This webinar series featured individual research projects funded by the NIEHS Superfund Research Program (SRP). In 2013, the SRP initiated a targeted research program to better understand how contaminants in the environment are affected by complex biological, geological, and chemical processes. By understanding these complex interactions, we are better equipped to optimize remediation strategies and, therefore, improve science-based decision making for site management, priority-setting, and remedy selection. The individual research project grants support problem-solving research on the mechanisms of biogeochemical interactions that may impact remediation of contaminated soil, sediment, surface water, or groundwater.

The awardees previously presented their research in 2015. This webinar series provided an update on their research findings as they came to the end of their SRP-funded research grants.

Session I – Innovative Approaches for Chlorinated Compound Bioremediation in Groundwater
April 22, 2019 • 1:00 – 3:00 p.m. EDT
To view an archive, visit EPA's CLU-IN Training & Events webpage.

In session 1, we heard from SRP-funded individual research project leaders at Johns Hopkins University, the University of Tennessee, and the University of California, Berkeley. The first session also included a brief introduction to the targeted research program and cohort of awardees.

Researchers led by Edward Bouwer, Ph.D., at Johns Hopkins Whiting School of Engineering were evaluating a novel technology — a flow-through barrier containing granular activated carbon coated with anaerobic and aerobic microorganisms — to see if it could completely break down chlorobenzenes and benzene contaminants, which are known or suspected carcinogens. The researchers sought to understand the environmental processes and conditions that influence interactions among contaminants and the barrier to improve its effectiveness in contaminated groundwater. Laboratory and field tests were being conducted at the Standard Chlorine of Delaware, Inc. Superfund site where dense non-aqueous phase liquid (DNAPL) chlorobenzene contamination is present in wetland sediments and groundwater. For more information, please visit: Dual-Biofilm Reactive Barrier for Treatment of Chlorinated Benzenes at Anaerobic-Aerobic Interfaces in Contaminated Groundwater and Sediments.

At the University of Tennessee, Frank Loeffler, Ph.D., and his research team were investigating the role of the microbial community for supplying specific nutrients called corrinoids, which organohalide-respiring Dehalococcoidia require to dechlorinate and detoxify solvents such as tetrachloroethene (PCE) and trichloroethene (TCE). The team was designing and validating the B12-qChip — an innovative, high-throughput quantitative PCR tool — that could be used to recognize when the bioavailability corrinoids limits dechlorination activity. Using samples from Third Creek, a polluted creek in Knoxville, Tennessee, they were conducting detailed studies that combine cultivation-based approaches, high-throughput sequencing, bioinformatics analyses, and state-of-the art analytical procedures to reveal the best biogeochemical conditions for bioremediation. For more information, please visit: Biogeochemical Controls over Corrinoid Bioavailability to Organohalide-Respiring Chloroflexi.

Assistant Project Scientist Shan Yi, Ph.D., described a project at the University of California, Berkeley led by Lisa Alvarez-Cohen, Ph.D., which used a combination of molecular, biochemical, and analytical tools to evaluate how microbes used for trichloroethene (TCE) bioremediation interact with co-existing organisms in various geological, chemical, and biological conditions. The researchers were constructing simplified groups of microbes living symbiotically that they exposed to stresses such as changes in salinity as well as the introduction of potential competitive electron acceptors to the system (e.g., sulfate ions) to see how TCE bioremediation is affected. They also combined intercellular data gained from both microarray and RNA sequencing techniques to develop mechanistic models that describe the effects of geochemical parameters on bioremediation. For more information, please visit: Metabolic Interactions Supporting Effective TCE Bioremediation under Various Biogeochemical Conditions.

Session II – Bioavailability of Mixtures of PAHs, Chlorinated Compounds, and Metals
May 13, 2019 • 1:00 – 3:00 p.m. EDT
For more information, visit EPA's CLU-IN Training & Events webpage.

In session 2, we heard from SRP-funded individual research projects at Virginia Institute of Marine Science, University of California, Riverside, and Colorado School of Mines.

