11 Future Voices in Geoscience- Undergraduate Research Posters

This session is for two-year college and four-year college and university students presenting research posters in any subdiscipline of geosciences. Posters and presentations will be judged for awards.

Monday, 18 May 2026
8:00 AM - 5:30 PM
Alvarado D/E

Anthropogenic impacts in the Forest Lake, MN sedimentary record for the last two centuries

Paper number: 11-7
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

We present research on changing sedimentary inputs to Forest Lake, MN, since ~1825. Forest Lake, located on the urban-rural boundary of the Twin Cities metro area has 3 distinct sub-basins that vary in mass accumulation rates (MARs), and lie within the city of Forest Lake, an area that was originally forested, then deforested, turned into agricultural land, and finally urbanized. This research is part of a partnership between the Comfort Lake Forest Lake Watershed District (CLFLWD), the University of St. Thomas, and the Science Museum of MN aimed at understanding lake water quality history and management across the CLFLWD. We collected elemental data using a Portable Xray Fluorescence (p-XRF) from lake cores taken from all three sub-basins of the lake. The elemental data along with previously collected Pb210 age data allowed us to calculate mass accumulation rates (MARs), to understand the significance of anthropogenic impacts in the surrounding watershed. In this research, we see Ba, Fe, Ti, Ru, Ca, K, Zn, As, Cu, and Pb increase in MARs in the sedimentary record after the 1850s. K and Zn concentrations approximately double, and As, Pb and Cu all increase to more than 4 times their Pre Colonization concentration.  Looking at the timing of chemical trends in these cores, they seem to line up with the introduction of various anthropogenic actors, such as land clearing, development, and urbanization. Starting ~1870, we seem to see the impacts of logging for railroad materials and agricultural space reflected in the sedimentary record of Forest Lake, drastically increasing erosion. Industrial development and regulations that follow also seem to be represented in the sedimentary record, with the introduction of lead-based gasoline seeming to align chronologically with a doubling of lead and other heavy metals MARs, and the clean air act seemingly aligning with a reduction in these MARs. After the year 2000, Forest Lake shifts from being an agricultural area to a fully suburban center, with its population close to tripling from 2000-2010 (~6000 to ~18000 persons). Again, we see this reflected in the sedimentary record, with concentrations of heavy metals increasing rapidly since 2000 from their relative lows after the Clean Air Act.  

Geological Society of America Abstracts with Programs. Vol. 58, No. 4

doi: 10.1130/abs/2026RM-410655

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