249-10 Tracking the chemical legacy of hurricane Helene in a Georgia freshwater system

Session: Emerging Contaminants: Geochemical Insights and Impacts on Human and Environmental Health

Presenting Author:

Srimanti Duttagupta

Authors:

Duttagupta, Srimanti¹, Stamm, Grace², Bhattacharjee, Arka³, Basapuram, Gayatri⁴, Myrick, Blaire⁵, Dutta, Avishek⁶

(1) Department of Geology, University of Georgia, Athens, GA, USA, (2) Department of Physics and Astronomy, UGA, Athens, GA, USA, (3) H. Milton Stewart School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA, USA, (4) Department of Geology, UGA, Athens, GA, USA, (5) Department of Anthropology, UGA, Athens, GA, USA, (6) Department of Geology, University of Georgia, Athens, GA, USA; Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA,

Abstract:

Tropical cyclones are increasingly recognized for their ability to induce rapid, watershed-scale changes in biogeochemical processes, yet their impacts in temperate, inland systems remain poorly characterized. This study investigates the post-hurricane chemical dynamics of the Oconee River watershed in Georgia, following Hurricane Helene’s inland trajectory in September 2024. Despite minimal visible disruption in Athens-Clarke County, high-frequency water sampling across three sites in the North Oconee River, one in the Oconee River, and one in Lake Chapman revealed significant alterations in riverine chemical signatures. Nitrate, phosphate, and sulfate concentrations surged following the storm, driven by enhanced runoff, sediment resuspension, and hydrological connectivity. These shifts were most pronounced in the North Oconee River sites, where urban and transitional land use likely amplified solute mobilization. The lake system, while also affected, exhibited a comparatively muted response, indicating spatial heterogeneity in storm impact and recovery trajectories. The observations suggest nutrient concentrations remained elevated for weeks post-disturbance, highlighting a prolonged period of ecological adjustment. Beyond inorganic anions, the storm likely introduced a complex mixture of organic contaminants and additional nutrient loads via stormwater runoff and atmospheric deposition, underscoring the multifaceted nature of post-hurricane water quality degradation. These processes not only alter chemical baselines but may also delay ecological resilience and recovery across freshwater systems. Studying Hurricane Helene’s chemical imprint in Athens, Georgia, is particularly critical. Unlike the hurricane-prone coastal regions of the southeastern U.S., this inland watershed is not typically associated with high-intensity cyclonic activity. The event marks a shift in climatic patterns and highlights the growing need to monitor and understand the chemical and ecological consequences of extreme weather in previously less-affected areas. This study underscores the urgency of developing region-specific resilience frameworks to assess long-term impacts on water quality, ecosystem function, and public health under intensifying storm regimes.

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

doi: 10.1130/abs/2025AM-7490

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