Cristina Maria Magalhães de Souza

Geochemical partitioning of heavy metals in sediments of three estuaries along the coast of Rio de Janeiro (Brazil)

Abstract The geochemical partitioning of Cu, Cd, Cr and Pb was studied in sediments of three estuaries along the coast of Rio de Janeiro. The results show that, under contaminated conditions, the lithogeneous fraction of the total metal concentration decreases in importance, and mobile fractions dominate. Dilution with less contaminated marine sediments and the effect of salinity on metal behaviour could only be observed in the uncontaminated estuary. Underoxic conditions the reducible fraction is the more important sink for metal among the mobile phases. However, in the area with high organic sewage inputs, the oxidizable fraction can account for the greater fraction of total metal content. This latter result suggests a synergistic effect between organic pollution and metal contamination, since metals in oxidizable forms may be remobilized during mixture with oxic marine sediments.

Essential (Se, Cu) and non-essential (Ag, Hg, Cd) elements: What are their relationships in liver of Sotalia guianensis (Cetacea, Delphinidae)?

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Trace elements in different species of cetacean from Rio de Janeiro coast

The present work tested whether ecological and biological parameters have an influence on the accumulation of trace elements (As, Cd, Cu, Pb, Se and Ag) by the liver of three cetaceans species: two species of coastal habit (Pontoporia blainvillei and Sotalia guianensis) and one of oceanic habit (Stenella frontalis), that were incidentally caught in fishing nets along the north of Rio de Janeiro coast. Inter-species difference was observed on the accumulation of Cd and Pb (5.12 ± 0.74 µg g-1 and 21.25 ± 1.35 µg g-1, respectively). However, the three cetacean species, S. guianensis, P. blainvillei and S. frontalis presented similar hepatic concentrations of As, Cu and Ag. No gender differences were found on the bioaccumulation of trace elements. Hepatic trace element accumulation was influenced by body length, according to the cetacean species. S. guianensis, which co-habits the same coastal marine environment that P. blainvillei species, presented a significant difference between hepatic selenium concentration (20.70 ± 32.22 µg g-1 and 3.24 ± 2.02 µg g-1, respectively). Based on these results, it is possible to conclude that, not only the different environmental conditions, but also total length and mainly the feeding habit influenced the accumulation of trace elements by the liver of these cetacean species.

Total mercury, organic mercury and selenium in liver and kidney of a South American coastal dolphin.

Selenium and total and organic mercury were determined in the liver and kidney of franciscana dolphin (Pontoporia blainvillei) incidentally caught in fishing nets along two Brazilian coastal areas (southeast and south). Regional differences in the concentrations of these contaminants were observed in P. blainvillei. Liver showed the highest organic and total mercury. In general, samples of individuals collected at the southern of Brazil had the highest concentrations of selenium and total and organic mercury. No significant gender differences were observed. Growth stage influenced the accumulation of these contaminants in both organs, and hepatic concentrations increased with the body length, according to the sampling area. Molar mercury and selenium concentrations in liver were significantly correlated, with a Se:Hg ratio close to 4. The among-site differences we found may be related to differences in preferred prey, bioavailability in the marine environment, environmental conditions, or these individuals may belong to distinct populations.

TRANSFERÊNCIA TRÓFICA DE MERCÚRIO E SELÊNIO NA COSTA NORTE DO RIO DE JANEIRO

Trophic transfer of trace elements along marine food chains has been recognized as an important process influencing metal and metalloid bioaccumulation. The trophic transfer of mercury was observed between trophic levels from prey (considering fish with different feeding habits and squid) to top predator (dolphin) in a Northern coastal food chain of Rio de Janeiro. Selenium showed some evidence of trophic transfer between lower trophic levels. Dolphin presented the highest mercury concentrations whereas the benthic carnivorous fish showed the highest selenium concentrations. Mercury is biomagnified through the food chain while selenium does not present the same behavior.

