scholarly journals Atmospheric OH reactivities in the Pearl River Delta – China in summer 2006: measurement and model results

2010 ◽  
Vol 10 (22) ◽  
pp. 11243-11260 ◽  
Author(s):  
S. Lou ◽  
F. Holland ◽  
F. Rohrer ◽  
K. Lu ◽  
B. Bohn ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Pearl River Delta ◽  
Trace Gases ◽  
Ambient Air ◽  
River Delta ◽  
Rural Site ◽  
Pearl River ◽  
Secondary Chemistry ◽  
Model Calculations

Abstract. Total atmospheric OH reactivities (kOH) have been measured as reciprocal OH lifetimes by a newly developed instrument at a rural site in the densely populated Pearl River Delta (PRD) in Southern China in summer 2006. The deployed technique, LP-LIF, uses laser flash photolysis (LP) for artificial OH generation and laser-induced fluorescence (LIF) to measure the time-dependent OH decay in samples of ambient air. The reactivities observed at PRD covered a range from 10 s−1 to 120 s−1, indicating a large load of chemical reactants. On average, kOH exhibited a pronounced diurnal profile with a mean maximum value of 50 s−1 at daybreak and a mean minimum value of 20 s−1 at noon. The comparison of reactivities calculated from measured trace gases with measured kOH reveals a missing reactivity of about a factor of 2 at day and night. The reactivity explained by measured trace gases was dominated by anthropogenic pollutants (e.g., CO, NOx, light alkenes and aromatic hydrocarbons) at night, while it was strongly influenced by local, biogenic emissions of isoprene during the day. Box model calculations initialized by measured parameters reproduce the observed OH reactivity well and suggest that the missing reactivity is contributed by unmeasured, secondary chemistry products (mainly aldehydes and ketones) that were photochemically formed by hydrocarbon oxidation. Overall, kOH was dominated by organic compounds, which had a maximum contribution of 85% in the afternoon. The paper demonstrates the usefulness of direct reactivity measurements, emphasizes the need for direct measurements of oxygenated organic compounds in atmospheric chemistry studies, and discusses uncertainties of the modelling of OVOC reactivities.

scholarly journals Atmospheric OH reactivities in the Pearl River Delta – China in summer 2006: measurement and model results

2009 ◽  
Vol 9 (4) ◽  
pp. 17035-17072 ◽  
Author(s):  
S. Lou ◽  
F. Holland ◽  
F. Rohrer ◽  
K. Lu ◽  
B. Bohn ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Pearl River Delta ◽  
Southern China ◽  
Ambient Air ◽  
River Delta ◽  
Rural Site ◽  
Pearl River ◽  
Secondary Chemistry ◽  
Model Calculations

Abstract. Total atmospheric OH reactivities (kOH) have been measured as reciprocal OH lifetimes by a newly developed instrument at a rural site in the densely populated Pearl River Delta (PRD) in Southern China in summer 2006. The deployed technique, LP-LIF, uses laser flash photolysis (LP) for artifical OH generation and laser-induced fluorescence (LIF) to measure the time-dependent OH decay in samples of ambient air. The reactivities observed at PRD covered a range from 10 s−1 to 120 s−1, indicating a large load of chemical reactants. On average, kOH exhibited a pronounced diurnal profile with a mean maximum value of 50 s−1 at daybreak and a mean minimum value of 20 s−1 at noon. The reactivity was dominated by anthropogenic pollutants (e.g., CO, NOx, light alkenes and aromatic hydrocarbons) at night, while it was strongly influenced by local, biogenic emissions of isoprene at day. The comparison of reactivities calculated from measured trace gases with measured kOH reveals a missing reactivity of about a factor of 2 at day and night. Box model calculations initialized by measured parameters reproduce the observed OH reactivity well and suggest that the missing reactivity is contributed by unmeasured, secondary chemistry products (mainly aldehydes and ketones) that were photochemically formed by hydrocarbon oxidation. Overall, kOH was dominated by organic compounds, which had a maxium contribution of 85% in the afternoon. The paper demonstrates the usefulness of direct reactivity measurements and emphasizes the need for direct measurements of oxygenated organic compounds in atmospheric chemistry studies.

