Relationships of ozone formation sensitivity with precursors emissions, meteorology and land use types, in Guangdong-Hong Kong-Macao Greater Bay Area, China

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Abstract

Due to the influences of precursors emissions, meteorology, geography and other factors, ozone formation sensitivity (OFS) is generally spatially and temporally heterogeneous. This study characterized detailed spatial and temporal variations of OFS in Guangdong-Hong Kong-Macao Greater Bay Area (GBA) from 2012 to 2016 based on OMI satellite data, and analyzed the relationships of OFS with precursors emissions, meteorology and land use types (LUTs). From 2012 to 2016, the OFS tended to be NOx-limited in GBA, with the value of FNR (HCHO/NO2) increasing from 2.04 to 2.22. According to the total annual emission statistics of precursors, NOx emissions decreased by 33.1% and VOCs emissions increased by 35.2% from 2012 to 2016, directly resulting in OFS tending to be NOx-limited. The Grey Relation Analysis results show that total column water (TCW), surface net solar radiation (SSR), air temperature at 2 m (T2) and surface pressure (SP) are the top four meteorological factors with the greatest influences on OFS. There are significant positive correlations between FNR and T2, SSR, TCW, and significant negative correlations between FNR and SP. In GBA, the OFS tends to be NOx-limited regime in wet season (higher T2, SSR, TCW and lower SP) and VOCs-limited regime in dry season (lower T2, SSR, TCW and higher SP). The FNR displays obvious gradient variations on different LUTs, with the highest in “Rural areas”, second in “Suburban areas” and lowest in “Urban areas”.

Introduction

Stratospheric ozone (the ozone layer) can block excessive ultraviolet entering the troposphere and reaching the earth's surface, but tropospheric ozone is harmful to human health and the environment (Aneja and Li, 1992; Weisel et al., 1995). Tropospheric ozone is a component of photochemical smog, which is detrimental to the eyes, respiratory system and lung function of human beings, and it can reduce crop production, especially at high concentrations (Reich and Amundson, 1985; Linn et al., 1994; White et al., 1994; Wang, 1999). Ozone is also a greenhouse gas (Xing et al., 2011).

The frequently reported air pollution episodes of fine particulate matter (PM2.5) and ozone (O3), are ascribed to rapid industrialization, urbanization, and growth of motor vehicles in China (Wang et al., 2006; Zhang et al., 2008a; Shao et al., 2009; Zhao et al., 2009; Jiang et al., 2010; Peng et al., 2011a). To improve air quality, the Chinese government has implemented stringent air pollution control measures for the reduction of sulfur dioxide (SO2), nitrogen oxides (NOx), particulate matter (PM) and volatile organic compounds (VOCs) from 2013 to 2017, which was embodied in the Action Plan for the Prevention and Control of Air Pollution.

According to 74 cities’ monitoring results in China, the percentage of ozone non-compliant cities had increased from 23% to 38% from 2013 to 2017. However, other pollutants achieved marked improvement (2013-2017 Report on the State of Environment in China, available at http://www.mep.gov.cn, in Chinese). There was a same circumstance in Guangdong-Hong Kong-Macao Greater Bay Area (GBA), with annual average ozone concentrations increasing from 48 to 58 μg/m3, whereas, other pollutants (SO2, NO2, and PM10) decreased by 36 μg/m3, 12 μg/m3, and 25 μg/m3, respectively, from 2006 to 2017 (Guangdong-Hong Kong-Macao-Pearl River Delta Regional Air Quality Monitoring Network: A Report of Monitoring Results in 2017, available at http://www.gdep.gov.cn/, in Chinese). In conclusion, ozone pollution control is urgent in GBA, and it needs more scientific strategies by considering ozone chemical formation sensitivity.

