Research Overview

“Environmental & Marine Biogeochemistry Laboratory” EDIT

The most important three issues in ocean & environmental sciences may be “climate change, ecosystem change, and pollution” which are driven mainly by humans. These issues are tightly linked to the fluxes of terrestrial materials to the ocean and their biogeochemical cycles in the ocean. We study (1) fluxes of chemical species via the atmosphere, groundwater, and river to the ocean, and (2) biogeochemical reactions, cycling, and sedimentation of chemical species in oceans (see the illustration). We take advantages of various radionuclides for tracing these environmental processes. Under this broad research scope, our main research fields can be divided into three specific areas: (1) Radionuclides – applications to key environmental studies; (2) Carbon-nitrogen-phosphorus cycling and ecological consequences; (3) Trace elements and rare earth elements – pollution and behaviors.

– Development of analytical techniques of all natural, artificial, and cosmogenic radioisotopes
– Behaviors of radionuclides in the atmosphere, lakes, sediments, and ocean
– Particle and organic matter scavenging and cycling: Th-234, Po-210, Pb-210
– Water and air mass mixing and exchange: Ra and Rn
– Magnitude of mechanisms of submarine groundwater discharge: Rn and Ra
– Bioaccumulation and bio-volatilization: Po-210
– Atmospheric deposition and sedimentation rates: Be-7, Pb-210, Cs-137, Bi-210
– Artificial Cs-137 and Sr-90 in the ocean

– Fluxes of macro- and micro-nutrients through rivers, groundwater, and atmosphere
– Behavior of C, N, P in estuaries and subterranean estuaries
– Consequences of coastal fluxes in the ocean: biological production, red tides, biogeochemistry
– POC, DOC, CDOM, DON, THAA, nutrients: sources, transport, cycling
– Groundwater dependent ecosystem: magnitude and linking mechanisms
– Sources and ages of refractory DOM
– Stable C and N isotopes as tracers
– Coastal acidification: impact of changes in coastal fluxes

– Fluxes of trace elements and REE through rivers, groundwater, glacier, and atmosphere to the ocean
– Behaviors of trace elements in estuaries and subterranean estuaries
– Consequences of trace fluxes in the ocean
– Cycling of trace elements in lakes and oceans
– Stable isotope systematics: Pb, Sr, Nd
– Se and Te bioaccumulation