scholarly journals Regional effect on urban atmospheric nucleation

2016 ◽  
Vol 16 (14) ◽  
pp. 8715-8728 ◽  
Author(s):  
Imre Salma ◽  
Zoltán Németh ◽  
Veli-Matti Kerminen ◽  
Pasi Aalto ◽  
Tuomo Nieminen ◽  
...  
Keyword(s):  
Particle Production ◽  
Large City ◽  
Urban Environments ◽  
Rural Site ◽  
Urban Site ◽  
Atmospheric Conditions ◽  
Regional Effect ◽  
Atmospheric Nucleation ◽  
Timing Properties

Abstract. Secondary aerosol particle production via new particle formation (NPF) has been shown to be a major contributor to the global aerosol load. NPF has also been observed frequently in urban environments. Here, we investigate the effect of regional NPF on urban aerosol load under well-defined atmospheric conditions. The Carpathian Basin, the largest orogenic basin in Europe, represents an excellent opportunity for exploring these interactions. Based on long-term observations, we revealed that NPF seen in a central large city of the basin (Budapest) and its regional background occur in a consistent and spatially coherent way as a result of a joint atmospheric phenomenon taking place on large horizontal scales. We found that NPF events at the urban site are usually delayed by > 1 h relative to the rural site or even inhibited above a critical condensational sink level. The urban processes require higher formation rates and growth rates to be realized, by mean factors of 2 and 1.6, respectively, than the regional events. Regional- and urban-type NPF events sometimes occur jointly with multiple onsets, while they often exhibit dynamic and timing properties which are different for these two event types.

scholarly journals Regional effect on urban atmospheric nucleation

2016 ◽  
Author(s):  
Imre Salma ◽  
Zoltán Németh ◽  
Veli-Matti Kerminen ◽  
Pasi Aalto ◽  
Tuomo Nieminen ◽  
...  
Keyword(s):  
Particle Production ◽  
Large City ◽  
Urban Environments ◽  
Rural Site ◽  
Urban Site ◽  
Atmospheric Conditions ◽  
Regional Effect ◽  
Atmospheric Nucleation ◽  
Timing Properties

Abstract. Secondary aerosol particle production via new particle formation (NPF) has been shown to be a major source for global aerosol load. It has been also observed frequently in urban environments affecting the human health. Here, we investigate the effect of regional NPF on urban aerosol load under well-defined atmospheric conditions. The Carpathian Basin, the largest orogenic basin in Europe, represents an excellent opportunity for exploring these interactions. Based on long-term observations, we revealed that NPF seen in a central large city of the basin (Budapest) and its regional background occur in a consistent and spatially coherent way as result of a joint atmospheric phenomenon taking place over large horizontal scales. We found that NPF events at the urban site are usually delayed by > 1 hour relative to the rural site or even inhibited above a critical condensational sink level. The urban processes require higher formation rates and growth rates to be realised, by mean factors of 2 and 1.6, respectively, than the regional events. Regional- and urban-type NPF events sometimes occur jointly with multiple onsets, while they often exhibit dynamic and timing properties which are different for these NPF types.

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

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.

scholarly journals Factors influencing satisfaction with oral contraceptive pills and injectables among past users in Kenya

2018 ◽  
Vol 51 (4) ◽  
pp. 491-504 ◽  
Author(s):  
George Odwe ◽  
Joyce Mumah ◽  
Francis Obare ◽  
Marylene Wamukoya ◽  
Kazuyo Machiyama ◽  
...  
Keyword(s):  
Family Planning ◽  
Unmet Need ◽  
Multivariate Logistic Regression Analysis ◽  
Ease Of Use ◽  
Rural Site ◽  
Urban Site ◽  
Baseline Survey ◽  
Prospective Longitudinal Study ◽  
Prospective Longitudinal

AbstractThis study examines factors associated with satisfaction with oral pills and injectables among past users in Kenya based on a baseline survey for the 2-year prospective longitudinal study Improving Measurement of Unintended Pregnancy and Unmet Need for Family Planning conducted in 2016. Married women aged 15–39 years were interviewed using a structured questionnaire that captured information on reproduction, contraceptive knowledge and beliefs and attitudes towards contraception in general and towards specific methods. A multivariate logistic regression analysis was used to examine factors that influenced satisfaction with oral pills and injectables among past users in one urban site (Nairobi slums) and one predominantly rural site (Homa Bay in western Kenya). Results showed that dissatisfaction with pills and injectables is common among past users in both rural and urban Kenya (ranging from 39% to 56%). The distinctive contribution of the study lies in its ability to relate method-specific beliefs to overall satisfaction. Perception of effectiveness, ease of use and safety for long-term use had statistically significant influences on satisfaction with pills in both urban and rural sites while partner’s approval was only important in Nairobi. For injectables, the perception of safety for long-term use was significant in the urban but not the rural site. Unlike pills, the belief that members of a woman’s social network had used a method and found it satisfactory was a particularly powerful influence on satisfaction (AOR=2.8 in rural and 3.2 in urban). Perception of accessibility and fears about infertility were not found to be statistically associated with satisfaction for either pills or injectables. Surprisingly, the effects of all perceived contraceptive attributes were the same for major socio-demographic strata of the populations. The findings underscore the need for targeted counselling and community-based communication interventions to address negative and erroneous perceptions about family planning methods.

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

2018 ◽  
Vol 18 (9) ◽  
pp. 6381-6392 ◽  
Author(s):  
David M. Nelson ◽  
Urumu Tsunogai ◽  
Dong Ding ◽  
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 be transported 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  ∼  +23 and +31 ‰ with higher values during winter and lower values in summer, which suggests the 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 and dry deposition in rural environments and wet deposition in urban 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.

