Biogeochemists in the AOS Department work at the intersection of Chemistry, Biology, Geology, and Physical Sciences to study processes and reactions that are important to the Earth system, our changing environment, and past, current, and future life on earth. Our work encompasses modelling the chemistry, biology and ecosystem of the oceans (Bianchi), studying the importance of geomicrobiological processes for marine element cycling (Treude), as well as the impact of chemical and physical changes in the environment on living organisms (Eagle). We also study the interactions between the land biosphere and the atmosphere (Seibt), the evolution of the chemistry and physical properties of the oceans and atmosphere through time (Tripati and Eagle), as well as the productivity of land ecosystems (Stutz and Seibt). We maintain field equipment and several laboratories with instrumentation for ocean, land, and stable isotope biogeochemistry. Faculty, students and researchers engage in field research in and around Los Angeles, but also far afield including in the forests of Costa Rica and Canada, the world oceans, and the even Arctic and Antarctic regions.