RESUMEN
Intermediate volatility organic compounds (IVOCs) are important precursors of secondary organic aerosols (SOA) but are currently not included in the conventional emissions inventories. Biomass burning represents an important source of IVOCs that could contribute to SOA formation. This study estimated the IVOC emissions from biomass burning in the Yangtze River Delta (YRD) region from 2010 to 2018 based on the fire inventory from NCAR (FINN) and the IVOCs/primary organic aerosol (POA) ratio reported in literature. During this period, the total number of fire events over the YRD region presented a declining trend, with an average of 104 fire events detected per year. During 2016-2018, the average number of fire events was approximately 6000 per year, which was 60% less than that prior to 2016. In terms of the monthly variation, the period from May to August was the period with the most fires observed, which was followed by a small peak in October. The results calculated based on the IVOCs/POA ratio method showed that the IVOC emissions from biomass burning exhibited large differences with different combinations of POA/OC and IVOCs/POA ratios, ranging from a maximum of 305.7×104 t to as small as 10.5×104 t. Monte Carlo simulation revealed that the uncertainties associated with the IVOCs/POA ratio method range from -99% to 68%.
Asunto(s)
Contaminantes Atmosféricos , Compuestos Orgánicos Volátiles , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Biomasa , Monitoreo del Ambiente , Ríos , Emisiones de Vehículos/análisis , Compuestos Orgánicos Volátiles/análisis , VolatilizaciónRESUMEN
Atmospheric ammonia plays an important role in the formation of secondary inorganic composition of PM2.5, which has attracted a high level of attention from researchers both in China and abroad. Quantifying ammonia emissions is of great scientific significance regarding research on the formation of secondary aerosol, realizing better model performance, and control of ammonia emissions. Previous studies have shown that agricultural activities are the dominant source of atmospheric ammonia, of which livestock and poultry farming contribute the most. Existing studies on estimating ammonia emissions from livestock and poultry farming activities are mostly based on emission factors and activities. However, the choice of different emission activities could lead to large differences in estimated ammonia emissions. This study makes a variety of assumptions from the selection of activity levels (volume vs. inventory) and emission coefficients (monthly vs. annual average temperature), and establishes eight scenarios from which to calculate atmospheric ammonia emissions from livestock and poultry farming in the Yangtze River Delta region in 2017. The results show that selection of different activity levels has the greatest impact on estimated ammonia emissions; estimation based on volume is higher than that based on inventory by 27.6%-34.1%. Calculation based on a more detailed monthly average temperature is higher than using average annual temperature by 3000 to 4000 tons per year. In addition, the spatial and temporal distributions of the ammonia emissions are also closely related to the choice of volume vs. inventory and the choice of monthly average temperature vs. annual average temperature. When using inventory as the emission activity, Zhoushan (Zhejiang Province) has the lowest ammonia emissions, while Huainan (Anhui Province) has the highest. In contrast, when volume is used, Lishui (Zhejiang Province) has the lowest ammonia emissions and Nanjing (Jiangsu Province) has the highest. Emissions calculations based on monthly average temperature are supposed to be more representative than those based on annual average temperature, with the highest emissions from May to September and the lowest in the winter (December, January, and February).
RESUMEN
Intermediate volatility organic compounds (IVOCs) have a significant contribution to the formation of secondary organic aerosols (SOA) in the atmosphere, but are not included in the current emission inventory. In this study, IVOC emissions from vehicles are estimated for the Yangtze River Delta region (YRD) for 2017 based on two methods:the emission factor method and the IVOCs/POA scaling factor method. Uncertainties in the estimated IVOCs emissions and the impact on their potential formation are discussed. The results based on the emission factor method showed that the total vehicular IVOCs emission in the YRD in 2017 was 35800 tons, and that the formation potential of SOA was an estimated 695 tons. IVOCs emissions from trucks accounted for>70% of total IVOCs emissions in most cities in the YRD region. In terms of fuel type, IVOCs emissions from diesel vehicles were much higher than of those from gasoline vehicles. Results based on the IVOCs/POA scaling factor method showed that the emissions calculated by different combinations of IVOCs/POA ratios and POA/PM2.5 ratios that could vary significantly, with a maximum of 64.2×104 tons and a minimum of just 5.2×104 tons. The resultant SOA formation potential was 1.55×104 tons and 1032 tons for the maximum and minimum, respectively. This study shows that the results of IVOCs emissions based on different estimation methods are associated with large uncertainties, which could directly affect the simulation results of SOA in subsequent air quality models. Therefore, it is necessary to use different inventory results in air quality models and perform model evaluation of SOA in order to obtain more accurate IVOCs emission inventories of vehicles in the YRD region.