ABSTRACT
This chapter is devoted to ecological risk assessment—protection of biota in the wild and entire ecosystems. Ecological risk assessment has been developed with a focus on problem formulation, and thus seems to follow the scientific method to a greater extent than does human health risk assessment. Ecological screening benchmarks exist for biota, soil, and sediment. Criteria exist for surface water. Criteria are acceptable regulatory values, whereas benchmarks are intended for use as screening values. The biological gradient of effects can often be used to develop a site-specific toxicity reference value. The risk characterization ideally provides the risk manager with contaminant concentration levels in various abiotic media that provide a upper and lower bounds on the estimated threshold for adverse ecological effects. In the carburetted water gas process, coal gas was produced and passed into a carburetor, where oil was introduced into the vapor.