scholarly journals Observation and modelling of OH and HO<sub>2</sub> concentrations in the Pearl River Delta 2006: a missing OH source in a VOC rich atmosphere

2011 ◽  
Vol 11 (4) ◽  
pp. 11311-11378 ◽  
Author(s):  
K. D. Lu ◽  
F. Rohrer ◽  
F. Holland ◽  
H. Fuchs ◽  
B. Bohn ◽  
...  
Keyword(s):  
Pearl River Delta ◽  
Southern China ◽  
River Delta ◽  
Rural Site ◽  
Pearl River ◽  
Recycling Process ◽  
Mixing Ratios ◽  
Suburban Areas ◽  
The Pearl River Delta ◽  
The Pearl River

Abstract. Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, 2006) campaign at a rural site downwind of the megacity of Guangzhou in Southern China. The observed OH concentrations reached daily peak values of (15–26) × 106 cm−3 which are among the highest values so far reported for urban and suburban areas. The observed OH shows a consistent high correlation with j(O1D) over a broad range of NOx conditions. The correlation cannot be reproduced by model simulations, indicating that OH stabilizing processes are missing in current models. The observed OH exhibited a weak dependence on NOx in contrast to model predictions. While modelled and measured OH agree well at NO mixing ratios above 1 ppb, a continuously increasing underprediction of the observed OH is found towards lower NO concentrations, reaching a factor of 8 at 0.02 ppb NO. A dependence of the modelled-to-measured OH ratio on isoprene cannot be concluded from the PRD data. However, the magnitude of the ratio fits into the isoprene dependent trend that was reported from other campaigns in forested regions. Hofzumahaus et al. (2009) proposed an unknown OH recycling process without NO, in order to explain the high OH levels at PRD in the presence of high VOC reactivity and low NO. Taking a recently discovered interference in the LIF measurement of HO2 into account, the need for an additional HO2 → OH recycling process persists, but the required source strength may be up to 20% larger than previously determined. Recently postulated isoprene mechanisms by Lelieveld et al. (2008) and Peeters and Müller (2010) lead to significant enhancements of OH expected for PRD, but an underprediction of the observed OH by a factor of two remains at low NO (0.1–0.2 ppb). If the photolysis of hydroperoxy aldehydes from isoprene is as efficient as proposed by Peeters and Müller (2010), the corresponding OH formation at PRD would be more important than the primary OH production from ozone and HONO. While the new isoprene mechanisms need to be confirmed by laboratory experiments, there is probably need for other, so far unidentified chemical processes to explain entirely the high OH levels observed in Southern China.

Development of an incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for autonomous field measurements of HONO and NO2 in a rural area

2021 ◽  
Author(s):  
Lingshuo Meng ◽  
Gaoxuan Wang ◽  
Cécile Coeur ◽  
Alexandre Tomas ◽  
Tao Wu ◽  
...  
Keyword(s):  
Rural Area ◽  
Absorption Spectroscopy ◽  
Atmospheric Chemistry ◽  
Nitrous Acid ◽  
Trace Gases ◽  
Ambient Air ◽  
Rural Site ◽  
Oh Radicals ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy

