Four Mile Creek watershed is the largest sub watershed that drains into Acton Lake. This is predominantly an agricultural watershed. Seeing recent changes in farming techniques, like the switch to conservation tillage, affects the soil and waterways nearby. The Vanni Lab here at Miami University monitors the effects of non-point source pollution from agriculture in Acton Lake and surrounding streams by measuring nutrient levels. The analysis of particulate carbon (C), nitrogen (N), and phosphorus (P) can be costly and time consuming. It has been determined that C, N, and P concentrations can be estimated using a regression curve in relation to suspended sediment calculations.
Previously, linear regressions have been used in lieu of conducting analysis. My goal for this study was to conduct analysis on current years to confirm that the linear regressions were still valid. I analyzed samples from 2016 and 2022 to compare to regression curves from 1995-1997. Water samples were collected using an ISCO gauging station at the stream sites. The water samples were filtered to catch particles greater than 1 µm. The dirty filters were analyzed with a CN analyzer to measure carbon and nitrogen and a Lachat analyzer for phosphorus. Suspended sediment values were measured by weighing the filter before and after filtration.
After analysis, it was evident that C, N, and P are all behaving differently. Carbon has decreased from 1995-97 to 2022 by 50.58%, nitrogen has stayed constant, and phosphorus increased by 127.45%. It is important to note the SS values have declined over the years, most likely due to the switch to conservation tillage, and we do not see as high of SS values anymore. These changes may suggest that a new regression is needed, perhaps a nonlinear fit, or the previous regressions need to be tweaked. Research is still ongoing.
Author(s): Kelsey Hess, Geography and Environmental Science Major
Advisor(s): Michael Vanni, Department of Biology
Amy Weber, Department of Biology
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