Superfund Research Program
Metals - Bioavailability
- Archived Seminar (4/9/03)
- Introduction - Larry Reed, NIEHS
- Joseph Graziano, Ph.D., Columbia University
- Jim Shine, Ph.D., Harvard University
This was the first in a series of three seminars on Metals sponsored by the Environmental Protection Agency (EPA) Technology Innovation Office and the NIEHS Superfund Research Program. The event highlighted recent advances in assessing and limiting the bioavailability of metal contaminants. Dr. Joseph Graziano, of Columbia University, discussed his team's current research into phosphate treatment of lead (Pb)-contaminated soils. Adding phosphate amendments to soil has been shown to dramatically reduce the absorption of Pb in humans. For example, Pb absorption from a contaminated soil obtained from a former smelter site in Joplin, Missouri, averaged 36% among a group of adult volunteers. However, Pb absorption from an adjacent soil that had been "fertilized" in the field 18 months earlier averaged only 15%. This 57% reduction in Pb bioavailability implies that the Pb hazard at many Superfund sites can be substantially reduced in a very cost effective manner. Dr. James Shine, of Harvard University, is developing a sampling device that can measure the free metal ion concentration of many metals at the same time. The sampler, called the "Gellyfish," functions through the equilibration of immobilized ligands (held in polyacrylamide gel) with the free metal ion concentration in the surrounding solution. This sampler can measure the free metal ion concentration of many metals at the same time. Knowledge of the free metal ion concentration is a critical determinant for understanding metal speciation, and thus understanding the environmental mobility and bioavailability of metals in aquatic ecosystems. This new analytical technique is ready to be demonstrated in a pilot scale application.
Metals - Remediation
- Archived Seminar (5/14/03)
- Introduction - Larry Whitson, MDB, Inc.
- Raina Maier, Ph.D., University of Arizona
- Harry Compton, US EPA Environmental Response Team
This was the second in a series of three seminars on Metals sponsored by the NIEHS Superfund Research Program and the EPA Technology Innovation Office. The event highlighted recent advances in technologies for remediation of metal-contaminated hazardous waste sites. Harry Compton, of the EPA's Environmental Response Team (ERT), examined a treatment technology for metals-contaminated soils that has potential for improving damaged mine lands. The technology uses soils residuals, including biosolids, to treat old mining sites and revegetate them, thus reducing the bioavailability of the contaminants. The use of the native plant species creates a viable habitat, improves land values and, potentially, helps with carbon sequestration. ERT also evaluated the attractive nuisance issue in this scenario. Dr. Raina Maier, of the University of Arizona, discussed her research into an alternative strategy—soil flushing using pump and treat technologies for in situ remediation of metal-contaminated soils. The research explored the use of alternative microbially-produced agents for remediation of metal contaminated sites. The work is based upon the fact that anionic surfactants have shown potential as soil washing agents. Microbially-produced surfactants—biosurfactants—have advantages over their synthetic counterparts because they are not petroleum-based, are less toxic, and are more biodegradable. Topics included an introduction to biosurfactants, the efficacy of several biosurfactants for remediation of artificially and historically metal-contaminated soils, and problems associated with application of biosurfactants to soil systems.
Metals - Analytical Methods
- Archived Seminar (6/11/03)
- Introduction - Beth Anderson, NIEHS
- Paul Bishop, Ph.D., University of Cincinnati
- Tammy Jones-Lepp, M.S., EPA National Exposure Research Laboratory, Las Vegas, NV
This was the third in a series of three seminars on Metals sponsored by the NIEHS Superfund Research Program and the EPA Technology Innovation Office. The event highlighted recent advances in analytical methods for detection of metals in environmental media. Dr. Paul Bishop, of the University of Cincinnati, discussed metals analysis at Superfund sites. This kind of analysis can be done off-site, on-site, ex-situ or in-situ. The technique selected will depend on cost factors, data reliability needed, the elements to be analyzed and available technologies. Dr. Bishop's talk focused on on-site analysis procedures, including the use of specialty microelectrodes, laser-induced breakdown spectroscopy (LIBS), X-ray fluorescence (XRF), and electrochemical techniques such as ultramicroelectrode arrays and voltammetry. The presentation concluded with the description of a new MEMS (micro-electro-mechanical system) lab-on-a-chip device being developed for rapid, highly sensitive on-site analysis of metals in groundwater. Tammy Jones-Lepp, of EPA's National Exposure Research Laboratory in Las Vegas, NV, discussed the state-of-the-science methods applied to real-world analytical chemistry problems of the Regions, the States, and Tribal Authorities. For example, high resolution mass spectrometry (HRMS) and a uniquely developed in-house software package for HRMS (ion composition elucidation - ICE) have been used to determine the compositions of unknown and potentially toxic pollutants that otherwise were undiscovered via conventional methodology. Their environmental chemistry expertise in volatile organics--using newly patented instrumentation (vacuum distillation), developed in-house--was applied to solving the migration of vinyl chloride (a known human carcinogen) into milk. One scientist worked closely with Tribal authorities and the State of Alaska to follow the transport and fate of mercury into indigenous food sources. The scientists also used state-of-the-art technologies (electrospray-ion trap mass spectrometry), to determine the source and fate of an industrial spill of organotins for the state of South Carolina. Other scientists worked diligently to develop extremely low-level (sub-part-per-trillion) pesticide methodology (extraction and detection) to help solve the mystery of the disappearance of the yellow-legged frog from the alpine lakes of the Sierra Nevada. The staff's expertise in mass spectrometry, analytical methods development, clean-up methodology, inorganics, organometallics, volatile organics, non-volatile organics, semi-volatile organics, separation technologies, has provided technical research support for many projects initiated by States, Regions, and Program Offices.