Anthropocene climate warming enhances autochthonous carbon cycling in an upland Arctic lake, Disko Island, West Greenland

Stevenson, Mark A.; Mcgowan, Suzanne; Pearson, Emma J.; Swann, George E.A.; Leng, Melanie J.; Jones, Vivienne J.; Bailey, Joseph J.; Huang, Xianyu; Whiteford, Erika

Abstract

The Arctic is rapidly changing, disrupting biogeochemical cycles and the processing, delivery and sedimentation of carbon (C), in linked terrestrial-aquatic systems. In this investigation, we coupled a hydrogeomorphic assessment of catchment soils, sediments and plants with a recent lake sediment sequence to understand the source and quality of organic carbon present in three Arctic upland lake catchments on Disko Island, located just south of the low- high Arctic transition zone. This varied permafrost landscape has exposed soils with less vegetation cover at higher altitudes, and lakes received varying amounts of glacial meltwater inputs. We provide improved isotope and biomarker source identifications for palaeolimnological studies in highlatitude regions, where terrestrial vegetation is at or close to its northerly and altitudinal range limit. The poorly developed catchment soils lead to lake waters with low dissolved organic carbon (DOC) concentrations (≤ 1.5 mgL-1). Sedimentary carbon=nitrogen (C/N) ratios, the C isotope composition of organic matter (δ13Corg) and biomarker ratios (n-alkanes, n-alkanols, n-alkanoic acids and sterols) showed that sedimentary organic matter (OM) in these lakes is mostly derived from aquatic sources (algae and macrophytes). We used a 210Pb-dated sediment core to determine how carbon cycling in a lake-catchment system (Disko 2) had changed over recent centuries. Recent warming since the end of the Little Ice Age (LIA ∼ 1860 CE), which accelerated after ca. 1950, led to melt of glacier ice and permafrost, releasing nutrients and DOC to the lake and stimulating pronounced aquatic algal production, as shown by a > 10-fold increase in β-carotene, indicative of a major regime shift. We also demonstrate that recent increases in catchment terrestrial vegetation cover contributed to the autochthonous response. Our findings highlight that in Arctic lakes with sparsely developed catchment vegetation and soils, recent Anthropocene warming results in pronounced changes to in-lake C processing and the deposition of more reactive, predominately autochthonous C, when compared with extensively vegetated low-Arctic systems.

Citation

Stevenson, M. A., Mcgowan, S., Pearson, E. J., Swann, G. E., Leng, M. J., Jones, V. J., Bailey, J. J., Huang, X., & Whiteford, E. (2021). Anthropocene climate warming enhances autochthonous carbon cycling in an upland Arctic lake, Disko Island, West Greenland. Biogeosciences, 18(8), 2465-2485. https://doi.org/10.5194/bg-18-2465-2021

• Journal Article Type: Article
• Acceptance Date: Feb 14, 2021
• Online Publication Date: Apr 19, 2021
• Publication Date: Apr 19, 2021
• Deposit Date: Apr 19, 2021
• Publicly Available Date: Apr 19, 2021
• Journal: Biogeosciences
• Print ISSN: 1726-4170
• Electronic ISSN: 1726-4189
• Publisher: European Geosciences Union
• Peer Reviewed: Peer Reviewed
• Volume: 18
• Issue: 8
• Pages: 2465-2485
• DOI: https://doi.org/10.5194/bg-18-2465-2021
• Keywords: Earth-Surface Processes; Ecology, Evolution, Behavior and Systematics
• Public URL: https://nottingham-repository.worktribe.com/output/5482226
• Publisher URL: https://bg.copernicus.org/articles/18/2465/2021/