A Study on Oxidative Potential of Fine Particles Measured at an Urban Site and a Rural Site

Abstract. To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM1.8 by MOUDI) were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%–60% of the total mass at both sites, indicating it must be taken into account in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO3)2 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. Linear regression gave a rough estimation that 69% of the PM10 and 87% of the PM1.8 at PKU were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing.

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Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: implication of regional secondary formation

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-947-2010 ◽

2010 ◽

Vol 10 (3) ◽

pp. 947-959 ◽

Cited By ~ 146

Author(s):

S. Guo ◽

M. Hu ◽

Z. B. Wang ◽

J. Slanina ◽

Y. L. Zhao

Keyword(s):

Fine Particles ◽

Secondary Compounds ◽

Water Soluble ◽

Rural Site ◽

Urban Site ◽

Condensation Process ◽

Pmf Model ◽

Secondary Formation ◽

Aerosol Pollution ◽

Peking University

Abstract. To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM1.8 by MOUDI) were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model analysis was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%–60% of the total mass at both sites, indicating that the gas-to-particle condensation process was important in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO3)2 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. A rough estimation was given that 69% of the PM10 and 87% of the PM1.8 in Beijing urban were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing.

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Characteristics of atmospheric ammonia over Beijing, China

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-3041-2011 ◽

2011 ◽

Vol 11 (1) ◽

pp. 3041-3070 ◽

Cited By ~ 1

Author(s):

Z. Y. Meng ◽

W. L. Lin ◽

X. M. Jiang ◽

P. Yan ◽

Y. Wang ◽

...

Keyword(s):

Diurnal Cycle ◽

Seasonal Variations ◽

Urban Areas ◽

Fine Particles ◽

Passive Samplers ◽

Rural Site ◽

Urban Site ◽

Annual Average ◽

Atmospheric Ammonia ◽

Beijing China

Abstract. Continuous measurements of atmospheric ammonia (NH3) were conducted using Ogawa passive samplers from February 2008 to July 2010 at an urban site and from January 2007 to July 2010 at a rural site in Beijing, China. NH4+ in fine particles was also collected at rural site during 2008–2009. The field comparison between the Ogawa passive samplers and an active analyzer for NH3 conducted at an urban site assures the quality and accuracy of the measurements. The concentrations of NH3 at urban site ranged from 0.7 to 85.1 ppb, with the annual average of 18.5 ± 13.8 and 23.5 ± 18.0 ppb in 2008 and 2009. The NH3 concentrations at rural site were lower than those at urban site, and varied from 0.8 to 42.9 ppb, with the annual average of 4.5 ± 4.6, 6.6 ± 7.0 and 7.1 ± 3.5 ppb in 2007, 2008 and 2009, respectively. The data showed marked seasonal variations at both sites. The results emphasized traffic to be a significant source of NH3 concentrations in winter in urban areas of Beijing. This was illustrated by the correlations of NH3 with the traffic related pollutants (NOx and CO) and also by the bimodal diurnal cycle of NH3 concentrations that was synchronized with traffic. These patterns were not observed during the summer, suggesting other sources became more important. At rural site, the daily NH4+ concentrations ranged from 0.10 to 36.53 μg/m3, with an average of 6.94 μg/m3 from June 2008 to December 2009. Monthly NH3 were significantly correlated with NH4+ concentrations. Average monthly NH3/NH4+ ratios varied from 0.13 to 2.28, with an average of 0.73.

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Characteristics of atmospheric ammonia over Beijing, China

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-6139-2011 ◽

2011 ◽

Vol 11 (12) ◽

pp. 6139-6151 ◽

Cited By ~ 128

Author(s):

Z. Y. Meng ◽

W. L. Lin ◽

X. M. Jiang ◽

P. Yan ◽

Y. Wang ◽

...

Keyword(s):

