Biogeochemical response to Holocene climate change in deep and shallow lakes: a case study comparison from southeastern Minnesota

Abstract:

Sedimentary deposits in lakes across the upper Midwest record the co-evolution of climate and biogeochemistry since the retreat of the Laurentide ice sheet at the end of the last glacial period. Here, we report two Holocene lake sediment records from contrasting lakes in southeastern Minnesota. Chub Lake, is a shallow (3 m maximum depth), eutrophic lake system while Holland Lake is deep (18 m maximum depth) and mesotrophic to oligotrophic. Our lake sediment records include high-resolution elemental data from core scanning XRF along with variations in organic, carbonate, and mineral content of sediments from loss-on-ignition. We compare lake systems responses to changes in climate that are inferred from well-established regional pollen reconstructions. Application of multivariate ordination methods reveal both similarities and differences in the way Chub Lake and Holland Lake respond to changing climate and vegetation during the Holocene. Preliminary results indicate key differences in lake stratification, redox conditions, and organic carbon accumulation rates between both lakes.