Representing the Urban Heat Island Effect in Future Climates

2020 ◽  
Author(s):  
Annkatrin Burgstall ◽  
Ana Casanueva ◽  
Elke Hertig ◽  
Erich Fischer ◽  
Reto Knutti ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Urban Areas ◽  
Rural Site ◽  
Urban Site ◽  
Heat Island ◽  
Hot Days ◽  
Urban Heat ◽  
Rural Sites ◽  
Urban Sites

<p>An increasing fraction of people living in urban areas and the expected increase in long lasting heat waves highlight the important role of urban climates in terms of future climate change impacts, especially with relation to the heat-health sector. Due to the urban heat island (UHI) effect and its (generally) increased intensity particularly during nighttime, people living in urban areas happen to be more affected by heat-related discomfort and health risks than those in non-urban regions. In this contribution, temperatures of both rural and urban sites (station couples) in Switzerland and Southern Germany are analyzed, using (i) observed as well as (ii) bias-corrected and downscaled climate model data for daily minimum (tmin) and daily maximum temperature (tmax) to account for the UHI in future climates. As meteorological data are often restricted to locations of long-term measurements at rural sites only, they need to be transferred to urban sites first. For this purpose, the well-established quantile mapping technique (QM) is tested in a two-step manner. The resulting products are urban time series at daily resolution for tmin and tmax. By analyzing the temperature differences of the observed climate at rural sites and their respective urban counterparts and by assuming a stationary relationship between both, we can represent the UHI in future climates, which is quantified in terms of heat indices based on tmin and tmax (tropical nights, summer days, hot days).</p><p>The QM performance is evaluated using long-term weather station data of a Zurich station couple in a comprehensive cross-validation framework. Results reveal a promising performance in the present-day climate, given very low biases in the validation.</p><p>Applying the proposed method to the employed station couples, projections indicate distinct urban-rural temperature differences (UHI) during nighttime (considering the frequency of tropical nights based on tmin) compared to weak differences during the day (considering the frequency of summer days and hot days based on tmax). Moreover, scenarios suggest the frequency of all indices to dramatically rise at the urban site by the end of the century under a strong emission scenario (RCP8.5): compared to the rural site, the number of tropical nights almost doubles while the number of summer days reveals about 15% more days at the urban site when focusing on the station couple in Zurich and the late scenario period. The lack of nighttime relief, indicated by tmin not falling below 20°C (i.e. a tropical night), is especially problematic in terms of human health and makes the study of the urban climate in general and the UHI effect in particular indispensable.</p>

scholarly journals Method-specific beliefs and subsequent contraceptive method choice: Results from a longitudinal study in urban and rural Kenya

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252977
Author(s):  
George Odwe ◽  
Yohannes Dibaba Wado ◽  
Francis Obare ◽  
Kazuyo Machiyama ◽  
John Cleland
Keyword(s):  
Sub Saharan Africa ◽  
Rural Site ◽  
Urban Site ◽  
Major Influence ◽  
Logit Analysis ◽  
Method Choice ◽  
Negative Beliefs ◽  
Family Planning Counseling ◽  
Sub Saharan

Introduction Evidence from sub-Saharan Africa, including Kenya, shows that negative beliefs about contraceptive methods are associated with non-use. However, little is known about the relationship between contraceptive beliefs and subsequent method choice. Methodology We used data from a two-year longitudinal survey of married women aged 15–39 years at enrollment from one urban site (Nairobi) and one rural site (Homa Bay) in Kenya. Analysis entails descriptive statistics and estimation of a conditional logit analysis to examine associations between method-specific beliefs and choice of injectables, implants or pills among women who were not using any method or were pregnant at baseline (round 1) but adopted these methods at 12-month follow-up (Nairobi, n = 221; Homa Bay n = 197). Results Beliefs about pills, injectables and implants among non-users were generally negative. With the partial exception of the pill in Nairobi, the majority thought that each method was likely to cause serious health problems, unpleasant side effects, menstrual disruption, and would be unsafe for long-term use. In both sites, satisfied past use of a method and the perception that a method is easy to use had a major influence on method choice. Concerns about menstrual disruption and safety for long-term use were unimportant in both sites. There were some marked differences between the two sites. Beliefs about long-term fertility impairment and perceived husband approval had strong influences on choice of injectables, implants or pills in the urban site but not in the rural site. Conclusion The relative importance of beliefs, some erroneous, in predisposing women to choose one method over another appears to be conditioned by the social context. There is need for family planning counseling programmes to pay attention to erroneous beliefs and misconceptions about contraceptives.

scholarly journals Salt Intake in Nigeria: a nationwide population survey

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

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

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.

scholarly journals Stability of graphene-based heterojunction solar cells

RSC Advances ◽  
2015 ◽  
Vol 5 (90) ◽  
pp. 73575-73600 ◽  
Author(s):  
Eric Singh ◽  
Hari Singh Nalwa
Keyword(s):  
Solar Cells ◽  
Environmental Stability ◽  
Light Illumination ◽  
Atmospheric Conditions ◽  
Air Humidity ◽  
Heterojunction Solar Cells ◽  
Commercial Applications

The long-term environmental stability and degradation of graphene-based heterojunction solar cells under different atmospheric conditions such as air, humidity, temperature, and light illumination for commercial applications are discussed.

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

2012 ◽  
Vol 12 (3) ◽  
pp. 1377-1395 ◽  
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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