【直播】【未来海洋全球公开课】 Using Th-Ra-Rn Isotopes to Understand Ocean

直播信息

活动名称

未来海洋全球公开课｜第1课 Using Th-Ra-Rn Isotopes to Understand Ocean

授课教师

Isaac Santos

Bochao XU

活动时间

2022年7月20日（周三）14:00

主办方

中国海洋大学未来海洋学院

直播二维码

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课程简介

Part1. Thorium as a tracer of marine carbon sequestration

Isaac Santos（7月20日  14:00-15:30)

The marine carbon pump transports large amounts of natural and anthropogenic carbon from the atmosphere into the dep ocean as settling particles. Quantifying the carbon pump and reducing uncertainties in estimates is a major challenge in chemical oceanography. Thorium isotopes are particle reactive and have been used to quantify the vertical flux of organic carbon into the deep ocean for decades. This lecture will discuss how the Th-234 approach can be used, its inherent assumptions, the key spatial and temporal drivers, and the insight obtained from Th-234 observations in the global oceans.

Part2. Radon as a tracer in coastal oceanography

Isaac Santos（7月21日  14:00-15:30)

Submarine groundwater discharge and porewater exchange play a major role on coastal biogeochemical budgets. The use of radon and radium isotopes have been essential to resolve how porewater and groundwater deliver nutrients and carbon to the coastal ocean. Carbon budgets in blue carbon ecosystems such as saltmarshes and mangroves are particularly impacted by tidally driven porewater flushing in organic-rich intertidal soils. In this lecture, I will discuss how radon can be used to quantify porewater exchange and close carbon budgets with a focus on blue carbon ecosystems. I will also discuss remaining challenges and uncertainties related to the radon approach.

Part3. Radium-226 in the global ocean as a tracer of thermohaline circulation

Bochao Xu（7月22日  9:00-10:30)

Ra-226 is the most abundant radium isotope in the ocean with the longest half-life (1600 years). This lecture will focus on the understanding and application of Ra-226 in the deep ocean. I will introduce a global picture of 226Ra distribution throughout the global ocean. The major sources and sinks of 226Ra in the global ocean will be discussed. Deep and bottom water masses are shown with characteristic 226Ra properties confirming that 226Ra can be used as a good thermohaline tracer in three major ocean basins.

Part4. Radium quartet as tracers in the land-ocean continuum

Bochao Xu（7月23日  9:00-10:30)

Naturally occurring radium isotopes are powerful natural tracers of marine processes and support the quantification of elemental budgets. This lecture will focus on the understanding and application of the four radium isotopes (radium quartet) in the river-estuary-coast continuum. I will first introduce the sources and sink of radium isotopes in the continuum. Then I will talk about how to use radium as tracer to assess the key land-ocean interaction process - submarine groundwater discharge. Radium will be shown as powerful tool to quantify hydrodynamics in different settings, such as coastal settings and river reservoirs.

授课教师简介

Professor Isaac Santos is an AGU Medalist and Fellow working at the interface between coastal oceanography, hydrology, and biogeochemistry. His experience includes quantifying carbon budgets in aquatic ecosystems, groundwater-surface water exchange, carbon sequestration, and greenhouse gas fluxes. He has performed research in a wide range of ecosystems from headwater streams to the deep ocean. He has received awards for excellence in research, teaching and community engagement. Santos has published >220 peer reviewed articles in leading disciplinary journals, including 33 papers in AGU journals and 125 papers first authored by his students. He holds an H index of 61 (Scholar) that has grown at a rate of >4 per year since PhD completion. His research relies on interdisciplinary international collaboration with >450 co-authors worldwide. Santos serves as the Editor in Chief of Global Biogeochemical Cycles.

Professor Bochao Xu is a chemical oceanographer focusing on hydrodynamics and sedimentary dynamics in land-ocean continuum by using geochemical tracing technique. His experience includes assessing water mixing dynamics, submarine groundwater discharge, sediment reworking, elemental composition on foraminiferal shells and its ecological indication. He has published more than 40 peer reviewed articles, including TOP journals such as Geochimica et Cosmochimica Acta, Geophysical Research Letters, Earth-Science Reviews. He joined GEOTRACES project. As a committee member, he worked for the organization of the 8th international Ra-Rn workshop. He served as reviewer for more than 20 international journals, such as GCA, Water Research, Chemical Geology, HESS, Journal of Hydrology, JGR-Oceans. He was supported as PI by 3 NSFC project, and joined some other nation class projects as key researcher.

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