&lt;p&gt;Nitrous acid (HONO) is one of the important atmospheric trace gases due to its contribution to the cycles of nitrogen oxides (NOx) and hydrogen oxides (HOx). In particular it acts as a precursor of tropospheric OH radicals, which is responsible for the self-cleansing capacity of the atmosphere [1,2]. We developed an instrument based on incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) for automatic measurement of HONO in a rural area in a summer period during a field &quot;Campagne d&amp;#8217;OBservation Intensive des Ae&amp;#769;rosols et pre&amp;#769;curseurs a&amp;#768; Caillou&amp;#235;l-Cr&amp;#233;pigny (COBIACC)&quot; in France. IBBCEAS technique is now extensively used in field applications for the measurements of both trace gases and aerosols [3,4].&lt;/p&gt;&lt;p&gt;Real-time in situ measurements of HONO and NO&lt;sub&gt;2&lt;/sub&gt; have been simultaneously carried out. The IBBCEAS instrument performance has been demonstrated and validated through lab-based tests, and in particular through field intercomparison via side-by-side measurements of temporal concentration profiles of HONO and NO&lt;sub&gt;2&lt;/sub&gt; in the rural area. The intercomparison of the concentration measurements between IBBCEAS and an instrument called MARGA (Monitor for AeRosols and Gases in Ambient air) for HONO, and IBBCEAS vs. a reference NOx analyzer for NO&lt;sub&gt;2&lt;/sub&gt;. Good agreements have been observed which demonstrated the performance of the developed IBBCEAS instrument for the measurement of atmospheric HONO concentration (&lt;5 ppb) in a rural area.&lt;/p&gt;&lt;p&gt;The preliminary experimental results will be presented and discussed.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgments&lt;/strong&gt; This work was supported by the CPER CLIMIBIO program and the Labex CaPPA project (ANR-10-LABX005). The authors highly appreciate the offers of Mr. Eric Wetzels from Polyfluor Plastics bv for the help in our instrumental conception involving Teflon pipe.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;[1] X. Li, T. Brauers, R. H&amp;#228;seler, R. Bohn, H. Fuchs, A. Hofzumahaus, F. Holland, S. Lou, et al., Exploring the atmospheric chemistry of nitrous acid (HONO) at a rural site in Southern China, Atmos. Chem. Phys. &lt;strong&gt;12&lt;/strong&gt; (2012) 1497-1513.&lt;/p&gt;&lt;p&gt;[2] H. Su, Y. Cheng, M. Shao, D. Gao, Z. Yu, L. Zeng, J. Slanina, et al., Nitrous acid (HONO) and its daytime sources at a rural site during the 2004 PRIDE&amp;#8208;PRD experiment in China, J. Geophys. Res. &lt;strong&gt;113&lt;/strong&gt; (2008) D14312.&lt;/p&gt;&lt;p&gt;[3] T. Wu, Q. Zha, W. Chen, Z. Xu, T. Wang, X. He, Development and deployment of a cavity enhanced UV-LED spectrometer for measurements of atmospheric HONO and NO&lt;sub&gt;2&lt;/sub&gt; in Hong Kong, Atmos. Environ. &lt;strong&gt;95&lt;/strong&gt; (2014) 544-551.&lt;/p&gt;&lt;p&gt;[4] L. Meng, G. Wang, P. Augustin, M. Fourmentin, Q. Gou, E. Fertein, T. N. Ba, C. Coeur, A. Tomas, W. Chen, Incoherent broadband cavity enhanced absorption spectroscopy-based strategy for direct measurement of aerosol extinction in lidar blind zone, Opt. Lett. &lt;strong&gt;45 &lt;/strong&gt;(2020) 1611-1614.&lt;/p&gt;

Evidences and implications of vegetation damage from ceramic industrial emission on a rural site in the Pearl River Delta of China

2006 ◽  
Vol 17 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Da-zhi Wen ◽  
Yuan-wen Kuang ◽  
Shi-zhong Liu ◽  
De-qiang Zhang ◽  
Yao-dong Lu ◽  
...  
Keyword(s):  
Pearl River Delta ◽  
River Delta ◽  
Rural Site ◽  
Pearl River ◽  
Industrial Emission ◽  
The Pearl River Delta ◽  
The Pearl River ◽  
Vegetation Damage

scholarly journals Top-down estimates of benzene and toluene emissions in Pearl River Delta and Hong Kong, China

2015 ◽  
Vol 15 (17) ◽  
pp. 24839-24870 ◽  
Author(s):  
X. Fang ◽  
M. Shao ◽  
A. Stohl ◽  
Q. Zhang ◽  
J. Zheng ◽  
...  
Keyword(s):  
Hong Kong ◽  
Urban Areas ◽  
Pearl River Delta ◽  
Transport Model ◽  
Measurement Data ◽  
River Delta ◽  
Rural Site ◽  
Pearl River ◽  
Top Down ◽  
Bottom Up

Abstract. Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For PRD and HK, the benzene emissions estimated in this study for 2010 were 44 (12–75) Gg yr−1 and 5 (2–7) Gg yr−1 for PRD and HK, respectively, and the toluene emissions were 131 (44–218) Gg yr−1 and 6 (2–9) Gg yr−1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutants) emissions in PRD and HK in the future.

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