scholarly journals Seasonal influences on surface ozone variability in continental South Africa and implications for air quality

2018 ◽  
Vol 18 (20) ◽  
pp. 15491-15514 ◽  
Author(s):  
Tracey Leah Laban ◽  
Pieter Gideon van Zyl ◽  
Johan Paul Beukes ◽  
Ville Vakkari ◽  
Kerneels Jaars ◽  
...  
Keyword(s):  
South Africa ◽  
Air Quality ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Surface Ozone ◽  
Source Area ◽  
Quality Standard ◽  
Early Spring ◽  
Late Winter ◽  
Surface O3

Abstract. Although elevated surface ozone (O3) concentrations are observed in many areas within southern Africa, few studies have investigated the regional atmospheric chemistry and dominant atmospheric processes driving surface O3 formation in this region. Therefore, an assessment of comprehensive continuous surface O3 measurements performed at four sites in continental South Africa was conducted. The regional O3 problem was evident, with O3 concentrations regularly exceeding the South African air quality standard limit, while O3 levels were higher compared to other background sites in the Southern Hemisphere. The temporal O3 patterns observed at the four sites resembled typical trends for O3 in continental South Africa, with O3 concentrations peaking in late winter and early spring. Increased O3 concentrations in winter were indicative of increased emissions of O3 precursors from household combustion and other low-level sources, while a spring maximum observed at all the sites was attributed to increased regional biomass burning. Source area maps of O3 and CO indicated significantly higher O3 and CO concentrations associated with air masses passing over a region with increased seasonal open biomass burning, which indicated CO associated with open biomass burning as a major source of O3 in continental South Africa. A strong correlation between O3 on CO was observed, while O3 levels remained relatively constant or decreased with increasing NOx, which supports a VOC-limited regime. The instantaneous production rate of O3 calculated at Welgegund indicated that ∼40 % of O3 production occurred in the VOC-limited regime. The relationship between O3 and precursor species suggests that continental South Africa can be considered VOC limited, which can be attributed to high anthropogenic emissions of NOx in the interior of South Africa. The study indicated that the most effective emission control strategy to reduce O3 levels in continental South Africa should be CO and VOC reduction, mainly associated with household combustion and regional open biomass burning.

scholarly journals Chemical composition of pre-monsoon air in the Indo-Gangetic Plain measured using a new air quality facility and PTR-MS: high surface ozone and strong influence of biomass burning

2014 ◽  
Vol 14 (12) ◽  
pp. 5921-5941 ◽  
Author(s):  
V. Sinha ◽  
V. Kumar ◽  
C. Sarkar
Keyword(s):  
Air Quality ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Air Pollutants ◽  
Surface Ozone ◽  
Ambient Air ◽  
Ambient Air Quality ◽  
Gangetic Plain ◽  
Indo Gangetic Plain