Diurnal Cycle ◽

Urban Areas ◽

Fine Particles ◽

Passive Samplers ◽

Rural Site ◽

Urban Site ◽

Strong Correlations ◽

Annual Average ◽

Atmospheric Ammonia ◽

Beijing China

Abstract. Continuous measurements of atmospheric ammonia (NH3) were conducted using Ogawa passive samplers from February 2008 to July 2010 at an urban site and from January 2007 to July 2010 at a rural site in Beijing, China. NH4+ in fine particles was also collected at the rural site during 2008–2009. The field comparison between the Ogawa passive samplers and an active analyzer for NH3 conducted at the urban site assures the quality and accuracy of the measurements. The concentrations of NH3 at the urban site ranged from 0.7 to 85.1 ppb, with the annual average of 18.5 ± 13.8 and 23.5 ± 18.0 ppb in 2008 and 2009, respectively. The NH3 concentrations at the rural site were lower than those at urban site, and varied from 0.8 to 42.9 ppb, with the annual average of 4.5 ± 4.6, 6.6 ± 7.0 and 7.1 ± 3.5 ppb in 2007, 2008 and 2009, respectively. The data showed marked seasonal variations at both sites. The results emphasized traffic to be a significant source of NH3 concentrations in winter in urban areas of Beijing. This was illustrated by the strong correlations of NH3 with the traffic related pollutants (NOx and CO) and also by the bimodal diurnal cycle of NH3 concentrations that was synchronized with traffic. Similar patterns were not observed during the summer, suggesting other non-traffic sources became more important. At the rural site, the daily NH4+ concentrations ranged from 0.10 to 36.53 μg m−3, with an average of 7.03 μg m−3 from June 2008 to December 2009. Monthly NH3 were significantly correlated with NH4+ concentrations. Average monthly NH3/NH4+ ratios varied from 0.13 to 2.28, with an average of 0.73. NH4+ in PM2.5 was primarily associated with SO4−2 at the rural site.

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Salt Intake in Nigeria: a nationwide population survey

European Heart Journal ◽

10.1093/ehjci/ehaa946.2866 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

A.N Odili ◽

B.S Chori ◽

B Danladi ◽

P.C Nwakile ◽

J.O Ogedengbe ◽

...

Keyword(s):

Salt Intake ◽

Sodium Intake ◽

Population Analysis ◽

Cost Effective ◽

Rural Site ◽

Urban Site ◽

Funding Source ◽

Salt Reduction ◽

High Salt Intake ◽

The Impact

Abstract Background Population wide salt reduction programmes are cost effective strategies for control of cardiovascular diseases (CVDs). Obtaining a nationwide salt consumption data in a multi-cultural setting as Nigeria's is key for proper implementation and monitoring of such strategy. Methods We measured sodium in 24-hour urine of free-living adult Nigerians selected from an urban and a rural site each from the 6 geopolitical zones of Nigeria to evaluate patterns of salt intake and its associations with blood pressures (BP). Results Across the 12 sites, sodium intake ranged from 97.9 in the rural South-South to 210 mmol/day in the urban site of the same zone. Overall, the median (IQR) daily sodium intake was 143.5 (97.8) mmol; with higher (p=0.0028) levels among the urban 149.7 (113.8) compared to the rural 133.1 (105.2) dwellers. Overall, 20% of the subjects consumed less than the recommended 2g (86mmol) of sodium daily. After adjustment for age, sex and BMI; sodium intake and BP (systolic and diastolic) were positively associated in 8 out of the 12 sites; significantly so in 2 (p<0.05) for systolic. Within population analysis; which included 973 individuals, increasing sodium intake tended (not significantly) to increase SBP but decrease DBP. However, among subjects whose sodium intake was in excess of 257mmol/day, a 100 mmol/day increase in sodium intake was significantly (p=0.04) associated with a 3.3 mmHg increase in SBP. Conclusion Salt intake among Nigerians is higher than the recommended. The impact of sodium intake on BP appears to be evident only among individuals with high salt intake. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Wellcome Trust

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A cross-sectional study measuring contact patterns using diaries in an urban and a rural community in South Africa, 2018

BMC Public Health ◽

10.1186/s12889-021-11136-6 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Jackie Kleynhans ◽

Stefano Tempia ◽

Meredith L. McMorrow ◽

Anne von Gottberg ◽

Neil A. Martinson ◽

...

Keyword(s):

South Africa ◽

Age Groups ◽

Cross Sectional Study ◽

Rural Site ◽

Urban Site ◽

Contact Rate ◽

Sectional Study ◽

Cross Sectional ◽

Contact Rates ◽

Contact Patterns

Abstract Background Describing contact patterns is crucial to understanding infectious disease transmission dynamics and guiding targeted transmission mitigation interventions. Data on contact patterns in Africa, especially South Africa, are limited. We measured and compared contact patterns in a rural and urban community, South Africa. We assessed participant and contact characteristics associated with differences in contact rates. Methods We conducted a cross-sectional study nested in a prospective household cohort study. We interviewed participants to collect information on persons in contact with for one day. We described self-reported contact rates as median number people contacted per day, assessed differences in contact rates based on participant characteristics using quantile regression, and used a Poisson model to assess differences in contact rates based on contact characteristics within age groups. We also calculated cumulative person hours in contact within age groups at different locations. Results We conducted 535 interviews (269 rural, 266 urban), with 17,252 contacts reported. The overall contact rate was 14 (interquartile range (IQR) 9–33) contacts per day. Those ≤18 years had higher contact rates at the rural site (coefficient 17, 95% confidence interval (95%CI) 10–23) compared to the urban site, for those aged 14–18 years (13, 95%CI 3–23) compared to < 7 years. No differences were observed for adults. There was a strong age-based mixing, with age groups interacting more with similar age groups, but also interaction of participants of all ages with adults. Children aged 14–18 years had the highest cumulative person hours in contact (116.3 rural and 76.4 urban). Conclusions Age played an important role in the number and duration of contact events, with children at the rural site having almost double the contact rate compared to the urban site. These contact rates can be utilized in mathematical models to assess transmission dynamics of infectious diseases in similar communities.

