Identifying Ammonia Hotspots in China Using a National Observation Network

Pan, Yuepeng; Tian, Shili; Zhao, Yuanhong; Zhang, Lin; Zhu, Xiaodong; Gao, Jian; Huang, Wei; Zhou, Yanbo; Song, Yu; Zhang, Qiang; Wang, Yuesi

doi:10.1021/acs.est.7b05235

Cited by 172 publications

(112 citation statements)

References 42 publications

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“…It is therefore difficult to control secondary pollution given the nonlinear relation between primary and secondary pollutants. In contrast, the ozone pollution has been mitigated in the last decades by efficient precursor emission control in the US (Parrish et al, 2017). Efficient ozone pollution control requires the knowledge of the effect of oxidation processes on the formation of secondary pollution because the atmospheric oxidation capacity (AOC) plays the key role in converting primary pollutants into secondary ones.…”

Section: Introductionmentioning

confidence: 99%

Daytime atmospheric oxidation capacity in four Chinese megacities during the photochemically polluted season: a case study based on box model simulation

et al. 2019

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Abstract. Atmospheric oxidation capacity is the basis for converting freshly emitted substances into secondary products and is dominated by reactions involving hydroxyl radicals (OH) during daytime. In this study, we present in situ measurements of ROx radical (hydroxy OH, hydroperoxy HO2, and organic peroxy RO2) precursors and products; the measurements are carried out in four Chinese megacities (Beijing, Shanghai, Guangzhou, and Chongqing) during photochemically polluted seasons. The atmospheric oxidation capacity is evaluated using an observation-based model and radical chemistry precursor measurements as input. The radical budget analysis illustrates the importance of HONO and HCHO photolysis, which account for ∼50 % of the total primary radical sources. The radical propagation is efficient due to abundant NO in urban environments. Hence, the production rate of secondary pollutants, that is, ozone (and fine-particle precursors (H2SO4, HNO3, and extremely low volatility organic compounds, ELVOCs) is rapid, resulting in secondary air pollution. The ozone budget demonstrates its high production in urban areas; also, its rapid transport to downwind areas results in rapid increase in local ozone concentrations. The O3–NOx–VOC (volatile organic compound) sensitivity tests show that ozone production is VOC-limited and that alkenes and aromatics should be mitigated first for ozone pollution control in the four studied megacities. In contrast, NOx emission control (that is, a decrease in NOx) leads to more severe ozone pollution. With respect to fine-particle pollution, the role of the HNO3–NO3 partitioning system is investigated using a thermal dynamic model (ISORROPIA 2). Under high relative humidity (RH) and ammonia-rich conditions, nitric acid converts into nitrates. This study highlights the efficient radical chemistry that maintains the atmospheric oxidation capacity in Chinese megacities and results in secondary pollution characterized by ozone and fine particles.

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Section: Introductionmentioning

confidence: 99%

Daytime atmospheric oxidation capacity in four Chinese megacities during the photochemically polluted season: a case study based on box model simulation

et al. 2019

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“…One of the factors limiting our ability to quantify the effects of NH 3 on aerosols formation in China is the lack of well-designed observations, focusing on gas-particle conversions involving NH 3 , SO 2 , NO x , etc. Although some networked observations of ambient NH 3 have been conducted (Meng et al, 2010;Pan et al, 2018) using passive NH 3 sampling techniques, the time resolutions were too low to study aerosol formation.…”

Section: Introductionmentioning

confidence: 99%

Role of Ammonia on the Feedback Between AWC and Inorganic Aerosol Formation During Heavy Pollution in the North China Plain

et al. 2019

Earth and Space Science

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Atmospheric NH3 plays a vital role not only in the environmental ecosystem but also in atmosphere chemistry. To further understand the effects of NH3 on the formation of haze pollution in Beijing, ambient NH3 and related species were measured and simulated at high resolutions during the wintertime Air Pollution and Human Health‐Beijing (APHH‐Beijing) campaign in 2016. We found that the total NHx (gaseous NH3+particle NH4+) was mostly in excess of the SO42−‐NO3−‐NH4+‐water equilibrium system during our campaign. This NHx excess made medium aerosol acidity, with the median pH value being 3.6 and 4.5 for polluted and nonpolluted conditions, respectively, and enhanced the formation of particle phase nitrate. Our analysis suggests that NH4NO3 is the most important factor driving the increasing of aerosol water content with NO3− controlling the prior pollution stage and NH4+ the most polluted stage. Increased formation of NH4NO3 under excess NHx, especially during the nighttime, may trigger the decreasing of aerosol deliquescence relative humidity even down to less than 50% and hence lead to hygroscopic growth even under RH conditions lower than 50% and the wet aerosol particles become better medium for rapid heterogeneous reactions. A further increase of RH promotes the positive feedback “aerosol water content‐heterogeneous reactions” and ultimately leads to the formation of severe haze. Modeling results by Nested Air Quality Prediction Monitor System (NAQPMS) show the control of 20% NH3 emission may affect 5–11% of particulate matter PM2.5 formation under current emissions conditions in the North China Plain.

