The use of equilibrium passive sampling with LDPE, POM, and PDMS for measuring PCBs, PAHs, dioxins/furans, DDTs and other hydrophobic contaminants in the water column and sediment interstitial waters has gained scientific and regulatory acceptance. A principle advantage of equilibrium passive sampling is the ability to measure the freely dissolved concentration (C_free) of hydrophobic organic contaminants. The C_free has been shown to be a very good surrogate for the bioavailable concentration of hydrophobic contaminants. Consequently, C_free can be a very useful tool for making informed environmental management decisions.

The use of equilibrium passive sampling for measuring the C_free of moderately hydrophobic munitions and lower molecular weight compounds (LMWCs) has not been fully explored. This is despite the existence of many aquatic sites around the United States where munitions and LMWCs are known to be present in contaminated sediments. The use of hydrophilic polymeric materials has been explored for munitions, but this approach generates semi-quantitative measures of concentration. Similar research on LMWCs has not been performed. A major data gap in environmental decision making is not having a valid and confirmed equilibrium passive sampling method for quantitatively measuring the C_free of munitions and LMWCs.

The objective of this Research Opportunity is to evaluate the use of hydrophobic and hydrophilic organic polymers as equilibrium passive samplers for measuring the C_free of munitions and LMWCs in the water column and sediment interstitial waters. Research will involve: (1) assessing a range of hydrophobic and hydrophilic polymers for sorption of munitions and LMWCs, (2) determining polymer-water partition coefficients (KPs) for promising polymers, and (3) preliminary studies examining partitioning of target contaminants in field sediments using promising equilibrium passive sampling polymers.

More information about our laboratory can be found at http://www.epa.gov/aed/

 

References

Belden JB, et al: Application of POCIS for exposure assessment of munitions constituents during constant and fluctuating exposure. Environmental Toxicology and Chemistry 34: 959-967, 2015

Booij K, et al: Passive sampling in regulatory chemical monitoring of nonpolar organic compounds in the aquatic environment. Environmental Science and Technology 50: 3-17, 2016

US EPA: Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Procedures for the Determination of the Freely Dissolved Interstitial Water Concentrations of Nonionic Organics. EPA-600-R-02-012. Office of Research and Development. Washington, DC, 2012

 

key words

Passive sampling; Hydrophilic and hydrophobic polymers; Munition chemicals; Low molecular weight compounds; Freely dissolved concentration (Cfree); Bioavailability;

Citizenship:  Open to U.S. citizens and permanent residents

Level:  Open to Postdoctoral and Senior applicants