해양산성화: 지질학적 기록으로부터의 학습(리뷰)

Abstract

Ocean acidification is a pressing concern related to atmospheric carbon dioxide concentrations and bio-diversity in the ocean. Geological records concerning this theme may provide valuable information on both topics, including future advances in research on ocean acidification. Therefore, this paper reviews the geological records of ocean acidification, and suggests main themes related to acidification.One of best examples of ocean acidification is the event that occurred at the Paleocene-Eocene thermal maximum (PETM), approximately 55 Mya. At that time, approximately 2,000×109 metric tons of carbon, in the form of methane, were released into the water column. Through oxidation and absorption by the ocean, the deep-sea pH was lowered, triggering rapid shoaling of the calcite compensation depth (CCD). A previous study clearly showed that massive sea-floor carbonate dissolution coincided with the PETM, and this was marked by rapid shoaling of the CCD (<10,000 years) and gradual recovery (>100,000 years) (Zachos et al., 2005).Recent advances in acidification study have involved nine themes: future scenarios of ocean acidification; effects of changes in seawater chemistry on nutrients and metal speciation; paleoceanographic perspectives; mechanisms of calcification; impact on benthic and pelagic calcifiers; physiological effects from microbes to fish; adaptation and micro-evolution; fisheries and food webs; and impact on biogeochemical cycling and feedback to the climate system (The high-CO2 world, 2nd symposium, 2008). Further study is necessary to understand and determine future perspectives on acidification.