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“…Reduced nitrogen (NH 3 +NH 4 + ) was monitored to contribute over 70% of total nitrogen deposition in China, revealing the importance of NH 3 on ecosystem (Pan et al, 2012). Along with the improved controls of SO 2 and NO X emissions, enhanced contribution of NH 3 emissions was found to secondary aerosol formation and nitrogen deposition for recent years in China (Liu et al, 2013;Fu et al, 2017;Pan et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Quantification and evaluation of atmospheric ammonia emissions with different methods: A case study for the Yangtze River Delta region, China

Yu¹,

Yuan²,

Huang³

et al. 2019

Preprint

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Abstract. To explore the effects of data and method on emission estimation, two inventories of NH3 emissions of the Yangtze River Delta (YRD) region in eastern China were developed for 2014 based on the constant emission factors (E1) and those characterizing the agricultural processes (E2), respectively. The latter integrated the detailed information of soil, meteorology and agricultural processes, and derived the monthly information of emission factors and activity data. The total emissions were calculated at 1765 and 1067&#8201;Gg, respectively, and agricultural activities (livestock farming and fertilizer use) were estimated to contribute 74&#8211;84&#8201;% to total emissions in the two inventories. Clear differences existed in seasonal and spatial distributions of NH3 emissions. Elevated emissions were found in March and September in E2, attributed largely to the increased top dressing fertilization and to the enhanced NH3 volatilization under high temperature, respectively. Relatively large discrepancy between the methods existed in northern Yangtze River Delta areas with abundant croplands. The two inventories were evaluated through air quality modeling and available ground and satellite observation. With the estimated emissions 38&#8201;% smaller in E2, the average of simulated NH3 concentrations using E2 was 27&#8201;% smaller than that using E1 at two ground observation sites in the YRD region. At the suburban SHPD site, the simulated NH3 concentrations with E1 were generally larger than observation, and the modeling performance was largely improved indicated by the smaller NMEs when E2 was applied. In contrast, very limited improvement was found at the urban site JSPAES, as E2 failed to improve the emission estimation of local sources including transportation and residential activities. Compared to NH3, the modeling performance for inorganic aerosols was better for most cases, and the differences between the simulated concentrations with E1 and E2 were clearly smaller, at 7&#8201;%, 3&#8201;% and 12&#8201;% (relative to E1) for NH4+, SO42&#8722;, and NO3&#8722;, respectively. Regarding the satellite-derived NH3 column, application of E2 significantly corrected the overestimation in vertical column density simulation for January and October with E1, but did not improve the model performance for July. The NH3 emissions might be underestimated with the assumption of linear correlation between NH3 volatilization and soil pH for acidic soil, particularly in warm seasons. Three additional cases, i.e., 40&#8201;% abatement of SO2, 40&#8201;% abatement of NOX, and 40&#8201;% abatement of both species were applied to test the sensitivity of NH3 and inorganic aerosol concentrations to precursor emissions. Under an NH3-rich condition for most of YRD, estimation of SO2 emissions was detected to be more effective on simulation of secondary inorganic aerosols compared to NH3. Reduced SO2 would restrain the formation of (NH4)2SO4, and thereby enhance the NH3 concentrations. Besides the emissions, uncertainties existed as well in the limitations of ground and satellite observation and incomplete mechanism of gas to particle conversion applied in the model. To improve the air quality more effectively and efficiently, NH3 emissions should be substantially controlled along with SO2 and NOX in the future.

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Identifying Ammonia Hotspots in China Using a National Observation Network

Cited by 172 publications

References 42 publications

Daytime atmospheric oxidation capacity in four Chinese megacities during the photochemically polluted season: a case study based on box model simulation

Daytime atmospheric oxidation capacity in four Chinese megacities during the photochemically polluted season: a case study based on box model simulation

Role of Ammonia on the Feedback Between AWC and Inorganic Aerosol Formation During Heavy Pollution in the North China Plain

Quantification and evaluation of atmospheric ammonia emissions with different methods: A case study for the Yangtze River Delta region, China

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