RESUMO
The effect of drying method, a process variable, on the powder and compaction properties of microcrystalline cellulose (MCC) obtained from the partial acid hydrolysis of bleached alpha (α) cellulose content of matured linters of Gossypium herbaceum (GH) was investigated. A portion of the wet MCC obtained was fluid bed dried at 60 ± 1 ºC, inlet air of 30 m3 min-1 for 3 h (coded MCC-GossF). The second portion was lyophilized at - 45 ± 2 ºC for 6 h (coded MCC-GossL). The physicochemical, scanning electron micrographs, X ray diffraction patterns and micromeritic properties of the derived MCCs were determined using standard methods. The cohesiveness and compactibility of the powders were investigated using Kawakita model while the deformation and compressibility pattern were determined using Heckel model. Avicel® PH 102 (AV-102) was used as comparing standard. Ash values of < 2%, pH (6.54 ± 0.23 to 6.58 ± 0.08), degree of polymerization, DP (231.50) was obtained. MCC-GossF had higher moisture content, swellability, better flow indices, and lesser porosity than MCC-GossL. Kawakita model demonstrated good consolidation and compactibility for both powders. Compacts of MCC-GossL were significantly (p < 0.05) harder than those of MCC-GossF. Heckel analysis demonstrated good compressibility and deformation pattern that was comparable with AV-102. Compacts of MCC-GossL had better mechanical and tablet compression properties than MCC-GossF
Assuntos
Pós , Cinzas/efeitos adversos , Celulose/classificação , Gossypium herbaceum/análise , Baías/análise , Ar , Concentração de Íons de Hidrogênio , Hidrólise , MétodosRESUMO
We used environmental magnetism methods to study recently deposited marine sediments from the estuarine ecosystems on the Caribbean coast of Colombia. Cartagena region has undergone an increasing sediment load during the last decades via sediment plumes from Magdalena River and its distributary man-made channel. Concentration dependent magnetic parameters show an increasing abundance of ferrimagnetic minerals on the uppermost sediments on sites located close to the continent (remanent magnetization SIRMâ¯=â¯5.4-9.5â¯×â¯10-3Am2â¯kg-1) as well as faraway sites (SIRMâ¯=â¯0.5-1.7â¯×â¯10-3Am2â¯kg-1 near Rosario Islands coral reef complex). The magnetic grain size and mineralogy along the cores are variable, showing the dominance of the magnetite-like minerals (remanent coercivity Hcrâ¯=â¯34.3-45.3â¯mT), with a minor contribution of high-coercivity minerals (Hcrâ¯=â¯472-588 mT). In addition, there is a moderate enrichment of elements Cu, Mo, and Zn (enrichment factor EFâ¯=â¯1.5-3.8) that indicates the additional land-derived contribution on sediments. The environmental magnetism approach, which shows significant signals of magnetic minerals and trace elements, is a reliable tool to prove the presence of continental sediment supply in coral reef ecosystems.
Assuntos
Recifes de Corais , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Sedimentos Geológicos/química , Baías/análise , Colômbia , Ecossistema , Meio Ambiente , Compostos Férricos/análise , Óxido Ferroso-Férrico/análise , Ilhas , Magnetismo , Minerais/análise , RiosRESUMO
Abstract Mangrove-fringed bays are highly variable ecosystems that provide critical habitats for fish species. In this study we assessed the fish assemblage in three mangrove-fringed bays (Punta Rocafuerte, Saca Calzón and Garrapatero) in the Southeast side of Santa Cruz Island, Galapagos Marine Reserve. Using gillnets, we carried out a total of 108 fieldtrips from January 2010 to December 2011. A total of 1 773 bony and 740 cartilaginous fishes belonging to 26 species and 15 families were identified at the same sampling sites. Species richness was higher in the protected bay (Garrapatero) than in those open to fishing (Punta Rocafuerte, Saca Calzón). Blacktip sharks (Carcharhinus limbatus, n= 729), Thoburn's mullets (Mugil thoburni, n= 492), Peruvian mojarras (Diapterus peruvianus, n= 440), milkfish (Chanos chanos, n= 206) and the yellow fin mojarras (Gerres cinereus, n= 197) were the most common species across sites and season (cold and warm). The abundance of the most common species varied seasonally, with C. limbatus and C. chanos being more abundant in the warm season (December to April), and M. thoburni, C. limbatus and G. cinereus in the cold season (June to October). Temperature was the most important driver of abundance in C. limbatus and C. chanos, while salinity influenced Umbrina galapagorum. This study represents the first evaluation of the fish assemblage composition and dynamics in mangrove-fringed bays in the Galapagos Marine Reserve. Rev. Biol. Trop. 66(2): 674-687. Epub 2018 June 01.
