scholarly journals Impact of International Shipping Emissions on Ozone and PM<sub>2.5</sub>: The Important Role of HONO and ClNO<sub>2</sub>

2021 ◽  
Author(s):  
Jianing Dai ◽  
Tao Wang
Keyword(s):  
Particulate Matter ◽  
Marine Boundary Layer ◽  
Transport Model ◽  
Fine Particulate Matter ◽  
Oxidative Capacity ◽  
Oh Radicals ◽  
Ship Emissions ◽  
Secondary Pollutants ◽  
Marine Areas ◽  
The Impact

Abstract. Ocean-going ships emit large amounts of air pollutants such as nitrogen oxide (NOx) and particulate matter. Ship-released NOx can be converted to nitrous acid (HONO) and nitryl chloride (ClNO2), which produce hydroxyl (OH) and chlorine (Cl) radicals and recycle NOx, thus affecting the oxidative capacity and production of secondary pollutants. However, these effects have not been quantified in previous investigations of the impacts of ship emissions. In this study, a regional transport model (WRF–Chem) revised to incorporate the latest HONO and ClNO2 processes was used to investigate their effects on the concentrations of ROx (RO2+HO2+OH) radicals, O3, and fine particulate matter (PM2.5) in Asia during summer. The results show that the ship-derived HONO and ClNO2 increased the concentration of ROx radicals by approximately two to three times in the marine boundary layer. The enhanced radicals then increased the O3 and PM2.5 concentrations in marine areas, with the ship contributions increasing from 9 % to 21 % and from 7 % to 10 %, respectively. The largest ROx enhancement was simulated over the remote ocean with the ship contribution increasing from 29 % to 50 %, which led to increases in ship-contributed O3 and PM2.5 from 21 % to 38 % and from 13 % to 19 %, respectively. In coastal cities, the enhanced levels of radicals also increased the maximum O3 and averaged PM2.5 concentrations from 5 % to 11 % and from 4 % to 8 % to 4 % to 12 %, respectively. These findings indicate that modeling studies without considering HONO and ClNO2 can significantly underestimate the impact of ship emissions on radicals and secondary pollutants. It is therefore important that these nitrogen compounds be included in future models of the impact of ship emissions on air quality.

scholarly journals Impact of international shipping emissions on ozone and PM<sub>2.5</sub> in East Asia during summer: the important role of HONO and ClNO<sub>2</sub>

2021 ◽  
Vol 21 (11) ◽  
pp. 8747-8759
Author(s):  
Jianing Dai ◽  
Tao Wang
Keyword(s):  
Particulate Matter ◽  
Marine Boundary Layer ◽  
Transport Model ◽  
Fine Particulate Matter ◽  
Oxidative Capacity ◽  
Oh Radicals ◽  
Ship Emissions ◽  
Secondary Pollutants ◽  
Modelling Studies ◽  
The Impact

Abstract. Ocean-going ships emit large amounts of air pollutants such as nitrogen oxide (NOx) and particulate matter. NOx emitted from ships can be converted to nitrous acid (HONO) and nitryl chloride (ClNO2), which produce hydroxyl (OH) and chlorine (Cl) radicals and recycle NOx, thereby affecting the oxidative capacity and production of secondary pollutants. However, these effects have not been quantified in previous investigations of the impacts of ship emissions. In this study, a regional transport model (WRF-Chem) revised to incorporate the latest HONO and ClNO2 processes was used to investigate their effects on the concentrations of ROx (RO2 + HO2 + OH) radicals, ozone (O3), and fine particulate matter (PM2.5) in Asia during summer. The results show that the ship-derived HONO and ClNO2 increased the concentration of ROx radicals by approximately 2–3 times in the marine boundary layer. The enhanced radicals then increased the O3 and PM2.5 concentrations in marine areas, with the ship contributions increasing from 9 % to 21 % and from 7 % to 10 % respectively. The largest ROx enhancement was simulated over the remote ocean with the ship contribution increasing from 29 % to 50 %, which led to increases in ship-contributed O3 and PM2.5 from 21 % to 38 % and from 13 % to 19 % respectively. In coastal cities, the enhanced levels of radicals also increased the maximum O3 and averaged PM2.5 concentrations from 5 % to 11 % and from 4 %–8 % to 4 %–12 % respectively. These findings indicate that modelling studies that do not consider HONO and ClNO2 can significantly underestimate the impact of ship emissions on radicals and secondary pollutants. Therefore, it is important that these nitrogen compounds be included in future models of the impact of ship emissions on air quality.