Near-surface ozone forms via a complex series of photochemical reactions among NOx and VOCs in the presence of sunlight (Haagen-Smit, 1952). The correct strategies for controlling ozone formation depend on the applicable photochemical regime, namely, whether ozone production is NOx-limited or VOCs-limited (Dodge, 1987). The major indicators of ozone formation sensitivity (OFS) to its precursors include VOCs/NOx ratio method, Smog Production Model, and Relative Incremental Reactivity (Li et al., 2017a). The VOCs/NOx ratio method is generally used in investigating the OFS based on satellite data. Formaldehyde (HCHO) is a short-lived oxidation product of VOCs, so it is usually regarded as a proxy for VOCs reactivity, especially in regions where biogenic activity is intense (Sillman, 1995; Witte et al., 2011). Sillman (1995) first used the concentrations ratio of HCHO to total reactive nitrogen (NOy) to determine the chemical sensitivity of ozone production. Martin et al. (2004) extended Sillman's method to space-based measurement from Global Ozone Monitoring Experiment (GOME) and proposed that the HCHO/NO2 ratio (FNR) is a more reasonable OFS indicator. Based on this indicator, many scholars explored the OFS around the world using satellite data. Martin et al. (2004) found that surface ozone was more sensitive to NOx emissions than VOCs emissions, over most continental regions of the Northern Hemisphere in summer. Duncan et al. (2010) found that surface ozone formation became more sensitive to NOx over most regions of the United States from 2005 to 2007, due to substantially reduction of NOx emission and increment of biogenic isoprene with rising temperature. Jin and Holloway (2015) implied that NOx controls would be more effective for O3 reduction in Pearl River Delta (PRD), regardless of season. Among several commonly used satellite data, the OMI data is more applicable for revealing the spatial and temporal gradient variations of OFS because of its finer resolution (Witte et al., 2011; Jin and Holloway, 2015; Shan et al., 2016; Jin et al., 2017; Wu et al., 2018).

Influenced by ozone precursors emissions, meteorology, geography and other relative factors, OFS is usually spatially and temporally heterogeneous (Zhang et al., 2008a; Xing et al., 2011; Li et al., 2013). There are many researches investigating the effects of chemical precursors and meteorology on surface ozone but seldom on surface OFS (Tu et al., 2007; Lou et al., 2015; Yadav et al., 2016; Sharma et al., 2017; Wang et al., 2017; Li et al., 2019; Wang et al., 2019). The emitted precursors are directly involved in the production of ozone and determine the sensitivity of local ozone formation. In addition to local precursors emissions, meteorological conditions are critical in the formation and transmission of ozone. Air temperature, solar radiation, relative humidity, boundary layer height, wind speed and direction play an important role in the formation, dilution, diffusion and transport of ozone and its precursors. Furthermore, the OFS characteristics are different between urban sites and rural sites (Duncan et al., 2010; Peng et al., 2011b; Carrillo-Torres et al., 2017), but few studies have investigated the OFS based on land use type classifications.

In this study, we presented the spatial and temporal characterizations of O3-VOCs-NOx sensitivity over GBA from 2012 to 2016, based on OMI remote sensing data with finer resolution of 0.125°. Subsequently, the impacts of chemical precursors emissions and meteorological factors on OFS were analyzed. Furthermore, the relationships between OFS and different land use types (LUTs) were given. This study can be combined with meteorological forecast and sources emission simulation to comprehensively evaluate and predict the OFS on regions. What's more, it will provide an important scientific basis for formulating more local and scientific ozone pollution prevention and control measures based on the refined spatial and temporal variation characteristics of OFS and the relationships between OFS and its associated factors.

Section snippets

Study area

The GBA is located in southern China (Fig. 1). It consists of 11 cities, including Guangzhou (GZ), Shenzhen (SZ), Foshan (FS), Dongguan (DG), Zhuhai (ZH), Zhongshan (ZS), Zhaoqing (ZQ), Jiangmen (JM), Huizhou (HZ), Hong Kong (HK) Special Administrative Region (SAR) and Macao (MC) SAR. The GBA covers a total area of about 56,000 square kilometers, and the resident population was more than 70 million in 2018. In recent years, the total gross domestic product of GBA was increasing rapidly, around

Spatial and temporal characteristics

The spatial variations of NO2, HCHO column concentrations and FNR in GBA from 2012 to 2016 are shown in Fig. 2. The spatial distribution of NO2 was characterized by higher concentrations in central cities (GZ, FS, DG, SZ, ZS, ZH, HK and MC) and lower concentrations in peripheral cities (ZQ, HZ and JM). The NO2 pollution is generally occurred in areas with larger populations, more industry and traffic, where human activities are comparably active (Boersma et al., 2008). The severe NO2 polluted

