Isotopes include stable and radioactive isotopes. The history of radioactive isotopes can be traced back to the study of radioactive materials by Rutherford and Madame Curie a hundred years ago. Since then radioactive isotope geochemistry was gradually developed. Radioactive isotopes are mainly used for accurate dating of environmental and geological samples. The history of stable isotopes can be traced back to Urey's first study of oxygen isotopes for temperature reconstruction, which gave birth to stable isotope geochemistry. Up to now, the basic theories of light-mass or traditional isotopes, including carbon, hydrogen, oxygen, nitrogen and sulfur, have been relatively well developed. They have made tremendous scientific breakthroughs regarding the Earth’s evolution, life origin and other important areas. From the end of 20th century to the beginning of 21st century, the rapid development of mass spectrometry technology and purification techniques enabled high-precision measurements of non-traditional stable isotopes (mainly metal stable isotopes), making metal stable isotope geochemistry a research hotspot in the past 20 years. Although the fractionation theories of some metal elements are not yet well constrained, their applications in environments, geochemistry, cosmochemistry etc. are rapidly expanding, exhibiting great potentials. Meanwhile, the rapid development of high-dimension isotopes such as Hg isotope systems (three fractionation manners), clumped isotopes (two or more atoms in the same molecule are replaced by their isotopes, such as 18O13C16O, 15N15N), intra-molecular position-specific isotopes (atoms in different functional positions in the same molecule are replaced by their isotopes, such as 15Nα15NβO), multiple/cross-linked isotopes (isotopes of different elements in the same molecule, such as S and O isotopes in SO42-, C and Hg isotopes in CH3Hg) also show innate advantages in areas such as paleotemperature construction and geochemical reaction pathway tracing.
At present, the Center for Advanced Science of Isotopes (CASI) of SESS Tianjin University is devoting to the advanced research domains of the stable isotope geochemistry, with a focus on the geochemistry of metal stable isotopes: on one hand, by improving the existing theoretical framework of metal stable isotopes (such as Hg, Cu, Zn, Fe, Li, Mg, Ba), expanding its application in surface earth system science; on the other hand, by developing measurement methods for new metal stable isotope systems (such as Ga, Sn, Sb), solving the outstanding scientific problems in surface earth system sciences. In addition to provide the fundamental technical support for various fields of surface earth system science, the CASI aims to make breakthroughs and innovations in the basic theory, measurement technologies and application areas of isotopes.
Development orientation
By means of experiments, observations, models and theory calculations, CASI will systematically study material cycles of main spheres of the surface earth system at different temporal (past, present and future) and spatial (molecular, basin and global) scales and their relationships with sustainable development of human beings, and aims to solve some basic, challenging and forward-looking scientific problems in surface earth system science. CASI will strive to 1) improve or establish new methods of isotope geochemistry, 2) explore and develop new theories of isotope fractionation in geosciences, 3) open up new fields for isotope application, 4) cultivate outstanding talents in frontier scientific research of isotope geochemistry, and 5) promote the development of surface geosciences.