Abstract. One seventh of the world's population lives in the Indo-Gangetic Plain (IGP) and the fertile region sustains agricultural food crop production for much of South Asia, yet it remains one of the most under-studied regions of the world in terms of atmospheric composition and chemistry. In particular, the emissions and chemistry of volatile organic compounds (VOCs) that form surface ozone and secondary organic aerosol through photochemical reactions involving nitrogen oxides are not well understood. In this study, ambient levels of VOCs such as methanol, acetone, acetaldehyde, acetonitrile and isoprene were measured for the first time in the IGP. A new atmospheric chemistry facility that combines India's first high-sensitivity proton transfer reaction mass spectrometer, an ambient air quality station and a meteorological station, was used to quantify in situ levels of several VOCs and air pollutants in May 2012 at a suburban site in Mohali (northwest IGP). Westerly winds arriving at high wind speeds (5–20 m s−1) in the pre-monsoon season at the site were conducive for chemical characterization of regional emission signatures. Average levels of VOCs and air pollutants in May~2012 ranged from 1.2 to 2.7 nmol mol−1 for aromatic VOCs, 5.9 to 37.5 nmol mol−1 for the oxygenated VOCs, 1.4 nmol mol−1 for acetonitrile, 1.9 nmol mol−1 for isoprene, 567 nmol mol−1 for carbon monoxide, 57.8 nmol mol−1 for ozone, 11.5 nmol mol−1 for nitrogen oxides, 7.3 nmol mol−1 for sulfur dioxide, 104 μg m−3 for PM2.5 and 276 μg m−3 for PM10. By analyzing the one-minute in situ data with meteorological parameters and applying chemical tracers (e.g., acetonitrile for biomass burning) and inter-VOC correlations, we were able to constrain major emission source activities on both temporal and diel scales. Wheat residue burning caused massive increases (> 3 times the baseline values) for all the measured VOCs and primary pollutants. Other forms of biomass burning at night were also a significant source of oxygenated VOCs and isoprene (r2 with acetonitrile ≥0.5 for nighttime data), which is remarkable in terms of atmospheric chemistry implications. Surface ozone exceeded the 8 h national ambient air quality limit of 100 μg O3 m−3 (~50 ppbv) on a daily basis, except for 17 May 2012, when a severe dust storm event (PM2.5 > 800 μg m−3; PM10 > 2700 μg m−3) characterized by long-range transport from the west impacted the site. The novel data set and results point to the occurrence of high primary emissions of reactive VOCs. They also highlight the urgent need for establishing more comprehensive observational facilities in the IGP to constrain the spatial and seasonal variability of atmospheric chemical constituents. Such efforts will enable a mechanistic-level understanding of the in situ chemical processes controlling the formation of surface ozone, a necessary step for effective ozone mitigation and improvement of the regional air quality.

scholarly journals Seasonal influences on surface ozone variability in continental South Africa and implications for air quality

2018 ◽  
Author(s):  
Tracey Leah Laban ◽  
Pieter Gideon van Zyl ◽  
Johan Paul Beukes ◽  
Ville Vakkari ◽  
Kerneels Jaars ◽  
...  
Keyword(s):  
South Africa ◽  
Air Quality ◽  
South African ◽  
Biomass Burning ◽  
Southern Africa ◽  
Seasonal Changes ◽  
The North ◽  
North Eastern ◽  
The Relationship ◽  
Surface O3

Abstract. Although elevated ozone (O3) concentrations are observed in many areas within continental southern Africa, few studies have investigated the regional atmospheric chemistry and dominant atmospheric processes driving surface O3 formation in this region. The aim of this study was to conduct an assessment of comprehensive continuous surface O3 measurements performed at four sites located in continental South Africa. These sites were representative of regional background (Welgegund and Botsalano) and industrial regions (Marikana and Elandsfontein) in the north-eastern interior in South Africa as indicated by comparison with other sites in this region. The regional O3 problem was also shown with O3 concentrations being higher than 40 ppb at many sites in the north-eastern interior, while the South African air quality standard limit for O3 was regularly exceeded at the four sites in this study. O3 levels were generally lower at other background sites in the Southern Hemisphere compared to the South African sites, while similar seasonal patterns were observed. The temporal O3 patterns observed at the four sites resembled typical trends for O3 in continental South Africa, i.e. O3 concentration peaking in late winter and early spring, and daytime O3 peaks associated with increased photochemical production. The seasonal O3 trends observed in continental South Africa were mainly attributed to the seasonal changes in emissions of O3 precursor species and changes in meteorological conditions. Increased O3 concentrations in winter were indicative of increased emissions of O3 precursors from household combustion for space heating and the concentration of low-level pollutants near the surface. A spring maximum was observed at all the sites, which was attributed to increased regional biomass burning during this time. Source area maps of O3 and CO indicated significantly higher O3 and CO concentrations associated with air masses passing over a region where a large number of seasonal open biomass burning occurred in southern Africa, which indicated CO associated with open biomass burning as a major source of O3 in continental South Africa. The relationship between O3, NOx and CO indicated a strong dependence of O3 on CO, while O3 levels remained relatively constant or decreased with increasing NOx. The seasonal changes in the relationship between O3 and precursors species also reflected the seasonal changes in sources of precursors. The instantaneous production rate of O3, P(O3), calculated at Welgegund indicated that at least 40 % of O3 production occurred in the VOC-limited regime. These relationships between O3 concentrations and P(O3) with O3 precursor species revealed that large parts of the regional background in continental South Africa can be considered CO- or VOC-limited, which can be attributed to high anthropogenic emissions of NOx in the interior of South Africa. It was indicated that the appropriate emission control strategy should be CO (and VOC) reduction associated with household combustion and regional open biomass burning to effectively reduce O3 pollution in continental South Africa.

