Methodology for environmental assessments of oil and hazardous substance spills

Abstract

Scientific assessment of the complex environmental consequences of large spills of oil or other hazardous substances has stimulated development of improved strategies for rapid and valid collection and processing of ecological data. The combination of coastal processes and geological measurements developed by Hayes & Gundlach (1978), together with selected field biological and chemical observations/measurements, provide an ecosystem impact assessment approach which is termed “integrated zonal method of ecological impact assessment.” Ecological assessment of oil and hazardous material spills has been divided into three distinct phases: (1) first-order response studies — conducted at the time of the initial spill event, which gather data to document acute impacts and assist decision-makers in prioritization of cleanup efforts and protection of ecologically sensitive habitats, (2) second-order response studies — conducted two months to one year post-spill, which document any delayed mortality and attempt to identify potential sublethal impacts in sensitive species, and (3) third-order response studies — conducted one to three years post-spill, to document chronic impacts (both lethal and sublethal) to specific indicator species. Data collected during first-order response studies are gathered in a quantitative manner so that the initial assessment may become a baseline for later, more detailed, post-spill scientific efforts. First- and second-order response studies of the “Peck Slip” oil spill in Puerto Rico illustrate the usefulness of this method. The need for contingency planning before a spill has been discussed along with the use of the Vulnerability Index, a method in which coastal environments are classified on a scale of 1–10, based upon their potential susceptibility to oiling. A study of the lower Cook Inlet section of the Alaskan coast illustrates the practical application of this method.