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.

Potential availability of trace metals in sediments in southeastern and southern Brazilian shipyard areas using the DGT technique and chemical extraction methods.

Speciation and partitioning of trace metals, from solid to solution phases of sediments, control their bioavailability and thus their potential ecological risk to organisms. Therefore, in order to obtain a broad evaluation of their risk, it is necessary to couple methodologies that are able to assess metal mobility in sediment. In this study, the Diffusive Gradients in Thin Films (DGT) technique and the application of 0.1 M HCl acid extraction methods, together with solid-state voltammetric sensors, were used with the objective of assessing mobility and potential availability of Cr, Cu, Ni, Pb, V and Zn in sediment porewaters and solid sediments in southeastern and southern Brazilian shipyard areas. The highest labile metal concentrations were found in shipyards with the longest histories of operations. Trace metal distributions in porewater and in the solid phase of sediments (labile metals) and significant correlations among metals enabled to distinguish the contribution of anti-fouling paint components. The diffusive flux of every metal measured at the surface of the sediment indicated that CuDGT had the highest flux (3.66E-03 mmol·m-2 d-1) in the shipyard with the longest operating time. Therefore, enrichment was observed for Cu, Pb and Zn in sediments, indicating a possible ecological risk level of 'Effects Range Median' to 'Apparent Effects Threshold' for oyster larvae (Mollusca) (Cu), bivalves (Pb) and the infaunal community (Zn). Probable Effect Concentrations (PEC) to sediment-dwelling biota can be expected as well, related to high concentrations of Cu and Zn in sediment. This study allowed a comprehensive evaluation of potential bioavailability and ecological risk of trace metals in aquatic systems where there is continuous and specific input of these elements. The use of the DGT technique with solid-state voltammetry in the sediment of distinct Brazilian estuarine systems demonstrated its potential to be applied in future environmental network programs.

Antimicrobial (including antimollicutes), antioxidant and anticholinesterase activities of Brazilian and Spanish marine organisms – evaluation of extracts and pure compounds

Abstract This work describes the antimicrobial, antioxidant and anticholinesterase activities in vitro of organic extracts from fourteen seaweeds, eleven sponges, two ascidians, one bryozoan, and one sea anemone species collected along the Brazilian and Spanish coast, as well as the isolation of the diterpene (4R, 9S, 14S)-4α-acetoxy-9β,14α-dihydroxydolast-1(15),7-diene (1) and halogenated sesquiterpene elatol (2). The most promising antimicrobial results for cell wall bacteria were obtained by extracts from seaweeds Laurencia dendroidea and Sargassum vulgare var. nanun (MIC 250 μg/ml), and by the bryozoan Bugula neritina (MIC 62.5 μg/ml), both against Staphylococcus aureus. As for antimollicutes, extracts from seaweeds showed results better than the extracts from invertebrates. Almost all seaweeds assayed (92%) exhibited some antimicrobial activity against mollicutes strains (Mycoplasma hominis,Mycoplasma genitalium,Mycoplasma capricolum and Mycoplasma pneumoniae strain FH). From these seaweeds, A1 (Canistrocarpus cervicornis), A11 (Gracilaria sp.) and A4 (Lobophora variegata) showed the best results for M. pneumoniae strain FH (MIC 250 μg/ml). Furthermore, compounds 1 and 2 were also assayed against mollicutes strains M. hominis,M. genitalium,M. capricolum,M. pneumoniae strain 129 and M. pneumoniae strain FH, which showed MIC > 100 μg/ml. Antioxidant activities of extracts from these marine organisms were inactive, except for E7 (from sponge Ircinia sp.), which exhibited moderated antioxidant activities for two methods assayed (IC50 83.0 ± 0.1 μg/ml, and 52.0 ± 0.8 mg AA/g, respectively). Finally, for the anticholinesterase activity, all the 29 samples evaluated (100%) exhibited some level of activity, with IC50 < 1000 μg/ml. From these, seaweeds extracts were considered more promising than marine invertebrate extracts [A10 (IC50 14.4 ± 0.1 μg/ml), A16 (IC50 16.4 ± 0.4 μg/ml) and A8 (IC50 14.9 ± 0.5 μg/ml)]. The findings of this work are useful for further research aiming at isolation and characterization of active compounds.

Avaliação da alteração de cor de diferentes compósitos restauradores: influência de corantes usados na cavidade oral - estudo in vitro / Evaluation of color alteration of direct restorative composite

Este trabalho foi realizado com o objetivo de verificar in vitro a influência das soluções de café e vinho na alteração de cor de diferentes compósitos restauradores diretos. Foram confeccionados com auxílio de uma matriz de silicona 13 corpos-de-prova com o compósito Herculite XRV e 13 corpos-de-prova com o compósito Z100. (3M) Após sua confecção, os corpos-de-prova ficaram imersos em água destilada por 24 horas. Em uma próxima etapa foram imersos nas soluções: controle, café e vinho tinto, permanecendo em estufa a 37°C. Os corpos-de-prova que foram imersos no café permaneceram por 15 dias em solução, e os imersos em vinho tinto permaneceram por 30 dias. O grupo controle permaneceu por 30 dias em água destilada. As soluções foram trocadas diariamente e no fim do experimento cada corpo-de-prova foi lavado em água corrente por 2 minutos. Em seguida, os corpos-de-prova foram moídos com auxílio de um moinho de martelo, imersos em etanol absoluto por 24 horas e submetidos à análise espectrofotométrica. As médias resultantes encontradas para Herculite XRV foram: controle - 0,103; vinho tinto - 0,241 e café - 0,656. As médias para Z100 foram: controle - 0,140; vinho tinto - 0,196 e café-0,401. Da análise dos resultados concluiu-se que houve influência na alteração de cor das resinas compostas Herculite XRV e Z100, quando estas foram submetidas às soluções de café e vinho e o café mostrou maior capacidade de pigmentação sobre as resinas compostas citadas, em relação ao vinho.