Ocean Alkalinity, Buffering and Biogeochemical Processes.

Area of Science:

• Oceanography
• Marine Chemistry
• Biogeochemistry

Background:

• Alkalinity, the excess of proton acceptors over donors, is fundamental to ocean chemistry.
• It plays a critical role in buffering the ocean and influencing calcium carbonate precipitation and dissolution.
• Understanding alkalinity dynamics is essential for quantifying ocean carbon dioxide uptake, especially during global change.

Purpose of the Study:

• To review ocean alkalinity and its buffering role.
• To elucidate the biogeochemical processes governing ocean alkalinity and pH.
• To differentiate between titration alkalinity and charge balance alkalinity for accurate calcification and carbonate dissolution quantification.

Main Methods:

• Review of existing literature on ocean alkalinity and buffering.
• Presentation of a general treatment of ocean buffering using sensitivity factors.
• Quantification of the impact of individual biogeochemical processes on ocean alkalinity and pH.

Main Results:

• Distinguishing between titration and charge balance alkalinity is crucial for understanding carbon dioxide system impacts.
• Sensitivity factors provide a means to link buffer and sensitivity factors and quantify process impacts.
• Longer-term processes like carbonate compensation and silicate weathering influence ocean alkalinity.

Conclusions:

• A comprehensive understanding of alkalinity dynamics is vital for predicting ocean responses to global change.
• The study provides a framework for quantifying the impact of biogeochemical processes on ocean alkalinity and pH.
• A near-balance ocean alkalinity budget for the modern ocean is derived, integrating various timescales and processes.