Theses and Dissertations

ORCID

https://orcid.org/0000-0001-7203-0071

Issuing Body

Mississippi State University

Advisor

Dash, Padmanava

Committee Member

Paul, Varun G.

Committee Member

Skarke, Adam

Committee Member

Rodgers, John C.

Committee Member

Li, Chunyan

Date of Degree

12-13-2024

Original embargo terms

Visible MSU only 2 years

Document Type

Dissertation - Campus Access Only

Major

Earth and Atmospheric Sciences

Degree Name

Doctor of Philosophy (Ph.D.)

College

College of Arts and Sciences

Department

Department of Geosciences

Abstract

Coastal water quality is intricately linked to environmental factors, particularly meteorological and hydrological conditions. Weather conditions determine wind speed and direction, which in turn influence coastal currents, and these currents play a critical role in the transport and variability of water quality parameters. Understanding how these dynamic interactions impact water quality is essential for the effective management and preservation of coastal ecosystems. This dissertation investigates the effects of varying flow conditions on key water quality parameters in the Louisiana Continental Shelf, utilizing data from two research cruises. The study specifically focuses on how concentration variability and transport mechanisms of water quality indicators respond to different environmental conditions, including the passage of cold fronts and periods of non-frontal conditions. In this research, data were collected using a conductivity-temperature-depth (CTD) system and through the analysis of water samples to assess changes in nutrient concentrations, dissolved oxygen levels, chlorophyll-a, and Colored Dissolved Organic Matter (CDOM). These samples were collected under two distinct environmental conditions: following a cold front and during non-frontal conditions. Analytical methods were used to quantify the water quality parameters, while hydrodynamic modeling was applied to assess the transport and dispersion patterns of these indicators. The results show that cold fronts increase nutrient concentrations and decrease dissolved oxygen levels due to enhanced mixing and upwelling. The cold front activity also promotes southwestward transport of water quality parameters, driven by the region's hydrodynamic forces. Under stable weather conditions, nutrient and chlorophyll-a concentrations increase, but transport is limited, with reduced dispersion resulting from weaker hydrodynamic forces. CDOM component analysis revealed that cold front conditions lower CDOM concentrations and improve light penetration, while non-frontal conditions elevate CDOM concentrations, reducing light penetration and impacting aquatic ecosystem productivity. These findings enhance our understanding of how meteorological events, hydrological conditions, and water quality interact in coastal regions. The research demonstrates how weather conditions distinctly influence nutrient dynamics and CDOM behavior. These insights are crucial for developing effective water quality management strategies for the Louisiana Continental Shelf and similar coastal regions worldwide, supporting global efforts to mitigate challenges posed by climate change and human activity in coastal ecosystems.

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