Unearthing Soil Solutions for Arsenic Remediation

NC State's Owen Duckworth works in his soil biogeochemistry lab

“The United Nations recently published a somewhat bleak report on worldwide soil contamination. A major challenge is reclaiming land and protecting human health from toxic exposures,” said Owen Duckworth, North Carolina State University professor of biogeochemistry.

Soil pollution may seem limited to headline-grabbing spills, but many pollutants result from mining, industrial activities, waste disposal, and even naturally occurring deposits. Toxic heavy metals are a silent threat to ecosystems and human health, most often through contaminated drinking water. 

Understanding Arsenic Mobility

Duckworth’s lab collaborates with the University of North Carolina’s Superfund Research Program to understand the distribution and effects of naturally occurring arsenic in North Carolina.

His group has worked with many collaborators to identify how geology impacts water contamination.  The Slate Belt of the Piedmont region is scattered with these natural deposits that can cause water contamination.  

North Carolina map showing geologic belts across the state.
Photo by the University of North Carolina

Modeling and experimental work by NC State Extension Specialist Robert Austin, student Hannah Peel, and recent graduate Taylor Alvarado show that Union and Chatham counties have pockets where groundwater has notoriously high concentrations of arsenic.

Duckworth explains that the population affected by these pockets of contamination can add up.  

“Approximately 2.4 million North Carolinians rely on well water that may go untested for tasteless toxins like arsenic. We estimate that around 45,000 consume well water that is above EPA limits for arsenic. 

Our work in the Superfund study is to research the mechanisms by which arsenic moves in the soil and enters groundwater to identify interventions to protect public health.”  

The Superfund Research Program has a significant outreach and education component that works with public health departments, state geologists, engineers, and citizens to communicate findings and shape policy.

Field soil testing for arsenic

Biochar for Arsenic Remediation

A graduate student subproject from Duckworth’s lab recently caught the attention of the National Institutes for Health.

Mathias Soares worked in Duckworth’s lab for a year, researching the feasibility of locally produced biochar to remediate arsenic-contaminated water in his home country of Brazil. The findings showed that biochar prepared with high temperatures was a particularly effective means of arsenic remediation. 

Duckworth stressed that locally tailored remediation strategies are key.

“Biogeochemical interactions are complicated and often have conflicting effects in an entire system. This was a great study showing an effective and economical in-situ remediation strategy for mining pollution in Brazil.”

Since many potentially dangerous soil deposits are naturally occurring, eradicating them is unrealistic. Keeping them from changing form and becoming more mobile is more plausible.

“There’s a growing trend towards stabilization rather than removing with heavy metals. Isolating and keeping known deposits undisturbed while using less invasive interventions like filtration and infrastructure improvements is a better option.”

Duckworth Named Soil Science Fellow

For his work in environmental science, the Soil Science Society of America recently named Duckworth as a Fellow. The awards are presented to Society members to recognize outstanding contributions to soil science through education, service, and research.

Josh Heitman, NC State professor of soil physics and hydrology, nominated Duckworth for the award. 

“Owen has an outstanding ability to recognize how his fundamental expertise in soil biogeochemistry can be brought to bear on real-world problems affecting NC citizens,” Heitman said. “This has driven his research program to tackle a broad range of pressing environmental problems that too often fly under the radar.”

“I really enjoy the welcoming nature of the Soil Science Society,” Duckworth said. “The award is nice recognition to be considered a part of this important community.”

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NC State's logo in a soil pit