A simple approach to integrate the ecotoxicological and chemical data for the establishment of environmental risk levels

Abstract

In this work, multivariate and numeric methods were used to integrate the chemical and ecotoxicological data obtained for the sediments from the Santos Estuarine System, and for the vicinity of the discharges of the Submarine Sewage Outfall of Santos, in order to establish more accurately the environmental risks, identify the priority areas and thus provide guidance to control the programs and public policies. For both the datasets, the concentrations which exceeded numeric sediment guidelines tended to be associated to toxicity. For the estuary, this trend was corroborated by the correlations between the toxicity and Cu and PAHs levels, whereas for the sewage outfall region, this was observed through the correlation between the toxicity and Hg contents. Ratio-to-mean values were calculated for each sample, in order to rank them according to the toxicity and contamination. Cluster analyses confirmed the ranking results. For the estuary, three categories of sediments were established: stations SSV-2, SSV-3 and SSV-4 were under major risks, followed by SSV-6. Stations SSV-1 and SSV-5 were not altered. Concerning to the sewage outfall, stations 1 and 2 presented better quality, whereas station 5 seemed to be under risk, followed by stations 3 and 4, which exhibited some signs of alteration.