Nitrous acid in marine boundary layer over eastern Bohai Sea, China: Characteristics, sources, and implications

Wen, Liang; Chen, Tianshu; Zheng, Penggang; Wu, Lin; Wang, Xinfeng; Mellouki, Abdelwahid; Xue, Likun; Wang, Wenxing

doi:10.1016/j.scitotenv.2019.03.225

Cited by 43 publications

(60 citation statements)

References 51 publications

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“…Tai meteorological station. These instruments have been widely applied in many previous studies, and the quality assurance and quality control protocols can be found elsewhere [46,[48][49][50]. For CO and O 3 , we performed multi-point calibrations every month and changed the filter every two weeks.…”

Section: Measurement Techniquesmentioning

confidence: 99%

Evaluation of the Performance of Low-Cost Air Quality Sensors at a High Mountain Station with Complex Meteorological Conditions

Zhu

Zhao³

et al. 2020

Atmosphere

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Low-cost sensors have become an increasingly important supplement to air quality monitoring networks at the ground level, yet their performances have not been evaluated at high-elevation areas, where the weather conditions are complex and characterized by low air pressure, low temperatures, and high wind speed. To address this research gap, a seven-month-long inter-comparison campaign was carried out at Mt. Tai (1534 m a.s.l.) from 20 April to 30 November 2018, covering a wide range of air temperatures, relative humidities (RHs), and wind speeds. The performance of three commonly used sensors for carbon monoxide (CO), ozone (O3), and particulate matter (PM2.5) was evaluated against the reference instruments. Strong positive linear relationships between sensors and the reference data were found for CO (r = 0.83) and O3 (r = 0.79), while the PM2.5 sensor tended to overestimate PM2.5 under high RH conditions. When the data at RH >95% were removed, a strong non-linear relationship could be well fitted for PM2.5 between the sensor and reference data (r = 0.91). The impacts of temperature, RH, wind speed, and pressure on the sensor measurements were comprehensively assessed. Temperature showed a positive effect on the CO and O3 sensors, RH showed a positive effect on the PM sensor, and the influence of wind speed and air pressure on all three sensors was relatively minor. Two methods, namely a multiple linear regression model and a random forest model, were adopted to minimize the influence of meteorological factors on the sensor data. The multi-linear regression (MLR) model showed a better performance than the random forest (RF) model in correcting the sensors’ data, especially for O3 and PM2.5. Our results demonstrate the capability and potential of the low-cost sensors for the measurement of trace gases and aerosols at high mountain sites with complex weather conditions.

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Section: Measurement Techniquesmentioning

confidence: 99%

Evaluation of the Performance of Low-Cost Air Quality Sensors at a High Mountain Station with Complex Meteorological Conditions

Zhu

Zhao³

et al. 2020

Atmosphere

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“…An improved empirical formula, Eq. 6, was applied to estimate [OH] using the NO2 and HONO concentrations and the photolysis rate constants (J) of NO2, O3, and HONO (Wen et al, 2019).…”

Section: Hono Photostationary-state Approachmentioning

confidence: 99%

“…Xinken/China Oct.-Nov.,2004 1.60 (Su et al, 2008a) Jinan/China Sep.,2015-Aug.,2016 0.68 (Li et al, 2018) Mar. (Wang et al, 2015) Shanghai/China Aug.2010-Jun.2012 0.70 (Wang et al, 2013) Eastern Bohai Sea/China Oct.-Nov., 2016 1.80 (Wen et al, 2019) Hongkong/China Aug.2011-May, 2012 0.52 (Xu et al, 2015) Kathmandu/South Asia Jan.-Feb.,2003 1.4 (Yu et al, 2009)…”

Section: Competing Interestsunclassified

Exploration of the atmospheric chemistry of nitrous acid in a coastal city of southeastern China: Results from measurements across four seasons

Duan

Hong

et al. 2020

Preprint

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Abstract. Because nitrous acid (HONO) photolysis is a key source of hydroxyl (OH) radicals, identifying the atmospheric sources of HONO is essential to enhance the understanding of atmospheric chemistry processes and improve the accuracy of simulation models. We performed seasonal field observations of HONO in a coastal city of southeastern China, along with measurements of trace gases, aerosol compositions, photolysis rate constants (J), and meteorological parameters. The results showed that the average observed concentration of HONO was 0.54 ± 0.47 ppb. Vehicle exhaust emissions contributed an average of 1.64 % to HONO, higher than the values found in most other studies, suggesting an influence from diesel vehicle emissions. The mean conversion frequency of NO2 to HONO in the nighttime was the highest in summer due to water droplets was evaporated under the condition of high temperatures. Based on a budget analysis, the rate of emission from unknown sources (Runknown) was highest at midday, with values of 14.78 ppb h−1 in summer, 6.49 ppb h−1 in autumn, and 2.18 ppb h−1 in spring. Unknown sources made up the largest proportion of all sources in summer (84.92 %), autumn (80.29 %), and spring (49.98 %), whereas the main source in winter was the homogeneous reaction of NO with OH (56.15 %), due to winter having the highest NO concentration of the four seasons. The value of Runknown had a positive logarithmic relationship with the photolysis of particulate nitrate in spring, summer, and autumn. However, Runknown was limited by particulate acidity under the condition of photolysis of particulate nitrate (J (NO3−_R) × pNO3−) > 1 µg m−3 s−1 in autumn and J(NO3−_R) × pNO3− > 2 µg m−3 s−1 in spring and summer. The variation of HONO at night can be exactly simulated based on the HONO / NOx ratio, while the main sources should be considered for daytime simulations. Compared with O3 photolysis, HONO photolysis has long been an important source of OH, particularly in the morning in spring and winter and around noon in summer and autumn. This study draws a full picture of the sources of HONO across all four seasons and improves the comprehension of HONO chemistry in southeastern coastal China.