scholarly journals A decadal analysis of particulate matter (PM2.5) and surface ozone (O3) over Vaal Priority Area, South Africa

2019 ◽  
Vol 29 (2) ◽  
Author(s):  
Kogieluxmie Govender ◽  
Venkataraman Sivakumar
Keyword(s):  
South Africa ◽  
Air Quality ◽  
Surface Ozone ◽  
Temporal Trends ◽  
Air Quality Monitoring ◽  
Vaal Triangle ◽  
Air Quality Monitoring Stations ◽  
Surface O3 ◽  
Pm2.5 Concentration

Atmospheric pollutants that affect human health most significantly are particulate matter (PM2.5) and surface ozone (O3). This paper analysed the long-term temporal trends for PM2.5 and ground level O3 for six air quality monitoring stations in the Vaal Triangle Area of South Africa from 2007 to 2017. Research has been conducted on the short-term temporal trends for PM2.5 concentration and surface O3 concentrations. There are no studies that have focussed on the long-term temporal trends for PM2.5 and O3 in the Vaal Triangle Area of South Africa, because these air quality monitoring stations have only existed for a period of approximately 11 years. The data used in this study is derived from ground-based instruments from the South African Weather Service. Temporal patterns for time of day, days of the week, and seasons were observed for all air quality stations. PM2.5 concentration increased during early mornings and late afternoons, with higher concentration during weekdays than weekends and an increase from late winter through to spring and summer. Surface O3 concentrations peaked during the spring and summer months and during midday when there was maximum sunlight acting as a catalyst for photochemical reactions. The long term trends illustrated that there has been no significant decrease in annual average concentration for PM2.5 in four of the six stations and surface O3 for the six stations in the past 10 years in the Vaal Triangle Area of South Africa.

scholarly journals Chemical composition of pre-monsoon air in the Indo–Gangetic Plain measured using a new PTR-MS and air quality facility: high surface ozone and strong influence of biomass burning

2013 ◽  
Vol 13 (12) ◽  
pp. 31761-31813 ◽  
Author(s):  
V. Sinha ◽  
V. Kumar ◽  
C. Sarkar
Keyword(s):  
Air Quality ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Air Pollutants ◽  
Surface Ozone ◽  
Ambient Air ◽  
Ambient Air Quality ◽  
Gangetic Plain ◽  
Indo Gangetic Plain

