Hokkaido University

Graduate School of Environmental Science

Division of Earth System Science

Course in Biogeochemistry

前へ
次へ

What's new

2019-4-4
Information on the Entrance Examination has been disclosed.
2019-4-1
Our course was renamed "Course in Biogeochemistry."
2019-3-1
New web page of Course in Biogeochemistry has been launched.
2018-12-1
Course in Geochemistry will be renamed to Course in Biogeochemistry from FY2019.

Overview

We aim to understand various phenomena occurring in the earth surface including atmosphere, soil, river, and ocean through the research on geochemical cycles and chemical reactions. It is essential to collect natural (geochemical) materials and analyze the chemical species in them, which is necessary to understand every geochemical process involved in material cycles on the earth.

We blieve that our research provides deep understandings of environmental problems on the earth such as global warming, ozone layer depletion, and acid rain as well as solutions to these problems. In order to archieve this purpose, it is necessary to nurture professionals through educations of basics and methods for analytical chemistry, atmospheric chemistry, marine chemistry, isotope geochemistry, and paleoclimatology.

All the members in the Course in Biogeochemistry are qualified to maintain this largest center of research and education for biogeochemical study in Japan.

Education

Students learning in the Course come from varous faculties such as chemistry, geology, fishery, oceanography, biology, agriculture, and engineering. In order to provide common necessary knowledge for research here, we maintain the carriculum including basic lectures such as atmospheric and marine chemistry, and ones suitable for each speciality such as atmospheric chemistry, chemical oceanography, and marine sedimentology. Through master course, students can learn how to collect natural materials and analyze them in an appropriate way. We also provide students a training for presentation of their new findings at academic meetings.

Because modern environmental problems are always related to chemical processes going on the earth surface, society requires professionals who are capable of understanding biogeochemical processes. Therefore, we aim to nurture excellent geochemists as will be helpful in academic and societal contexts of problems.

Our Research

Our studies begin with sampling of aerosol, soil, seawater, and/or sediments in the fields such as urban area, forest, ocean, and polar region. To analyze chemical tracers such as organic compounds, elements, and isotopes, state-of-the-art instruments (e.g., high-performance liquid chromatograph, gas chromatograph, elemental analyzer, and mass spectrometer) are used. Then we try to synthesize the results aiming to new findings

Biogeochemistry of the atmosphere

Atmospheric trace gases and aerosols are important factors controlling global climate and ecosystems. We measure atmospheric components that are relevant to climate and biogeochemistry, and work to understand their origin and chemical/biogeochemical processing. In particular, field measurements of atmospheric trace gases/aerosols in oceanic and forest regions allow us to to elucidate processes for atmosphere-biosphere interaction via atmospheric constituents. We also try to establish new methods to measure atmospheric constituents to better understand their effects on climate change and biogeochemical cycling of bioelements.

Larch forest and CO2 flux tower (40-m height) in Tomakomai. Air samples are taken from the tower to investigate monitoring of emission of volatile organic compounds such as terpene and production of aerosols above the forest.

Extraction and purification of CO2 from air samples collected in Eastern Siberia to analyze stable carbon isotopic composition of CO2. The 13C values of CO2 increase in summer due to photosynthesis by terrestrial plants.

Studies for terrestrial environment

We have been conducting field campaigns at various terrestrial environments, i.e., forests, wetlands and rivers. Recently, we are studying key processes/factors affecting the methane emission from wetlands, photosynthesis/production of plants, and water cycle of permafrost ecosystem in the arctic region of eastern Siberia. We are also trying to understand the transport processes controlling fluxes of inorganic nutrients, suspended solids, and organic matter from terrestrial ecosystems to coastal environments, in particular at Hokkaido.

We have been carried out field research at the rivers in northern Japan, Far East Russia and northern China. The river water samples are analyzing for characteristics of organic matter, mineral and elemental compositions to understand migration behavior of these materials.

Marine research

We have been conducting biogeochemical studies in the oceans and seas including the North Pacific, the Sea of Okhotsk, the Sea of Japan, and the Southern Ocean. Through sample collection and the subsequent analyses of chemical and biological parameters using state-of-the-art techniques, we aim at clarifying important marine biogeochemical processes and quantifying their spatiotemporal variability. Our main research targets are as follows: phytoplankton which can drive ocean biogeochemistry, nutrients and trace metals which control marine biological production, gasses such as carbon dioxide, methane and dimethyl sulfide which influence the global warming, and dissolved organic matter which dominates the ocean carbon pool.

Sampling of seawater. CTD-RMS system enable us to obtain seawater samples from surface to deep sea together with monitoring seawater temperature, salinity, and dissolved oxygen.

Studies on paleoenvironment

The prediction and projection of future climate need a thoroughly understanding of the behavior of Earth’s climate system. The study of the paleoclimate is indispensable to understand the whole climate system because it deals with larger climate variabilities than documents and instrumental records could depict. We investigate the climate of the past using “paleoclimate archives” such as marine and lacustrine sediments, ice cores, tree rings and coral rings as well as soils in archaeological sites. Marine and lacustrine sediments and ice sheet cores are useful to reconstruct low resolution but longer paleoclimate records on millennial, ten millennial and even more, while tree rings, alpine glacier ice cores and coral rings are useful to generate high-resolution seasonal to annual climate records on centennial time scale. Soils and marine sediments are often used to understand changes in human activities and their impacts on environments. Tools we often use are mainly geochemical techniques such as analyses of elemental and isotopic compositions and biomarkers in these paleoclimate archives. Application of these multi-disciplinary approaches enables us to reconstruct the variablities in atmospheric, oceanic, and terrestrial environments that are synthesized to understand the driving forces and causal mechanisms of global climate changes. The elucidation of climate system is a challenge in science, like an action of finding missing pieces in a puzzle. It is our big pleasure to propose a new hypothesis on the cause and mechanisms of climate changes.

Sampling of deep sea sediment core. Core is about to be on deck. It's a difficult job to obtain sediments from sea floor as deep as several thousands of meters. "Good luck!"

Studies for ecosystem

Energy and material cycles in ecosystems are apparently balanced and regulated even thought ecosystems are exposed to large heterogeneity in physiology, ecology, and geochemistry. On the other hand, ecosystems are frequently disrupted by a tiny little change, and it always induces the evolution of organisms. We would like to understand ‘ecological stability, instability, and lability’ from the end of ‘energy and material cycles’, based on the molecular and isotopic analysis of organic compounds for organisms collected from natural environments as well as reared in laboratory.

Ecosystem structures reconstucted based on stable isotope analyses

Go to page top