Researchers led by Michael Unger, Ph.D., and Aaron Beck, Ph.D., at the Virginia Institute of Marine Science (VIMS) were developing new analytical techniques to help evaluate and quantify the mechanisms controlling the transport and the bioavailability of polycyclic aromatic hydrocarbons (PAH) at contaminated sediment sites. They have employed an antibody-based biosensor developed at VIMS that allowed rapid evaluation of the mechanisms controlling PAH transport at contaminated sediment sites saving effort and costs over traditional GC-MS based methods. Biosensor measured PAH in porewater was highly correlated to GC-MS analysis in split samples and was also correlated to benthic amphipod toxicity in laboratory tests. PAH concentrations in porewater samples were better predictors of toxicity than whole sediment PAH concentrations currently used for regulatory evaluation of remediation effectiveness. Future remediation plans at contaminated sediment sites that involve sediment removal and/or capping will need to address controlling the PAH flux to the aqueous phase. These new technologies allow this assessment to be accomplished more rapidly and economically than traditional methods. The technology has also been adapted for the rapid quantification of PAH concentrations in oysters and soils and is being developed as a potential tool for quick response during flood or oil spill events. For more information, please visit: Impact of Groundwater-Surface Water Dynamics on in situ Remediation Efficacy and Bioavailability of NAPL Contaminants.

Jay Gan, Ph.D., and Daniel Schlenk, Ph.D., lead a project at the University of California, Riverside to develop a simple method for measuring and accounting for contaminant aging in risk assessments and remediation. They will apply the method to sediment samples collected from various depths (reflecting deposition at different historical times) and location (reflecting different sediment properties) at the Palos Verdes Shelf Superfund site off the Los Angeles coast. Sediments at this site contain high levels (up to 200 mg/kg) of DDTs and PCBs deposited from as far back as 60 years ago. For more information, please visit: Exploring the Importance of Aging in Contaminant Bioavailability and Remediation.

Researchers led by James Ranville, Ph.D., at the Colorado School of Mines were developing and refining techniques — including environmental molecular diagnostics and stable isotope assays — used to detect, assess, and evaluate the bioavailability of metals that occur in mixtures and can be taken up by aquatic organisms, including nickel, zinc, copper and cadmium. They tested these approaches in a metals-contaminated stream at the North Fork Clear Creek Superfund site in central Colorado. Stream remediation began in 2017 by lime-treatment of the major mining inputs. This project was designed to improve knowledge on the risks posed by mixtures of contaminant metals and assist in evaluating remediation effectiveness. For more information, please visit: Investigating Biogeochemical Controls on Metal Mixture Toxicity Using Stable Isotopes and Gene Expressions.

Session III – Mercury Bioremediation and Biotransformation Under Varying Biogeochemical Conditions
May 20, 2019 • 1:00 – 2:30 p.m. EDT
To register, visit EPA's CLU-IN Training & Events webpage.

In session 3, we heard from SRP-funded individual research projects at Duke University and University of Maryland-Baltimore County.

At Duke University, scientists led by Heileen Hsu-Kim, Ph.D., were studying sediment dwelling microorganisms that methylate mercury, and identifying factors that may be used to control and reduce toxic methylmercury production. The research is focusing on strategies to measure mercury bioavailability and biomethylation potential in sediments. Their work has demonstrated that passive samplers such as diffusive gradient in thin-films (DGT) can be used to predict the bioavailable fraction of mercury to methylating organisms. The work also evaluated biomolecular techniques targeting microbes carrying the hgcA and hgcB genes specific for mercury methylation. Together, these methods can be used to determine mercury biomethylation potential in sediments and help site managers understand the controlling factors leading to methylmercury risk at field sites. For more information, please visit: Biogeochemical Framework to Evaluate Mercury Methylation Potential During in-situ Remediation of Contaminated Sediments.

At the University of Maryland Baltimore County, Upal Ghosh, Ph.D., led a research team to develop an empirical model of the factors influencing mercury and methylmercury bioavailability in contaminated areas. Using this model, they planned to identify biogeochemical characteristics that make sites suitable for remediation with sorbent remediation approaches, such as activated carbon amendments. The researchers also sought to design sorbent amendment/thin capping strategies that reduce methylmercury bioavailability. The main study site was a salt marsh in Berry's Creek, N.J., where they were conducting a field trial of in situ sorbent remediation using activated carbon and also evaluating the relative efficacy of a wider range of black carbons. For more information, please visit: Development of in-situ Mercury Remediation Approaches Based on Methylmercury Bioavailability.