The objective of this course is to learn how chemical, biological, and geological processes control the distribution of chemical elements on Earth and the solar system. Geochemical processes are central to a variety of environmental issues, including the distribution of CO2 on Earth and the transformation and storage of inorganic and organic contaminants. Simultaneously, geochemical processes are involved in the transformation of natural species, including nutrients, carbon, and minerals. In this course, we will study the fundamental geochemical processes regulating the distribution of chemicals in aqueous solutions and at the mineral-water interface and will learn how to predict the distribution of these species in aquatic systems and soils using an equilibrium approach. This course will also introduce stable and radiogenic isotopic techniques essential for tracing elements through biogeochemical cycles and dating the age of planetary materials. This course is designed for students interested in securing jobs in environmental agencies or consulting companies or pursuing graduate studies in the geosciences, environmental science, or environmental engineering. Through a semester-long Wikipedia editing project, students will gain experience in scientific writing on notable topics in environmental sciences of high interest to the public. The Wikipedia editing project will also provide students with experience in identifying an audience, citing literature, peer review, revising, and ethical standards to avoid plagiarism.