Turning Sour, Bloated, and Out of Breath: Ocean Chemistry under Global Warming

Presented on October 31, 2019 at 7:30 p.m. in Salon 4 of the Georgia Tech Hotel & Conference CenterTakamitsu “Taka” Ito is an associate professor in the School of Earth and Atmospheric Sciences, where he teaches physical and chemical oceanography. He received a Ph.D. in Earth, Atmospheric, and Planetary Sciences in 2005 from Massachusetts Institute of Technology. His research has focused on the cycling of carbon, oxygen, and iron in the global oceans, using observations, theory, and computational modeling.Runtime: 49:03 minutesIn 1997, the Japanese oceanographer Yoshiyuki Nozaki compiled a periodic table of ocean chemistry, encapsulating the distribution of elements as a function of depth. In this periodic table, many elements share similar patterns, classified into just a few categories. The similarities indicate a common set of mechanisms behind the ocean cycling of elements. The interaction of ocean circulation, chemistry, and biology sets the distribution of elements in the ocean. For example, nonreactive elements are nearly uniformly distributed in the water column, homogenized by ocean circulation and mixing. Nutrient elements are depleted near the surface because of biological consumption and enriched in mid-depth due to decomposition of organic matter. Some trace metals – such as Fe, Zn, Ni, and Cd – follow this pattern. In contrast, some heavy metals – like Al, Mn, Co, and Pb – are subsumed into particles and removed from seawater. Building on the insights from Nozaki’s periodic table, this talk will interpret recent measurements of changing seawater chemistry, highlighting the importance of rising carbon dioxide concentration in the air, climate change, and pollution of rivers and atmosphere