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“…Ring Down Spectrometry (CRDS) (O' Keefe and Deacon, 1988;Scherer et al, 1997;Wheeler et al, 1998), Differential…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the photochemical reaction involving a nitrate series (HNO3, NO3 -) was considered as a major daytime HONO source (Han et al, 2017;Li et al, 2018;Ye et al, 2017;Tsai et al, 2018;Cui et al, 2019). The HONO production reaction is still controversial due to a wide variety of environments involving NOx, RH, and surfaces and incomplete understanding of multi-phase reaction (Bao et al, 2018;Zhang et al, 2019c;Wen et al, 2019;Zhang et al, 2019b). In this context, new approaches are needed to elucidate the HONO formation mechanism.…”

Section: Introductionmentioning

confidence: 99%

The role of HONO in O<sub>3</sub> formation and insight into its formation mechanism during the KORUS-AQ Campaign

Gil

Kim

Lee

et al. 2019

Preprint

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Abstract. Photolysis of nitrous acid (HONO) has long been recognized as an early morning source of OH radicals in urban air, but the detailed mechanism of its formation is still unclear. During the Korea-US Air Quality (KORUS-AQ) campaign, HONO was measured using Quantum Cascade Tunable Diode Laser Absorption Spectroscopy (QC-TDLAS) at Olympic Park in Seoul from 17 May to 10 June, 2016. HONO concentrations ranged from 0.07 ppbv to 3.46 ppbv with an average of 0.93 ppbv. HONO remained high at night from 1 am to 5 am, during which the mean concentration was higher in high-O3 episodes (1.82 ppbv) than non-episode (1.20 ppbv). In the morning, OH budget due to HONO photolysis were higher by 50 % (0.95 pptv) during high-O3 episodes compared to non-episode. Diurnal variations of HOx and O3 simulated by the F0AM model demonstrated a difference of ~ 20 ppbv in daily maximum O3 between the two periods. The HONO concentration increased with relative humidity (RH) until 80 %, of which the highest HONO was associated with the top 10 % NOx, confirming that NOx is a crucial precursor of HONO and its formation is facilitated by humidity. The conversion ratio of NOx to HONO was estimated to be 0.86 × 10−2 h−1 at night and also increased with RH. As surrogate for the catalyst surface, the mass concentrations of black carbon (eBC) and the surface areas of particles smaller than 120 nm showed a tendency for RH similar to conversion ratio. Using an Artificial Neuron Network (ANN) model, HONO concentrations were successfully simulated with measured variables (r = 0.8 for the best suite), among which NOx, surface area, and RH were found to be main factors affecting ambient HONO concentrations with weigh values of 26.2 %, 11.9 %, and 10.6 %, respectively. This study demonstrates the coupling of HONO with HOx-VOCs-O3 cycle in Seoul Metropolitan Areas (SMA) and provides practical evidence for heterogeneous formation of HONO by employing the ANN model to atmospheric chemistry.

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Nitrous acid in marine boundary layer over eastern Bohai Sea, China: Characteristics, sources, and implications

Cited by 43 publications

References 51 publications

Evaluation of the Performance of Low-Cost Air Quality Sensors at a High Mountain Station with Complex Meteorological Conditions

Evaluation of the Performance of Low-Cost Air Quality Sensors at a High Mountain Station with Complex Meteorological Conditions

Exploration of the atmospheric chemistry of nitrous acid in a coastal city of southeastern China: Results from measurements across four seasons

The role of HONO in O<sub>3</sub> formation and insight into its formation mechanism during the KORUS-AQ Campaign

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Nitrous acid in marine boundary layer over eastern Bohai Sea, China: Characteristics, sources, and implications

Cited by 43 publications

References 51 publications

Evaluation of the Performance of Low-Cost Air Quality Sensors at a High Mountain Station with Complex Meteorological Conditions

Evaluation of the Performance of Low-Cost Air Quality Sensors at a High Mountain Station with Complex Meteorological Conditions

Exploration of the atmospheric chemistry of nitrous acid in a coastal city of southeastern China: Results from measurements across four seasons

The role of HONO in O&lt;sub&gt;3&lt;/sub&gt; formation and insight into its formation mechanism during the KORUS-AQ Campaign

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Product

Resources

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The role of HONO in O<sub>3</sub> formation and insight into its formation mechanism during the KORUS-AQ Campaign