scholarly journals Effect of Short-Term Exposure to Fine Particulate Matter and Temperature on Acute Myocardial Infarction in Korea

2021 ◽  
Vol 18 (9) ◽  
pp. 4822
Author(s):  
Jiyoung Shin ◽  
Jongmin Oh ◽  
In Sook Kang ◽  
Eunhee Ha ◽  
Wook Bum Pyun
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Particulate Matter ◽  
Fine Particulate Matter ◽  
Ambient Air ◽  
Cold Season ◽  
Short Term ◽  
Fine Particulate ◽  
Short Term Exposure ◽  
The Impact

Background/Aim: Previous studies have suggested that the short-term ambient air pollution and temperature are associated with myocardial infarction. In this study, we aimed to conduct a time-series analysis to assess the impact of fine particulate matter (PM2.5) and temperature on acute myocardial infarction (AMI) among adults over 20 years of age in Korea by using the data from the Korean National Health Information Database (KNHID). Methods: The daily data of 192,567 AMI cases in Seoul were collected from the nationwide, population-based KNHID from 2005 to 2014. The monitoring data of ambient PM2.5 from the Seoul Research Institute of Public Health and Environment were also collected. A generalized additive model (GAM) that allowed for a quasi-Poisson distribution was used to analyze the effects of PM2.5 and temperature on the incidence of AMI. Results: The models with PM2.5 lag structures of lag 0 and 2-day averages of lag 0 and 1 (lag 01) showed significant associations with AMI (Relative risk [RR]: 1.011, CI: 1.003–1.020 for lag 0, RR: 1.010, CI: 1.000–1.020 for lag 01) after adjusting the covariates. Stratification analysis conducted in the cold season (October–April) and the warm season (May–September) showed a significant lag 0 effect for AMI cases in the cold season only. Conclusions: In conclusion, acute exposure to PM2.5 was significantly associated with AMI morbidity at lag 0 in Seoul, Korea. This increased risk was also observed at low temperatures.

scholarly journals Key chemical NO<sub>x</sub> sink uncertainties and how they influence top-down emissions of nitrogen oxides

2013 ◽  
Vol 13 (17) ◽  
pp. 9057-9082 ◽  
Author(s):  
T. Stavrakou ◽  
J.-F. Müller ◽  
K. F. Boersma ◽  
R. J. van der A ◽  
J. Kurokawa ◽  
...  
Keyword(s):  
South Asia ◽  
Transport Model ◽  
Field Studies ◽  
Anthropogenic Source ◽  
Oh Radicals ◽  
Top Down ◽  
Model Calculations ◽  
Tropical Regions ◽  
Recent Developments ◽  
The Impact

Abstract. Triggered by recent developments from laboratory and field studies regarding major NOx sink pathways in the troposphere, this study evaluates the influence of chemical uncertainties in NOx sinks for global NOx distributions calculated by the IMAGESv2 chemistry-transport model, and quantifies their significance for top-down NOx emission estimates. Our study focuses on five key chemical parameters believed to be of primary importance, more specifically, the rate of the reaction of NO2 with OH radicals, the newly identified HNO3-forming channel in the reaction of NO with HO2, the reactive uptake of N2O5 and HO2 by aerosols, and the regeneration of OH in the oxidation of isoprene. Sensitivity simulations are performed to estimate the impact of each source of uncertainty. The model calculations show that, although the NO2+OH reaction is the largest NOx sink globally accounting for ca. 60% of the total sink, the reactions contributing the most to the overall uncertainty are the formation of HNO3 in NO+HO2, leading to NOx column changes exceeding a factor of two over tropical regions, and the uptake of HO2 by aqueous aerosols, in particular over East and South Asia. Emission inversion experiments are carried out using model settings which either minimise (MINLOSS) or maximise (MAXLOSS) the total NOx sink, both constrained by one year of OMI NO2 column data from the DOMINO v2 KNMI algorithm. The choice of the model setup is found to have a major impact on the top-down flux estimates, with 75% higher emissions for MAXLOSS compared to the MINLOSS inversion globally. Even larger departures are found for soil NO (factor of 2) and lightning (1.8). The global anthropogenic source is better constrained (factor of 1.57) than the natural sources, except over South Asia where the combined uncertainty primarily associated to the NO+HO2 reaction in summer and HO2 uptake by aerosol in winter lead to top-down emission differences exceeding a factor of 2. Evaluation of the emission optimisation is performed against independent satellite observations from the SCIAMACHY sensor, with airborne NO2 measurements of the INTEX-A and INTEX-B campaigns, as well as with two new bottom-up inventories of anthropogenic emissions in Asia (REASv2) and China (MEIC). Neither the MINLOSS nor the MAXLOSS setup succeeds in providing the best possible match with all independent datasets. Whereas the minimum sink assumption leads to better agreement with aircraft NO2 profile measurements, consistent with the results of a previous analysis (Henderson et al., 2012), the same assumption leads to unrealistic features in the inferred distribution of emissions over China. Clearly, although our study addresses an important issue which was largely overlooked in previous inversion exercises, and demonstrates the strong influence of NOx loss uncertainties on top-down emission fluxes, additional processes need to be considered which could also influence the inferred source.

