Grantee Research Project Results
Advanced Analytical Methods for the Direct Quantification and Characterization of Ambient Metal Species in Natural Waters
EPA Grant Number: R826187Title: Advanced Analytical Methods for the Direct Quantification and Characterization of Ambient Metal Species in Natural Waters
Investigators: Hering, Janet G.
Institution: California Institute of Technology
EPA Project Officer: Aja, Hayley
Project Period: January 1, 1998 through June 30, 1999 (Extended to March 31, 2000)
Project Amount: $116,985
RFA: Exploratory Research - Environmental Chemistry (1997) RFA Text | Recipients Lists
Research Category: Water , Air , Safer Chemicals , Land and Waste Management
Description:
The project objective is to develop a method using electrospray mass spectrometry (ESMS) to determine metal speciation directly in model systems and natural waters. Method development will include: 1) validation of the ESMS method using model systems (i.e., well-defined mixtures of metals and complexing agents of known metal affinities), 2) systematic application of the ESMS method to examine trace metal complexation by natural organic matter (with isolated humic and fulvic substances and whole water samples) to generate data compatible with equilibrium speciation modeling (using codes such as MINEQL) and comparable with studies based on detection of free (or labile) metal species, 3) use of the ESMS method to investigate competitive effects (both kinetic and equilibrium effects) in multi-metal systems, and 4) determination of requirements (e.g., for pre-concentration or chromatographic separation) for the application of the ESMS characterization method to whole water samples.
Approach:
The proposed project will take advantage of current advances in analytical instrumentation to develop methods for the direct quantification and characterization of ambient metal species. This approach will combine the sensitivity of mass spectrometry (MS) with the newly-developed electrospray (ES) interface for MS analysis of non-volatile species. Studies will be conducted with model metal-organic and colloidal metal species as well as with whole water samples. Studies will emphasize investigation of metal competition in multi-metal system and integration of metal complexation data with geochemical models of equilibrium speciation.
Expected Results:
The fate and ecotoxicological effects of metal inputs to aquatic environment cannot be fully understood without careful consideration of the physicochemical forms in which the metals occur (i.e., metal speciation). Explicit consideration of metal speciation is not yet, however, incorporated into water quality criteria. An impediment to such incorporation is the lack of information on the dominant metal species in natural waters at ambient metal concentrations. The proposed project will address this research need by developing methods, based on advanced analytical techniques, for the direct quantification and characterization of ambient metal species.
Publications and Presentations:
Publications have been submitted on this project: View all 1 publications for this projectSupplemental Keywords:
heavy metals, speciation, mass spectrometry, toxicity,, Air, Scientific Discipline, Ecology, Environmental Chemistry, Engineering, Chemistry, & Physics, equilibrium speciation modeling, heavy metals, water quality, natural waters, ambient metal species, metal speciation, electrospray mass spectrometry, chemical kinetics, quantification, physicochemicalProgress and Final Reports:
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.