Mirian Araújo Carlos Crapez

Benthic foraminifera distribution in high polluted sediments from Niterói Harbor (Guanabara Bay), Rio de Janeiro, Brazil

Dockyards and harbors are recognized as being important locations where sediment-associated pollutants can accumulate, which constitutes an environmental risk to aquatic life due to potential uptake and accumulation of heavy metals in the biota. The aim of this paper is to assess the concentrations and the effects of some heavy metals in the benthic foraminifera assemblage in Niterói Harbor. Low concentrations in the benthic foraminifera as well as the dominance of indicative species such as Ammonia tepida, Buliminella elegantissima and Bolivina lowmani can be associated with an environment under stress. In addition, the occurrence of test abnormalities among foraminifera may represent a useful biomarker for evaluating long-term environmental impacts in a coastal region.

Concentration and Bioavailability of Heavy Metals in Sediments from Niterói Harbour (Guanabara Bay/S.E. Brazil)

Abstract The coastal area of Niterói is marked by intensive naval activities and holds one of the countries main naval estates. The harbour and dockyards have been sited in the international literature as potential sources and sinks for accumulation of heavy metals and hence contaminated sediments. The aim of this paper is to assess the concentrations of heavy metals in Niterói Harbour and verify their bioavailability by determining the catalytic effects of the bacteria using esterase activity (EST) and electron transport system activity (ETSA). Samples were analysed for Ni, Zn, Pb, Cr and Cu and normalisation procedures were used to assess whether their concentrations represent background or contamination of the sediment. Heavy metal concentrations, especially for Cu, Zn and Pb were found to be much higher than natural background levels and the index of “geoaccumulation” shows moderate to extreme contamination. However, the absence of the inhibition of dehydrogenase activity indicated that the analysed heavy metals are not bioavailable in the EC50 values.

Alternative methodology for isolation of biosurfactant-producing bacteria

Wide biosurfactant application on biorremediation is limited by its high production cost. The search for cheaper biossurfactant production alternatives has guided our study. The use of selective media containing sucrose (10 g x L(-1)) and Arabian Light oil (2 g x L(-1)) as carbon sources showed to be effective to screen and maintain biosurfactant-producing consortia isolated from mangrove hydrocarbon-contaminated sediment. The biosurfactant production was assayed by kerosene, gasoline and Arabian Light Emulsification activity and the bacterial growth curve was determined by bacterial quantification. The parameters analyzed for biosurfactant production were the growth curve, salinity concentration, flask shape and oxygenation. All bacteria consortia screened were able to emulsify the petroleum derivatives tested. Biosurfactant production increased according to the incubation time; however the type of emulsification (non-aqueous phase or aqueous phase) did not change with time but with the compound tested. The methodology was able to isolate biosurfactant-producing consortia from superficial mangrove sediment contaminated by petroleum hydrocarbons and was recommended for selection of biosurfactant producing bacteria in tropical countries with low financial resources.

Bacteriological study of the superficial sediments of Guanabara bay, RJ, Brazil

Thirty sediment samples were collected in Guanabara Bay in August, November and December 2005. The material was analyzed for organic matter, total and faecal coliforms, heterotrophic bacteria, bacterial respiratory activity, esterase activity and electron transport system activity. The organic matter in the superficial sediments (2 cm) ranged from 4 to 6%. The highest level of total coliforms and faecal coliforms were 1.7 x 105 MPN/g and 1.1 x 103 MPN/g, respectively. Heterotrophic bacteria presented the highest values at station 7 (4.1 x 106 CFU/g) and the lowest values at station 3 (7 x 104 CFU/g) (northwestern part of Guanabara Bay). Esterase enzyme activity showed activity in the sediment of all 30 stations. Electron transport system activity ranged between 0.047 mL O2/h/g and 0.366 mL O2/h/g at six stations. The benthic microbial foodweb is anaerobic. Anaerobic processes such as fermentation, denitrification and sulphate-reduction are responsible for the biogeochemical cycles in the sediment of Guanabara Bay. The input of untreated sewage in the Mangue Channel outflow in Guanabara Bay has favored the increase of the organic load, and the maintenance of the total coliforms and faecal coliforms in the sediment. Faecal coliforms have been reported to be a good indicator of aquatic pollution and organic contamination in the water column, but total coliforms may be an ideal candidate group for sediment quality tests as well.

Impact of the Icaraí Sewage Outfall in Guanabara Bay, Brazil

The present study aimed to evaluate the water quality of the Icarai Sewage Outfall (ISEO) area. Sampling was conducted during winter and summer, and water samples were analyzed for dissolved oxygen, pH, temperature, salinity, dissolved inorganic nutrients (DIN), seston, particulate organic matter (POM), and pigments. Results showed that the water chemistry of the area suffers temporal and spatial variation. Great variability was also seen in the C:N:P ratios of POM (August, 112:30:1; December, 59:11:1) and in the DIN concentrations. Chlorophyll-a and ammonium concentrations (4.5 µg L-1 - 71.2 µg L-1, and 0.20 µM - 52,6 µM, respectively) characterized the ISEO area as eutrophic. The dispersal of the material was not effective under certain oceanographic conditions.

