Brent Pautler, Ph.D. (Ontario) will present “Performance Reference Compounds: Non-Equilibrium Correction Evaluation and Anomalies” and Michael Healey (Ontario) will present “Equilibrium Passive Sampling for Groundwater/Sediment/Surface Water Interactions: Optimizing for Monitoring Groundwater Directly” at the SETAC North America 42nd Annual Meeting Virtual Conference on 14-18 November 2021.

Brent’s co-presenters are Jeff Roberts & Michael Healey (SiREM) Alice Wang Ph.D., Courtney Thomas, Ph.D., Jay Thompson, Ph.D. & Jason Conder, Ph.D. (Geosyntec Consultants).

Michael’s co-presenters are Brent Pautler & Jeff Roberts (SiREM) Alice Wang Ph.D. & Jason Conder, Ph.D. (Geosyntec Consultants), John Haney (Hart Crowser), William Ryan Henry, Patricia McIsaac, Jeff Ogle & Robert Mitzel (Eurofins Environment Testing America).

Brent is SiREM’s Chemistry Services Manager and received his Ph.D. in environmental analytical chemistry in 2013 where he gained advanced technical experience in spectroscopy, chromatography, mass spectrometry, passive sampling, and chemistry informatics. Throughout his career, he has worked with scientists, engineers, and consultants, applying his chemistry and information technology expertise to help them solve unique problems in the laboratory and the field. His role includes managing and advancing SiREM’s passive sampling portfolio, analytical testing services while supporting Compound Specific Isotope Analysis (CSIA) business development.

Michael is the Treatability and SP3™ Services Supervisor at SiREM with eight years of experience. Michael has managed numerous bench-scale studies evaluating remediation technologies for contaminants including chlorinated solvents, petroleum hydrocarbons, emerging contaminants and other recalcitrant compounds in soil, sediment, and groundwater. Michael has several years of passive sampling experience and was a lead member in the development and commercialization of the SP3™ sampler.

The Society of Environmental Toxicology and Chemistry (SETAC) is a not-for-profit, worldwide professional organization comprised of about 5,300 individuals and institutions in over 90 countries dedicated to the study, analysis and solution of environmental problems, the management and regulation of natural resources, research and development, and environmental education. Their mission is to support the development of principles and practices for protection, enhancement and management of sustainable environmental quality and ecosystem integrity.

 Abstracts

Performance Reference Compounds: Non-Equilibrium Correction Evaluation and Anomalies

Passive sampling devices (PSDs) have been shown to present many advantages over conventional sampling methods for quantifying the availability of hydrophobic organic compounds (HOC) in sediment, soil, surface water and storm water as they provide data to estimate contaminant bioavailability and toxicity to environmental receptors that are more accurate than conventional grab or mechanically extracted samples, as they quantify the freely dissolved contaminant concentrations (Cfree). Non-equilibrium correction protocols using performance reference compounds (PRCs) have been developed to enhance the accuracy of PSDs to assess Cfree of HOCs during short-term field deployments. The protocols have matured through laboratory experiments and field trials performed by academic, industry, and government programs. Despite the rigorous application of standardized sampler preparation and analysis, PRC desorption anomalies have often been observed by multiple investigators at sites of different hydrodynamic conditions, while using different PSDs, and while using different classes of PRCs. PRC desorption anomalies occur when a PRC is measured in a PSD after retrieval from a field exposure at a concentration that is much higher or lower than is expected given the hydrophobicity of the PRC and/or the behavior or other PRCs used in the same device. Such anomalies are outliers with respect to other PRC data from the same device, typically resulting in exclusion of the data which leads to increased error and uncertainty associated with estimation of Cfree values.

Previous studies where representative datasets from PSDs with deuterated PAH and rare PCB congener PRCs were evaluated for anomalies. The evaluated data sets included tidal and non-tidal systems, in situ and ex situ deployments, and sediment and surface water matrices. Non-equilibrium correction factors were calculated by fitting a mass transfer relationship, using the PRC initial and final concentrations, time of deployment, and PSD thickness. These results showed that PRC desorption anomalies are neither site specific, PRC specific, laboratory specific, nor sampler material specific. Reducing the limitations of mass transfer could reduce observations of these anomalies, as a dataset with agitated PE samplers exhibited no PRC anomalies. Options to enhance mass transfer and correct Cfree calculations for anomalies have been developed and will be discussed.

Equilibrium Passive Sampling for Groundwater/Sediment/Surface Water Interactions: Optimization for Monitoring Groundwater Directly

Passive sampling devices (PSDs) have been shown to present many advantages over conventional sampling methods for quantifying the availability of hydrophobic organic compounds (HOC) in sediment, soil, surface water and stormwater. PSDs can provide data to estimate contaminant bioavailability and toxicity to environmental receptors that are more accurate than conventional grab or mechanically extracted samples, as they quantify the freely dissolved contaminant concentrations (Cfree). Approaches that rely on using Performance Reference Compounds (PRCs) added to PSDs prior to deployment are standard practice for short-term deployments in which equilibrium concentrations in the PSDs are not achieved in the deployed environment. Cfree determination using PSDs have been applied via in situ deployments to measure impacts of contaminant groundwater upwelling to sediment porewater and surface water and have drawn interest from hydrogeologists for direct monitoring of groundwater due to its advantages compared to traditional active low-flow pumping.

To explore the applicability of PSDs for Cfree determination of subsurface contamination, PSDs containing rare congener PCBs were deployed in groundwater monitoring wells situated in a variety of hydrogeological conditions for three-month time intervals. Samplers were analyzed by standard EPA methods and Cfree calculations were performed.

PSDs deployed in wells with low water exchange/flow (e.g. 0.15 ft/day) exhibited PRC anomalies, suggesting a negative PRC depletion rate, a highly unlikely phenomenon. This is likely due to unfavorable (slow) thermodynamic equilibration between the water and samplers, as well as the low well volume, that limits the mass of PRCs that diffuses out of the samplers (into the water) during deployment.  In contrast, PSDs deployed in groundwater monitoring wells in a fast-moving aquifer (2,000 – 3,000 ft/day) revealed favorable equilibration that is comparable to conditions in aquatic systems (surface water and sediment). These results will be used to outline the best working conditions for the application of PSDs to measure  groundwater Cfree.

More Information

About the event: https://scicon4.setac.org/
About SETAC: https://www.setac.org
For consultation regarding SiREM’s passive sampling services, contact Brent at bpautler@siremlab.com.
Learn more about Brent: www.linkedin.com/in/brent-g-pautler-18052060
Learn more about Michael: https://www.linkedin.com/in/michael-healey-596b53160/