This paper is the result of environmental geological survey engineering.

Objective Calcium is a primary rock−forming element and essential for life processes, and the key element connecting the lithosphere, hydrosphere, biosphere, and atmosphere. Although calcium isotopes theoretically hold significant research potential, their development has been limited by detection methods and instrument precision. With advancements in analytical techniques since the 1990s, calcium isotopes have gradually become a research hotspot in isotope geochemistry.

Methods This paper systematically reviews the progress in calcium isotope geochemistry based on comprehensive literature research. It covers advances in calcium isotope analytical techniques, fractionation mechanisms, calcium isotopic composition in different geological bodies, and their applications in hydrology, soil, ocean, environment, biomedicine, and archaeology.

Results With improvements in experimental techniques and analytical precision, the research scope of calcium isotopes has expanded significantly, achieving substantial progress. Currently, calcium isotopic composition in different geological bodies have been largely determined, but the understanding of their fractionation mechanisms remains incomplete. Calcium isotopes have broad application potential, including tracing calcium sources, chemical weathering, reconstructing ancient seawater evolution, paleoclimate reconstruction, calcium cycling in forest ecosystems, and applications in biomedicine and archaeology.

Conclusions Calcium isotope geochemistry is a promising research field. Despite the increase in related studies in recent years, the research remains relatively limited, with many new applications yet to be explored. Future research should focus on further optimizing calcium isotope analytical methods, refining fractionation mechanisms, and fostering interdisciplinary collaborations to achieve more accurate and extensive advancements and applications in calcium isotope research.