Contribution of Marine Phytoplankton to Seawater Alkalinity

• Main Author: 김현철
• Other Authors: 일반대학원 환경공학부, 포항공과대학교 환경공학부
• Format: Thesis
• Language: English
• Published: 포항공과대학교 2011
• Subjects: Ocean acidification
• Online Access: http://postech.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000000899031; https://oasis.postech.ac.kr/handle/2014.oak/1063

Doctor Rising atmospheric carbon dioxide (CO2) concentration over the past two centuries have led to greater CO2 uptake by the ocean, resulting in the increase of hydrogen ion concentration and a decrease in carbonate ion concentrations. The changes of carbonate chemistry in seawater such as ocean acidification can be described by measurements of CO2 parameters in which AT (total alkalinity) is the most measured parameter. Understanding of the changes in seawater chemistry requires the performance of a high quality measurement of the four measureable properties of the carbon dioxide system, namely AT, CT (total inorganic carbon), fCO2 (CO2 fugacity), and pH. This thesis work concentrates on improving our understanding of the carbonate chemistry by the estimation of unprecedented source of AT during phytoplankton growth, and the geological significance of such in over-determined oceanic AT. To attain these goals, first, the contribution of phytoplankton cells to AT was studied. Second, the contribution of freshly produced dissolved organic matter (DOM) to AT was estimated with six phytoplankton culture experiments. Finally, the geological significances of the unidentified sources of AT was investigated in the open ocean.Phytoplankton and bacterial cells make a significant contribution to the measured alkalinity of unfiltered seawater their contribution is probably 3~5 &#61549 mol kg-1, next to that of borate ion in most seawater samples. This nonnegligible contribution of particulate organic matter to the measured alkalinity is due largely to the presence of negatively charged surface groups on the phytoplankton and bacterial cells that react with protons during titration with hydrochloric acid. The contribution of organic particles to the measured alkalinity of unfiltered seawater could potentially be an important factor when evaluating the accuracy of presently available carbonate thermodynamic models using at-sea carbon system parameters that include measured alkalinity.The accuracy of the ...