Model to Determine the Likelihood of Sediment Contamination in Freshwater Systems: A 'Concern Ranking' Approach to Prioritizing Field Identification of Synthetic Organic Chemicals

摘要

The report presents a model which uses basic properties of chemicals -- the octanol-water partition coefficient (log P), Henry's Law Constant (Hc), and the biodegradation half-life (t1/2) -- to generate 'concern ranking.' The concern rankings indicate the relative likelihood that a given compound, if discharged into freshwater systems, will accumulate in bottom sediments. The goal of the model is to enable predictions of which compounds out of the often complex matrix of pollutants discharged into aquatic systems are most likely to accumulate in sediments. Such predictions would greatly facilitate (and reduce the cost) of laboratory identification by allowing sites to be pre-screened prior to analytical testing. Moreover, they would assist managers in making first-order approximations of the relative toxicity of different sites in order to prioritize dredging/clean-up projects. The report includes a simple case study of a hypothetical watershed with a single pollutant source, a municipal wastewater treatment plant, in order to demonstrate application of the model. The results of the case study demonstrate that a number of compounds have a high likelihood of accumulating in sediments, including PCBs, pesticides, and plasticizers.