John Bargar

Environmental Science Area Leader

Dr. John Bargar is the Environmental Transformations and Interactions Science Area group leader at the Environmental Molecular Sciences Laboratory (EMSL). His research interests focus on understanding and modeling biogeochemical processes across scales, from molecular to continental. He has extensive experience leveraging community science to generate molecular data at unprecedented scale to transform our understanding and prediction of Earth systems.

For more than 28 years, Bargar has led projects focused on basic and applied energy research. Before joining Pacific Northwest National Laboratory (PNNL) in 2022, Bargar led the SLAC National Accelerator Laboratory geosciences program, including the Department of Energy-Biological and Environmental Research program-funded Floodplain Hydro-Biogeochemistry Sciences Focus Area (SFA), a SLAC-led multi-laboratory synchrotron nuclear forensics research program, and the SLAC deep subsurface geochemistry project program.

Bargar’s work on the behavior of essential metal micronutrients and contaminants in soils and natural waters has improved our understanding and prediction of metal behavior in soils and groundwater. At systems scales, his research has focused on understanding how, where, and when molecular reactions occur and interact across larger distances, from floodplains to regions. Bargar’s SFA team’s work demonstrated that soil organic matter controls uranium accumulation and release in shallow sediments across the upper Colorado River Basin. This behavior is significant because it moderates the dissolved concentrations of persistent regional uranium groundwater contamination. Similarly, Bargar’s deep subsurface team’s work on hydraulically stimulated unconventional reservoirs provided critical new insights and modeling tools to understand geochemical reaction networks and predict the impact of fluid additives on fracture permeability and water quality. At PNNL, Bargar has led the launch of the Molecular Observation Network (MONet), a community science activity within the EMSL user program. MONet is generating high-volume, high-quality, artificial-intelligence ready molecular data on biogeochemical and atmospheric processes at continental scale across the United States.

Bargar has participated as a reviewer for numerous geochemistry, hydrology, and chemistry journals, has chaired and organized numerous committees and symposia, and has been published in more than 195 scholarly articles.