Isotopic compositions of atmospheric trace gases and particulate matter provide unique and powerful tools for tracing sources, sinks, and physico-chemical transformations in the atmosphere. These insights have significant implications for air quality, ecosystem health, and climate. Recent advances in isotope-based investigations, including innovations in sampling and analytical techniques, field and remote sensing observations, laboratory experiments, and both regional and global modeling, have greatly improved our understanding of the sources and fates of atmospheric constituents and their interactions with climate and the biosphere.

We warmly invite contributions from researchers applying stable and radiogenic isotopes (e.g., N, O, H, C, S, and metal isotopes) to explore topics such as:

• Sources and sinks of atmospheric gases and aerosols;

• Atmospheric physico-chemical processes and reaction mechanisms;

• Gas-phase and heterogeneous chemistry in various environments;

• Atmosphere–hydrosphere–biosphere exchanges;

• Understanding isotopic fractionations in atmospheric chemistry processes;

• Applications of isotopes in planetary atmospheres.

• B - Biogeosciences
• C - Cryosphere
• EP - Earth and Planetary Surface Processes
• GC - Global Environmental Change