Intrinsic Stable Isotopic Tracers of Environmental ContaminantsEPA Grant Number: R825420
Title: Intrinsic Stable Isotopic Tracers of Environmental Contaminants
Investigators: Macko, Stephen A. , Kennicutt, Mahlon C.
Institution: University of Virginia , Texas A & M University
EPA Project Officer: Lasat, Mitch
Project Period: October 1, 1996 through September 30, 1999 (Extended to September 30, 2000)
Project Amount: $358,949
RFA: Exploratory Research - Water Engineering (1996) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Engineering and Environmental Chemistry
The stable isotopic composition of a contaminant in the environment is the end-result of a complex chain of events. Chemicals produced from disparate sources by fundamentally different processes would be expected to exhibit intrinsic isotopic compositions that could be used to identify sources. Compound specific isotope analysis (CSIA) based on gas chromatography /isotope ratio mass spectrometry (GC/IRMS) will be used to uniquely identify naturally occurring pollutants, such as PAH in petroleum, and synthetic or manufactured pollutants, such as pesticides and PCBs. The expected benefit to be derived from the application of CSIA to environmental questions is to be able to more accurately define the sources, fate, and transformation of pollutant mixtures in the environment. Effective environmental regulation can only be accomplished if contaminant distributions can be unambiguously linked to known processes or sources. As concerns about the quality of the environment have increased it has become clear that our ability to inventory, trace and provide a mass balance of pollutants in the environment is poor.
The study proposed here will include development of purification techniques, optimization of instrumental conditions, development of models based on study results, and field testing of the concepts developed. Selected polycyclic aromatic hydrocarbons, pesticides, and PCBs will be the analytes of interest. Fused silica capillary columns will be used to provide resolution of complex mixtures, minimize co-elution and background interferences, and limit column bleed during GC/IRMS analysis. The resolution and accuracy of the method will be determined by analyzing authentic standards, primary sources of contaminants, extracts of effluents and well characterized pollutant occurrences.
The proposed study has four primary objectives: (1) development of isolation techniques that produce high purity, unaltered concentrates that maintain the stable isotopic integrity of the analytes; (2) determine the stable isotopic composition of target analytes in primary sources of contaminants; (3) determine the stable isotopic composition of priority pollutants in selected processes that introduce contaminants to the environment; and (4) verify the techniques and models developed with well-characterized pollutant occurrence using selected samples from EPA's Casco Bay National Estuarine Program, EPA's Galveston Bay National Estuarine Program, EPA's Environmental Monitoring and Assessment Program-Near Coastal, and NOAA's Status and Trends Program.