Assessment of environmentally friendly fuel emissions from in-use vehicle exhaust: low-blend iso-stoichiometric GEM mixture as example.

Gasoline-ethanol-methanol fuel blends were formulated with the same stoichiometric air-to-fuel ratio and volumetric energy concentration as any binary ethanol-gasoline blend. When the stoichiometric blends operated in a vehicle, the time period, injector voltage, and pressure for each fuel injection event in the engine corresponded to a given stoichiometric air-to-fuel ratio, and the load was essentially constant. Three low oxygen content iso-stoichiometric ternary gasoline-ethanol-methanol fuel blends were prepared, and the properties were compared with regular-type fuel without added oxygen. One of the ternary fuels was tested using a fleet of in-use vehicles for15 weeks and compared to neat gasoline without oxygenated compounds as a reference. Only a small number of publications have compared these ternary fuels in the same engine, and little data exist on the performance and emissions of in-use spark-ignition engines. The total hydrocarbon emissions observed was similar in both fuels, in addition to the calculated ozone forming potential of the tailpipe and evaporative emissions. In ozone non-attainment areas, the original purpose for oxygenate gasolines was to decrease carbon monoxide emissions. The results suggest that the strategy is less effective than expected because there still exist a great number of vehicles that have suffered the progressive deterioration of emissions and do not react to oxygenation, while new vehicles are equipped with sophisticated air/fuel control systems, and oxygenation does not improve combustion because the systems adjust the stoichiometric point, making it insensitive to the origin of the added excess oxygen (fuel or excess air). Graphical abstract Low level ternary blend of gasoline-ethanol-methanol were prepared with the same stoichiometric air-fuel ratio and volumetric energy concentration, based on the volumetric energy density of the pre-blended components. Exhaust and evaporative emissions was compared with a blend having no oxygen in a fleet of 12 in-use vehicles. Vehicles that had suffer a normal deterioration of emissions and do not react to oxygenation, and new vehicles with more sophisticated air/fuel control systems do not improve combustion.

Propuesta de un índice numérico para evaluar la calidad del sedimento influenciado por la industria petrolera / Proposal of a numerical index to evaluate the quality of sediments influenced by the oil industry

El presente estudio tiene por objeto la integración, en un índice numérico, de los parámetros de sedimento derivados de la caracterización granulométrica, mineralógica, química, biológica y toxicológica, además del contenido de Ni y V, a fin de evaluar la calidad del sedimento del río Pánuco, México. Para ello se llevó a cabo una serie de análisis durante dos épocas de estudio (secas ó estiaje y nortes) y tres zonas del río (margen derecho, centro y margen izquierdo), con el fin de detectar la variación espacial y temporal. A fin de integrar todos estos parámetros y evaluar la calidad del sedimento con base a esos dos metales, se creó el Indice de la Calidad del Sedimento (ICS). Los resultados del ICS mostraron una mejor calidad ambiental en la época de secas, fenómeno atribuible a la menor resuspensión del sedimento que en la época de nortes y al dragado. El ICS mostró un comportamiento similar al del Indice Trófico de la Infauna, explicando el 65 por ciento de la variabilidad espacial y temporal en el sistema acuático. Considerando que no hay índices similares al planteado en el presente estudio, el ICS se considera como una herramienta útil para la evaluación de la calidad sedimentaria de la zona de estudio.