278-5 Tracing Human Impact on Lake Erie Sediments Accumulation Through Pollen Records

Session: Understanding Temporal Dynamics in Hydrogeochemistry and Sedimentary Processes in Estuarine Environments

Presenting Author:

Gabrielle Guevara

Authors:

Guevara, Gabrielle¹, White, Trinity², Benzenhafer, Rose³, Robinson, Dylan⁴, Zobaa, Mohamed K.⁵, Adojoh, Onema C⁶, Saylor, Beverly Z.⁷

(1) Department of Geosciences, The University of Texas Permian Basin, Odessa, Texas, USA, (2) Department of Geosciences, The University of Texas Permian Basin, Odessa, Texas, USA, (3) Geosciences, The University of Texas Permian Basin, Odessa, Texas, USA, (4) Geosciences, The University of Texas Permian Basin, Odessa, Texas, USA, (5) Geosciences, The University of Texas Permian Basin, Odessa, Texas, USA, (6) Department of Natural Sciences - Geology, Northwest Missouri State University, Maryville, MO, USA, (7) Earth, Environmental, and Planetary Sciences, Case Western Reserve University, Cleveland, OH, USA,

Abstract:

Lake Erie, the fourth largest of the five Great Lakes by surface area, is the shallowest and smallest by volume. Despite its size, it is the most biologically active of the Great Lakes, making it an ideal site for reconstructing anthropogenic influence through palynomorph analysis. While previous studies have examined sediment particle size, pollution, and other environmental factors to assess human impact, few have utilized pollen records-highly sensitive indicators of ecological change.

This study analyzes 21 core samples from the ER 36 core about 41 cm long collected in the Central basin of Lake Erie to investigate shifts in species diversity and extinction patterns over time. Pollen taxa examined include Cupressus, Pinus, Chenopods, Quercus, Ambrosia, Juglans, Carya, and Tilia. Five major trends (0-41 cm) were identified from the graphical plots: 1) Palynomorph abundance is highest in the oldest core sections and declines toward the surface. 2) Quercus (oak) and Pinus (pine) are the most dominant taxa throughout, with oak increasing at the expense of pine over time. 3) Cupressus (cypress) and Chenopods (goosefoot) show fluctuating abundance but no significant long-term trend. 4) Ambrosia (ragweed) peaks in the lower and middle sections (9-41 cm) of the core, with minimal presence near the top. 5) Juglans (walnuts) vary in abundance, reaching their highest levels near the surface and lowest in deeper layers.

The initial result apparently does not show distinct pollen zones but nonnative Cupressus (cypress) with no significant long-term trend indicates long-distance sediment transport to Lake Erie.  Ambrosia (~ 25 %) increase at 9-41 cm provides evidence of prior and intense human activities (~2000 cal Yr. BP) linked to forest disturbance around the Great Lakes region.  

Additionally, two microplankton species were observed to peak at a depth of 18–19 cm and disappear by 6–7 cm. Microplastics first appear at 9–10 cm and become most abundant in the uppermost layers, highlighting recent human caused contamination. Future work will include a robust age modelling to clearly integrate sediment accumulation rates, pollen, and elemental tracers to determine different sources of contaminants in Lake Erie.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11228

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