The Stability and Utility of Diagnostic Ratio Hydrocarbon Fingerprinting for Soils Contaminated With Petroleum Hydrocarbons
Gregory S. Douglas and Sara McMillen
In order to recover costs for oil spill cleanup and restoration regulatory agencies and trustees of natural resources are interested in identifying parties responsible for hydrocarbon releases, and for associated environmental damages. Chemical analyses of contaminated soil and groundwater samples are currently used to identify the sources of contamination in soil and groundwater systems. However, conventional hydrocarbon fingerprinting approaches such as EPA Method 8015, EPA Method 8270, and ASTM Method 3328-91 afford a low resolution fingerprint that is easily degraded in the environment. The challenge to the hydrocarbon chemist is to develop an analytical approach that minimizes the impact of environmental weathering and biodegradation on the oil signature and improves the accuracy of oil source identification.
An advanced chemical fingerprinting strategy is presented that combines
sensitive and hydrocarbon specific analytical methods with a detailed
interpretive
strategy designed to minimize the impacts of environmental
weathering and biodegradation. Data will be presented from a series of oil
biodegradation studies in soil that clearly demonstrate the utility and
stability of source ratio analysis over a wide range of oil degradation states
and oil types. Using principal component analysis, stable source ratios of C3-
dibenzothiophenes/C3-phenanthrenes, and C2-dibenzothiophenes/C2-phenanthrenes
were identified and evaluated. These source ratios retain their characteristic
source ratio signature even after 95 percent of the PAH and dibenzothiophene
target analytes and 70 percent of the total oil has been biodegraded.
AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California