Geochemical Distribution of Cd, Cu, Cr and Pb in Sediments of Estuarine Areas along the Southeastern Brazilian Coast

The coastline of the State of Rio de Janeiro, Brazil, presents a great diversity of coastal environments which support a significant part of the state’s economy. Wood production from mangrove forests, fisheries and tourism are the main activities that sustain a sizable portion of the local population. Increasing industrialization and urbanization of the Rio de Janeiro littoral have, however, presented a serious threat to the utilization of these coastal resources. Development has introduced urban wastes, trace metals, oil and general eutrophication which comprise the main environmental problems along this coastal state area (Lacerda 1983). Trace metals, due to persistence in the environment, have received special attention from local authorities, and its has been determined that knowledge of their fate in coastal environments is urgently needed.

Different Species of Mercury in the Livers of Tropical Dolphins

Abstract Four kinds of mercury species (inorganic mercury (Hginorg), methylmercury (MeHg), total organic mercury (ΣHgorg), and insoluble mercury, deemed to be mercuric selenide (HgSe), were determined in the livers of dolphins from the Brazilian coast. The MeHg was identified and quantified in the toluene layer on a Gas Chromatograph with an Electron Capture Detector (GC-ECD). The ΣHgorg was isolated by acid leaching (H2SO4-KBr-CuSO4) and then extracted into CH2Cl2. The ΣHgorg and Hginorg were determined by Cold-Vapor Atomic Absorption Spectroscopy (CV-AAS). The MeHg was the smallest fraction of Hgtot, with a median of 9%, whereas the highest fraction of the Hgtot was as HgSe, corresponding to 53%. The fractions of Hginorg and ΣHgorg corresponded to 30% and 39%, respectively. The lowest fraction of MeHg and the highest fraction of HgSe in the liver of all animals are related to different capacities or strategies of detoxification of methylmercury in this organ.

Structural and ecophysiological alterations of the water hyacinth [Eichhornia crassipes (Mart.) Solms] due to anthropogenic stress in Brazilian rivers

In this work, the structural and ecophysiological a lterations (chlorophyll a fluorescence and photosyn thetic pigments), and quantification of Cr, Pb and Zn in t he leaf limb, petiole and younger and older roots o f water hyacinth from the lower, medium and upper Paraiba driver (PSR) and Imbe river were evaluated. Th e plants from the medium and upper PSR (more industrialized and populated regions) exhibited lower turgid cell in the root cortex, less root hairs and leaf epidermis, chlorop lasts with plastoglobules and increased stroma volu me. Higher concentrations of metals were observed in the young er and older roots from the medium PSR plants. The results suggested that the plants from more anthropized reg ions were able to maintain the maximum quantum yiel d (Fv/Fm) which was a result from the metabolic fitting, incr easing the non-photochemical quenching, reducing to tal chlorophyll/carotenoids and leading to the structur al modifications.

Isotopic profile and mercury concentration in fish of the lower portion of the rio Paraíba do Sul watershed, southeastern Brazil

The aim of this study was to evaluate the isotopic profile and mercury (Hg) concentrations in fish (carnivores, omnivores and detritivores) in the lower portion of the rio Paraiba do Sul watershed, southeastern Brazil. Carbon (δ13C) isotopic analyses revealed that pelagic and benthonic sources are part of the feeding of the fish from the different guilds (-14.0 to -24.8 ‰). The benthic sources are usually enriched in δ13C (-16.9‰, from watershed runoff) compared to pelagic sources because the phytoplankton, important primary producer that supports several pelagic chains, has δ13C signature lighter (-23.9‰). The nitrogen (δ15N) isotopic signatures indicated that most guilds were at the same trophic position (10.0 to 15.5 ‰), except for pelagic omnivorous fish, which had a lower trophic position. Niche overlap was observed among pelagic and demersal carnivorous fish, demersal omnivorous fish, and demersal detritivorous fish. The lower isotopic niche breadth of pelagic carnivorous fish reveals the specialized resource use by this guild. Hg concentrations (ng g-1 dry weight) differed significantly between demersal carnivorous fish (185.3 dry weight; 27.8 wet weight) and demersal omnivorous fish (277.9 dry weight; 41.7 wet weight) and between pelagic omnivorous fish (197.2 dry weight; 29.6 wet weight) and demersal omnivorous fish due to (1) differences in food sources: guilds that fed on bottom resources were more affected by contamination because the sediment is an important Hg accumulator in the study area, and (2) because of its trophic positions. Considering that the fish consumed prey of similar trophic positions, the guilds did not show a well-defined food hierarchy. Therefore, in this study, there was no clear relationship between Hg and δ15N.