Harmonised framework for ecological risk assessment of sediments from ports and estuarine zones of North and South Atlantic

This paper presents a harmonised framework of sediment quality assessment and dredging material characterisation for estuaries and port zones of North and South Atlantic. This framework, based on the weight-of-evidence approach, provides a structure and a process for conducting sediment/dredging material assessment that leads to a decision. The main structure consists of step 1 (examination of available data); step 2 (chemical characterisation and toxicity assessment); decision 1 (any chemical level higher than reference values? are sediments toxic?); step 3 (assessment of benthic community structure); step 4 (integration of the results); decision 2 (are sediments toxic or benthic community impaired?); step 5 (construction of the decision matrix) and decision 3 (is there environmental risk?). The sequence of assessments may be interrupted when the information obtained is judged to be sufficient for a correct characterisation of the risk posed by the sediments/dredging material. This framework brought novel features compared to other sediment/dredging material risk assessment frameworks: data integration through multivariate analysis allows the identification of which samples are toxic and/or related to impaired benthic communities; it also discriminates the chemicals responsible for negative biological effects; and the framework dispenses the use of a reference area. We demonstrated the successful application of this framework in different port and estuarine zones of the North (Gulf of Cadiz) and South Atlantic (Santos and Paranagua Estuarine Systems).

Integrated sediment quality assessment in Paranagua Estuarine System, Southern Brazil

Sediment quality from Paranagua Estuarine System (PES), a highly important port and ecological zone, was evaluated by assessing three lines of evidence: (1) sediment physical-chemical characteristics; (2) sediment toxicity (elutriates, sediment-water interface, and whole sediment); and (3) benthic community structure. Results revealed a gradient of increasing degradation of sediments (i.e. higher concentrations of trace metals, higher toxicity, and impoverishment of benthic community structure) towards inner PES. Data integration by principal component analysis (PCA) showed positive correlation between some contaminants (mainly As, Cr, Ni, and Pb) and toxicity in samples collected from stations located in upper estuary and one station placed away from contamination sources. Benthic community structure seems to be affected by both pollution and natural fine characteristics of the sediments, which reinforces the importance of a weight-of-evidence approach to evaluate sediments of PES. (C) 2008 Elsevier B.V. All rights reserved.

Sediment toxicity assessment of Guanabara Bay, Rio de Janeiro, Brazil.

Guanabara Bay (GB) comprises of estuarine and marine environments of high ecological and socio-economic relevance, together with port, industrial and urban areas. The anthropogenic activities produce environmental impacts, including the aquatic pollution. The sediment quality assessment is important to evaluate the effects of contamination, once sediments are a repository for most of the contaminants. In this Study, the quality of sediments from GB was evaluated, in rainy and dry periods, throughout the employment of acute toxicity tests with the amphipod Tiburonella viscana, and chronic bioassays with embryos of the sea-urchin Lytechinus variegatus. In the dry period, acute toxicity was found in the sediments from stations 1, 2 3 (NW) and 7 (near Guapimirim Environmental Protection Area). The bioassays with liquid phases showed effects, but were strongly influenced by the unionized ammonia levels, which were high in this period. In the rainy period, acute toxicity was found in sediments samples from stations 1, 2, 3, 6, 8, 10, 11, 12 and 15. Chronic toxicity could be clearly detected, as ammonia concentrations tended to be low in the most part of the samples. The results showed that the sediment toxicity is influenced by precipitation rates, which increase the input of contaminants to the Bay, and also allowed subdividing GB in three main zones: northwest (stations 1, 2, 3, 5), northeast (stations 6, 7, 8, 9) and centre-south (stations 10, 11, 12, 13, 14, 15). Results also showed that the quality of GB sediments is poor, and that toxicity tests could determine the combined effects of pollutants.