275-2 Mapping Spatial and Temporal Variations of Key Water Parameters Affecting Environmental and Human Health in the Lower Brazos River, Texas

Session: Advancing the Understanding and Management of Groundwater Pollution with Arsenic and Other Geogenic Contaminants Using Geospatial Tools, Machine Learning, and Data Science, Part II

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Abstract:

Anthropogenic activities including rapid urbanization, intensive agricultural practices, and discharge from industrial sources are some factors contributing to the rising microbial and chemical pollution in the Lower Brazos River (LBR), upon which some 400,000 people depend for their supply of fresh water. In this study, we identify temporal and spatial variations of several indicators of water pollution to assess the water quality in the LBR. Samples are collected from eight locations along the LBR in Southeast, Texas over two cycles in a calendar year to account for seasonality. We analyze surface water samples for indicators of microbial pollution such as E.coli along with the presence of organic contaminants such as per-and polyfluorinated substances (PFAS) (PFOS, PFBA, etc.), polycyclic aromatic hydrocarbons (PAHs) (Acenaphthene, Anthracene, etc.) carcinogenic substances such as dioxins and volatile organic compounds (VOCs) (Benzene, Chloroethene, etc.). Furthermore, we also measure physiochemical parameters including pH, dissolved organic carbon (DOC), and concentrations of major cations and anions in the water samples to study the weathering processes that relay from the water constituents. Our initial results show that all eight locations are positive for microbial pollution with two locations showing elevated levels of E.coli (686.7 MPN/100 mL and 770.1 MPN/100 mL) and total coliform (>2419.6 MPN/100 mL). The average concentration of Na⁺ is measured at 479.8 ± 189.3 mg/L, followed by Ca²⁺ at 76.5 ± 9.3 mg/L, and Mg²⁺ at 51.4 ± 18.2 mg/L. For anions, the average concentration of Cl^- is measured at 1049.7 ± 328.9 mg/L, followed by SO₄^-2 at 155.0 ± 45.7 mg/L, and Br^- at 4.1 ± 0.9 mg/L. The analysis of organic chemicals (e.g. PFAS and dioxins) is ongoing; however, we are prioritizing certain downstream locations based on their proximity to potential point sources, given the increased likelihood of elevated concentrations. These results can be attributed to high anthropogenic activities from point and nonpoint sources thus underlining the need for continuous monitoring of key water parameters including organic and microbial contaminants in a major Texas river, providing key insight to pave the way for creating effective water-resources management.

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

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