Geomicrobiology of cores from Suruí Mangrove - Guanabara Bay - Brazil

The aim of this work was to quantify the biopolymers associated to esterase enzymes and identify bacterial respiratory activity in four cores collected in Suruí Mangrove, Guanabara Bay - RJ. Biopolymer concentration was 1000 times lower than previously reported in the literature, indicating the need for creating and establishing eutrophication indicative rates and records compatible with tropical coastal systems. The biochemical representative relationships in the cores were equivalent to those from studies on coastal marine environments made in the Northern Hemisphere. The esterase enzymes in the sediment proved efficient in the mineralization of biopolymers, even with preferentially anaerobic metabolic physiology. Despite the lack of incipient geomicrobiological studies, the results highlighted the possible application of microbiology to a better understanding of geological processes.

Acute and chronic impacts caused by aromatic hydrocarbons on bacterial communities at Boa Viagem and Forte do Rio Branco Beaches, Guanabara Bay, Brazil.

The bacterial community presented significantly different hydrocarbonoclastic activity under acute and chronic impacts. Benzoic acid, toluene, benzene and xylene were used in final concentrations of 5, 10 and 15 mM and bacterial biomass was quantified through protein dosage. Under acute impact, the highest biomass percentages occurred between the 11th and 14th days; under chronic impact, between the 20th and 29th days. Under acute and chronic impacts, the bacterial biomass presented higher nutritional specialization at Boa Viagem Beach, using the aromatic hydrocarbons up to a concentration of 15 mM. Under acute impact, the concentration of the hydrocarbons constituted a critical factor for the bacterial flora from Forte do Rio Beach, because biomass increases only occurred in concentrations of 5 mM; under chronic impact, the aromatic hydrocarbons induced the specialization and increased bacterial biomass for 15 mM toluene. Benzoic acid (15 mM) was used by the bacteria from Boa Viagem and Forte do Rio Branco Beaches.

Superficial distribution of aromatic compounds and geomicrobiology of sediments from Suruí Mangrove, Guanabara Bay, RJ, Brazil

The distribution of selected aromatic compounds and microbiology were assessed in superficial sediments from Suruí Mangrove, Guanabara Bay. Samples were collected at 23 stations, and particle size, organic matter, aromatic compounds, microbiology activity, biopolymers, and topography were determined. The concentration of aromatic compounds was distributed in patches over the entire mangrove, and their highest total concentration was determinated in the mangroves central area. Particle size differed from most mangroves in that Suruí Mangrove has chernies on the edges and in front of the mangrove, and sand across the whole surface, which hampers the relationship between particle size and hydrocarbons. An average @ 10% p/p of organic matter was obtained, and biopolymers presented high concentrations, especially in the central and back areas of the mangrove. The biopolymers were distributed in high concentrations. The presence of fine sediments is an important factor in hydrocarbon accumulation. With high concentration of organic matter and biopolymers, and the topography with chernies and roots protecting the mangrove, calmer areas are created with the deposition of material transported by wave action. Compared to global distributions, concentrations of aromatic compounds in Suruí Mangrove may be classified from moderate to high, showing that the studied area is highly impacted.

Characterization and Distribution of Polycyclic Aromatic Hydrocarbons in Sediments from Suruí Mangrove, Guanabara Bay, Rio de Janeiro, Brazil

Abstract Four sediment cores were collected in Suruí Mangrove. Cores 0.30-m long were sliced into small cores corresponding to 0–0.03, 0.05–0.10, 0.10–0.15, 0.15–0.20, 0.20–0.25, and 0.25–0.30-m depths. Polycyclic aromatic hydrocarbons, total organic carbon (TOC), and total sulfur (TS) were determined. Total organic carbon varied between 0.8% and 7.8%, with mean values varying according to sampling location (5.2% for core 1, 3.2% for core 2, 4.2% for core 3, and 2.7% for core 4). Total sulfur also varied in the studied cores with a mean ± standard deviation of 1.1% ± 0.7%. The lowest value (0.01%) was found in core 2 (0.10–0.15 m), and the largest one (2.6%) was observed in core 4 (0.25–030 m). The TOC/TS ratio indicated that most sediments showed reducing characteristics, except for four samples (core 1 of 0.10–0.15 m and 0.25–0.30 m, and core 2 of 0–0.03 m and 0.05–0.10 m). Total PAH concentrations varied between 4.4 and 1387 µg g−1, indicating a local and restricted contamination of parts of the studied area. The highest percentages for total and carcinogenic PAHs and toxic equivalent factors were found in the sediment from core 1 from Suruí Mangrove, with a predominance of benzo[k]fluoranthene, benzo[a]pyrene, and naphthalene. In cores 3 and 4, collected closer to Guanabara Bay, benzo[a]anthracene and benzo[a]pyrene were also found. The sediment in Suruí Mangrove is functioning as a reservoir of compounds that are carcinogenic to the fauna and flora of the mangrove itself, and to the adjacent waters of Guanabara Bay.

Organic matter and pyritization relationship in recent sediments from a tropical and eutrophic bay

The degree of pyritization (DOP) and the extension of metals incorporation into pyrite was investigated at Guanabara Bay sediments. Maximum concentrations of total organic carbon (TOC), total sulfur, biopolymers and viable bacteria cells were observed in silted stations close to discharge points of sewage and minimum concentrations at sandy stations at the entrance of the bay. Pyrite iron concentrations (Fepy) was always lower than the reactive iron and Fepy were below the detection limit at sandy stations. The same trend was found to metals, which its degree of pyritization was Mn=Cu>As=Co>Ni>Cd>Zn≫Pb>Cr. The bay gathers all required factors to sulfate reduction and pyrite formation, once the C:S ratio express the reduced tendency conditions, almost half of the TOC present in its sediments is labile and both reactive sulfur and iron are available. However the degree of trace metals pyritization did not exceed 20%, consistent with the median DOP (29%).