Figure 28. Selected Frequency Distributions for Metal Concentrations in Sediments.The horizontal axes refer to concentration in µg/g. The vertical axes indicate the number of analyses within classes. The dashed vertical lines demarcate screening criteria for effects-based toxicity levels (Long et al., 1995) for bottom organisms. ERL and ERM values denote concentration levels of metals corresponding to the 10 and 50 percentile levels for toxic effects in a variety of test organisms. L.P. – Lake Pontchartrain, B.T. – Bayou Trepagnier. Bayou Trepagnier is an inlet formerly discharging to Lake Pontchartrain. It has been severely contaminated by effluent from a petroleum refining and petrochemical complex.
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