Contaminated sediments are a significant environmental problem that impacts the use and enjoyment of waterbodies worldwide and contribute to the 3,200 fish consumption advisories issued annually in the US (USEPA). Hydrophobic organic compounds such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and pesticides in sediment pose particular problems because they bioaccumulate in aquatic food webs, presenting risks to wildlife and humans that consume fish.
Understanding the chemistry of hydrophobic compounds in sediment has challenged environmental decision makers for decades, especially identifying contaminated sediments and selecting appropriate management options. Sediment investigation and remedial assessments involve quantifying the availability of the compounds, which relates directly to risks. Direct testing of bulk sediment samples using exhaustive extraction techniques greatly overestimates availability and risk, as the adsorbed contaminants are also quantified. An alternative to extraction methods is mechanically collected porewater samples using probes. Mechanically derived samples are difficult to obtain and are often compromised by surface water and like extraction methods also greatly overestimate contaminant availability and risk.
Dr. Jason Conder
The use of passive sampling techniques to quantify availability is a solution to the challenges of traditional sediment sampling methods. Passive sampling involves exposure of an inert, sorptive solid media to sediment, followed by the analysis of the chemicals absorbed by the sampler. Through known partition coefficients, the data are converted to a concentration of “freely dissolved” compounds in porewater. Because the sampler is a mild absorbent, like an organism, passive sampling results correlate well with bioavailability and risk. This enables robust site assessments, cleanup goal derivation and remedial treatment evaluations. The use of passive sampling methods avoids the overestimation of availability by traditional methods and allows more precise decision making that is not encumbered with overly conservative assumptions.
To meet the increasing need for passive samplers, SiREM developed the SP3™ sampler and data interpretation service. The sampler can be mounted on a variety of support options facilitating easily placement into sediment. After absorbing contaminants, the sampler is removed and sent to the lab for the specified analysis (e.g., PCB congener
The Strategic Environmental Research and Development Program (SERDP)/Environmental Security Technology Certification Program (ESTCP) and United States Environmental Protection Agency (U.S. EPA’s) Office of Research and Development (ORD) recently released a Draft User’s Manual for Laboratory, Field, and Analytical Procedures for Using Passive Sampling in the Evaluation of Contaminated Sediments. Within the document, SiREM is listed as a commercial analytical laboratory capable of performing passive sampling analyses.
Dr. Jason Conder of Geosyntec Consultants, and a co-developer of the SP3™ sampler, sees the SERDP/ ESTCP and USEPA endorsement as a milestone in the acceptance of passive sampling for sediment characterization.
“SERPDP/ESTCP and USEPA have been champions of this powerful technology, so it’s great that they recognize SiREM’s pioneering work in transitioning passive sampling from the research laboratory into a commercial service that can be easily used by the environmental community to make decisions at real world sites.”
The growing acceptance of SP3™ has led to significant in situ deployments at US sediment sites including:
At the Lower Duwamish project, SiREM is supporting a large USEPA-directed study to evaluate PCB availability before and after remedial pilot studies. In July 2016, over 200 samplers were deployed in various locations and approximately 1,000 additional samplers will be deployed in future monitoring efforts during the 5-year study.
The ability to accurately quantify porewater concentrations will ultimately allow better site characterization and remediation decision making that can only help make our rivers, lakes, marshes, estuaries and coast lines healthier for all life including fish and those that eat them.
SiREM's Waterloo Membrane Sampler (WMS) was featured on the cover and in an article entitled "Experimentally validated mathematical model of…
Sandra Dworatzek, a Senior Manager at SiREM, will be featured as a session keynote speaker for session number 5 "1,4-Dioxane:…
Jeff Roberts will deliver a presentation entitled "Passive Sampling Approaches and Tools for Sediment Pore Water and Soil Gas Surveys"…
How has environmental microbiology research changed since you started working in the field? Laura Hug: The field has changed dramatically…