The relationship between carbon dioxide flux and environmental parameters at a tropical coastal sea on different timescales

• Published in: Marine pollution bulletin 2023-08, Vol.193, p.115106-115106, Article 115106
• Main Authors: Yusup, Yusri, Swesi, Abdulghani Essayah, Sigid, Muhammad Fikri, Almdhun, Haitem M., Jamshidi, Ehsan Jolous
• Format: Article
• Language: English
• Subjects: Atmospheric surface layer; Carbon Cycle; Carbon Dioxide; Carbon Sequestration; CO2 flux; Eddy covariance; Monsoon; Seasons; Seawater; Tropical coastal sea
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2023.115106

This paper analyzes CO2 flux between the atmosphere and a tropical coastal sea using the eddy covariance technique. Coastal carbon dioxide flux studies are limited, particularly in tropical regions. Data was collected from the study site in Pulau Pinang, Malaysia, since 2015. The research found that the site is a moderate CO2 sink and experiences seasonal monsoonal changes that affect its carbon-sink or carbon-source capability. The analysis showed that the coastal sea systematically shifted from being a carbon-sink at night to a weak carbon-source during the day possibly due to cause by the synergistic influence of wind speed and seawater temperature. The CO2 flux are also influenced by small-scale, unpredictable winds, limited fetch, developing waves, and high-buoyancy conditions caused by low wind speeds and an unstable surface layer. Furthermore, it exhibited a linear relationship with wind speed. In stable conditions, the flux was influenced by wind speed and drag coefficient, while in unstable conditions, it was mostly controlled by friction velocity and atmospheric stability. These findings could improve our understanding of the critical factors that drive CO2 flux at the tropical coast. •In-depth analysis of CO2 flux between atmosphere & tropical coastal sea surface using eddy covariance technique.•The tropical coast moves from being a carbon-sink at night to a weak carbon-source at day.•In stable conditions, the flux was influenced by wind speed and drag coefficient.•In unstable conditions, it was mostly controlled by friction velocity and atmospheric stability.