Wet deposition of inorganic ions in 320 cities across China: spatio-temporal variation, source apportionment, and dominant factors

Li, Rui; Cui, Lulu; Zhao, Yilong; Zhang, Ziyu; Sun, Tianming; Li, Junlin; Zhou, Wenhui; Meng, Yaobin; Huang, Kan; Fu, Hongbo

doi:10.5194/acp-19-11043-2019

Cited by 41 publications

(30 citation statements)

References 155 publications

(160 reference statements)

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“…The level of salinity as indicated by the colour-coded map confirms the elevated levels of Chloride Ion Wet Deposition in these countries. Wuhan has been noted to be one of the cities with the least salinity in the air 7 Healthy levels of endo-tracheal sodium chloride protect the respiratory airways from disease. Ciliary action is improved when the saline content of the endobronchial tree is optimal.…”

Section: Discussionmentioning

confidence: 99%

Covid-19 Pandemic in relation to levels of Pollution with PM2.5 and Ambient Salinity – An Environmental Wake-up Call

Baron

2020

Preprint

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INTRODUCTION: Covid-19 infection continues to be a source of great loss of life and global suffering, necessitating national lockdowns. There are however some countries and cities which appear to have contained the pandemic. Common to these countries are environmental factors including the levels of particulate matter (PM2.5) and ambient salinity. METHOD: PM2.5 and ambient salinity were assessed in a number of cities, differentially affected by Covid-19 infection. The cities chosen to be assessed were divided into two groups. The first group included cities having significantly high rates of Covid-19 infection, while the second group consisted of coastal cities or small island countries, all of which have low rates of Covid-19 infection. Minimum and maximum levels of PM2.5 were obtained from the Air Quality Index, one month before and one month after statutory lockdown. Salinity levels were obtained from a study that assessed chloride ion wet deposition, a surrogate for ambient salinity. RESULTS: One month prior to the statutory national lock-down or mandatory restrictions, there appear to be high levels of particulate matter, PM2.5 (min-max 67.4 - 118.7 AQI), in countries which had a high incidence of Covid-19 infection compared to lower levels in countries that have contained the infection (min-max 45.6 - 79.8) (p<0.046). One month after national restrictions there still appeared to be higher levels of particulate matter, PM2.5 (min-max 51 - 90.5 AQI), in countries which had a high incidence of Covid-19 infection compared to countries that have contained the infection (min-max 42.7 - 69.5 AQI) but this was not statistically significant. There seemed to be an inverse relationship between Covid-19 infection and ambient salinity levels. Countries that were spared high Covid-19 infection rates, besides their geographical isolation, also have higher ambient salinity levels (124 - 617mgCl/m2/TAG) compared to salinity levels noted in countries with high Covid-19 rates of infection (28.4 - 162. mgCl/m2/TAG) (p<0.003). CONCLUSION: High levels of PM2.5 in the presence of low ambient salinity may increase the risk of Covid-19 infection in the population. Addressing these two environmental factors may attenuate the severity of the pandemic. Keywords: Covid-19, environmental factors, PM2.5, ambient salinity.

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Section: Discussionmentioning

confidence: 99%

Covid-19 Pandemic in relation to levels of Pollution with PM2.5 and Ambient Salinity – An Environmental Wake-up Call

Baron

2020

Preprint

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“…Chloride ion wet deposition, a variable reflecting the ambient salinity could be obtained from a colour-coded map of the distribution of the earth's salt content. 13 Wuhan has been noted to be one of the cities in China with the least salt content in the air 14 . The cities hard hit by COVID-19 infection are distant from the sea and consequently have low salt content levels [14][15][16][17][18][19][20][21][22] .…”

Section: Discussionmentioning

confidence: 99%

“…13 Wuhan has been noted to be one of the cities in China with the least salt content in the air 14 . The cities hard hit by COVID-19 infection are distant from the sea and consequently have low salt content levels [14][15][16][17][18][19][20][21][22] . Rotterdam with an elevated salt content PM2.5 (0.4µg/m 3 ) had lower rates of COVID-19 compared to Vredepeel in the inland Limburg region (0.2µg/m 3 ).…”