Resumen Las bahías de manglar son ecosistemas muy variables que proveen hábitats críticos para especies de peces. En este estudio se evaluó los ensamblajes de peces de tres bahías de manglar (Punta Rocafuerte, Saca Calzón y Garrapatero) ubicadas en el sureste de la isla Santa Cruz, Reserva Marina de Galápagos. Usando redes de trasmallos iguales a los usados por la pesca artesanal, se llevaron a cabo un total de 108 salidas de campo entre enero 2010 y diciembre 2011. Un total 1 773 peces óseos y 740 peces cartilaginosos correspondiendo a 26 especies y 15 familias fueron capturados, identificados y liberados con vida. La riqueza de especies fue mayor en Garrapatero (sitio protegido) que en Punta Rocafuerte y Saca Cazón (sitios abiertos a la pesca). Las mayores capturas estuvieron representadas por el tiburón punta negra (Carcharhinus limbatus; n= 729), seguido la lisa rabo negro (Mugil thoburni; n= 492), la mojarra peruana (Diapterus peruvianus; n= 440), la diabla (Chanos chanos; n= 206) y la mojarra rayada (Gerres cinereus; n= 197). A pesar que éstas especies fueron consistentemente las más importantes a través de los sitios y temporadas (caliente y fría), se observó una mayor abundancia de C. limbatus y C. chanos durante la temporada caliente (enero a abril), y de M. thoburni, C. limbatus y G. cinereus durante la temporada fría (junio a octubre). La temperatura fue determinada como el factor más importante que influye en la abundancia de C. limbatus y C. Chanos, mientras la salinidad lo fue para Umbrina galapagorum. Este estudio representa una importante contribución para el entendimiento de la composición de los ensamblajes de peces en las bahías de manglar de la Reserva Marina de Galápagos.
Assuntos
Animais , Aquicultura/métodos , Estuários , Baías/análise , Equador , Áreas Alagadas , Pesqueiros/tendênciasRESUMO
Changes in the structure of benthic macrofauna and its relationship with hydrocarbon contamination were determined at different spatial scales in sublittoral sediments of two large estuaries in Brazil. Guanabara Bay (GB) is a heavily polluted estuary due to the presence of a large industrial complex and high demographic density. Laranjeiras Bay (LB) lies in an Environmental Protection Area and can still be considered as preserved from human activities. Despite some spatial differences within each bay, the PAHs concentrations were significantly and consistently higher in GB, with values generally above the threshold effect levels. No signs of hydrocarbon contamination were observed in LB. Macrofauna abundance, diversity and overall assemblage structure were largely different between bays. Canonical analysis of principal coordinates (CAP), used to model the relationship between macrofauna and PAHs levels, indicated that this class of hydrocarbons is the main structuring factor of soft-bottom assemblages in both bays.
