ozone sensitivity
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2022 ◽  
Vol 160 ◽  
pp. 107048
Author(s):  
Jiexiao Xue ◽  
Ting Zhao ◽  
Yifu Luo ◽  
Congke Miao ◽  
Pinjie Su ◽  
...  

2022 ◽  
Author(s):  
Andong Cai ◽  
Bin Wang ◽  
Tianjing Ren ◽  
Wenju Zhang ◽  
Xiaoke Wang ◽  
...  

Abstract Global crop yield loss due to ground-level ozone (O3) concentrations is a major challenge to food security, but a dose-response association is not easy to quantify. Here, we propose using a new metric, O3 sensitivity of crop yield (Yo), to estimate yield loss under different O3 time intervals using four observational databases. The Yo metric shows a non-linear parabola with elevated atmospheric O3 for wheat, maize, rice, soybean, and assorted vegetables. Spatial heterogeneity of yield loss varies as a function of crop type and O3 intervals. Estimates of yield loss from ozone suggest recent losses (2017-2019) may reach as high as 537 million tonnes, with a significant proportion coming with lower (30-40 ppb) exposure (325 million tonnes). Our results suggest that previous research, which only included higher (>40 ppb ozone), may have had grossly underestimated the negative effect of atmospheric O3 on crop production. Suppose these results are endemic to global crop production. In that case, additional research will be necessary to reassess ozone sensitivity and dose-responses, both spatially and temporally, to determine future air pollution impacts.


Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1673
Author(s):  
Mao-Chang Liang ◽  
Yi-Chun Chen ◽  
Yi-Qin Gao ◽  
Xi Zhang ◽  
Yuk L. Yung

The delta values of the isotope composition of atmospheric ozone is ~100‰ (referenced to atmospheric O2). Previous photochemical models, which considered the isotope fractionation processes from both formation and photolysis of ozone, predicted δ49O3 and δ50O3 values, in δ49O3 versus δ50O3 space, that are >10‰ larger than the measurements. We propose that the difference between the model and observations could be explained either by the temperature variation, Chappuis band photolysis, or a combination of the two and examine them. The isotopic fractionation associated with ozone formation increases with temperature. Our model shows that a hypothetical reduction of ~20 K in the nominal temperature profile could reproduce the observations. However, this hypothesis is not consistent with temperatures obtained by in situ measurements and NCEP Reanalysis. Photolysis of O3 in the Chappuis band causes O3 to be isotopically depleted, which is supported by laboratory measurements for 18O18O18O but not by recent new laboratory data made at several wavelengths for 49O3 and 50O3. Cloud reflection can significantly enhance the photolysis rate and affect the spectral distribution of photons, which could influence the isotopic composition of ozone. Sensitivity studies that modify the isotopic composition of ozone by the above two mechanisms are presented. We conclude isotopic fractionation occurring in photolysis in the Chappuis band remains the most plausible solution to the model-observation discrepancy. Implications of our results for using the oxygen isotopic signature for constraining atmospheric chemical processes related to ozone, such as CO2, nitrate, and the hydroxyl radical, are discussed.


2021 ◽  
Vol 21 (20) ◽  
pp. 15447-15460
Author(s):  
Danran Li ◽  
Shanshan Wang ◽  
Ruibin Xue ◽  
Jian Zhu ◽  
Sanbao Zhang ◽  
...  

