ABSTRACT The aim of this work was to investigate the effect of marine diesel oil on the development and survival of three different species of mangrove propagules with or without a hydrocarbon-degrading bacterial consortium and the possible use of propagules for the recovery of mangroves impacted by oil. The study was conducted in a greenhouse, near a mangrove from which we collected samples of sediments and propagules of Laguncularia racemosa, Avicennia schaueriana and Rhizophora mangle. The bacterial consortium comprised Bacillus spp., Rhizobium spp., Pseudomonas spp., Ochrobactrum spp. and Brevundimonas spp. After six months, L. racemosa and A. schaueriana only survived in control treatments and R. mangle showed the highest survival rates of the three species, indicating that different mangrove species do not respond uniformly to oil spills. Propagules of R. mangle are much more resistant and the hydrocarbon-degrading bacterial consortium we tested can be applied in the phytoremediation of pollutants.

A extensão, forma e as concentrações da matéria das plumas de pequena escala geradas pelos canais dos rios São Francisco e Guandu, se diferenciaram consideravelmente entre os eventos de alta e baixa descarga. A pluma durante o evento de alta descarga apresentou maior potencial de fertilização da parte central interna da Baía de Sepetiba, enquanto a pluma de baixa descarga fluvial reteve materiais próximo da costa em área rasa. As plumas foram impactadas por múltiplas fontes de materiais, incluindo o aporte lateral fluvial e os sedimentos do fundo. A baixa profundidade da área foi responsável pelo acoplamento nítido da água e do sedimento. O bombeamento da maré com, provavelmente, o atrito no fundo gerado pelo fluxo fluvial, foram responsáveis pela ressuspensão de matéria em suspensão e a liberação de nutrientes dos sedimentos superficiais. As plumas apresentaram um desacoplamento nítido entre as zonas de turbidez e a clorofila, e um acoplamento entre as zonas de turbidez e de mistura estuarina, geralmente não observado em plumas de médio a grande porte que se proliferam na costa e plataforma continental.

Coastal river plumes represent one of the final stages of material transport across the land-sea interface. Most studies, however have focused on the behavior of medium to large sized river plumes of coastal-shelf waters, whereas small sized river plumes acting within estuaries have been neglected. This study addressed the behavior of suspended particulate matter (SPM), dissolved inorganic nutrients (DIN, DIP and DSi) and Chlorophyll a (Chl. a) of a small sized river plume derived from the closely lain São Francisco and Guandú river channels, set in the Sepetiba Bay estuary, SE-Brazil. Two surface water sampling campaigns were conducted, one in January 2003 (humid summer conditions) and the other in June 2003 (dry winter conditions). On both occasions, the plumes dispersed in a SE direction towards the inner portion of the bay. The "wet" event plume was more turbid, nutrient rich and dispersed beyond nearshore waters, whereas the "dry" event plume proliferated as a narrow, less turbid and more nutrient poor film alongshore. Both exhibited a marked degree of patchiness, induced by the differential input of materials from the river sources and resuspension processes from the shallow nearshore bottom. The São Francisco river channel was the main source of freshwater, SPM and nutrients, except for ammonia (NH4+-N) derived from domestic effluents of the Guandú river. The mesohaline portion of the estuarine mixing zone of the plumes behaved as a slight source for SPM, DSi and DIP, due to bottom resuspension processes. N:P molar ratios ranged between 80:1 and 20:1 along the estuarine gradient, being higher in the summer than in the winter event, indicating that DIP was the potential nutrient limiting primary production. Chl. a concentrations increased at the outer premises of the plume, suggesting that the short residence times and turbidity of the plume waters, hampered primary production nearshore, particularly during the summer occasion. The small sized plume lacked the spatial decoupling between the estuarine mixing and turbidity zones, generally observed in larger sized coastal-shelf plumes.

As enseadas de Icaraí e Jurujuba, localizadas na porção sudoeste da Baía de Guanabara, são sujeitas a impactos ambientais decorrentes da ocupação humana nas suas bacias de drenagem. No presente trabalho foi determinada a composição elementar (C e N) e molecular (esteróides) da matéria orgânica em amostras de sedimentos superficiais (n = 24) e de um testemunho curto (c = 47 cm) nas enseadas. As concentrações de coprostanol, em comparação com outras áreas da Baía de Guanabara, indicaram elevado nível de contaminação por esgotos nas estações mais próximas ao ponto de lançamento de efluentes, na Enseada de Icaraí. A Enseada de Jurujuba, mais enclausurada e eutrófica, apresentou uma maior contribuição de matéria orgânica autóctone, conforme evidenciado pelos marcadores colesterol, dinosterol, e parcialmente, também , brassicasterol. A presença de estigmasterol e b-sitosterol indicaram leve contribuição de matéria orgânica oriunda de vegetação terrestre, conforme revelou a análise por componentes principais. No registro sedimentar, foram observados maiores teores de matéria orgânica e esteróis na camada superior, corroborando a acumulação recente de esgotos e de matéria orgânica fitoplanctônica, como conseqüência do processo de eutrofização do sistema. A presença de processos de degradação da matéria orgânica foi evidenciada pelas razões entre esteróis/estanóis, e o perfil do dinosterol indicou que na Enseada predomina o acúmulo de material fitoplanctônico anteriormente ao processo de eutrofização.

The interconnected Icaraí and Jurujuba embayments, set within the lower south-eastern portion of Guanabara Bay, SE-Brazil, have been subject to the direct input of domestic effluents and other associated contaminants from human activities in their watersheds. This study addresses the composition of carbon, nitrogen and molecular steroid markers of surface sediments (n = 24) and a short core (L = 47 cm), in order to evaluate the impact by sewage, the contribution between allochthonous and autochthonous derived organic matter and eutrophication of the embayments. Coprostanol concentrations revealed, when compared to other regions in Guanabara Bay, high contamination by sewage close to the point of sewage discharge in Icaraí embayment. In contrast, the more enclosed and eutrophic Jurujuba embayment exhibited a larger contribution of autochthonous organic matter, as shown by the combination of cholesterol, dinosterol and, partially, also brassicasterol. The presence of stigmasterol and b-sitosterol also indicated a minor contribution of organic matter from terrestrial plants, as revealed by principal component analysis. The sedimentary record of the Jurujuba embayment exhibited highest concentrations of all sterol markers in the top layer, corroborating the recent increase in the accumulation of sewage, plankton derived organic carbon and also eutrophication. Trend in degradation of organic matter was evidenced by sterol/stanol ratios and the behavior of dinosterol indicated that the embayment has been dominated by the accumulation of phytoplankton derived organic matter since earlier times.