Edward M. Heithmar, Ph.D.
Environmental Chemistry, Environmental Sciences, NERL/ORD
EXPERTISE: Analytical atomic spectrometry and inorganic mass spectrometry, with emphasis on environmental applications; hyphenated techniques for elemental speciation; sample introduction techniques for inductively coupled plasma mass spectrometry (ICPMS).
INDIVIDUAL RESEARCH MISSION: Immediate research objectives: Development of speciation approaches for arsenic, selenium, tin, and mercury in environmental samples. Two levels of speciation will be developed: measurement of individual chemical species, and determination of elemental concentration by compound class (either chemically or operationally defined). Long-term research objectives: (1) Application of elemental speciation techniques to the study of chemical and physical processes affecting transport and fate of toxic trace elements in the environment and exposure of humans and ecological receptors to those elements. (2) Development of an EPA ecological chemistry research program to apply environmental analytical chemistry to (i) the characterization of the baseline distribution of a broad range of chemical stressors and indicators of exposure or stress at selected ecological index sites, ii) the temporal trends of those distributions, (iii) investigation of the processes affecting those distributions, and (iv) development of new indicators of exposure or stress.
SIGNIFICANCE/RELEVANCE OF RESEARCH IN RISK ASSESSMENT PARADIGM: A primary goal of the EPA Office of Research and Development (ORD) Strategic Plan is the reduction of uncertainties associated with assessing risk. EPA and its surrogates make hundreds of decisions regarding risks due to trace-element pollutants each year, most of which have high degrees of uncertainty because the exposure estimates are based on measurement of total element concentrations. The use of such data assumes one of the following: the element is present in a single physical and chemical form, or all forms of the element pose the same risk. Unfortunately, low-concentration species often pose the most risk because of high toxicity or other factors, and detection limits of methods that separately measure the relevant species are therefore often inadequate to assist risk assessment. A goal of this research is to develop speciation methods that meet EPA's needs for high sensitivity, speed, and simplicity.
A primary goal of ORD's comprehensive strategy for ecological research consistent with the risk assessment paradigm is to provide the means to evaluate the relative vulnerability of ecosystems to multiple stressors via multiple pathways. The ecological chemistry research program being developed here will further this goal by providing baseline and trends data on the distribution of both known and occult chemical stressors at selected ecological index sites.
SIGNIFICANT PIONEERING CONTRIBUTIONS: Coupling on-line high performance iminodiacetate preconcentration with ICPMS to minimize interferences and increase sensitivity. Interfacing microbore high-performance liquid chromatography with ICPMS, using a high-efficiency nebulizer, for elemental speciation. Development of operationally defined speciation approach for mercury-contaminated soils and sediments.
IMPACT OF CONTRIBUTIONS ON SCIENTIFIC/REGULATED COMMUNITY: Conventional ICPMS analysis of complex samples such as soil or sludge digests, brine, or sea water is precluded by the physical and spectral interferences caused by the matrix. The on-line preconcentration technique developed here allows the analysis of these types of environmental samples by ICPMS without resorting to massive dilution or other procedures that reduce sensitivity. Similarly, microbore separations and the use of a high-efficiency nebulizer allow ICPMS to be used with chromatographic eluants that would cause massive interferences if conventional flows were used. This greatly increases the utility of HPLC/ICPMS for elemental speciation, which is critical for meaningful risk assessments for many toxic elements. The operationally defined speciation method allowed the available fraction of mercury in soils and sediments to be estimated with far fewer costly and time-consuming bio-assays, thus allowing higher Superfund clean-up goals to be set without increased risk. This saved over $100 million in remediation costs at just one Superfund site.
EXTERNAL COLLABORATIONS: Served on a multi-agency steering committee of a workshop on mercury speciation. Worked with private sector scientists (John Riviello of Dionex Corp.) on the preconcentration sample introduction technique. Collaborated with James Winefordner of University of Florida to investigate capacitively coupled plasmas as atomization devices.
EDUCATION: B.A. in mathematics and chemistry, Biscayne College, Miami, FL; Ph.D. in analytical chemistry, University of Pittsburgh, thesis: "Application of the Hydride Generation Techniques to Continuum Source Atomic Fluorescence Spectrometry."
PROFESSIONAL EXPERIENCE: August 1985 - present: Research Chemist, U.S. EPA, National Exposure Research Laboratory, Environmental Sciences Division, Las Vegas, Nevada. September 1978 - May 1985: Assistant Professor of Chemistry, University of New Orleans.
ANCILLARY AGENCY RESPONSIBILITIES: Research planning for chemistry components of the Ecological Research Program and the Hazardous Waste Research Program; chairperson of the EPA, Las Vegas Occupational Health and Safety Committee; member of the SW-846 Inorganics Workgroup; co-chair of the EMMC Inorganics Workgroup; member of the ORD Networked Analytical Data Systems task group.
American Chemical Society (Boulder Dam
Society for Applied Spectroscopy
NERL Internal Grant Arwardee (1996) "Elemental Speciation Using Hyphenated Techniques"
PUBLICATIONS: 18 publications in peer-reviewed journals.
Selected recent publications:
Heithmar, E. M. and S. Pergantis. Characterizing Concentrations and Size Distributions of Metal-Containing Nanoparticles in Waste Water. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-10/117, 2010. Published 10/06/10.
Bradford, D. F., E. M. Heithmar, N. G. Tallent-HalsellL, G. Momplaisir, C. G. Rosal, K. E. Varner, M. S. Nash, and L. A. Riddick. Temporal Patterns and Sources of Atmospherically Deposited Pesticides in Alpine Lakes of the Sierra Nevada, California , USA. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 44(10):4609-4614, (2010). Published 05/24/2010.
Cizdziel, J. V., T. A. Hinners, J. E. Pollard, E. M. Heithmar, and C. L. Cross. 2002. Mercury concentration in fish from Lake Mead, USA, related to fish size, condition, trophic level, location, and consumption risk. Archives of Environmental Contamination and Toxicology. Vol. 43, No. 3, pp. 309-317.
Bradford, D. F., E. M. Heithmar, C. L. Cross, B. Gentry, G. M. Momplaisir, M. S. Nash, N. G. Tallent-Halsell, L. Riddick, C. Rosal, and K. E. Varner. 2001. Distributions of airborne agricultural ontaminants relative to amphibian populations in the southern Sierra Nevada, California. EPA/ORD/NERL Research Plan. NERL-LV 01-065.
"Microscale flow injection and microbore high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry via a high-efficiency nebulizer" Pergantis, S. A.; Heithmar, E. M.; Hinners, T. A. Anal. Chem. 1995, 67, 4530-5.
"Determination of metals in solid samples by complexation-supercritical fluid extraction and gas chromatography-atomic emission detection" Liu, Y.; Lopez-Avila, V.; Alcaraz, M.; Beckert, W. F.; Heithmar, E. M. J. Chromatogr. Sci. 1993, 31, 310-6.
"Minimization of interferences in inductively coupled plasma-mass spectrometry using on-line preconcentration" Heithmar, E. M.; Hinners, T. A.; Rowan, J. T.; Riviello, J. M. Anal. Chem. 1990, 62, 857-64.