Biogeochemistry explores the intersection of biological, chemical, and geological processes that shape the environment. In an era of unprecedented human-induced environmental and climate change, research in this field is advancing rapidly. This seminar course explores the biogeochemical cycles of major and trace elements including carbon, nitrogen, phosphorus, sulfur and mercury, and examines how humans alter these cycles resulting in many of the environmental issues we are faced with today, such as eutrophication, climate change, ocean acidification and pollution by toxic contaminants. Additionally, the course focuses on the mechanisms controlling biogeochemical processes at local to global scales, including interactions between abiotic and biotic factors, such as climate, redox conditions, microbial metabolism, and ecology.