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Spatial and seasonal variability of PM<sub>2.5</sub> acidity at two Chinese megacities: insights into the formation of secondary inorganic aerosols

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-1377-2012 ◽

2012 ◽

Vol 12 (3) ◽

pp. 1377-1395 ◽

Cited By ~ 105

Author(s):

K. He ◽

Q. Zhao ◽

Y. Ma ◽

F. Duan ◽

F. Yang ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Temporal Variations ◽

Early Summer ◽

Heterogeneous Reactions ◽

Rural Site ◽

Urban Site ◽

Simultaneous Increase ◽

Northwestern Pacific ◽

Inorganic Aerosols ◽

Aerosol Acidity

Abstract. Aerosol acidity is one of the most important parameters influencing atmospheric chemistry and physics. Based on continuous field observations from January 2005 to May 2006 and thermodynamic modeling, we investigated the spatial and seasonal variations in PM2.5 acidity in two megacities in China, Beijing and Chongqing. Spatially, PM2.5 was generally more acidic in Chongqing than in Beijing, but a reverse spatial pattern was found within the two cities, with more acidic PM2.5 at the urban site in Beijing whereas the rural site in Chongqing. Ionic compositions of PM2.5 revealed that it was the higher concentrations of NO3− at the urban site in Beijing and the lower concentrations of Ca2+ within the rural site in Chongqing that made their PM2.5 more acidic. Temporally, PM2.5 was more acidic in summer and fall than in winter, while in the spring of 2006, the acidity of PM2.5 was higher in Beijing but lower in Chongqing than that in 2005. These were attributed to the more efficient formation of nitrate relative to sulfate as a result of the influence of Asian desert dust in 2006 in Beijing and the greater wet deposition of ammonium compared to sulfate and nitrate in 2005 in Chongqing. Furthermore, simultaneous increase of PM2.5 acidity was observed from spring to early summer of 2005 in both cities. This synoptic-scale evolution of PM2.5 acidity was accompanied by the changes in air masses origins, which were influenced by the movements of a subtropical high over the northwestern Pacific in early summer. Finally, the correlations between [NO3−]/[SO42−] and [NH4+]/[SO42−] suggests that under conditions of high aerosol acidity, heterogeneous reactions became one of the major pathways for the formation of nitrate at both cities. These findings provided new insights in our understanding of the spatial and temporal variations in aerosol acidity in Beijing and Chongqing, as well as those reported in other cities in China.

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Impact of rural versus urban setting on kidney markers: a cross-sectional study in South-Kivu, DRCongo

BMC Nephrology ◽

10.1186/s12882-021-02431-w ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Mannix Imani Masimango ◽

Michel P. Hermans ◽

Espoir Bwenge Malembaka ◽

Pierre Wallemacq ◽

Ernest Kiswaya Sumaili ◽

...

Keyword(s):

