Distribution of acid-volatile sulfides and simultaneously extracted metals in Guanabara Bay: combination of anthropogenic, sedimentological, and geochemical processes.

Coastal sedimentary systems are affected by continental and marine metal pollutant inputs associated with different hydrodynamic characteristics and geochemical processes. These include the formation of acid-volatile sulfides (AVS) within sediments, which affects metal bioavailability and associated aquatic biota toxicity risks. Physicochemical changes in these environments in the face of extreme natural or man-made environmental influences can dramatically alter metal bioavailability and toxicity through metal binding and immobilization as insoluble sulfides. Surface sediments from Guanabara Bay, river mouths, and two mangrove areas were collected, and AVS and simultaneously extracted metals Cd, Cu, Fe, Mn, Ni, Pb, and Zn and ΣSEM were determined to assess sediment quality. A severe eutrophication history favored AVS concentrations exceeding or close to the sum-SEM concentrations, demonstrating that AVS play an important role in making trace metals unavailable for assimilation by living organisms, mitigating the risks of contamination for the local biota. This eutrophication-driven sulfide accumulation may attenuate the sediment toxicity in sites heavily polluted by metals, while some fewer eutrophic sites became more exposed to metals in excess to AVS.

Hydrolytic enzyme production from açai palm (Euterpe precatoria) endophytic fungi and characterization of the amylolytic and cellulolytic extracts.

Enzymes are biocatalysts that are widely used in different industries and generate billions of dollars annually. With the advancement of biotechnology, new enzymatic sources are being evaluated, especially microbial ones, in order to find efficient producers. Endophytic fungi are promising sources of biomolecules; however, Amazonian species are still poorly studied as to their enzymatic production potential. In this sense, the production of hydrolases (amylases, lipases, cellulases and pectinases) was evaluated in endophytic fungi isolated from the leaves, roots and stems of açai palms (Euterpe precatoria). A qualitative test was carried out to detect the enzymatic synthesis in each isolate, and the most promising ones were cultivated using submerged fermentation. The enzyme extracts were quantified to determine those with the greatest activity. Cellulolytic and amylolytic extracts showed the highest enzymatic activities and were partially characterized. Among 50 isolates, 82.9% produced pectinase, 58.5% produced cellulase, 31.7% produced amylase, and 12.2% produced lipase. Penicillium sp. L3 was the best producer of amylase and Colletotrichum sp. S1 was the best producer of cellulase in liquid medium cultivation. The amylolytic extract showed the highest enzymatic activity at pH 8.0 and 45 °C, and the cellulolytic extract at pH 5.0 and 35 °C. The cellulase and amylase produced by the endophytes had their molecular masses estimated between 38 and 76 kDa. These results indicate that endophytic fungi from the açai palm can be used as a new source of hydrolytic enzymes, which can be applied in numerous biotechnological processes.

Volatile Organic Compounds in the Atmosphere of the Botanical Garden of the City of Rio de Janeiro: A Preliminary Study.

Volatile organic compounds (VOCs) play a central role in atmospheric chemistry. In this work, VOCs in the Botanical Garden of Rio de Janeiro were determined using the TO-15 Method. The park occupies 1,370,000 m2 in the southern area of the city and is next to the Tijuca Forest, which is considered the largest secondary urban forest in the world. The total VOC concentrations ranged from 43.52 to 168.75 µg m-3, depending on the sampling site and dates. In terms of concentration isoprene represented 4 %-14 % of the total VOC masses. The results suggested that the differences in biomass, distance from the street and activities within the park affected the concentrations of VOCs. The ratios of isoprene/aromatic compounds were higher than those determined in other areas of the city, confirming that the atmosphere of this green area has the contribution of other sources. Kinetic and mechanistic reactivities were also evaluated.

PM2.5-bound polycyclic aromatic hydrocarbons in an area of Rio de Janeiro, Brazil impacted by emissions of light-duty vehicles fueled by ethanol-blended gasoline.

The aim of this study was to characterize the PM2.5-bound polycyclic aromatic hydrocarbon (PAH) concentrations and their diagnostic ratios in an area impacted by light-duty vehicles fueled by neat ethanol and ethanol-blended gasoline. Samples were collected using a high-volume sampler, extracted, and analyzed for all 16 EPA-priority PAHs using gas chromatography/mass spectrometry (GC/MS) following the EPA 3550B Method. The most abundant PAHs were benzo[g,h,i]perylene, benzo[b]fluoranthene, benzo[a]pyrene and indeno[1,2,3-c,d]pyrene. The total mean concentration was 3.80 ± 2.88 ng m(-3), and the contribution of carcinogenic species was 58 ± 16 % of the total PAHs. The cumulative health hazard from the PAH mixture was determined, and the carcinogenic equivalents and mutagenic equivalents were 0.80 ± 0.82 and 1.17 ± 1.04 ng m(-3), respectively. Diagnostic ratios and normalized ratios were calculated for the individual samples.

Trace metals in PM10 and PM 2.5 samples collected in a highly industrialized chemical/petrochemical area and its urbanized surroundings.

The aim of this study was to determine the potential impact of a highly industrialized area on its urbanized surroundings. The area studied is home to a refinery, a thermoelectric plant and several petrochemical facilities industries. The concentrations of twelve elements were determined in PM10 and PM2.5 samples collected along a busy highway and near the petrochemical complex. Significantly higher concentrations of Ca, Mg, Mn, Fe, Cu and Al were observed in the petrochemical zone, but principal component analysis revealed similar patterns for both the highway site and a site approximately 1.5 km from the petrochemical complex, suggesting that the main pollution source in the area is vehicular flux. Higher concentrations in the industrial area may be attributed to intense diesel-powered truck and bus traffic movement, mainly due to the transport of supplies, fuel and gas. The observed concentrations of the elements Cr, Co, Ni, Cd and Pb were always lower than the detection limits of the technique used.