High Resolution Passive Profiling to Monitor Contaminated Sediments in Support of Remediation Evaluation and Risk Characterization

The overall objective of this project was to demonstrate a sediment High Resolution Passive Profiler (sHRPP) that is capable of evaluating the bioavailable distribution of contaminants (metals and organics) in sediments via passive sampling at cm vertical resolution, while simultaneously evaluating dominant redox processes at the same resolution, key gene/microbial densities, and pore water velocity. The sHRPP is driven into the sediment and can sample depths as deep as ~80cm. The sHRPP can evaluate at fine-scale: (1) contaminant types and concentrations using either equilibration cell water (e.g. metals, cVOCs, VOCs) or by incorporating SPME fibers for HOCs (e.g. PCBs, PAHs, DDX); (2) the concentrations of biogeochemical species (e.g. DOC, Cl-, NO3-, NO2-, Fe 2,FeT, SO4-2, S-2, CH4, etc.); (3) pore water velocity; (4) the composition of relevant microbial communities via qPCR analysis of Bio-Sep beads. The ability of the sHRPP to improve the measurement of the occurrence, fate, and transport of contaminants in sediment was demonstrated at 4 sites. The sHRPP was able to measure concentrations of key contaminants at equal or greater sensitivity than comparable traditional technologies. It produced high resolution concentration profiles of geochemical species and measured pore water velocities with depth. It provided increased model resolution and reliability and increased statistical power to evaluate the impact of remedial efforts. The technology required less cost, time, and effort to evaluate sites and produced data not obtainable by other traditional methods.