Neal Durant, Ph.D. coauthored a paper entitled "Sequential biodegradation of 1,2,4-trichlorobenzene at oxic-anoxic groundwater interfaces in model laboratory columns" that was published in the Journal of Contaminant Hydrology in Volume 231 on May 2020.

Neal Durant's coauthors were Steven Chow, Michelle Lorah, Amar Wadhawan, and Edward Bouwera.     

Neal Durant is a Senior Principal based in Washington, D.C. with more than 28 years of experience investigating, remediating, and managing complex contaminated sites.

The Journal of Contaminant Hydrology is an international journal publishing scientific articles contributing to a broad understanding of contamination of water resources. Emphasis is placed on investigations of the physical, chemical, and biological processes influencing the behavior and fate of organic and inorganic contaminants in the aqueous environment including ecological impacts. Water-based science, technology and management approaches that monitor, assess, control, and mitigate contamination and its eco-environmental impacts at multiple scales are invited. Broad latitude is allowed in identifying contaminants of interest, and includes legacy and emerging pollutants, nutrients, nanoparticles, microorganisms (e.g., bacteria, viruses, and protozoa), microplastics, and various constituents associated with energy production (e.g., methane, carbon dioxide, and hydrogen sulfide).

Abstract

Halogenated organic solvents such as chlorobenzenes (CBs) are frequent groundwater contaminants due to legacy spills. When contaminated anaerobic groundwater discharges into surface water through wetlands and other transition zones, aeration can occur from various physical and biological processes at shallow depths, resulting in oxic-anoxic interfaces (OAIs). This study investigated the potential for 1,2,4-trichlorobenzene (1,2,4-TCB) biodegradation at OAIs. A novel upflow column system was developed to create stable anaerobic and aerobic zones, simulating a natural groundwater OAI. Two columns containing (1) sand and (2) a mixture of wetland sediment and sand were operated continuously for 295 days with varied doses of 0.14–1.4 mM sodium lactate (NaLac) as a model electron donor. Both column matrices supported anaerobic reductive dechlorination and aerobic degradation of 1,2,4-TCB spatially separated between anaerobic and aerobic zones. Reductive dechlorination produced a mixture of di- and monochlorobenzene daughter products, with estimated zero-order dechlorination rates up to 31.3 μM/h. Aerobic CB degradation, limited by available dissolved oxygen, occurred for 1,2,4-TCB and all dechlorinated daughter products. Initial reductive dechlorination did not enhance the overall observed extent or rate of subsequent aerobic CB degradation. Increasing NaLac dose increased the extent of reductive dechlorination, but suppressed aerobic CB degradation at 1.4 mM NaLac due to increased oxygen demand. 16S-rRNA sequencing of biofilm microbial communities revealed strong stratification of functional anaerobic and aerobic organisms between redox zones including the sole putative reductive dechlorinator detected in the columns, Dehalobacter. The sediment mixture column supported enhanced reductive dechlorination compared to the sand column at all tested NaLac doses and growth of Dehalobacter populations up to 4.1 × 108 copies/g (51% relative abundance), highlighting the potential benefit of sediments in reductive dechlorination processes. Results from these model systems suggest both substantial anaerobic and aerobic CB degradation can co-occur along the OAI at contaminated sites where bioavailable electron donors and oxygen are both present.

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Learn more about the article: Journal of Contaminant Hydrology
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Learn more about Neal Durant at: https://www.geosyntec.com/people/neal-durant