Assuntos
Biodiversidade , Poluição Ambiental/efeitos adversos , Invertebrados , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Animais , Baías/análise , Brasil , Monitoramento Ambiental , Poluição Ambiental/análise , Estuários , Gastrópodes , Sedimentos Geológicos/análise , Hidrocarbonetos/análise , Oligoquetos , Poluição por Petróleo , Poliquetos , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análiseRESUMO
Heavy metals influence the population size, diversity, and metabolic activity of bacteria. In turn, bacteria can develop heavy metal resistance mechanisms, and this can be used in bioremediation of contaminated areas. The purpose of the present study was to understand how heavy metals concentration influence on diversity and distribution of heavy metal-resistant bacteria in Araça Bay, São Sebastião, on the São Paulo coast of Brazil. The hypothesis is that activities that contribute for heavy metal disposal and the increase of metals concentrations in environment can influence in density, diversity, and distribution of heavy metal-resistant bacteria. Only 12 % of the isolated bacteria were sensitive to all of the metals tested. We observed that the highest percentage of resistant strains were in areas closest to the São Sebastião channel, where port activity occurs and have bigger heavy metals concentrations. Bacterial isolated were most resistant to Cr, followed by Zn, Cd, and Cu. Few strains resisted to Cd levels greater than 200 mg L(-1). In respect to Cr, 36 % of the strains were able to grow in the presence of as much as 3200 mg L(-1). Few strains were able to grow at concentrations of Zn and Cu as high as 1600 mg L(-1), and none grew at the highest concentration of 3200 mg L(-1). Bacillus sp. was most frequently isolated and may be the dominant genus in heavy metal-polluted areas. Staphylococcus sp., Planococcus maritimus, and Vibrio aginolyticus were also isolated, suggesting their potential in bioremediation of contaminated sites.
Assuntos
Bactérias/metabolismo , Baías/análise , Baías/microbiologia , Farmacorresistência Bacteriana Múltipla , Sedimentos Geológicos/microbiologia , Metais Pesados/análise , Poluentes Químicos da Água/metabolismo , Bacillus/efeitos dos fármacos , Bacillus/isolamento & purificação , Bacillus/metabolismo , Bactérias/efeitos dos fármacos , Bactérias/genética , Bactérias/isolamento & purificação , Sequência de Bases , Biodegradação Ambiental , Biodiversidade , Brasil , Cádmio/química , Cromo/química , Cobre/química , DNA Bacteriano , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Monitoramento Ambiental , Sedimentos Geológicos/análise , Metais Pesados/toxicidade , Testes de Sensibilidade Microbiana , Técnicas Microbiológicas , Análise Multivariada , Compostos Orgânicos , RNA Ribossômico 16S/genética , Zinco/químicaRESUMO
This paper reports the bioavailability of the metals (cadmium, copper, zinc, lead, and nickel) in sediment samples collected in seven stations from the São Paulo Estuary, Todos os Santos Bay, Brazil. The bioavailability was determined by employing the technique "acid-volatile sulfide (AVS) and simultaneously extracted metal (SEM)". The elements cadmium, copper, lead, and zinc were determined using differential pulse anodic stripping voltammetry (DPASV), while nickel was quantified utilizing electrothermal atomic absorption spectrometry (ET AAS). The accuracy of these methods was confirmed using a certified reference material of estuarine sediment (NIST 1646). The sulfide was quantified using potentiometry with selective electrode and the organic matter determination employing an indirect volumetric method using potassium dichromate and iron(II) sulfate solutions. The bioavailability of the metals was estimated by relationship between the concentration of AVS and the sum of the concentrations of the simultaneously extracted metals (ΣSEM), considering a significant toxicity when (ΣSEM)/(AVS) is higher than 1. The bioavailability values in the seven stations studied varied from 0.93 to 1.31 (June, 2014) and from 0.34 to 0.58 (September, 2014). These results demonstrated a critical condition of toxicity (bioavailability >1) in six of the seven sediment samples collected during the rainy season (June, 2014). In the other period (September, 2014), the bioavailability was always lower than 1 for all sediment samples collected in the seven stations. The individual values of the concentrations of the five metals were compared with the parameters PEL (probable effects level) and TEL (threshold effects level), which are commonly employed for characterization of ecological risk in environmental systems. This comparison revealed that all metals have concentrations lower than the PEL and only zinc and lead in some stations have contents higher than the TEL. The bioavailability evaluation and the concentrations achieved for the five elements in the sediments samples analyzed demonstrated that the ecosystem studied does not present an environmental risk.
