This paper reports a method for simultaneous determination of H2, O2, N2, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H4 (propadiene and propyne), C3H6, C3H8 and C4H10 (n-butane and isobutane) by gas chromatography using thermal conductivity and flame ionization detectors. A single porous layer open tubular column (0.53 mm internal diameter ? 30 m length ? 30 µm thick) was applied and no catalytic converter was needed to convert CO and CO2 into CH4 to enable identification by a flame ionization detector. The most appropriate chromatographic conditions were defined for the method and it was validated according to the recommendations of the National Health Surveillance Agency and the National Institute of Metrology, Standardization and Industrial Quality. Chromatographic conditions defined for the target gases presented satisfactory linearity (r > 0.99), and limits of detection ranged between 0.0916 and 2.75 ppm. High accuracy (98-101%) obtained for the gas chromatography/thermal conductivity detector/flame ionization detector method associated to low relative standard deviation (?λτ; 2%) confirmed its applicability in routine quantification of target gases formed during the pyrolysis of municipal refuse-derived fuel.

A comunidade zooplanctônica de seis ecossistemas lacustres localizados no Distrito Federal (Brasil Central) foi estudada com base em amostras coletadas durante a estação seca (julho a setembro). Foi registrado o total de 71 taxas: 44 rotíferos, 17 cladóceros e 10 copépodos. O maior número de espécies zooplanctônicas foi encontrado no ambiente oligotrófico da Lagoa Bonita (32 espécies) e o menor número ocorreu nas águas hipertróficas das lagoas de estabilização de esgotos (7 espécies). Essa tendência de redução da diversidade com o aumento do estado trófico foi consistente com a análise de agrupamento das amostras baseada no índice de similaridade de Sorensen. Com base no dendrograma geral de similaridade, foram estabelecidos dois grupos de ecossistemas: um contendo as lagoas naturais Bonita e Formosa e o outro compreendendo os reservatórios de Santa Maria, Descoberto e Paranoá. O papel das características morfométricas na determinação da comunidade zooplanctônica destes ecossistemas lacustres é também discutido.

Zooplankton community from six lacustrine ecosystems located in Federal District (Central Brazil) was studied based on samples collected during the dry season (July to September). A total of 71 taxa were recorded: 44 rotifers, 17 cladocerans and 10 copepods. The highest number of zooplankton species was recorded in oligotrophic Bonita Pond (32 species) and the lowest number in hypertrophic waste stabilisation ponds (7 species). This tendency of decreasing the diversity with increasing trophic level was consistent with a cluster analysis of the samples based on Sorensen index of similarity. From the overall similarity dendrogram, two groups of ecosystems were distinguished: one containing the natural ponds Bonita and Formosa and the other comprising the reservoirs Santa Maria, Descoberto and Paranoá. The role of morphometric features in determining the zooplankton community in such lacustrine ecosystems was also discussed.