Correlation between trace contaminant mixtures in complex effluents and structure of benthic macroinvertebrates.

摘要

Scope of study. The objective of this study was to determine the in-situ levels of trace contaminants which effect the assemblage of benthic macroinvertebrates of Boggy and Skeleton creeks. Water, sediment, and biological samples were collected concurrently with in-situ physicochemical conditions at seasonal intervals over a two year period from an upstream control site, two impacted stations, and two recovery zones. Water and sediment samples were analyzed for organic contaminants (GC/MS), 15 selected heavy metals (AA), and a number of conventional parameters. The species diversity, number of taxa, density, and similarity indices were responses used to differentiate the effects of the effluent discharges and to test for correlation with concentration of chemical contaminants.; Findings and conclusions. The highest correlation with species diversity of the benthic macroinvertebrate population was the methylene chloride extractable organics from the sediment and water as shown by principal component, stepwise multiple regression, and Pearson's product moment correlation analyses. Suspended zinc and dissolved arsenic levels also showed a similar inverse relationship with the species diversity index. Trace contaminant levels in water samples were generally highest at stations immediately below point source discharges while lowest concentrations were usually found at the upstream control station or below potential recovery zones. Sediment heavy metal levels were highest at the first recovery zone, most probably due to the greater percentage of silt and clay also present in this zone. The lowest concentrations were found at the final recovery zone. Organic chemical concentrations in sediment samples were highest at the impacted stations and lowest at the recovery zones. Specific physicochemical, heavy metal, and organic chemical contaminant levels detected in water and sediment samples after refinery closure were less than those determined prior to refinery shutdown.