George Satander Sá Freire

The impact of urbanization on tropical mangroves (Fortaleza, Brazil): Evidence from PAH distribution in sediments

This investigation represents the first environmental diagnosis of the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments from a tropical mangrove in Fortaleza, northeastern Brazil. Sediment cores from six sampling stations in the Cocó and Ceará Rivers were retrieved in June-July 2006 to determine 17 priority PAHs. The total PAH concentrations (Sigma(PAHs)) ranged from 3.04 to 2234.76 microg kg(-1)(Cocó River) and from 3.34 to 1859.21 microg kg(-1) (Ceará River). These levels are higher than those of other cities with more industrial development. PAH concentrations did not reach probable effect levels (PELs). However, from 4.5 to 87.5% of individual PAH concentrations can occasionally cause adverse biological effects for aquatic organisms. The PAH molecular ratios indicate that the PAHs in the sediment core were derived mainly from petroleum, wood, and charcoal combustion (pyrogenic source), and that atmospheric deposition and urban runoff may serve as important pathways for PAH input to the sediment. Clearly, the Sigma(PAHs) in sediments collected in the Cocó and Ceará Rivers indicate that ongoing pollution is more severe than past pollution.

Técnicas de extrações e procedimentos de clean-up para a determinação de hidrocarbonetos policílicos aromáticos (HPA) em sedimentos da costa do Ceará

Extraction and clean-up are essential points in polycyclic aromatic hydrocarbon (PAHs) analysis in a solid matrix. This work compares extraction techniques and clean-up procedures for PAH analysis. PAH levels, their toxicological significance and source were also evaluated in the waters of the Coco and Ceara rivers. The efficiency of PAH recovery was higher for the soxhlet and ultrasonic techniques. PAH recovery varied from 69.3 to 99.3%. Total PAH concentration (ΣHPA) varied from 720.73 to 2234.76 µg kg-1 (Coco river) and 96.4 to 1859.21 µg kg-1 (Ceara river). The main PAH sources are pyrolytic processes and the levels were classified as medium so that adverse effects are possible.

UTILIZAÇÃO DA EXTRAÇÃO EM FASE SÓLIDA (SPE) NA DETERMINAÇÃO DE HIDROCARBONETOS POLICÍCLICOS AROMÁTICOS EM MATRIZES AQUOSAS AMBIENTAIS

Polycyclic aromatic hydrocarbons (PAHs) are a great environmental concern mainly because of their toxic, mutagenic and carcinogenic potential. This paper reports utilization of the solid-phase extraction (SPE) technique to determine PAHs in environmental aqueous matrices. The recovery from environmental aqueous matrices fortified with PAHs varied from 63.7 to 93.1% for atmospheric liquid precipitation, from 38.3 to 95.1% for superficial river water, and from 71.0 to 95.5% for marine water. No negative matrix effect was observed for the recovery of PAHs from atmospheric liquid precipitation and marine water, but was observed for superficial river water, particularly for PAHs possessing 5 and 6 aromatic rings.

Estruturas rasas na margem equatorial ao largo do nordeste brasileiro (Estado do Ceará): análise de relevo e anomalias gravimétricas residuais

A area pesquisada localiza-se na plataforma continental da margem equatorial atlântica, ao largo do Estado do Ceara, formada durante a abertura do oceano Atlântico Equatorial (Aptiano). O mapa gravimetrico residual evidencia estruturas do arcabouco crustal continental ao largo da area estudada, em especial o Lineamento Transbrasiliano e sua continuacao offshore (Lineamento Transversal). As bacias da margem continental (Ceara e Potiguar submersa) sao bem marcadas por minimos gravimetricos. O mapa de anomalias de relevo demonstra que estruturas pre-cambrianas de trend NE-SW controlam feicoes superficiais, principalmente ao largo de Acarau. Ja na plataforma externa ao largo de Camocim, o controle e exercido por feicoes NW-SE e E-W, possivelmente relacionadas a deformacao transformante na Sub-bacia Piaui-Camocim. No setor central, ha a influencia de trends E-W, possivelmente relacionados a fraturas oceânicas, e trends NW-SE, provavelmente relacionados a estruturas pre-cambrianas. Ja no setor sudeste, trends subparalelos a direcao da plataforma aproximam-se do contato entre embasamento raso e Bacia Potiguar submersa. O estado de esforcos neotectonico e inferido como transcorrente com esforco maximo horizontal subparalelo a direcao da margem, atuando principalmente na plataforma interna, e extensional com esforco maximo horizontal perpendicular a direcao da margem, na plataforma externa.

Distribuição espacial de minerais pesados nos sedimentos superficiais da Plataforma Continental Oeste do Ceará, Nordeste do Brasil

The continental shelf sediments of the west coast of Ceara were investigated about their texture, calcium carbonate and heavy minerals with the generation of digital bottom model of this shelf. Multivariate statistics analyses were applied for mineralogical data to aid interpretation of heavy mineral provenance. Despite the predominance of carbonate sedimentation, the western Ceara continental shelf presents significant concentrations of heavy mineral (4.54 %), resulting in placer deposits in litoclastic and litobioclastic sands located further east of the study area (Fortaleza Chart). It was possible identify irregularities in the submarine bottom, which indicate paleochannels and ancient shoreline and support heavy minerals concentration. The mineral assemblage (ilmenite, tourmaline, epidote, hornblende, monazite, staurolite, sillimanite, rutile, magnetite, zircon, andalusite, kyanite, garnet, leucoxene, diopside, apatite, spinel and cassiterite) suggests regional contributions of the reworking of sediments Barreiras Formation and local contribuition of metamorphic rocks of Ceara Complex. Crystalline basement outcrops on the continental shelf near Pecem Port (Sao Goncalo do Amarante) contribute directly to sediment supply of terrigenous, hence the heavy minerals are concentrated in these places. Multivariate statistics distinguish two types of sources which were described above, however it should take attention to other contributions as coastal black sands, present fluvial supply (continental), past fluvial supply (drowned river valleys) and marine sediments from longshore drift.

Ancient Coastlines in the Continental Shelf of the State of Ceará, Northeast Brazil: Evidence from Sediment Chemistry and Stable Isotopes

Continental shelf sediments from the state of Ceará, northeastern Brazil, have been studied to investigate meteoric diagenesis of marine sediments of previously defined ancient coastal lines. Major elements for 131 samples of carbonate sediments and C and O isotopes for 51 carapace samples of benthonic foraminifers of the Amphistegina radiata and Peneroplis planatus species were analyzed. Geochemical signatures of δ13C, δ18O, SiO2 (stoichiometrically calculated as quartz %), Sr and Mn, and XRD document the impact of meteoric diagenesis on relict sediments from current depths of 25-30 m, 45 m, and 80 m. Morphologies of the marine shelf at these depths, interpreted from previous bathymetric profiles, correspond to holocenic marine terraces. Despite a recent sedimentary cover, it was possible to confirm that these terraces possess relict detrital, biogenic, and continental material, that resulted from erosional reworking of ancient coastlines during the Flandrian transgression.