Ambient sulfur dioxide, nitrogen dioxide, and ammonia at ten background and rural sites in China during 2007–2008

Meng, Zhaoyang; Xu, Xiaobin; Wang, Tao; Zhang, Xing Ying; Yu, Xiao Lan; Wang, Shu Feng; Lin, W. L.; Chen, Yi Zhen; Jiang, Yi An; An, Xing Qin

doi:10.1016/j.atmosenv.2010.04.008

Cited by 107 publications

(84 citation statements)

References 27 publications

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“…Field observation showed that ground surface levels of NO 2 and SO 2 are similar in inland China. For example, annual means of NO 2 and SO 2 in Xi'an were 43 and 41 µg m −3 during (Shen et al, 2008, 0.7 ± 0.4 and 0.6 ± 0.4 ppbv in Waliguan during -2008(Meng et al, 2010, and 2.7 ± 1.6 and 2.2 ± 0.7 ppbv in Qinghai Lake in March-April, 2012 (unpublished data). Therefore, relative abundance of nitrate to sulfate higher in the urban air and lower in the mountain atmosphere can be explained firstly by the different formation rates and secondly by cloud processing at the summit of Mt.…”

Section: Difference In Chemical Composition Between Xi'an and Mt Huamentioning

confidence: 99%

“…However, simultaneous observation for dust-laden aerosols between the boundary layer and the free troposphere has been conducted only in the Asian continental outflow region such as the ACE-Asia 2001 in Northwest Pacific (Huebert et al, 2003;Seinfeld et al, 2004;Simoneit et al, 2004a, b) and the INTEX-2006 in Northeast America Peltier et al, 2008;van Donkelaar et al, 2008), but there is no such a simultaneous measurement conducted in inland China. Located in central China, Guanzhong Basin is one of the most polluted regions in the world, where the annual average level of fine particles was more than 80 µg m −3 in 2001(van Donkelaar et al, 2010Wang et al, 2006aWang et al, , b, 2010. In the spring of 2009, an intensive observation of atmospheric aerosols was performed simultaneously in Xi'an (109 • 39 E,34 • 45 N), Mt.…”

Section: G H Wang Et Al: Impact Of Gobi Desert Dust On Aerosol Chementioning

confidence: 99%

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Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

et al. 2013

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Abstract. Composition and size distribution of atmospheric aerosols from Xi'an city (∼ 400 m, altitude) in inland China during the spring of 2009 including a massive dust event on 24 April were measured and compared with a parallel measurement at the summit (2060 m, altitude) of Mt. Hua, an alpine site nearby Xi'an. EC (elemental carbon), OC (organic carbon) and major ions in the city were 2-22 times higher than those on the mountaintop during the whole sampling period. Compared to that in the non-dust period a sharp increase in OC was observed at both sites during the dust period, which was mainly caused by an input of biogenic organics from the Gobi desert. However, adsorption/heterogeneous reaction of gaseous organics with dust was another important source of OC in the urban, contributing 22 % of OC in the dust event. In contrast to the mountain atmosphere where fine particles were less acidic when dust was present, the urban fine particles became more acidic in the dust event than in the non-dust event, mainly due to enhanced heterogeneous formation of nitrate and diluted NH 3 . Cl − and NO − 3 in the urban air during the dust event significantly shifted toward coarse particles. Such redistributions were further pronounced on the mountaintop when dust was present, resulting in both ions almost entirely staying in coarse particles. On the contrary, no significant spatial difference in size distribution of SO 2− 4 was found between the urban ground surface and the mountain atmosphere, which dominated in the fine mode (< 2.1 µm) during the nonevent and comparably distributed in the fine (< 2.1 µm) and coarse (> 2.1 µm) modes during the dust event.

