scholarly journals Consumption of Hydrocarbons and Its Relationship with Ozone Formation in Two Chinese Megacities

Atmosphere ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 326
Author(s):  
Chih-Chung Chang ◽  
Hwa-Kwang Yak ◽  
Jia-Lin Wang
Keyword(s):  
Hydroxyl Radicals ◽  
Pearl River Delta ◽  
Urban Site ◽  
Pearl River ◽  
Ozone Formation ◽  
Relative Consumption ◽  
The Pearl River ◽  
Photochemical Aging ◽  
Consumption Efficiency ◽  
Suburban Site

Continuous measurements of ozone and its precursors were performed at sites in two Chinese megacities, i.e., an urban site in Beijing and a suburban site in the Pearl River Delta (PRD). At both sites, the total oxidants (O3 + NO2) varied with the ratio of ethylbenzene to m,p-xylenes, which serves as an indicator of photochemical aging. An observation-based method (OBM) was derived for calculating the photochemical consumption of individual non-methane hydrocarbons (NMHCs) based on the observed NMHC concentrations and the ratio of ethylbenzene to m,p-xylenes. The results show a strong correlation between the oxidant level and the derived consumption of precursors at the two sites (R2 = 0.81 for the PRD site and R2 = 0.83 for the Beijing site), demonstrating a strong cause–effect relationship. The relative “consumption efficiency” among NMHCs was calculated based on the integrated amount of hydroxyl radicals derived from the ratio of ethylbenzene to xylenes. Thus, the percent contributions to ozone formation from each individual NMHC can be calculated. This concept of consumption is purely observation-based and provides an easy way to bypass complicated modeling and the necessity of knowing instantaneous concentrations of hydroxyl radicals, which are highly illusive in nature.

scholarly journals Sources of humic-like substances in the Pearl River Delta, China: positive matrix factorization analysis of PM<sub>2.5</sub> major components and source markers

2014 ◽  
Vol 14 (17) ◽  
pp. 23913-23947
Author(s):  
B. Y. Kuang ◽  
P. Lin ◽  
X. H. H. Huang ◽  
J. Z. Yu
Keyword(s):  
Matrix Factorization ◽  
Formation Process ◽  
Pearl River Delta ◽  
Pearl River ◽  
Residual Oil ◽  
Positive Matrix ◽  
Secondary Formation ◽  
The Pearl River ◽  
Source Markers ◽  
Suburban Site

Abstract. HUmic-LIke Substances (HULIS), the hydrophobic part of water soluble organic carbon (WSOC), account for a significant fraction of PM2.5 mass. Their source studies are so far largely qualitative. In this study, HULIS and WSOC were determined in 100 PM2.5 samples collected in 2009 at an urban site (Guangzhou) and a suburban site (Nansha) in the Pearl River Delta in South China. The annual average concentration of HULIS was 4.83 and 4.71 μg m−3, constituting 8.5 and 10.2% of the PM2.5 mass, while HULIS-C (the carbon component of HULIS) contributed 48 and 57% of WSOC at the two sites, respectively. HULIS was found to correlate with biomass burning (BB) tracers (i.e., levoglucosan and K) and secondary species (e.g., sulfate and ammonium), suggesting its association with BB emissions and secondary formation processes. Sources of HULIS were investigated using positive matrix factorization analysis of PM2.5 chemical composition data, including major components and source markers. In addition to secondary formation process and BB emissions, residual oil combustion related to shipping was identified for the first time as a significant source of HULIS. Secondary formation process contributed the most, accounting for 49–82% of ambient HULIS at the two sites in different seasons. BB emissions contributed a seasonal average of 8–28%, with more contributions observed in the winter months (November–February) due to crop residue burning during harvest season. Residual oil combustion was revealed to be an important source at the suburban site in summer (44% of HULIS-C) due to its proximity to one of the ports and the shipping lane in the region. Vehicle emissions were found to contribute little to HULIS but had contributions to the hydrophilic WSOC fraction. The contrast in contributions from different combustion sources to HULIS and hydrophilic WSOC suggests that primary sources of HULIS are linked to inefficient combustion. This source analysis suggests further study of HULIS be focused on secondary formation process and source characteristics of HULIS from BB and residual oil combustion.

scholarly journals Assessing photochemical ozone formation in the Pearl River Delta with a photochemical trajectory model

2010 ◽  
Vol 44 (34) ◽  
pp. 4199-4208 ◽  
Author(s):  
H.R. Cheng ◽  
H. Guo ◽  
S.M. Saunders ◽  
S.H.M. Lam ◽  
F. Jiang ◽  
...  
Keyword(s):  
Pearl River Delta ◽  
River Delta ◽  
Pearl River ◽  
Ozone Formation ◽  
Trajectory Model ◽  
The Pearl River Delta ◽  
Photochemical Ozone ◽  
The Pearl River

scholarly journals Sources of humic-like substances in the Pearl River Delta, China: positive matrix factorization analysis of PM<sup>2.5</sup> major components and source markers

2015 ◽  
Vol 15 (4) ◽  
pp. 1995-2008 ◽  
Author(s):  
B. Y. Kuang ◽  
P. Lin ◽  
X. H. H. Huang ◽  
J. Z. Yu
Keyword(s):  
Matrix Factorization ◽  
Formation Process ◽  
Pearl River Delta ◽  
Pearl River ◽  
Residual Oil ◽  
Positive Matrix ◽  
Secondary Formation ◽  
The Pearl River ◽  
Source Markers ◽  
Suburban Site

Abstract. Humic-like substances (HULIS), the hydrophobic part of water-soluble organic carbon (WSOC), account for a significant fraction of PM2.5 mass. Their source studies are so far largely qualitative. In this study, HULIS and WSOC were determined in 100 PM2.5 samples collected in 2009 at an urban site (Guangzhou) and a suburban site (Nansha) in the Pearl River Delta in South China. The annual average concentration of HULIS was 4.83 and 4.71 μg m−3, constituting 8.5 and 10.2% of the PM2.5 mass, while HULIS-C (the carbon component of HULIS) contributed 48 and 57% of WSOC at the two sites, respectively. HULIS were found to correlate with biomass burning (BB) tracers (i.e., levoglucosan and K) and secondary species (e.g., SO42− and NH4+), suggesting its association with BB emissions and secondary formation processes. Sources of HULIS were investigated using positive matrix factorization analysis of PM2.5 chemical composition data, including major components and source markers. In addition to secondary formation process and BB emissions, residual oil combustion related to shipping was identified for the first time as a significant source of HULIS. Secondary formation process contributed the most, accounting for 49–82% of ambient HULIS at the two sites in different seasons. BB emissions contributed a seasonal average of 8–28%, with more contributions observed in the winter months (November–February) due to crop residue burning during harvest season. Residual oil combustion was revealed to be an important source at the suburban site in summer (44% of HULIS-C) due to its proximity to one of the ports and the shipping lane in the region. Vehicle emissions were found to contribute little to HULIS, but had contributions to the hydrophilic WSOC fraction. The contrast in contributions from different combustion sources to HULIS and hydrophilic WSOC suggests that primary sources of HULIS are linked to inefficient combustion. This source analysis suggests further study of HULIS be focused on secondary formation process and source characteristics of HULIS from BB and residual oil combustion.

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