306-3 Summer Water Pollution Trends of an Urban Ohio Stream

Abstract:

Climate change has led to an increase in extreme weather events, characterized in Ohio by increased short-term drought bracketed by extreme precipitation and temperature. Deviations in precipitation and increased occurrence of drought can impact the transport and storage of chemicals in local surface waterways. For example, pollutants (i.e. heavy metals, agricultural runoff, and microplastics), dissolved ions, and nutrients can accumulate on or near the surface during dry periods and may be readily flushed into streams and lakes by rainfall overland flow. However, the variables that control how watersheds, especially with high levels of human influence and management, chemically respond to drought are unclear. To test this, we collected weekly water samples across four points from head to mouth from Adena Brook, an urban stream running through the densely populated Clintonville neighborhood of Columbus, Ohio. The samples were analyzed for pH, dissolved oxygen, water isotopes, anions (F-, Cl-, SO42-, NO3-, PO43-), cations (Li+, K+, Na+, Ca2+, Mg2+), nutrients (NH3, NO2-, NO3-, PO43-), metals (Pb, Cu, As), dissolved and particulate organic carbon, and microplastics over the course of the summer 2026 season (June to September). We will share our comparisons of water quality to flow rate, temperature, humidity, precipitation, and drought indices from the same time period to demonstrate which factors most greatly impact water quality parameters. Water isotope analysis will also inform the timing and source of water movement through the stream. We anticipate that the head samples will have the highest concentrations of pollutants because of decreased flow rates allowing for increased accumulation, and because the head of the stream likely receives more direct pollutant input from highway/road runoff that then accumulates further downstream at the more stagnant mouth. Changes in precipitation will show the most impact on pollutant concentrations, with spikes in runoff bringing more dissolved and particulate matter into the stream from the surrounding watershed. As shifts in precipitation and temperature become more severe in the Midwest, understanding the factors contributing to chemical stability in streams, and how chemistry varies throughout, can aid surrounding communities in addressing surface water quality hazards and contribute to local environmental remediation efforts.

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