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Section: Difference In Chemical Composition Between Xi'an and Mt Huamentioning

confidence: 99%

Section: G H Wang Et Al: Impact Of Gobi Desert Dust On Aerosol Chementioning

confidence: 99%

Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

et al. 2013

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“…Assessing sensor performance at lower SO 2 concentrations is thus important for understanding the potential for sensors and calibration algorithms to be used under a wider range of conditions. Sensor performance under lower-SO 2 conditions can be evaluated using the present dataset by removing all points in which the reference value was greater than some threshold value (chosen here to be 25 ppb SO 2 , a reasonable value for cities in India and China; Meng et al, 2010;O'Shea et al, 2016). Figure 8 shows kNN regression results for node SO2-02 under lower-SO 2 conditions only; these were generated using the same technique for generating Fig.…”

Section: Measuring So 2 At Low(er) Concentrationsmentioning

confidence: 99%

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

et al. 2018

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Abstract. The use of low-cost air quality sensors for air pollution research has outpaced our understanding of their capabilities and limitations under real-world conditions, and there is thus a critical need for understanding and optimizing the performance of such sensors in the field. Here we describe the deployment, calibration, and evaluation of electrochemical sensors on the island of Hawai'i, which is an ideal test bed for characterizing such sensors due to its large and variable sulfur dioxide (SO 2 ) levels and lack of other co-pollutants. Nine custom-built SO 2 sensors were colocated with two Hawaii Department of Health Air Quality stations over the course of 5 months, enabling comparison of sensor output with regulatory-grade instruments under a range of realistic environmental conditions. Calibration using a nonparametric algorithm (k nearest neighbors) was found to have excellent performance (RMSE < 7 ppb, MAE < 4 ppb, r 2 > 0.997) across a wide dynamic range in SO 2 (< 1 ppb, > 2 ppm). However, since nonparametric algorithms generally cannot extrapolate to conditions beyond those outside the training set, we introduce a new hybrid linear-nonparametric algorithm, enabling accurate measurements even when pollutant levels are higher than encountered during calibration. We find no significant change in instrument sensitivity toward SO 2 after 18 weeks and demonstrate that calibration accuracy remains high when a sensor is calibrated at one location and then moved to another. The performance of electrochemical SO 2 sensors is also strong at lower SO 2 mixing ratios (< 25 ppb), for which they exhibit an error of less than 2.5 ppb. While some specific results of this study (calibration accuracy, performance of the various algorithms, etc.) may differ for measurements of other pollutant species in other areas (e.g., polluted urban regions), the calibration and validation approaches described here should be widely applicable to a range of pollutants, sensors, and environments.

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“…NO x in the lower troposphere is derived primarily from emissions at the surface [16]. The OMI NO 2 columns discriminate differences in ground NO 2 and the results well reflect the distribution of surface NO 2 concentrations [17,18].…”

Section: No 2 Measurements From Omi Satellitementioning

confidence: 83%

“…To verify the reliability and validity of the OMI measurements, the retrieved OMI NO 2 columns have been compared with ground-based remote sensing measurements [19,20], aircraft measurements [21,22], as well as groundbased in-situ NO 2 measurements [18,[23][24][25]. These findings suggest that the OMI NO 2 columns are suitable for regional air quality studies.…”

Section: No 2 Measurements From Omi Satellitementioning

confidence: 99%

Formation and causes of NO x pollution on the east side of the Taihang Mountains in China

et al. 2011

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Tropospheric column amounts of NO 2 from OMI/Aura products were applied to investigate the seasonal variation of NO x on the east side of the Taihang Mountains (ESTM) in China. The NO 2 concentration varied seasonally, with winter maxima and summer minima. To explore the causes of the heavy NO 2 pollution in this region, wind field simulations were conducted by using the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5). MM5 simulations showed that wind directions in the ESTM region were dominated by northeasterly and northwesterly winds throughout the year and to a lesser degree by southwesterlies. Elevated NO 2 concentrations (higher than 50×10 15 molec/cm 2 ) occurred in three meteorological situations: convergent wind fields (5 days), northeasterly winds (2 days), and calm days (1 day) in January. Although the local anthropogenic NO x emission strength was not so high as that in other developed areas, the calms and frequent occurrence of convergent wind fields, as well as unfavorable terrains for diffusion, resulted in the accumulation of atmospheric pollutants and hence heavy NO x pollution. Furthermore, long-distance NO x transportation from the Beijing-Tianjin-Tangshan region to the ESTM area could be seen when the wind was from a northeasterly direction, especially under high wind speeds.

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Ambient sulfur dioxide, nitrogen dioxide, and ammonia at ten background and rural sites in China during 2007–2008

Cited by 107 publications

References 27 publications

Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

Formation and causes of NO x pollution on the east side of the Taihang Mountains in China

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