Dr. Johnson research research aims to answer scientific questions that will further the development of tools for managing risk from environmental contaminants. Most of his groups’ projects involve applied environmental aquatic chemistry, sediment biogeochemistry, and biological and chemical processes related to contaminant transport and transformations. Dr. Johnson typically tries to complement field or laboratory investigations with mathematical modeling. He has working relationships with state and federal resource management agencies interested in the management of sulfate discharges to freshwater resources in northeastern Minnesota and sediment contamination in the St. Louis River Estuary. During the summer, Dr. Johnson’s group typically consists of 5-10 undergraduate and graduate students working on a variety of projects seeking to quantify and understand the transport and transformation of sediment-associated contaminants.