Abstract. In recent years, satellite remote sensing has been increasingly used in the long-term observation of ozone (O3) precursors and its formation regime. In this work, formaldehyde (HCHO) data from Ozone Monitoring Instrument (OMI) were used to analyze the temporal and spatial distribution of HCHO vertical column densities (VCDs) in Shanghai from 2010 to 2019. HCHO VCDs exhibited the highest value in summer and the lowest in winter, the high VCD being concentrated in western Shanghai. Temperature largely influences HCHO by affecting the biogenic emissions and photochemical reactions, and industry was the major anthropogenic source. The satellite-observed formaldehyde-to-nitrogen dioxide ratio (FNRSAT) reflects that the O3 formation regime had significant seasonal characteristics and gradually manifested as a transitional ozone formation regime dominating in Shanghai. The uneven distribution in space was mainly reflected in the higher FNRSAT and surface O3 concentration in suburban areas. To compensate for the shortcoming of FNRSAT that it can only characterize O3 formation around satellite overpass time, correction of FNRSAT was implemented with hourly surface FNR and O3 data. After correction, the O3 formation regime showed the trend moving towards being VOC-limited in both time and space, and the regime indicated by FNRSAT can better reflect O3 formation for a day. This study can help us better understand HCHO characteristics and O3 formation regimes in Shanghai and also provide a method to improve FNRSAT for characterizing O3 formation in a day, which will be significant for developing O3 prevention and control strategies.


Urban Climate ◽  
2021 ◽  
Vol 39 ◽  
pp. 100980
Author(s):  
Ashima Sharma ◽  
Sudhir Kumar Sharma ◽  
Tuhin Kumar Mandal

2021 ◽  
Author(s):  
Zhenze Liu ◽  
Ruth M. Doherty ◽  
Oliver Wild ◽  
Fiona M. O’Connor ◽  
Steven T. Turnock

Abstract. Tropospheric ozone is important to future air quality and climate. We investigate ozone changes and ozone sensitivity to changing emissions in the context of climate change from the present day (2004–2014) to the future (2045–2055) under a range of shared socio-economic pathways (SSPs). We apply the United Kingdom Earth System Model, UKESM1, with an extended chemistry scheme including more reactive volatile organic compounds (VOCs) to quantify ozone burdens as well as ozone sensitivities globally and regionally based on nitrogen oxide (NOx) and VOC concentrations. We show that the tropospheric ozone burden increases by 4 % under a development pathway with higher NOx and VOC emissions (SSP3-7.0), but decreases by 7 % under the same pathway if NOx and VOC emissions are reduced (SSP3-7.0-lowNTCF) and by 5 % if atmospheric methane (CH4) concentrations are reduced (SSP3-7.0-lowCH4). Global mean surface ozone concentrations are reduced by 3–5 ppb under SSP3-7.0-lowNTCF and by 2–3 ppb under SSP3-7.0-lowCH4. However, surface ozone changes vary substantially by season in high-emission regions under future pathways, with decreased ozone concentrations in summer and increased ozone concentrations in winter when NOx emissions are reduced. VOC-limited areas are more extensive in winter (7 %) than in summer (3 %) across the globe. North America, Europe and East Asia are the dominant VOC-limited regions in the present day but North America and Europe become more NOx-limited in the future mainly due to reductions in NOx emissions. The impacts of VOC emissions on O3 sensitivity are limited in North America and Europe because reduced anthropogenic VOC emissions are offset by higher biogenic VOC emissions. O3 sensitivity is not greatly influenced by changing CH4 concentrations. South Asia becomes the dominant VOC-limited region under future pathways. We highlight that reductions in NOx emissions are required to transform O3 production from VOC- to NOx-limitation, but that these lead to increased O3 concentrations in high-emission regions, and hence emission controls on VOC and CH4 are also necessary.


2021 ◽  
Vol 21 (9) ◽  
pp. 7253-7269
Author(s):  
Wannan Wang ◽  
Ronald van der A ◽  
Jieying Ding ◽  
Michiel van Weele ◽  
Tianhai Cheng

