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Science Areas
Environmental Transformations and Interactions

Remembering John Zachara

Prominent leader in subsurface science has passed away

Genoa Blankenship |
portrait of man in blue dress shirt
John Zachara

Geoscientist John Zachara, a Battelle and Pacific Northwest National Laboratory (PNNL) fellow, died June 1 from a rare form of leukemia. He was 69.

Zachara was regarded as an early leader in subsurface science and played a significant role in contaminant biogeochemistry research. He worked at PNNL for 37 years, retiring in 2016.

Among his greatest scientific accomplishments were his contributions to resolving technical challenges at the U.S. Department of Energy’s (DOE) Hanford Site, specifically his research on how toxic metals and radionuclides travel in the subsurface.

“John built the foundation for EMSL’s leadership and capabilities in biogeochemistry that continues to address important national challenges today. His focus on identifying the molecular mechanisms informed remediation strategies at Hanford and other DOE sites,” said Nancy Hess, who leads the Environmental Transformations and Interactions Science Area for the Environmental Molecular Sciences Laboratory (EMSL), a DOE user facility.

EMSL Director Douglas Mans called Zachara “an unbelievably curious and creative scientific leader at PNNL and within the EMSL community.” Zachara helped establish one of EMSL’s flagship “Grand Challenges” to uncover the mechanisms by which microbial species obtain energy from inert materials within the Earth’s subsurface. This work leveraged EMSL’s expertise in microbial biology, subsurface geochemistry, and molecular surface interactions. 

“John’s legacy in creating audacious and inspiring scientific questions is still reflected today in EMSL’s world-class expertise and capabilities in biogeochemistry that extend John’s initial pursuit of understanding microbe-mineral interactions to more broadly the interactions, flow, and transport of key minerals, nutrients, and compounds in critical zones of the Earth subsurface,” Mans said.

Zachara was the principal scientist for DOE’s Biological and Environmental Research (BER) program for four years. He conducted research on geochemical, biogeochemical, and hydrologic processes that control the concentrations, fate, and transport of organic, metal, and radionuclide contaminants in soil and subsurface environments.

Tim Scheibe, a PNNL fellow and EMSL lead scientist, worked with Zachara on the PNNL River Corridor Scientific Focus Area (SFA) project, which was funded by BER. When the SFA began in 2009, Zachara was the principal investigator for the project.

“The thing that stood out to me most about John as a scientist was his ability to focus everyone’s attention on the critical issues, even in areas that were outside his primary expertise. He could be counted on to ask questions that were both insightful and challenging, making us all better thinkers and communicators in our science,” Scheibe said.

The SFA is a multidisciplinary BER project, which often required Zachara to understand things that were outside his primary areas of expertise. By nature, Zachara was interested in and continually learning about a broad spectrum of things, Scheibe recalled. As Scheibe transitioned into the principal investigator role in 2016, Zachara supported him personally as well as the SFA team as a whole.

“His emphasis on high-quality science and multidisciplinary integration has made a strong imprint on all of us as we aim to build on his legacy into the future,” Scheibe said.

He conducted research and projects, including the EMSL Grand Challenge, with his longtime friend and colleague, Jim Fredrickson. Zachara and Fredrickson connected at Washington State University in Pullman and began running together during their lunch breaks. They both went to work at PNNL in the same group and continued to run and bike together on their lunch breaks. Over 30 years, they covered 16,000 miles together.

“We had very different personalities, but we clicked very much on the science and the view on what was important outside of work,” Fredrickson.

Zachara and Fredrickson took backcountry trips and skied together. Fredrickson said some of their brainstorming sessions about science happened on the chairlift.

“That one-on-one time really allowed us to spend a lot of quality time brainstorming and talking about things, research, and papers,” Fredrickson said. “I think that was some of our most productive time.”

Project coordinator Sonia Enloe worked with Zachara for more than 30 years. They became like family.

“John was one of the most intelligent and strongest men I’ve known,” Enloe said. “He was highly respected and loved by many.”

Zachara’s colleagues across BER are meeting online later this month to remember him in a special session.