Assuntos
Baías/análise , Disponibilidade Biológica , Monitoramento Ambiental , Sedimentos Geológicos/análise , Metais Pesados/análise , Ácidos/análise , Brasil , Cádmio/análise , Cobre/análise , Estuários , Sedimentos Geológicos/química , Intoxicação por Metais Pesados , Chumbo/análise , Níquel/análise , Intoxicação , Análise de Componente Principal , Sulfetos/análise , Zinco/análiseRESUMO
Deteriorating water quality of Kingston Harbour, due primarily to sewage discharge and its effect on nearby Hellshire Coast, has been an issue since the 1970s. The implementation of a new sewage treatment facility in 2007 to receive the harbour’s waste at Soapberry was expected to make a positive difference. Physico-chemical and biological parameters were used to assess water quality to determine the effect of the facility. Eleven stations used in earlier studies (1990 to 1998) were re-sampled to represent Kingston, Hunts Bay and North East Hellshire coastline over a four week sampling regime between May and June 2011. While temperature, salinity, turbidity, dissolved oxygen and pH remained unchanged between the 1990’s and 2011, BOD5, faecal coliform and nitrate concentrations indicated that the water quality had improved minimally in Kinsgton and Hellshire,and deteriorated significantly in Hunts. Phytoplankton biomass decreased in Kingston (from 3.84 mg m-3 in 1998 to 2.81 mg m-3 in 2011) and increased significantly in Hunts (from 14.69 mg m-3 in 1998 to 24.17 mg m-3 in 2011). Biomass along Hellshire was similar (2.15 mg m-3 in 1998; 2.45 mg m-3 in 2011). In 1998 the nanoplankton biomass (2.7 to 20μm) dominated throughout the Harbour. In 2011 Hunts Bay was dominated by net-plankton (>20μm), indicative of eutrophic waters.
El deterioro de la calidad del agua del puerto de Kingston es debido principalmente a la descarga de aguas residuales y su efecto en los alrededores de la Costa de Hellshire, esto ha sido un problema desde la década de 1970. La implementación de una nueva planta de tratamiento de aguas residuales en 2007 para recibir residuos del Puerto de Kingston en Soapberry se esperaba hiciera una diferencia positiva. Parámetros físico-químicos y biológicos fueron utilizados para evaluar la calidad del agua y determinar el efecto de la planta de tratamiento. Once estaciones que fueron utilizadas en estudios anteriores (1990-1998) se muestrearon nuevamente para representar el puerto de Kingston, Bahía Hunts y la costa North East Hellshire sobre un régimen de muestreo de cuatro semanas entre mayo y junio de 2011. Mientras la temperatura, salinidad, turbidez, oxígeno disuelto y pH se mantuvieron sin cambios entre los años noventa y 2011, BOD5, coliformes fecales y concentraciones de nitratos indicaron que había mejorado la calidad del agua del puerto y la costa mínimamente mientras que la calidad del agua en la bahía Hunts se había deteriorado significativamente. La biomasa del fitoplancton disminuyó en el puerto de Kingston (de 3.84mg m-3 en 1998 a 2.81mg m-3 en el 2011), y aumentó significativamente en bahía Hunts (de 14.69mg m-3 en 1998 a 24.17mg m-3 en el 2011). La biomasa en la costa permaneció similar (de 2.15mg m-3 en 1998 a 2.45mg m-3 en 2011). En 1998 la biomasa de nanoplancton (2.7 a 20μm) dominó a lo largo del puerto. En el 2011 la bahía Hunts era dominada por neto-plancton (>20μm), indicativo de aguas eutróficas.
