alkanoic acids, and n-alkanols; β-sitosterol, campesterol, and stigmasterol) were detected in the five Fildes Lakes, with the smallest basin (i.e., Meltwater) showing a particularly strong moss imprint. Aquatic source indicators such as low C/N and terrestrial over aquatic ratios (TAR), or less negative δ13C values were preferentially found in the mid-sized lakes (i.e., Drake and Ionospheric). Sedimentary carbon in the larger lakes (i.e., Uruguay and Kitezh) displayed a largely biogenic origin (i.e., values of carbon preference index, CPI, ≫1), whereas the three lakes close to Collins Glacier (i.e., Drake, Meltwater, and Ionospheric) showed certain contribution from petrogenic sources (CPI ~ 1). The results suggest that the geochemical signature of the surface sediments in the five Fildes lakes is determined by factors such as the distance to the retreating Collins Glacier, the proximity to the coast, or the lake depth. This study illustrates the forensic interest of combining lipid biomarkers, compound-specific isotopic analysis, and bulk geochemistry to reconstruct paleoenvironments and study climate-sensitive regions. This study was partially founded by the Instituto Antártico Uruguayo (IAU). Scuba Divers (Rodrigo Toledo and Oscar Correa) are acknowledged for their field assistance during sampling. All authors thank the crew members from the Artigas Base (BCAA). P. M. Sarmiento is acknowledged for the stable isotopes analysis. The authors D. Carrizo and L. Sánchez-García ...