Abstract. Ground-level ozone (O3) pollution has been steadily getting worse in most parts of eastern China during the past 5 years. The non-linearity of O3 formation with its precursors like nitrogen oxides (NOx= NO + NO2) and volatile organic compounds (VOCs) are complicating effective O3 abatement plans. The diagnosis from space-based observations, i.e. the ratio of formaldehyde (HCHO) columns to tropospheric NO2 columns (HCHO / NO2), has previously been proved to be highly consistent with our current understanding of surface O3 chemistry. HCHO / NO2 ratio thresholds distinguishing O3 formation sensitivity depend on regions and O3 chemistry interactions with aerosol. To shed more light on the current O3 formation sensitivity over China, we have derived HCHO / NO2 ratio thresholds by directly connecting satellite-based HCHO / NO2 observations and ground-based O3 measurements over the major Chinese cities in this study. We find that a VOC-limited regime occurs for HCHO / NO2 < 2.3, and a NOx-limited regime occurs for HCHO / NO2 > 4.2. The HCHO / NO2 between 2.3 and 4.2 reflects the transition between the two regimes. Our method shows that the O3 formation sensitivity tends to be VOC-limited over urban areas and NOx-limited over rural and remote areas in China. We find that there is a shift in some cities from the VOC-limited regime to the transitional regime that is associated with a rapid drop in anthropogenic NOx emissions, owing to the widely applied rigorous emission control strategies between 2016 and 2019. This detected spatial expansion of the transitional regime is supported by rising surface O3 concentrations. The enhanced O3 concentrations in urban areas during the COVID-19 lockdown in China indicate that a protocol with simultaneous anthropogenic NOx emissions and VOC emissions controls is essential for O3 abatement plans.


2021 ◽  
Author(s):  
Adalena V Nanni ◽  
Alison M Morse ◽  
Jeremy RB Newman ◽  
Nicole E Choquette ◽  
Jessica M Wedow ◽  
...  

The maize pangenome has demonstrate large amounts of presence/absence variation and it has been hypothesized that presence/absence variation contributes to stress response. To uncover whether the observed genetic variation in physiological response to elevated ozone (a secondary air pollutant that causes significant crop yield losses) concentration is due to variation in genic content, and/or variation in gene expression, we examine the impact of sustained elevated ozone concentration on the leaf tissue from 5 diverse maize inbred genotypes (B73, Mo17, Hp301, C123, NC338). Analysis of long reads from the transcriptomes of the 10 conditions found expressed genes in the leaf are part of the shared genome, with 94.5% of expressed genes from syntenic loci. Quantitative analysis of short reads from 120 plants (twelve from each condition) found limited transcriptional response to sustained ozone stress in the ozone resistant B73 genotype (151 genes), while more than 3,300 genes were significantly differentially expressed in the more sensitive NC338 genotype. The genes underpinning the divergence of B73 from the other 4 genotypes implicates ethylene signaling consistent with some findings in Arabidopsis. For the 82 of the 83 genes differentially expressed among all 5 genotypes and the 788 of 789 genes differentially expressed in 4 genotypes (excluding B73) in sensitivity to ozone is associated with oxidative stress tolerance being associated with a weaker response to a reactive oxygen species (ROS) signal and suggests that genetic variation in downstream processes is key to ozone tolerance.


2021 ◽  
Author(s):  
Noel Clancy ◽  
William Collins ◽  
Pier Luigi Vidale ◽  
Gerd Folberth

&lt;p&gt;Carbon uptake by land ecosystems is a hugely important carbon sink for the Earth's climate. Plants uptake carbon dioxide from the atmosphere via pores on the surface of their leaves called stomata. However, ozone can also be taken up by plants in this way leading to damage to the plant, a decrease in its growth rate and an impact on the carbon cycle. Ozone damage to plants also modifies other processes within the ecosystem such as transpiration and respiration rates, thereby effecting the hydrological cycle and energy cycle. The Joint UK Land and Environment Simulator (JULES) land-surface model includes ozone sensitivity parameters for all its vegetation cover (plant functional types). Our recent results from JULES experiments at FLUXNET sites show that ozone reduces photosynthesis and suppresses transpiration, thereby impacting the carbon, heat and water fluxes in JULES. Furthermore, we identify differences in a quantitative impact on leaf phenology.&lt;/p&gt;


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