Section: Discussionmentioning

confidence: 99%

COVID-19 and PM2.5 Sodium Chloride content

Baron¹

2020

Preprint

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INTRODUCTION: Following national lockdown instituting physical distancing, COVID-19 infection and mortality decreased in most countries. Simultaneously due to diminished economic and human activity, the atmospheric levels of PM2.5, an important airborne pollutant, decreased significantly. COVID-19 has been found adherent to PM2.5. PM2.5 has various components including sodium chloride which determines the amount of PM2.5 salt-derived water content. Atmospheric salt content in part determines the sodium chloride content and the consequential hygroscopicity of PM2.5. COVID-19 possesses a C-terminal protein which is hydrophobic.METHOD: The sodium chloride content of the PM2.5 species was assessed in two groups of cities. Cities were chosen as opposed to countries, because substantial regional differences in infection rates were noted between inland and coastal cities. These cities were differentiated by the rate COVID-19 infection and consequent mortality. Atmospheric salt content was obtained from research that assessed chloride ion wet deposition, a proxy for airborne salinity. The salt content of the relevant PM2.5 species was obtained from publications from the various cities assessed.RESULTS: Cities with high COVID-19 infection rates had PM2.5 species with significantly lower salt content than the cities with low Covid-17 infection. The PM2.5 salt content in the cities with elevated COVID-19 rates was 0.196µg/m3 SD 0.05µg/m3, while cities with low COVID-19 rates had a PM2.5 salt content of 0.81µg/m3 SD 0.32µg/m3 (p<0.0001).There was a significant correlation between atmospheric salinity and the salt content of PM2.5. PM2.5 salt content correlated with minimum atmospheric salinity (R=0.53, p < 0.01) and maximum atmospheric salinity (R=0.64, p <0.002). There appears to be an inverse relationship between COVID-19 infection and atmospheric salt content levels. Cities that were spared high COVID-19 infection rates, have higher maximum/minimum atmospheric salinity content levels (216-1080 mgCl/m2/day) compared to sodium chloride levels noted in cities with high COVID-19 rates of infection (40-125. mgCl/m2/day) (p<0.005).CONCLUSION: PM2.5 with low salt content, in the presence of low ambient salinity may be linked to an increased risk of COVID-19 infection in the population.

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“…However, the updated record especially after the Action Plan is important to assess the mitigation of the air pollutants not only in the atmosphere but also in rainfall. A nationwide investigation of the wet deposition of inorganic ions in 320 cities across China was recently made based on observations between 2011 and 2016 from the National Acid Deposition Monitoring Network (NADMN), which was established by the China Meteorological Administration (Li et al, 2019). Briefly, both SO4 2and NO3across China experienced significant changes before and after 2014, with increases from 2011 to 2014 and then decreases from 2014 to 2016.…”

Section: Inter-annual Variations In Chemical Componentsmentioning

confidence: 99%

Inter-annual variations of wet deposition in Beijing during 2014–2017: implications of below-cloud scavenging of inorganic aerosols

Ge¹,

Xu²,

Wild³

et al. 2020

Preprint

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Abstract. Wet scavenging is an efficient pathway for the removal of particulate matter (PM) from the atmosphere. High levels of PM have been a major cause of air pollution in Beijing but have decreased sharply under the Air Pollution Prevention and Control Action Plan launched in 2013. In this study, four years of observations of wet deposition have been conducted using a sequential sampling technique to investigate the detailed variation in chemical components through each rainfall event. We find that the major ions, SO42−, Ca2+, NO3− and NH4+, show significant decreases over the 2013–2017 period (decreasing by 39 %, 35 %, 12 % and 25 %, respectively), revealing the impacts of the Action Plan. An improved sequential sampling method is developed and implemented to estimate the contribution of below-cloud and in-cloud wet deposition over the four-year period. Overall, below-cloud scavenging accounts for between half and two thirds of wet deposition of the four major ions, with the highest contribution for NH4+ at 65 % and lowest for SO42− at 50 %. The contribution of below-cloud scavenging for Ca2+, SO42− and NH4+ decreases from above 50 % in 2014 to below 40 % in 2017. This suggests that the Action Plan has mitigated PM pollution in the surface layer and hence decreased scavenging due to the washout process. In contrast, we find little change in the annual volume weighted average concentration for NO3− where the contribution from below-cloud scavenging remains at ~44 % over the period 2015–2017. While highlighting the importance of different wet scavenging processes, this paper presents a unique new perspective on the effects of the Action Plan and clearly identifies oxidized nitrogen species as a major target for future air pollution controls.

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Wet deposition of inorganic ions in 320 cities across China: spatio-temporal variation, source apportionment, and dominant factors

Cited by 41 publications

References 155 publications

Covid-19 Pandemic in relation to levels of Pollution with PM2.5 and Ambient Salinity – An Environmental Wake-up Call

Covid-19 Pandemic in relation to levels of Pollution with PM2.5 and Ambient Salinity – An Environmental Wake-up Call

COVID-19 and PM2.5 Sodium Chloride content

Inter-annual variations of wet deposition in Beijing during 2014–2017: implications of below-cloud scavenging of inorganic aerosols

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