Degree
Doctor of Philosophy (PhD)
Department
Oceanography
Document Type
Dissertation
Abstract
The ocean is the second largest carbon reservoir on Earth and a significant carbon sink to mitigate the adverse effects of climate change. However, ocean carbon sink is expected to decrease in the future with continuing seawater acidification, more stable ocean stratification, and intensified extreme weather events. Estuaries, the connection between land and the coast, undergo complex carbon reforming and pose the greatest uncertainty in global carbon budgets. Coupled physical-biogeochemical models over the Gulf of Mexico (GoM) were configured using biogeochemical boundary conditions from a global climate model (GCM), preserving the long-term climate variability and the conservation of carbon pools in the regional model (RM). Subsequently, a nested domain over the Barataria Basin was built to quantify the carbon export in the eroding estuary. Intensive model-data comparison confirmed that the RM could reliably simulate the ocean carbon system in the GoM, and added values (AVs) were achieved both at the GCM scale and the RM scale. Model results reveal that the GoM water has been experiencing a ~ 0.0016 yr-1 decrease in surface pH over the past two decades, accompanied by a ~ 1.66 µatm yr-1 increase in sea surface pCO2. The river-dominated northern GoM (NGoM) is a substantial carbon sink, and the open GoM is a carbon source during summer and a carbon sink for the rest of the year. Based on the sensitivity test for higher river discharge scenarios, the NGoM was predicted to become a stronger ocean CO2 sink in the future. Stronger fluvial influence will increase the ecosystem resilience after hurricanes’ impact but reduce its resistance at the same time. The model estimated that Barataria Basin exports approximately 52.5 ×106 kg yr-1 dissolved inorganic carbon (DIC) and 9.68 ×106 kg yr-1 total organic carbon (TOC) to the coastal water. The biggest carbon loss term of the Barataria Basin was in the form of CO2 outgassing in quantity of 98.8×106 kg yr-1.
Date
1-21-2025
Recommended Citation
Zhang, Le, "UNDERSTANDING AND QUANTIFYING CARBON EXPORT TO COASTAL OCEANS THROUGH DELTAIC SYSTEMS" (2025). LSU Doctoral Dissertations. 6659.
https://repository.lsu.edu/gradschool_dissertations/6659
Committee Chair
Xue, Z. George
Included in
Atmospheric Sciences Commons, Biogeochemistry Commons, Climate Commons, Oceanography Commons, Sustainability Commons, Water Resource Management Commons