Conclusions

During the research period, the NO2 column concentrations decreased by 1.82 × 1015 mol/cm2 in central cities and 0.95 × 1015 mol/cm2 in peripheral cities, while the HCHO column concentrations decreased by 1.77 × 1015 mol/cm2 in central cities and 0.64 × 1015 mol/cm2 in peripheral cities. As a result, the FNR increased in GBA, indicating that OFS was tending to be more sensitive to NOx during the five years. The OFS results are mostly consistent with those investigated by other scholars, though

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 41605092), and the National Key R&D Program of China (No. 2017YFC0212801). We acknowledge the Tropospheric Emission Monitoring Internet Service for OMI tropospheric NO2 column and HCHO column products. We also thank Tsinghua University, ECMWF and NASA for free access to the Multi-resolution Emission Inventory for China (MEIC) data, the reanalysis meteorological data (ERA-Interim) and the MODIS land cover type

References (63)

  • Y.P. Peng et al.

    Applying model simulation and photochemical indicators to evaluate ozone sensitivity in southern Taiwan

    J. Environ. Sci.

    (2011)
  • M. Shao et al.

    Ground-level ozone in the Pearl River Delta and the roles of VOC and NOx in its production

    J. Environ. Manag.

    (2009)
  • J. Tu et al.

    Temporal variations in surface ozone and its precursors and meteorological effects at an urban site in China

    Atmos. Res.

    (2007)
  • P. Wang et al.

    Responses of PM2.5 and O3 concentrations to changes of meteorology and emissions in China

    Sci. Total Environ.

    (2019)
  • T. Wang et al.

    Ozone pollution in China: a review of concentrations, meteorological influences, chemical precursors, and effects

    Sci. Total Environ.

    (2017)
  • X. Wang et al.

    Decoupled direct sensitivity analysis of regional ozone pollution over the Pearl River Delta during the PRIDE-PRD2004 campaign

    Atmos. Environ.

    (2011)
  • M.C. White et al.

    Exacerbations of childhood asthma and ozone pollution in Atlanta

    Environ. Res.

    (1994)
  • J.C. Witte et al.

    The unique OMI HCHO/NO2 feature during the 2008 Beijing Olympics: Implications for ozone production sensitivity

    Atmos. Environ.

    (2011)
  • R. Yadav et al.

    Role of long-range transport and local meteorology in seasonal variation of surface ozone and its precursors at an urban site in India

    Atmos. Res.

    (2016)
  • Y.H. Zhang et al.

    Regional integrated experiments on air quality over Pearl River Delta 2004 (PRIDE-PRD2004): Overview

    Atmos. Environ.

    (2008)
  • Y.H. Zhang et al.

    Regional ozone pollution and observation-based approach for analyzing ozone–precursor relationship during the PRIDE-PRD2004 campaign

    Atmos. Environ.

    (2008)
  • V.P. Aneja et al.

    Characterization of ozone at high elevation in the eastern United States: trends, seasonal variations, and exposure

    J. Geophys. Res.

    (1992)
  • S. Beirle et al.

    Weekly cycle of NO2 by GOME measurements: a signature of anthropogenic sources

    Atmos. Chem. Phys.

    (2003)
  • K.F. Boersma et al.

    Error analysis for tropospheric NO2 retrieval from space

    J. Geophys. Res.: Atmos.

    (2004)
  • K.F. Boersma et al.

    An improved tropospheric NO2 column retrieval algorithm for the Ozone Monitoring Instrument

    Atmos. Meas. Tech.

    (2011)
  • E.R. Carrillo-Torres et al.

    Use of combined observational-and model-derived photochemical indicators to assess the O3-NOx-VOC system sensitivity in urban areas

    Atmosphere.

    (2017)
  • E.A. Celarier et al.

    Validation of ozone monitoring instrument nitrogen dioxide columns

    J. Geophys. Res.

    (2008)
  • H. Cheng et al.

    On the relationship between ozone and its precursors in the Pearl River Delta: application of an observation-based model (OBM)

    Environ. Sci. Pollut. Res.

    (2010)
  • I. De Smedt et al.

    Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations

    Atmos. Chem. Phys.

    (2015)
  • J. Deng

    Introduction to grey system theory

    J. Grey Syst.

    (1989)
  • M.C. Dodge

    Chemistry of Oxidant Formation: Implications for Designing Effective Control Strategies

    (1987)
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