A Spatiotemporal Evaluation of Estuarine-Coastal Carbon and Nutrient Interactions and Lateral Fluxes in Deltaic Regions Undergoing Growth and Deterioration Phases in Coastal Louisiana, USA

Author

Ivan Alexis Vargas-Lopez, Louisiana State University and Agricultural and Mechanical CollegeFollow

Degree

Doctor of Philosophy (PhD)

Department

Oceanography and Coastal Sciences

Document Type

Dissertation

Abstract

Coastal ecosystems and associated wetlands are characterized by a high biological diversity and productivity where intricate biogeochemical reactions occur. Yet, these carbon/nutrient biogeochemical dynamics are not well understood. One of the major unknowns is the estimation of net lateral carbon and nutrient fluxes between the coastal zone and the adjacent coastal ocean. Thus, the main goal of this dissertation was to evaluate the lateral export of carbon and nutrients in the Mississippi River Delta Plain to understand how carbon and nutrients are transported and exported across these areas. A combination of intensive field sampling and remote sensing tools were used to evaluate the spatiotemporal distribution of water column primary productivity [Chlorophyll-a] (Chapter 2) and dissolved organic matter [Chromophoric Dissolved Organic Matter, CDOM] (Chapter 3) as major components of the water total carbon pool. In Chapter 4, based on the discrete and continuous carbon (i.e., inorganic dissolved, [DIC]; dissolved organic, [DOC]; particulate organic, [POC]) and inorganic nutrients ([N+N], [NH₄⁺], [PO₄^-]) values discussed in Chapters 2 and 3, the net export of these materials into the adjacent coastal waters was estimated using previously calibrated and validated 2- (FREHD) and 3-(SCHISM) dimensional numerical hydrodynamic models at different spatiotemporal scales during 2019-2021, and in two estuarine regions representing erosional (i.e., Barataria Basin complex) and growth (i.e., Wax Lake Delta Outlet system) stages in the delta cycle. The main hypothesis is that the Wax Lake Delta Outlet system functions as a “pipe” that directly delivers sediment and nutrients to the adjacent Atchafalaya Basin and the continental shelf. In contrast, the Barataria Basin is a “bioreactor” where most of the nutrients are recycled and transformed in situ as a result of the lack of freshwater inputs. Finally, based on the comparative analysis of the biogeochemical patterns in both the Wax Lake Delta Outlet system and the Barataria Basin complex, it is discussed how the successful, yet unplanned, “building” of the man-made Wax Lake Delta might be not the best proxy to project the implementation and footprint of sustainable freshwater diversions in the Barataria Basin complex or other coastal areas.

Date

4-21-2023

Recommended Citation

Vargas-Lopez, Ivan Alexis, "A Spatiotemporal Evaluation of Estuarine-Coastal Carbon and Nutrient Interactions and Lateral Fluxes in Deltaic Regions Undergoing Growth and Deterioration Phases in Coastal Louisiana, USA" (2023). LSU Doctoral Dissertations. 6114.
https://repository.lsu.edu/gradschool_dissertations/6114

Committee Chair

Rivera-Monroy, Victor H.

DOI

10.31390/gradschool_dissertations.6114