Dear colleagues, We invite you to contribute an abstract to our session titled Seawater Chemistry Through Time: Reconstructions, Mechanisms, and Feedbacks <https://conf.goldschmidt.info/goldschmidt/2026/meetingapp.cgi/Session/8826> at the Goldschmidt 2026 (12-17 July in Montreal, Canada). Tittle: *Seawater Chemistry Through Time: Reconstructions, Mechanisms, and Feedbacks <https://conf.goldschmidt.info/goldschmidt/2026/meetingapp.cgi/Session/8826>* Session: 12h <https://conf.goldschmidt.info/goldschmidt/2026/meetingapp.cgi/Session/8826> Theme: Oceans and Atmosphere: Chemical and Physical Evolution and Modern Processes <https://conf.goldschmidt.info/goldschmidt/2026/meetingapp.cgi/Program/1196> *Keynote speaker:* Gaojun Li (Nanjing University) *Session conveners*: Mebrahtu F. Weldeghebriel (Princeton University), Pan Zhang (Northwest University), Kang-Jun Huang (Northwest University), Weiqiang Li (Nanjing University), Tim K. Lowenstein (Binghamton University) Abstract deadline: *February 26, 2026* Abstract submission link: https://conf.goldschmidt.info/goldschmidt/2026/cfp.cgi Grant application deadline: *12 February 2026 <https://conf.goldschmidt.info/goldschmidt/2026/meetingapp.cgi/ModuleMeetingInfo/GrantProgram>* Session description: 12h - *Seawater Chemistry Through Time: Reconstructions, Mechanisms, and Feedbacks* <https://conf.goldschmidt.info/goldschmidt/2026/meetingapp.cgi/Session/8826> The chemical composition of seawater—major and trace elements, isotopic compositions, alkalinity, redox conditions, pH, and salinity—has varied throughout Earth's history. These changes record the complex interactions among Earth's spheres and provide key insights into the evolution of biosphere habitability, fluctuations in atmospheric oxygen and carbon dioxide levels, shifts in lithospheric composition and weathering, and material cycling between Earth’s interior and surface. Documenting the long-term variations in seawater chemistry, understanding the key drivers behind these changes, and their quantitative links to geological processes greatly advance our knowledge of Earth's surface system evolution and long-term habitability. This session invites studies that reconstruct seawater chemistry across various timescales and explore its implications for interactions among Earth's spheres. We welcome work that address the evolution and controls of seawater chemistry in the geological record through the development and application of marine geochemical proxies and archives (e.g., Li, Sr, Mg, Ca, SO4, Cl, B, C, P, REEs; redox and pH indicators, etc.), as well as studies employing experimental simulations, data integration, numerical modeling, and big data analysis. Our goal is to foster a comprehensive understanding of secular variations in seawater chemistry and links to key geological processes across Earth's spheres, biogeochemical cycling, and climate change. Best Regards, Mebrahtu ------------ Mebrahtu F. Weldeghebriel, Ph.D. Postdoctoral Research Fellow Department of Geosciences C461 Briger Hall, Princeton University Princeton, NJ 08544