Geochemical fractionation of trace metals and ecological risk assessment of surface sediments in Sepetiba Bay, Brazil.

The Sepetiba Bay (Southeast Brazil) is a known Cd- and Zn-contaminated site that received spills of a large slag pile leachate from a Zn smelter. With important harbors, Sepetiba Bay demands periodic dredging operations which affect the mobility of the metals. The main goal of this work was to assess metal mobility in sediments and its associated toxicity in a fictive dredging area, to evaluate the risks of the operation. To achieve this goal, 18 superficial sediment samples were collected and characterized for pH and Eh. Sediments were analyzed for grain size, organic carbon, and total nitrogen, and metal mobility was evaluated with a sequential extraction procedure, proposed by the European Community Bureau of Reference (BCR). The results demonstrate that Cd and Zn are mainly associated with the exchangeable fraction (mean concentrations 1.4 mg kg-1 and 149.4 mg kg-1, respectively) and reducible fractions (mean concentrations 0.3 mg kg-1 and 65.5 mg kg-1, respectively), while Fe, Cr, Cu, Ni, and Al were associated with the residual fraction. Metals in the residual fraction are probably associated with the mineral lattice of the sediment and should not represent an environmental risk for the biota. The application of the enrichment factor and three risk assessment indexes (Risk Assessment Code, Risky Pollution Index, and Bioavailability Risk Assessment Index) show that the sediments are considerably enriched in metals that constitute a relevant risk for the sediment biota. In the case of dredging operations, Cd and Zn should be released to the overlying waters and be available to organisms, threatening the whole ecosystem. The proposed approach was shown to be much more precise than what is frequently presented in the Environmental Impact Assessments that only consider the threshold limits of the legislation.

Labile metal assessment in water by diffusive gradients in thin films in shipyards on the Brazilian subtropical coast.

Shipyards impact on estuarine environments because of the use of antifouling paints and petroleum products, which release trace metals that may remain in their bioavailable or labile form. Regardless of its importance, the relation between continuous input of trace metals (hotspot area) and their availability in the water column has been scarcely studied. This study evaluated seasonal variations in the concentrations of labile fractions of metals in shipyards located in estuarine areas on the Brazilian subtropical coast. These fractions were determined by the Diffuse Gradients in Thin Films (DGT) technique. Maximum labile fraction concentrations of Cr (0.3 µg L-1), Ni (2.2 µg L-1) and V (2.0 µg L-1) are directly related to (i) their specific source: antifouling paints (for Cr), metal and steel alloys (for Cr and Ni) and petroleum products (for V), besides (ii) periods of intensive traffic and vessel repair. Additionally, variations in labile fractions of Ni and V in the Patos Lagoon estuary were influenced by salinity, which is known to affect metal desorption from surface sediments in resuspension events. Even though Cr is affected by the same processes, it is available as Cr(III) and does not represent any ecological risk in the study areas. Although the areas under study are affected by variations in physical and chemical conditions, shipyards were effectively hotspots of trace metals in their labile fraction in various estuarine systems in southeastern and southern Brazil. Thus, they represent areas where Ecological Risk Assessment, mainly of V, should be carried out.

Cross-cultural adaptation of an environmental health measurement instrument: Brazilian version of the health-care waste management • rapid assessment tool.

BACKGROUND: Periodic assessment is one of the recommendations for improving health-care waste management worldwide. This study aimed at translating and adapting the Health-Care Waste Management - Rapid Assessment Tool (HCWM-RAT), proposed by the World Health Organization, to a Brazilian Portuguese version, and resolving its cultural and legal issues. The work focused on the evaluation of the concepts, items and semantic equivalence between the original tool and the Brazilian Portuguese version. METHODS: A cross-cultural adaptation methodology was used, including: initial translation to Brazilian Portuguese; back translation to English; syntheses of these translation versions; formation of an expert committee to achieve consensus about the preliminary version; and evaluation of the target audience's comprehension. RESULTS: Both the translated and the original versions' concepts, items and semantic equivalence are presented. The constructs in the original instrument were considered relevant and applicable to the Brazilian context. The Brazilian version of the tool has the potential to generate indicators, develop official database, feedback and subsidize political decisions at many geographical and organizational levels strengthening the Monitoring and evaluation (M&E) mechanism. Moreover, the cross-cultural translation expands the usefulness of the instrument to Portuguese-speaking countries in developing regions. CONCLUSION: The translated and original versions presented concept, item and semantic equivalence and can be applied to Brazil.

Combined SEM/AVS and attenuation of concentration models for the assessment of bioavailability and mobility of metals in sediments of Sepetiba Bay (SE Brazil).

This study proposes a new methodology to study contamination, bioavailability and mobility of metals (Cd, Cu, Ni, Pb, and Zn) using chemical and geostatistics approaches in marine sediments of Sepetiba Bay (SE Brazil). The chemical model of SEM (simultaneously extracted metals)/AVS (acid volatile sulfides) ratio uses a technique of cold acid extraction of metals to evaluate their bioavailability, and the geostatistical model of attenuation of concentrations estimates the mobility of metals. By coupling the two it was observed that Sepetiba Port, the urban area of Sepetiba and the riverine discharges may constitute potential sources of metals to Sepetiba Bay. The metals are concentrated in the NE area of the bay, where they tend to have their lowest mobility, as shown by the attenuation model, and are not bioavailable, as they tend to associate with sulfide and organic matter originated in the mangrove forests of nearby Guaratiba area.

Planning dredging services in contaminated sediments for balanced environmental and investment costs.

Dredging of contaminated sediments has shown to be a harmful activity for the environment, because a number of contaminants can be resuspended and become available to the organisms. Furthermore, dredged contaminated sediments may cause significant damages in the dumping site. In order to avoid the drawbacks of this activity, better techniques have to be developed and the present article presents a new procedure for the planning of dredging that reduces the environmental impacts by reducing the amount of dredged sediments and, at the same time, reduces costs. The new technique uses screening of contaminant concentrations in the sediments that are normally part of the environmental impact assessment for dredging activity. A detailed mapping of the contamination, layer by layer is carried out and the areas where the action levels are reached are outlined with polygons, establishing limits within which sediments have to be dredged with safe procedures. In the case presented, construction of a harbor in Sepetiba Bay, Rio de Janeiro, Brazil, the safe procedure is cutter/suction dredging and pumping into a sub-aquatic confined disposal facility (CDF). A detailed evaluation of costs showed that if the whole layers of sediment were to be dumped into the CDF, the cost of the activity would be at least 63.82% more expensive than the proposed procedure, constituting an attractive advantage. Furthermore, as the size of the CDF is significantly smaller, less dredging is necessary, causing smaller environmental impact.