“Passive Multi-Sampling Method to Measure Contaminant Bioavailability in Aquatic Sediments” by Dr. Rainer Lohmann

This SERDP-funded project supported DoD goals to simplify and speed up acquisition of relevant exposure to contaminants of interest in situ. Specific project objectives included developing a passive sampling method utilizing polyethylene (PE) samplers capable of determining polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and a wide range of other hydrophobic organic contaminants (HOCs). Beyond PCDD/Fs, we targeted polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs) with the PE multisamplers both in the water column and in the porewater of the Passaic River in New Jersey. We observed good agreement between porewater concentrations derived from sediment equilibrated in the laboratory and in situ samplers with percent differences ranging from 0.3 – 39 for PCBs and 1.0 – 22 for PCDD/Fs. Based on our results, exposure to porewater and to a lesser extent river water and the probable ingestion of sediment particles are the possible sources of bioaccumulation of PCBs and PCDD/Fs in the lower Passaic River. The newly constructed sampler was able to determine spatial and temporal variability in the detected concentrations of PCDD/Fs and PCBs, as would be needed for cleanup design and post-remediation monitoring of contaminated sites.

“Evaluating the Efficacy of Bioaugmentation for In Situ Treatment of PCB Impacted Sediments” by Dr. Kevin Sowers

In situ amendment with activated carbon (AC) has been shown to be effective at reducing the bioavailability of polychlorinated biphenyls (PCBs) in sediments. However, a more desirable goal is to ultimately reduce the inventory of legacy PCBs in sediments while also reducing bioavailability to the food chain. We describe results from pilot scale in situ treatment of PCB impacted sediments sites treated with AC amended with PCB transforming microorganisms. The innovative aspects of the technology are (1) the identification of the true kinetic limitation for PCB degradation in sediments, (2) circumventing the threshold PCB concentration for growth by scaling up the organisms without PCBs in bioreactors, and (3) the application of anaerobic organohalide respiring bacteria and aerobic PCB oxidizing bacteria to sediments with a pelleted AC agglomerate as a delivery system. The bioamended AC serves as a solid substrate for the dual purpose of bioamendment delivery into sediments and long-term sequestration of hydrophobic PCBs. Production-level scale-up of microorganisms, field deployment and treatment results will be discussed. These pilot-scale field studies show the promise of bioremediation as a new strategy to reduce contamination of the aquatic food web from exposure to sediment-bound PCBs.

Dr. Ranier Lohmann is a professor of oceanography at the University of Rhode Island’s Graduate School of Oceanography in Narragansett. Since 2000, he has been working on the use of passive samplers to detect various hydrophobic organic contaminants in porewater and water column. He has obtained funding from NSF, EPA, SERDP and private foundations to validate and use passive samplers to detect the concentrations, fluxes and bioaccumulation of hydrophobic organic contaminants at a wide range of sites, covering the Great Lakes, remote ocean sites and the highly contaminated Passaic River/Newark Bay region. Contaminants of interest included polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and others. Rainer has authored more than 100 peer-reviewed articles and book chapters. He currently serves as editor for the Environmental Toxicology and Chemistry journal. Rainer obtained a bachelor’s degree in chemical engineering from EHICS in Strasbourg, France, and a doctoral degree in environmental science from Lancaster University in the United Kingdom.

Dr. Kevin Sowers is the associate director of the Institute of Marine and Environmental Technology, professor at the University of Maryland Baltimore County, and co-founder of RemBac Environmental. One of Kevin’s research areas for the past 20 years has focused on the process of microbial dechlorination of polychlorinated biphenyls (PCBs) and the development of sustainable in situ technologies for treating PCB-contaminated sites. Kevin has been PI or co-PI on several DoD, NSF and NIEHS grants focused on identifying PCB-dechlorinating bacteria, characterizing their physiology, and developing approaches for scale-up and deployment of both anaerobic dechlorinators and aerobic degraders at sediment sites. He is currently conducting field trials in collaboration with federal, municipal and private stakeholders. His research has generated over 75 peer-reviewed journal articles, 20 book chapters, and several patents. His research on PCB degradation has been featured in radio interviews and newspaper articles. Kevin received his doctoral degree in microbiology from Virginia Tech.