The Impact of The Pico Y Placa Policy On Fine Particulate Matter In Lima, Peru

2021 ◽  
Author(s):  
Yovitza Romero ◽  
Priyanka deSouza ◽  
Fabio Duarte ◽  
Patrick Kinney ◽  
Carlo Ratti ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Fine Particulate Matter ◽  
Vehicular Emissions ◽  
Government Officials ◽  
Pollution Levels ◽  
Particulate Matter Concentration ◽  
Fine Particulate ◽  
The Impact ◽  
The City ◽  
Matter Concentration

Abstract Lima has been ranked among the top most polluted cities in the Americas. Vehicular emissions are the dominant source of pollution in the city. In order to reduce congestion and pollution levels during the XVIII Pan- and Parapan-American Games, Lima government officials enacted the pico y placa policy to restrict the number of vehicles on certain heavily trafficked roads in the city at rush hours between Monday to Thursday based on the last digit of their license plates. This policy was retained after the Games. In this paper we evaluate the impact of this policy on fine particulate matter concentration levels (PM2.5) at a background site in the city using a difference-in-difference approach. We find that the policy resulted in increases on PM2.5 levels on Monday-Thursday compared to Friday-Sunday levels after the policy was enacted, compared to previous years. However, such an increase was not significant. These results suggest the need for additional policies to reduce pollution due to traffic in Lima. It also suggests the need to track the response to this policy over time to evaluate its efficacy.

scholarly journals Influences of hydroxyl radicals (OH) on top-down estimates of the global and regional methane budgets

2020 ◽  
Author(s):  
Yuanhong Zhao ◽  
Marielle Saunois ◽  
Philippe Bousquet ◽  
Xin Lin ◽  
Antoine Berchet ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Climate Models ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Temporal Variations ◽  
Oh Radicals ◽  
Chemical Transport Model ◽  
Top Down ◽  
Ch4 Emissions ◽  
The Impact

Abstract. The hydroxyl radical (OH), which is the dominant sink of methane (CH4), plays a key role to close the global methane budget. Previous research that assessed the impact of OH changes on the CH4 budget mostly relied on box modeling inversions with a very simplified atmospheric transport and no representation of the heterogeneous spatial distribution of OH radicals. Here using a variational Bayesian inversion framework and a 3D chemical transport model, LMDz, combined with 10 different OH fields derived from chemistry-climate models (CCMI experiment), we evaluate the influence of OH burden, spatial distribution, and temporal variations on the global CH4 budget. The global tropospheric mean CH4-reaction-weighted [OH] ([OH]GM-CH4) ranges 10.3–16.3 × 105 molec cm−3 across 10 OH fields during the early 2000s, resulting in inversion-based global CH4 emissions between 518 and 757 Tg yr−1. The uncertainties in CH4 inversions induced by the different OH fields are comparable to, or even larger than the uncertainty typically given by bottom-up and top-down estimates. Based on the LMDz inversions, we estimate that a 1 %-increase in OH burden leads to an increase of 4 Tg yr−1 in the estimate of global methane emissions, which is about 25 % smaller than what is estimated by box-models. The uncertainties in emissions induced by OH are largest over South America, corresponding to large inter-model differences of [OH] in this region. From the early to the late 2000s, the optimized CH4 emissions increased by 21.9 ± 5.7 Tg yr−1 (16.6–30.0 Tg yr−1), of which ~ 25 % (on average) is contributed by −0.5 to +1.8 % increase in OH burden. If the CCMI models represent the OH trend properly over the 2000s, our results show that a higher increasing trend of CH4 emissions is needed to match the CH4 observations compared to the CH4 emission trend derived using constant OH. This study strengthens the importance to reach a better representation of OH burden and of OH spatial and temporal distributions to reduce the uncertainties on the global CH4 budget.

