RESUMO
The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enriched natural seawater, in order to assess its suitability as biodiesel feedstock. Optimal and nitrogen-stress (N-stress) conditions were analyzed. Under optimal conditions, the strain's growth rate was 0.73 div day(-1) and the biomass concentration was 1.5 g L(-1), while it had a maximum lipid yield under N-stress conditions (lipid content: 26% of dry weigh and lipid productivity: 56 mg L(-1) day(-1)). Lipid accumulation was mainly due to a significant increase of triacylglycerol content. Neutral lipids were characterized by a dominance of monounsaturated fatty acids and displayed a fatty acid profile that is suitable for biodiesel. This work offers an interesting alternative for sustainable microalgal oil synthesis for biodiesel production without using freshwater resources. However, further studies are necessary in order to optimize the lipid productivities required for commercial biodiesel production.
Assuntos
Biocombustíveis/microbiologia , Lipídeos/biossíntese , Lipídeos/química , Microalgas/classificação , Microalgas/metabolismo , Água do Mar/microbiologia , Especificidade da EspécieRESUMO
This paper is the first comprehensive survey of polycyclic aromatic hydrocarbons (PAHs) in coastal sediments in Bahia Blanca, Argentina, and provides useful information on their levels of concentration, composition, and sources of these pollutants. The total concentrations of PAHs ranged from 15 to 10,260 ng g(-1). The highest contents (mean 3,315 ng g(-1)) of total PAHs in marine sediments were found in the inner channels of the estuary, while the lower ones (204 ng g(-1)) belong to samples collected far away from contamination sources. The global average recorded in this study (1,500 ng g(-1)) indicates that the studied area lies within the referenced category of industrialized coastal zones under chronic pollution. The diagenetic PAH contribution was found to be negligible at all sampled locations; however, the calculation of molecular ratios determined an overimposition of pyrolitic PAHs over the petrogenic input. Further, the use of principal components analysis (PCA) clearly separated ring group compounds and enabled the determination of pyrolitic/combustion PAHs dominancy.
Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , ArgentinaRESUMO
Butylated hydroxytoluene (BHT) is an antioxidant utilized as additive in foods and packaging plastic. Its presence in drinking water is possible if it is used as an antioxidant in the packaging plastic because it may migrate into the package's contents. A method for the determination of BHT in water by means of solid-phase microextraction and gas chromatography-mass spectrometry has been developed and evaluated with respect to the time of fiber exposure, limits of detection and quantitation, linearity and precision. Finally, the method was applied to evaluate the presence of this substance in samples of mineral and mineralized bottled drinking water, and it appeared to be present in seven out of a total of fifteen commercial brands.