Assuntos
Controle da Qualidade da Água , Baías/análise , Águas Residuárias/análise , JamaicaRESUMO
Guanabara Bay, located in Rio de Janeiro state. It is surrounded by the second most important metropolitan area of the country. Over recent decades, land disturbance and urbanization in the surrounding area has significantly increased sediment input to the bay and had a negative effect on its overall environmental. This is especially related to high volumes of untreated sewage and industrial effluents. This study evaluates the history of this human impact through detailed examination of a sediment core taken from the northern portion of Guanabara Bay. A geochronology is established using ²¹°Pb dating and related to organic carbon and heavy metal fluxes to the sediments. This gave a calculated net average sedimentation rate for the core of 0.67 cm.year⻹. The organic carbon and heavy metals flux started to increase at the beginning of the last century and the highest values was observed in the top of the cores.
Assuntos
Baías/química , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/análise , Esgotos , Poluentes Químicos da Água/análise , Baías/análise , Brasil , HumanosRESUMO
This research investigated whether environmental conditions, biological fish characteristics and anthropogenic impacts influenced mercury (Hg) assimilation into the muscle tissue of two fish species from two Brazilian bays, Ilha Grande Bay and Guanabara Bay. Fish and superficial water were collected in different periods. Hg was determined by CV-AAS. Methylmercury (MeHg) was identified and quantified by ECD-GC. Chlorophyll a concentrations in the water column indicated that Ilha Grande Bay and Guanabara Bay were oligotrophic and eutrophic, respectively. Hg in fish ranged from 2.10 to 870.17 µg kg(-1) dry wt. in Ilha Grande Bay and 40.90 to 809.24 µg kg(-1) dry wt. in Guanabara Bay. Slight differences were found between the length-normalized Hg concentrations and its percent of Hg in a voracious predator from the bays. In Guanabara Bay, where the presence of a chlor-alkali plant causes Hg input, the iliophagous fish species showed the highest length-normalized Hg concentrations and the voracious predator the lowest. Iliophagous fish is consumed by voracious predator and, consequently, acts as their MeHg food supply. Iliophagous fish from Ilha Grande Bay presented a higher percent of MeHg (80.0 %) than specimens from Guanabara Bay (54.5 %). This fact suggests that more MeHg was transferred from iliophagous fish to voracious predator in Ilha Grande Bay. At Guanabara Bay, the bioproduction is greater than that at Ilha Grande Bay, presenting the highest biomass in it ecosystem, which may subsequently dilute Hg and reduce its availability to the biota; i.e., influencing in Hg and MeHg availability throughout the food chain. Consequently, more MeHg is available in the aquatic environment of Ilha Grande Bay.
Assuntos
Peixes/metabolismo , Compostos de Metilmercúrio/análise , Poluentes Químicos da Água/análise , Animais , Baías/análise , Baías/química , Tamanho Corporal , Brasil , Clorofila/análise , Clorofila A , Produtos Pesqueiros/análise , Contaminação de Alimentos , Mercúrio/análise , Compostos de Metilmercúrio/farmacocinética , Músculos/metabolismo , Smegmamorpha/metabolismo , Clima Tropical , Poluentes Químicos da Água/farmacocinéticaRESUMO
In order to evaluate the diversity and infestation level of Teredinidae wood-boring molluscs, ten satations were chosen along the coast of Rio de Janeiro State. Using five pine-wood panels in each station, it was possible to distinguish five areas according to species dominance. Ilha Grande Bay is characterized by the dominance of Lyrodus floridanus (Bartsch, 1922); Sepetiba Bay, by Bankia fimbriatula Moll & Roch, 1931, Tijuca Lagoon by Teredo navalis Linnaeus, 1758; Guanabara Bay by Notoredo knoxi (Bartsch, 1917) and Araruama Lagoon by Teredo furcifera Martens, 1894. Specific composition and dominance of these species were due mainly to abiotic factors such as salinity whereas infestation level was associated not only to salinity but also to other factors such as the quantity and quality of fouling, the presence of larval dispersion focus and the wood supply in each area.