The impact of polar fraction of the fine particulate matter on redox responses in different rat tissues

2019 ◽  
Vol 26 (31) ◽  
pp. 32476-32487 ◽  
Author(s):  
Joaquim de Paula Ribeiro ◽  
Ana Cristina Kalb ◽  
Sabrina de Bastos Maya ◽  
Adriana Gioda ◽  
Pablo Elias Martinez ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Fine Particulate Matter ◽  
Polar Fraction ◽  
Rat Tissues ◽  
Fine Particulate ◽  
The Impact

scholarly journals Constraints and biases in a tropospheric two-box model of OH

2019 ◽  
Vol 19 (1) ◽  
pp. 407-424 ◽  
Author(s):  
Stijn Naus ◽  
Stephen A. Montzka ◽  
Sudhanshu Pandey ◽  
Sourish Basu ◽  
Ed J. Dlugokencky ◽  
...  
Keyword(s):  
Transport Model ◽  
Absolute Magnitude ◽  
Oxidative Capacity ◽  
Box Model ◽  
Surface Measurement ◽  
Positive Trend ◽  
Model Inversion ◽  
Methyl Chloroform ◽  
The Impact ◽  
Bias Corrections

Abstract. The hydroxyl radical (OH) is the main atmospheric oxidant and the primary sink of the greenhouse gas CH4. In an attempt to constrain atmospheric levels of OH, two recent studies combined a tropospheric two-box model with hemispheric-mean observations of methyl chloroform (MCF) and CH4. These studies reached different conclusions concerning the most likely explanation of the renewed CH4 growth rate, which reflects the uncertain and underdetermined nature of the problem. Here, we investigated how the use of a tropospheric two-box model can affect the derived constraints on OH due to simplifying assumptions inherent to a two-box model. To this end, we derived species- and time-dependent quantities from a full 3-D transport model to drive two-box model simulations. Furthermore, we quantified differences between the 3-D simulated tropospheric burden and the burden seen by the surface measurement network of the National Oceanic and Atmospheric Administration (NOAA). Compared to commonly used parameters in two-box models, we found significant deviations in the magnitude and time-dependence of the interhemispheric exchange rate, exposure to OH, and stratospheric loss rate. For MCF these deviations can be large due to changes in the balance of its sources and sinks over time. We also found that changes in the yearly averaged tropospheric burden of CH4 and MCF can be obtained within 0.96 ppb yr−1 and 0.14 % yr−1 by the NOAA surface network, but that substantial systematic biases exist in the interhemispheric mixing ratio gradients that are input to two-box model inversions. To investigate the impact of the identified biases on constraints on OH, we accounted for these biases in a two-box model inversion of MCF and CH4. We found that the sensitivity of interannual OH anomalies to the biases is modest (1 %–2 %), relative to the uncertainties on derived OH (3 %–4 %). However, in an inversion where we implemented all four bias corrections simultaneously, we found a shift to a positive trend in OH concentrations over the 1994–2015 period, compared to the standard inversion. Moreover, the absolute magnitude of derived global mean OH, and by extent, that of global CH4 emissions, was affected much more strongly by the bias corrections than their anomalies (∼10 %). Through our analysis, we identified and quantified limitations in the two-box model approach as well as an opportunity for full 3-D simulations to address these limitations. However, we also found that this derivation is an extensive and species-dependent exercise and that the biases were not always entirely resolvable. In future attempts to improve constraints on the atmospheric oxidative capacity through the use of simple models, a crucial first step is to consider and account for biases similar to those we have identified for the two-box model.

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