Ramstack, J. M. Lehigh University, jor5@lehigh.edu
Fritz, S. M. Lehigh University, scf2@lehigh.edu

 
NONPOINT POLLUTION TRENDS IN MINNESOTA LAKES: THE USE OF FOSSIL DIATOMS AS PALEOINDICATORS OF HUMAN IMPACT
 
Knowledge of baseline conditions and natural variability are crucial for an accurate assessment of pollution trends in aquatic ecosystems. Here we develop a transfer function to reconstruct trophic state from modern diatom assemblages in fifty-five Minnesota lakes. The transfer function will be applied to pre-settlement horizons in sediment cores to establish water-chemistry gradients prior to European settlement. These patterns will be compared with modern conditions to determine the proportion of lakes in various regions affected by human activities. The lakes span four different ecoregions, which differ in their history of settlement and land use, as well as in surficial geology, climate, and vegetation. Lakes in the Northern Lakes and Forests Ecoregion are nearly pristine, whereas the other regions are strongly affected by urban or agricultural pollutants. Current water-chemistry gradients in the state show that levels of nitrogen and phosphorus are low in the northeast and increase to the south and west; pH shows a similar pattern throughout the state, with lakes in the northeast being the most acidic.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: CS59WE1398S