Research Progress of Cadmium Stable Isotopes

Abstract

BACKGROUND Cadmium is a volatile element with chalcophile affinity. In the marine environment, Cd is a micronutrient element, while in the ecological environment and agricultural soil environment, Cd is a toxic element. Therefore, Cd isotopes have been used in marine science, earth science, environmental science, and agricultural scientific research, and show great application potential. OBJECTIVES To summarize the high-precision analytical technology and applications of Cd isotopes in different research fields. METHODS The recent research progress in digestion methods, separation and purification of Cd, and double-spikes calibration methods for organic matter-rich environmental samples, plant samples and biological samples were summarized. RESULTS For organic matter-rich samples including environmental, plant and biological samples, microwave digestion, high-pressure ashing and perchloric acid digestion can eliminate the influence of organic matter in Cd isotope analysis. Combined AG MP-1(M) resin with hydrochloric acid leaching system can effectively separate the matrix and interfering elements, which will not result in Cd isotope fractionation. The precision of Cd isotope with 111Cd-113Cd isotope double-spike correction was around 0.1εCd/amu. The application of Cd isotopes in marine science, geoscience, environmental science, and agricultural science were also summarized in this paper. Cadmium isotopes were used successfully for building marine biological geochemistry cycles, inversion of ancient marine environments and primary productivity change. In sulfide deposits, Cd isotopes were used to trace the evolution of ore fluids and the source of ore metals, and to discriminate different deposit types. In environmental systems, Cd isotopes were applied to distinguish Cd pollution sources, and to investigate Cd sources, migration, circulation and storage mechanisms in agricultural sciences. CONCLUSIONS The research of the high-precision Cd isotope analytical method and Cd isotope fractionation mechanism and model, will promote to establishment the tracer system of Cd isotope biogeochemistry fractionation and innovative development of non-traditional stable isotope geochemistry.

Keywords

• cd isotope
• double spike correction
• isotopic fractionation effect
• isotope tracer
• paleoenvironmental evolution
• discrimination of pollution source