139 documents found, page 1 of 14
Conteúdo de mercúrio em espécies de tubarão da costa Sudeste do Brasil
Lacerda, Luiz Drude de; Paraquetti, Heloísa Helena M.; Marins, R. V.; Rezende, C. E.; Zalmon, I. R.; Gomes, M. P.; Farias, V.We present here the first results of Hg concentrations in three small shark species (Rhizoprionodon lalandei, R. porosus and Mustelus higmani) from the SE Brazilian coast. Mercury concentrations in R. lalandei ranged from 21.5 to 280.0 ng.g–1 dry weight (d.w.) (average 74.6 ng.g–1 d.w.; 17.9 ng.g–1 wet weight). In R. porosus, concentrations ranged from 7.6 to 90.5 ng.g–1 d.w. (average 42.2 ng.g–1 d.w., 9.4 ng.g...
Mercury speciation changes in waters of the sepetiba Bay, SE Brazil during tida...
Paraquetti, Heloísa Helena M.; Lacerda, Luiz Drude de; Almeida, Marcelo D.; Marins, Rozane Valente; Mounier, StephaneThis work describes changes in Hg speciation in water along the transport from Sepetiba Bay, SE Brazil, to the adjacent continental platform during tide events and in different seasons. The chemical evaluation of Sepetiba Bay waters showed that the bay exports suspended particulate material (SPM) impoverish in organic carbon to adjacent continental platform areas, mainly during the wet season and imports SPM en...
Distribuição de mercúrio total como indicador de poluição urbana e industrial n...
Marins, Rozane Valente; Paula Filho, Francisco José de; Maia, Saulo Robério Rodrigues; Lacerda, Luiz Drude de; Marques, Wanessa Sousahe monitoring of the pollution status of the Brazilian coast is hampered by the lack of a consistent environmental indicator. We propose Hg as an environmental proxy to anthropogenic pollution of coastal regions due to its absence in the Brazilian geology, its ubiquity in anthropogenic effluents, and its toxicity. Available data suggest Hg "backgrounds" in coastal sediments of 1-10 ng g-1, in the East and 15-30...
Organic micropollutants in the Rio de Janeiro coastal region, Brazil
Lacerda, Luiz Drude de; Japenga, J. D; Wagebar, W. J.; Salomons, W.; Patchineelam, Sambasiva Rao; Leitão Filho, C. MSediment samples from two protected bays and a lagoon with different environmental charac- teristics in the Rio de Janeiro coastal area (Brazil) were analyzed for four groups of hydrophobic organic micropollutants: PAHs, PCBs (both of industrial origin), DDT derivatives and Drins (chlorinated pesticides). Differences in contamination levels of the three studied areas reflect the different land use in the vicini...
Heavy metal distribution, availability and fate in Sepetiba Bay, S.E. Brazil
Lacerda, Luiz Drude de; Pfeiffer, Wolfgang Christian; Fiszman, M.The total flux, distribution and fate of Cu, Cr, Cd, Zn, Mn and Pb were studied in Sepetiba Bay, Rio de Janeiro, SE Brazil. Metal contamination in the bay is of the same order of magnitude as historically contaminated areas of Europe and North America, inspite of the recent (15–20 years) contamination of the area. The estimated metal fluxes to the bay in tons per year are: Cu, 2.7; Cr, 10.9; Cd, 0.9; Zn, 11.5; ...
Geochemical partitioning of heavy metals in sediments of three estuaries along ...
Lacerda, Luiz Drude de; Souza, Cristina Maria Magalhães de; Pestana, Maria Heloisa DegraziaThe 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 frac- tions dominate. Dilution with less contaminated marine sediments and the effect of salinity on metal behaviour could only be obser...
Chromium in water, suspended particles, sediments and biota in the Irajá River ...
Pfeiffer, W.C.; Fiszman, M.; Lacerda, Luiz Drude de; Weerelt, M. van; Carbonell, N.Analyses of chromium concentrations in waters, suspended particles, bottom sediments, fish ( Poecilia reticulata), plan ts (Paspalum vaginatum, Sesuvium portu- lacastrum, Philoxeros vermicularis), soils and barnacles (Balanus sp.) were per- formed from August 1976 to September 1980 in samples collectedfrom the lraj6 River and inside its estuary in Guanabara Bay (Rio de Janeiro, Brazil). Sediments and water from...
Sex-related mercury bioaccumulation in fish from the Madeira River, Amazon
Bastos, Wanderley R; Dórea, José G.; Bernardi, José Vicente E.; Manzatto, Angelo G.; Mussy, Marilia H.; Lauthartte, Leidiane C.; Lacerda, Luiz Drude deSex plays an important role in the kinetics and dynamics of methylmercury in some animals. Although fish is the main source of mercury exposure to consumers, the role of sex in fish-Hg bioaccumulation is less known. We studied total Hg (THg) concentrations in 2538 samples (males ¼1052, females ¼1486) of fish from different trophic levels (herbivorous, planctivorous, detritivorous, omnivorous, carnivorous, pisci...
Mercury anomaly, Deccan volcanism, and the end-Cretaceous mass extinction
Font, Eric; Adatte, Thierry; Sial, Alcides Nobrega; Lacerda, Luiz Drude de; Keller, Gerta; Punekar, JahnaviThe contribution of the Deccan Traps (west-central India) volcanism in the CretaceousPaleogene (KPg) crisis is still a matter of debate. Recent U-Pb dating of zircons interbedded within the Deccan lava flows indicate that the main eruptive phase (>1.1 × 106 km3 of basalts) initiated ~250 k.y. before and ended ~500 k.y. after the KPg boundary. However, the global geochemical effects of Deccan volcanism in the ma...
Degradation and conservation of Brazilian mangroves, status and perspectives.
Ferreira, Alexander Cesar; Lacerda, Luiz Drude deMangroves are one of the most human-affected coastal ecosystems, despite their important social and ecological roles, and after decades of devastation these forests continue facing different processes of conversion, threatening their global future. Brazilian mangroves are not an exception, despite the exis- tence of severe protection legislation. Conversions to aquaculture, industrial and urban development amon...