ABSTRACT
We evaluated impacts of progressive technological updates to bus rapid transit (BRT) systems on in-cabin concentrations of particulate matter with an aerodynamic diameter ≤2.5 µm (PM2.5), and the various polyaromatic hydrocarbons (PAHs) to which commuters were exposed. PM2.5 samples were collected and real-time concentrations measured from October 2017 to March 2020 inside cabins of BRT buses equipped with Euro IV, V and VI diesel emission standards in the Mexico City Metropolitan Area (MCMA). For effective comparison, similar samplings and measurements were carried out on trains in the MCMA underground (MCU) system. Peak in-cabin PM2.5 concentrations decreased significantly (p < 0.05) by 35% from Euro IV to Euro V buses, and by 80% from Euro IV to Euro VI buses. PM2.5 concentrations inside Euro VI buses were significantly lower (p < 0.05) than in Euro IV and Euro V buses and in underground trains. The in-cabin excess (ICE) of PM2.5 relative to ambient concentrations was significantly (p < 0.05) higher for Euro IV than for Euro V buses during morning the traffic peak, and consistently higher than for Euro VI buses. Indeed, ICEs calculated for Euro VI buses were always lower than those for electricity-powered underground trains. The frequency of hotspots decreased from Euro IV to Euro VI buses due to the combined effect of low emissions and closed, air-conditioned cabins. Concentrations of total PAHs including carcinogenic species also decreased from Euro IV to Euro V buses and were below limits of detection aboard Euro VI buses. This work shows that in real-life conditions, advanced diesel technologies and cabin design significantly reduce commuters' exposure to PM2.5 and to toxic PAH compounds.
Subject(s)
Air Pollutants , Air Pollutants/analysis , Vehicle Emissions/analysis , Mexico , Particulate Matter/analysis , Motor Vehicles , Environmental MonitoringABSTRACT
The objective of this research was to evaluate the production of biomass of the aquatic macrophytes water hyacinth (Eichhornia crassipes) and egeria (Egeria densa) in three hydraulic detention times in a organic pisciculture effluent treatment system. The system was composed for 18 experimental tanks of 2.00 x 1.00 x 0.65m length, width and depth respectively, coated with polypropylene canvas. An entirely randomized 2 macrophytes x 3 hydraulic detention times (HDT) and 3 repetitions. The HDT used was 4, 8, and 12 hours. The biomass production was evaluated at the end of the experiment which was extended at 08/07 to 19/08/2006. The water hyacinth showed the best results of biomass production (P0.05). For egeria the treatment that presented the best production of biomass was reached which TDH of 12 hours, being of 0.10 kg.m-2, followed for the HDT of 8 and 4 hours, not differing between the HDT (P>0.05). One concludes that the water hyacinth produced higher biomass than egeria in all of the HDT evaluated.
O presente trabalho teve por o objetivo avaliar a produção de biomassa das macrófitas aquáticas aguapé (Eichhornia crassipes) e egeria (Egeria densa) em um sistema de tratamento de efluente de piscicultura orgânica, sob 3 condições de tempo de detenção hidráulica. O sistema foi composto por 18 tanques experimentais de 2,00 x 1,00 x 0,65 m de comprimento, largura e profundidade, respectivamente, revestidos com lona de polipropileno. O delineamento foi inteiramente casualizado, com 2 macrófitas, 3 tempos de detenção hidráulica (TDH) e 3 repetições. Os TDH utilizados foram de 4, 8 e 12 horas. O sistema foi operado de 08/07 a 19/08/2006. A produção de biomassa foi avaliada ao final do experimento. O aguapé apresentou os melhores resultados de produção de biomassa (P0,05). Para a egeria o tratamento que apresentou a melhor produção de biomassa foi no TDH de 12 horas, sendo de 0,10 kg.m- 2, seguido pelos TDH de 8 e 4 horas, não diferindo entre os TDH (P>0,05). Concluiu-se que o aguapé produziu mais biomassa que a egeria em todos os TDH avaliados.
ABSTRACT
The objective of this research was to evaluate the production of biomass of the aquatic macrophytes water hyacinth (Eichhornia crassipes) and egeria (Egeria densa) in three hydraulic detention times in a organic pisciculture effluent treatment system. The system was composed for 18 experimental tanks of 2.00 x 1.00 x 0.65m length, width and depth respectively, coated with polypropylene canvas. An entirely randomized 2 macrophytes x 3 hydraulic detention times (HDT) and 3 repetitions. The HDT used was 4, 8, and 12 hours. The biomass production was evaluated at the end of the experiment which was extended at 08/07 to 19/08/2006. The water hyacinth showed the best results of biomass production (P0.05). For egeria the treatment that presented the best production of biomass was reached which TDH of 12 hours, being of 0.10 kg.m-2, followed for the HDT of 8 and 4 hours, not differing between the HDT (P>0.05). One concludes that the water hyacinth produced higher biomass than egeria in all of the HDT evaluated.
O presente trabalho teve por o objetivo avaliar a produção de biomassa das macrófitas aquáticas aguapé (Eichhornia crassipes) e egeria (Egeria densa) em um sistema de tratamento de efluente de piscicultura orgânica, sob 3 condições de tempo de detenção hidráulica. O sistema foi composto por 18 tanques experimentais de 2,00 x 1,00 x 0,65 m de comprimento, largura e profundidade, respectivamente, revestidos com lona de polipropileno. O delineamento foi inteiramente casualizado, com 2 macrófitas, 3 tempos de detenção hidráulica (TDH) e 3 repetições. Os TDH utilizados foram de 4, 8 e 12 horas. O sistema foi operado de 08/07 a 19/08/2006. A produção de biomassa foi avaliada ao final do experimento. O aguapé apresentou os melhores resultados de produção de biomassa (P0,05). Para a egeria o tratamento que apresentou a melhor produção de biomassa foi no TDH de 12 horas, sendo de 0,10 kg.m- 2, seguido pelos TDH de 8 e 4 horas, não diferindo entre os TDH (P>0,05). Concluiu-se que o aguapé produziu mais biomassa que a egeria em todos os TDH avaliados.