Suspended particulate matter distribution,composition and size characteristics in two coastal estuaries (Gulf of Mexico): seasonal variability and influence on hyperspectral reflectance signatures

Document Type

Article

Publication Date

7-25-2025

Abstract

Estuaries are important pathways between land and the marine environment for exchanges of particulate matter that strongly impact ecosystems. In this study, suspended particulate matter (SPM) concentrations and characteristics of size distribution, particulate matter composition, optical properties of particle beam attenuation and absorption coefficients along with hydrological conditions were examined during spring, summer and fall of 2015/16 in two coastal estuaries (Apalachicola Bay and Barataria Bay) that revealed contrasting particle characteristics. In Apalachicola Bay, elevated river discharge in spring of 2015 contributed to higher SPM (6.91 ± 5.75 mg L−1) compared to fall (3.28 ± 1.71 mg L−1), while in the summer of 2016 longer-term effect of large spring precipitation events was evident in both field observations and satellite-derived SPM imagery. In Barataria Bay, high SPM (66.36 ± 29.17 mg L−1) in spring was dominated by inorganic, smaller-sized particles influenced by frequent weather fronts. Differences in SPM concentration and characteristics were observed in the two estuaries that varied both seasonally and spatially, with particle size distribution slope of the power law distribution on average (− 3.43) consistent with other coastal waters. Principle component analysis also indicated differences between the two estuaries, with Apalachicola Bay showing stable, more organic-rich SPM and Barataria Bay greater variability in particle composition. Optical properties, such as, particle volume concentrations and beam attenuation coefficients measured by LISST-100X laser particle sizer, were highly correlated to SPM but exhibited deviations due to composition, and particle size. Particulate and dissolved matter absorption, along with SPM concentrations and characteristics showed spatiotemporal variability in both estuaries that appear to influence hyperspectral in situ remote sensing reflectance, with time-lagged PACE-OCI satellite data showing characteristic reflectance patterns that could be used to optimize bio-optical algorithms for the two estuaries. This work offers new insights on estuarine particle characteristics and dynamics to improve water quality, biogeochemical and satellite ocean color studies.

Publication Source (Journal or Book title)

Science of the Total Environment

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