Standardizing Polymeric Sampling Method for Measuring Freely-Dissolved Organic Contaminants in Sediment Porewater

Abstract

The primary purpose of this effort was to demonstrate standardized polymeric sampler procedures for measuring freely-dissolved organic contaminant concentrations Cfree in sediment porewater by multiple academic- and private-sector analytical laboratories, thereby increasing commercial availability, promoting wider acceptance, and increased use. Polymeric samplers consist of hydrophobic polymers e.g. low-density polyethylene LDPE, polydimethylsiloxane PDMS,which absorb organic compounds present in sediment porewater. Polymeric samplers can be directly inserted into sediment in the laboratory ex situ or in the field in situ to yield depth-discreet measures of Cfree present in sediment porewater. Commercial and academic laboratories participated in three separate tasks to test and validate standard methods for polymeric sampling, culminating in the final task of using the standardized polymeric sampling method to measure Cfree PAHs and PCBs in a sediment sample. Results showed that 1 LDPE and PDMS polymers yielded equivalent Cfree results for PAHs and PCBs, regardless of static or active exposures 2 polymeric samplers provided better quantitation compared to the manual extraction reference method for high molecular weight PAHs and PCBs, which were present at low concentrations and 3active exposures achieved equilibrium following continuous mixing for approx. 30 days, suggesting that if polymeric samplers are used to characterize sediment porewater under active exposure conditions for longer than 30 days in the laboratory, performance reference compounds use may be omitted. Due to the unique nature of estimating costs for individual projects, a cost per polymeric sampler is not provided here and should be coordinated directly with the appropriate commercial laboratory supplying these services.