Ocean Energy in Belgium - 2019

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Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data

Mobile emissions represent a significant fraction of the total anthropogenic emissions burden in the Mexico City Metropolitan Area (MCMA) and, therefore, it is crucial to use top-down techniques informed by on-road exhaust measurements to evaluate and improve traditional bottom-up official emissions inventory (EI) for the city. We present the measurements of on-road fleet-average emission factors obtained using the Aerodyne mobile laboratory in the MCMA in March 2006 as part of the MILAGRO/MCMA-2006 field campaign. A comparison of our on-road emission measurements with those obtained in 2003 using essentially the same measurement techniques and analysis methods indicates that, in the three year span, NO emission factors remain within the measured variability ranges whereas emission factors of aldehydes and aromatics species were reduced for all sampled driving conditions. We use a top-down fuel-based approach to evaluate the mobile emissions from the gasoline fleet estimated in the bottom-up official 2006 MCMA mobile sources. Within the range of measurement uncertainties, we found probable slight overpredictions of mean EI estimates on the order of 20–28% for CO and 14–20% for NO. However, we identify a probable EI underprediction of VOC mobile emissions between 1.4 and 1.9; although estimated benzene and toluene mobile emissions in the inventory seem to be well within the uncertainties of the corresponding emissions estimates. Aldehydes mobile emissions in the inventory, however, seem to be under predicted by factors of 3 for HCHO and 2 for CH3CHO [CH subscript 3 CHO]. Our on-road measurement based estimate of annual emissions of organic mass from PM1 particles suggests a severe underprediction (larger than a factor of 4) of PM2.5 [PM subscript 2.5] mobile emissions in the inventory. Analyses of ambient CO, NOx [NO subscript x] and CO/NOx [CO/NO subscript x] concentration trends in the MCMA indicate that the early morning ambient CO/NOx [CO/NO subscript x] ratio has decreased at a rate of about 1.9 ppm/ppm/year over the last two decades and that the decrease has been driven by reductions in CO levels rather than by NOx [NO subscript x] concentration changes, suggesting that the relative contribution of diesel vehicles to overall NOx [NO subscript x] levels has increased over time in the city. Despite the impressive increases in the size of the vehicle fleet between 2000 and 2006, the early morning ambient concentrations of CO and NOx [NO subscript x] have not increased accordingly, probably due to the reported low removal rates of older vehicles, which do not have emissions control technologies, and partially due to the much lower emissions from newer gasoline vehicles. This indicates that an emission-based air quality control strategy targeting large reductions of emissions from mobile sources should be directed towards a significant increase of the removal rate of older, highly-polluting, vehicles.Atmospheric Sciences Program (U.S.) (DE-FG02-05ER63980)Atmospheric Sciences Program (U.S.) (DE-FG02-05ER63982)United States. Dept. of EnergyNational Science Foundation (U.S.) (Atmospheric chemistry program ATM-0528170)National Science Foundation (U.S.) (Atmospheric chemistry program ATM-528227

Quantification Of Emissions From Lawn And Garden Equipment In Central Florida

The objective of this study was to evaluate the practical limits of EPA\u27s NONROAD 2005 to accurately simulate Central Florida conditions, especially with regard to lawn and garden equipment. In particular we investigated a NONROAD emission inventory using default inputs and then created a locally specific emission inventory. These emission inventories were prepared for Orange, Osceola, and Seminole county and focused only on the VOC and NOx emissions caused by lawn and garden equipment. The model was manipulated to assess its ability to represent this specific category of nonroad equipment for a given airshed first by running a base case scenario using default data and then by developing a locally-specific scenario through administration of a survey. The primary purpose of the survey was to evaluate local values for equipment population, equipment characteristics, activity estimates, and other relevant information. To develop these local input estimates, data were collected concerning population and usage statistics in the Central Florida area and were combined with emission factors, load factors, allocation factors, and other needed values that have been previously established by the U.S. EPA. The results of the NONROAD model were compared with the resulting emission estimates calculated from locally derived inputs, and as a result of the analysis an accurate emission estimate was calculated. In addition, several possible air quality action steps were further assessed according to feasibility, cost, and predicted emission benefit. These potential management projects were further investigated by assessing the success of other similar projects in other cities in an effort to establish specific costs and emission benefits as they relate to the tri-county area