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| April 19, 2024 | ||
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Internet-based seminar
| Hosted by National Institutes of Health, National Institute of Environmental Health Sciences, Superfund Basic Research Program |
This, the second of the three sessions, will feature Dr. Edward Neuhauser, Principal Environmental Engineer, National Grid, and Dr. Danny Reible, the Bettie Margaret Smith Chair of Environmental Health Engineering at the University of Texas.
Dr. Neuhauser's presentation is titled: True Measurement of PAH Bioavailability in Sediments - Traditional regulatory guidance for screening PAH contaminated sediments have used the total EPA 16 parent PAH's and have correlated these values with summary values from a wide variety of studies. This approach has given very inconsistent results when comparing the EPA total 16 PAH's with actual laboratory toxicology testing. This study has developed a PAH measurement method, the Solid-Phase Microextraction (SPME) method, that actually measures the true bioavailability of PAH's in sediments. The SPME method does not measure the total amount of PAH's present in a sediment sample, but rather only that fraction of PAH's in sediments that are actually present in sediment pore water and are available to benthic organisms. This research has shown that the actual PAH toxicity is concentrated in the alkylated low molecular weight PAH's and that 5- and 6-ring PAH's actually contribute very little to sediment toxicity.
The definition of exposure and risk to contaminants in sediments depends upon access to those contaminants, the extent to which accessible contaminants are bioavailable and the extent to which contaminants accumulate in organisms of interest. Dr. Reible's presentation will focus on efforts to understand and quantify these processes. Recent research associating interstitial water concentrations of PAHs and PCBs to bioaccumulation in benthic organisms will be reviewed. This research has provided an increasingly strong basis for the use of interstitial water concentrations as an indicator of bioavailability, bioaccumulation and ultimately exposure and risk of these contaminants to the benthic community. Building on this basis, field deployable solid phase microextraction devices were developed and used to evaluate bioavailabilty and mobility of organic contaminants in sediments. The use of these devices to assess, in situ, mechanisms and rates of chemical transport and the effectiveness of permeable containment or sorptive barriers (sediment caps) will be summarized.
The session will be moderated by Dr. Karl Gustavson, Contaminated Sediment Liaison to US EPA, US Army Engineer Research and Development Center. For general information contact Jean Balent by telephone at 202-566-0832
| Upcoming Events No upcoming events. Archives of past CLU-IN internet seminars are available in the CLU-IN Studio at http://clu-in.org/studio/. You will be able to view the slide and hear an audio stream of the presentation as it occurred.  |
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Live Online Class, Internet Based 
