The use of Defensible Analytical Chemical Measurements for Oil Spill Natural Resource Damage Assessment

Abstract

ABSTRACT Scientific research on and natural resource damage assessments (NRDA) of oil spill incidents require the appropriate selection and application of analytical chemical and data interpretation techniques. Estimates of injuries to natural resources (surface waters, geological resources, biological resources), determinations of pathways of exposure, and assessment of recoverability and recovery of injured resources should, in part, be based on methods that are scientifically. defensible and acceptable in their application to the regulatory and legal communities. Recent spill incidents underline the need for significant revision of regulatory methods (such as EPA-approved procedures), so as to target the spilled material (petroleum) and its specific chemical composition. Standard operating procedures for the determination of the saturate and aromatic hydrocarbon concentrations and compositions (normal alkanes and polynuclear aromatic hydrocarbons) of environmental samples have been drafted for use in oil spill assessments. These methods rely on the use of gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) methods that target specific indicators of source material composition and weathering processes. These proposed methods for analysis of oil spill assessment environmental samples are contrasted with EPA methods such as EPA Method 418.1 (total petroleum hydrocarbons), EPA Methods 625 and 8270 (GC/MS analyses of semivolatile priority pollutant organics), and other methods. Using data from three recent oil spills as examples, this paper examines the current “approved” methods for the analysis of environmental samples, and contrasts the scientific rigor and defensibility of the recommended GC (saturated hydrocarbons) and GC/MS (polynuclear aromatic hydrocarbons and heterocyclics) methods for oil spill chemical analyses in NRDA programs. The approaches presented are recommended as important elements of future technical guidance documents relating to the NRDA federal regulations, in contrast with the inappropriate methods now suggested for use in the existing regulations.