Positive Predictive Value ◽

Negative Predictive Value ◽

Predictive Value ◽

Democratic Republic Of Congo ◽

Urban Setting ◽

Sub Saharan Africa ◽

Rural Site ◽

Urban Site ◽

Cross Sectional ◽

South Kivu

Abstract Background Most studies of chronic kidney disease (CKD) in Sub-Saharan Africa (SSA) have been conducted in urban settings. They relied on GFR estimated from serum creatinine alone and on the inexpensive, convenient urinary dipstick to assess proteinuria. The dipstick for proteinuria has not been directly compared with the gold standard albumin-to-creatinine ratio (ACR) in a large-sized study in SSA. We hereby assessed the influence of rural versus urban location on the level, interpretation, and diagnostic performance of proteinuria dipstick versus ACR. Methods In a cross-sectional population-based study of CKD in both urban (n = 587) and rural (n = 730) settings in South-Kivu, Democratic Republic of Congo (DRC), we assessed the prevalence, performance (sensitivity, specificity, positive predictive value and negative predictive value) and determinants of a positive dipstick proteinuria as compared with albuminuria (ACR). Albuminuria was subdivided into: A1 (< 30 mg/g creatinine), A2 (30 to 299 mg/g creatinine) and A3 (≥ 300 mg/g creatinine). Results The overall prevalence of positive dipstick proteinuria (≥ 1+) was 9.6 % (95 % CI, 7.9–11.3) and was higher in rural than in urban residents (13.1 % vs. 4.8 %, p < 0.001), whereas the prevalence of albuminuria (A2 or A3) was similar in both sites (6 % rural vs. 7.6 % urban, p = 0.31). In both sites, dipstick proteinuria ≥ 1 + had a poor sensitivity (< 50 %) and positive predictive value (< 11 %) for the detection of A2 or A3. The negative predictive value was 95 %. Diabetes [aOR 6.12 (1.52–24.53)] was a significant predictor of A3 whereas alkaline [aOR 7.45 (3.28–16.93)] and diluted urine [aOR 2.19 (1.35–3.57)] were the main predictors of positive dipstick proteinuria. Conclusions ACR and dipstick proteinuria have similar positivity rates in the urban site whereas, in the rural site, dipstick was 2-fold more often positive than ACR. The poor sensitivity and positive predictive value of the dipstick as compared with ACR makes it unattractive as a screening tool in community studies of CKD in SSA.

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Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition

10.5194/acp-2017-1071 ◽

2018 ◽

Author(s):

David M. Nelson ◽

Urumu Tsunogai ◽

Ding Dong ◽

Takuya Ohyama ◽

Daisuke D. Komatsu ◽

...

Keyword(s):

Dry Deposition ◽

Wet Deposition ◽

Urban Environments ◽

Rural Site ◽

Urban Site ◽

Peroxy Radicals ◽

Long Distance ◽

Wet And Dry Deposition ◽

Atmospheric Nitrate ◽

Nitrate Deposition

Abstract. Atmospheric nitrate deposition resulting from anthropogenic activities negatively affects human and environmental health. Identifying deposited nitrate that is produced locally vs. that originating from long-distance transport would help inform efforts to mitigate such impacts. However, distinguishing the relative transport distances of atmospheric nitrate in urban areas remains a major challenge since it may be produced locally and/or come from upwind regions. To address this uncertainty we assessed spatiotemporal variation in monthly weighted-average Δ17O and δ15N values of wet and dry nitrate deposition during one year at urban and rural sites along the western coast of the northern Japanese island of Hokkaido, downwind of the East Asian continent. Δ17O values of nitrate in wet deposition at the urban site mirrored those of wet and dry deposition at the rural site, ranging between ~ +22 and +30 ‰ with higher values during winter and lower values in summer, which suggests greater relative importance of oxidation of NO2 by O3 during winter and OH during summer. In contrast, Δ17O values of nitrate in dry deposition at the urban site were lower (+19–+25 ‰) and displayed less distinct seasonal variation. Furthermore, the difference between δ15N values of nitrate in wet and dry nitrate deposition was, on average, 3 ‰ greater at the urban than rural site, and Δ17O and δ15N values were correlated for both forms of deposition at both sites with the exception of dry deposition at the urban site. These results suggest that, relative to nitrate in wet deposition in urban environments and wet and dry deposition in rural environments, nitrate in dry deposition in urban environments forms from relatively greater oxidation of NO by peroxy radicals and/or oxidation of NO2 by OH. Given greater concentrations of peroxy radicals and OH in cities, these results imply that dry nitrate deposition results from local NOx emissions more so than wet deposition, which is transported longer distances. These results illustrate the value of stable isotope data for distinguishing the transport distances and reaction pathways of atmospheric nitrate pollution.

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Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-1139-2016 ◽

2016 ◽

Vol 16 (2) ◽

pp. 1139-1160 ◽

Cited By ~ 17

Author(s):

L. Xu ◽

L. R. Williams ◽

D. E. Young ◽

J. D. Allan ◽

H. Coe ◽

...

Keyword(s):

Biomass Burning ◽

Solid Fuel ◽

Field Studies ◽

Rural Site ◽

Urban Site ◽

High Temporal Resolution ◽

Volatile Organics ◽

Aerosol Mass ◽

Rural And Urban ◽

Wide Range

Abstract. The composition of PM1 (particulate matter with diameter less than 1 µm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical processing as rBC in the atmosphere. Although the atomic O : C ratio of OOA is substantially larger than that of solid fuel OA and hydrocarbon-like OA, these three factors have similar volatility, which is inferred from the change in mass concentration after heating at 120 °C. Finally, we discuss the relationship between the mass fraction remaining (MFR) of OA after heating in the TD and atomic O : C of OA and find that particles with a wide range of O : C could have similar MFR after heating. This analysis emphasizes the importance of understanding the distribution of volatility and O : C in bulk OA.

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