Distribution of chlorinated hydrocarbons in stream-bottom material

Six stream-bottom samples, contaminated in situ with high levels of chlorinated hydrocarbons, were size graded and the separates were analyzed. The contaminants were found distributed throughout the sample. The complexity of bottom-material samples is such that the distribution of chlorinated hydrocarbons may be controlled to a major extent by the organic matter and associated organisms. All particle-size fractions must be considered if representative samples are to be taken and quantitatively related to a stream.