The physical and chemical oceanographic properties of the Gulf of Mexico (GOM, recognized by the United States as the Gulf of America) remain incompletely characterized. Evidence suggests that GOM carbonate chemistry is mainly influenced by physical mixing, changes in atmospheric CO2 levels, and localized processes including eutrophication, hypoxia, and upwelling. The purpose of this dissertation is to increase sampling coverage in the northwestern Gulf (nwGOM), analyze decadal trends using both new and existing data, explore two cross-shelf transects from surface to bottom over 16+ years, and develop statistical models to estimate pH and ΩAragonite from hydrographic measurements. The research incorporates both laboratory and computational analyses across all chapters, including data collected from sensors (moored and shipboard). Samples for carbonate chemistry parameters were analyzed in the lab following standard practices. Computational work was conducted using RStudio, Python, and MATLAB. The statistical models can estimate water column pH and ΩAragonite with R2 values over 0.93 with small mean square errors (<0.0005 and <0.04 for pH and ΩAragonite, respectively), demonstrating their effectiveness. Key findings include seasonal patterns and long-term temperature trends in the nwGOM, as well as spatial variability and upward shoaling of the aragonite saturation horizons (ΩAragonite) from full water-column transects. These results reveal that subsurface waters are experiencing both declining dissolved oxygen (DO) and a shoaling saturation horizon. At the same time, surface waters also show progressive acidification, marked by decreasing pH and rising CO2 partial pressure (pCO2), despite significant seasonal fluctuations and an overall warming trend. The collected data provide essential spatial and temporal coverage of carbonate chemistry. The numerous changes occurring in the Gulf highlight the importance of quantifying these variations to guide resource management and conservation efforts.
Jundt E. P., 2026. Ocean acidification in the Northwestern gulf of America. PhD thesis, Texas A&M University. 143 p. Thesis.
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