普林斯顿大学François M. M. Morel教授是著名的地球化学学家，发表了多篇Nature与Science文章。Morel教授将于本周五到访我实验室，并受邀为大家做一场学术报告，详情如下：
报告题目：Carbon Dioxide in the Oceans and Atmosphere: Global Processes and Molecular Mechanisms
报告时间：5月20日（星期五）14:30pm-16:00pm
Biogeochemical processes transfer carbon among various global reservoirs on Earth over time scales from hours to billions of years. The present day composition of the Earth surface and its atmosphere, including a high concentration of O2and a low concentration of CO2, results from the photosynthetic activity of the evolving biota over some 3.5 billion years. On a shorter time scale, the processes that transfer carbon between the atmosphere and the deep oceans are responsible for the variations in atmospheric CO2during glacial/interglacial cycles. The time scale of hundreds to thousands of years over which this exchange of carbon operates is relevant to the ongoing build up in atmospheric CO2caused by anthropogenic activities.
Photosynthesis by oceanic phytoplankton and settling of biomass play a critical role in exporting CO2to the deep ocean. But this vertical transport of carbon from the sea surface to the abyss –known as the “biological carbon pump”-- is accompanied by an export of all major and trace nutrients necessary for growth. The functioning of the biological pump is thus critically dependent on the evolution of molecular mechanisms that allow marine phytoplankton to acquire the necessary nutrients from depleted surface seawater and to fix inorganic carbon into organic biomass at very low ambient CO2concentration.
We are now beginning to understand some of the key molecular mechanisms that allow marine phytoplankton, particularly diatoms, to photosynthesize and grow efficiently under the low nutrient and CO2depleted conditions of the surface ocean. Among those are uptake systems for essential nutrients that function at the limits allowed by physics and chemistry, an ability to replace essential elements in short supply by others in key enzymes, and an inorganic carbon acquisition system that is similar to that of C4 plants on land. A question of major interest is how these organisms will be responding to the ongoing increase in the concentration of CO2in surface seawater and the resulting acidification of surface seawater.
