Grantee Research Project Results
Objective Decision-Making Tools for Modeling the Fate of Complex Petroleum Products in the EnvironmentEPA Grant Number: FP917295
Title: Objective Decision-Making Tools for Modeling the Fate of Complex Petroleum Products in the Environment
Investigators: McIlroy, John W
Institution: Michigan State University
EPA Project Officer: Packard, Benjamin H
Project Period: August 1, 2011 through July 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Emerging Environmental Approaches and Challenges: Innovative Investigations for Oil Spill Impacts
The oil spill in the Gulf of Mexico has highlighted the environmental hazards of petroleum discharges and the knowledge gaps that hinder accurate risk assessment and remediation. Part of the challenge in assessing petroleum discharges is the complexity of the sample and the changes in the physical and chemical properties that occur due to weathering processes. Improvements in the fundamental understanding of these transport processes promise to improve impact assessments of discharges and to test remediation effectiveness. The proposed research aims to develop empirical rate constants for relevant physical and chemical weathering processes to serve as the foundation for models of fate of petroleum and biofuel constituents.
Diesel fuels will serve as an example of a complex pollutant mixture. The fuel samples will undergo four different simulated weathering processes: evaporation, photooxidation, hydrolysis and microbial degradation. These weathering processes were chosen to closely simulate a spill on water, but the methodology and results can be expanded to other environments as well. The chemical changes will be monitored over time, using both gas and liquid chromatography with mass spectrometry. Multivariate statistical techniques will be applied to identify the components that are changing during each of the weathering processes. These components will then be modeled to predict rates of degradation or formation. The model will be developed for constituents with well-defined physical parameters, and then extended to other constituents with similar chemical properties. This will provide the kinetic information for the determination of the rate constants and reaction orders. The final model will consist of an array of rate constants and reaction orders for individual compounds as well as classes of chemical compounds, such as alkanes, alkyl benzenes and polycyclic aromatic hydrocarbons (PAHs).
The proposed research will provide a comprehensive model that can predict the loss and formation of compounds as a result of weathering of petroleum products. This will build on past models by modeling not only individual compounds, but also by modeling classes of compounds. As a result, a more comprehensive model that takes into account the properties of the bulk mixture will be developed. In addition, multivariate statistical procedures will be applied to help identify the relevant sources of variation between samples. Evaporative loss is expected to be the dominant weathering process, and potentially mask changes from the other weathering processes. By modeling each weathering process individually, it will be possible to correct and minimize the masking that may occur. The model can be used to guide decision-making, as it will predict the loss or formation of compounds. Toxic compounds, such as PAHs, are of particular interest, due to their toxicity and potential reactions that may occur during photooxidation. The model also can be used to evaluate the effectiveness of remediation procedures. Successful remediation procedures will remove constituents faster than the model predicts. Finally, the model can be used to derive the original composition of the petroleum product, based on predicted weathering processes. This would then allow for the comparison of fuels to determine responsibility or origin of the pollution.
Potential to Further Environmental / Human Health Protection
This research will provide a more comprehensive understanding of the compounds that are present at a petroleum spill site. In addition, it will allow for the prediction of newly formed compounds. A more complete understanding of the weathering processes will help to direct cleanup efforts and provide a better estimation of the long-term effects of a petroleum spill. Prediction of the degradation processes that are occurring also may lead to targeted remediation, lessen the economic impact and better assist relief organizations in strategic planning.