Gordon Brown specializes in environmental geochemistry and aqueous and surface geochemistry.  He and his research group focus on chemical and microbiological interactions at environmental interfaces, which are defined as interfaces between solids and aqueous solutions, solids and gases, aqueous solutions and gases, solids and microbial organisms (including microbial biofilms), and solids and natural organic matter.  They utilize molecular-scale methods, particularly those involving very intense x-rays from synchrotron radiation sources, to study the interactions of contaminants and pollutants, particularly heavy metals such as lead and mercury, metalloids such as arsenic and selenium, and actinides such as uranium, with mineral surfaces, with the aim of understanding reactions that can sequester or release these species or transform them into more or less toxic forms.