Abstract. One seventh of the world population lives in the Indo–Gangetic Plain (IGP) and the fertile region sustains agricultural food crop production for much of South Asia. Yet it remains one of the most under-studied regions of the world in terms of atmospheric composition and chemistry. In particular, the emissions and chemistry of volatile organic compounds (VOCs) that form surface ozone and secondary organic aerosol through photochemical reactions involving nitrogen oxides is not well understood. In this study, ambient levels of VOCs such as methanol, acetone, acetaldehyde, acetonitrile and isoprene were measured for the first time in the IGP. A new atmospheric chemistry facility that combines India's first high sensitivity proton transfer reaction mass spectrometer, an ambient air quality station and meteorological station, was used to quantify in-situ levels of several VOCs and air pollutants in May 2012 at a suburban site in Mohali (N. W. IGP). Westerly winds arriving at high wind speeds (5–20 m s−1) in the pre-monsoon season at the site, were conducive for chemical characterization of regional emission signatures. Average levels of VOCs and air pollutants in May 2012 ranged from 1.2–1.7 nmol mol−1 for aromatic VOCs, 5.9–37.4 nmol mol−1 for the oxygenated VOCs, 1.4 nmol mol−1 for acetonitrile, 1.9 nmol mol−1 for isoprene, 567 nmol mol−1 for carbon monoxide, 57.8 nmol mol−1 for ozone, 11.5 nmol mol−1 for nitrogen oxides, 7.3 nmol mol−1 for sulphur dioxide, 104 μg m−3 for PM2.5 and 276 μg m−3 for PM10. By analyzing the one minute in-situ data with meteorological parameters and applying chemical tracers (e.g. acetonitrile for biomass burning) and inter-VOC correlations, we were able to constrain major emission source activities on both temporal and diel scales. Wheat residue burning activity caused massive increases (> 3 times of baseline values) for all the measured VOCs and primary pollutants. Other forms of biomass burning at night were also a significant source for oxygenated VOCs and isoprene (r2 with acetonitrile ≥ 0.5 for night-time data), which is remarkable in terms of atmospheric chemistry implications. Surface ozone exceeded the 8 h national ambient air quality limit of 100 μg O3 m−3 on a daily basis, except for 17 May 2012, when a severe dust storm event (PM2.5 > 800 μg m−3; PM10 > 2700 μg m−3) characterized by long range transport from the west impacted the site. The novel dataset and results point to occurrence of high primary emissions of reactive VOCs. They also highlight the urgent need for establishing more comprehensive observational facilities in the IGP to constrain the spatial and seasonal variability of atmospheric chemical constituents. Such efforts will enable mechanistic level understanding of the in-situ chemical processes controlling formation of surface ozone, a necessary step for effective ozone mitigation and improvement of the regional air quality.

scholarly journals Spatio-temporal of surface ozone (O3) variations at urban and suburban sites in Sarawak region of Malaysia

2021 ◽  
Vol 880 (1) ◽  
pp. 012004
Author(s):  
H Mahidin ◽  
M T Latif ◽  
A Hamdan ◽  
J Salleh ◽  
D Dominick ◽  
...  
Keyword(s):  
Air Quality ◽  
Surface Ozone ◽  
Ambient Air ◽  
Quality Standard ◽  
Transportation Systems ◽  
Pollutant Emissions ◽  
Daily Maximum ◽  
Spatio Temporal ◽  
Ambient Air Quality Standard ◽  
The Relationship

Abstract Sarawak Region of Malaysia is currently experiencing a high demand for capital needs such as transformation forest to plantations, economic development, and improving transportation systems. Those land cover changes will increase primary pollutant emissions and trigger surface O3 formation. Surface O3 is a secondary pollutant and a significant greenhouse gas contributing to climate change and declining air quality. In this study, variations in surface O3 concentrations at urban and suburban sites in Sarawak were explored using the Malaysian Department of Environment data spanning a two-year cycle (2018-2019). The primary aim of this study is to ascertain the variation of surface O3 concentrations reported at four monitoring stations in Sarawak, namely Kuching (SQ1) (Urban), Sibu (SQ2) (Suburban), Bintulu (SQ3) (Suburban), and Miri (SQ4) (Suburban). The study also analysed the relationship between O3 distribution and nitrogen oxides (NO and NO2). The findings showed that O3 concentrations observed in the region during the study period were lower than the maximum permissible value of 100 ppbv suggested by the Malaysian Ambient Air Quality Standard (2020). SQ4 (Miri) at suburban sites recorded the highest average surface O3 concentrations with an hourly average and daily maximum O3 concentration of 15.7 and 89.5 ppbv, respectively. Temperatures, UV exposure, and wind speed all impact the concentration of surface O3 in Sarawak. In all stations, concentrations of O3 were inversely linked with NO, NO2, and relative humidity (RH). This research will assist the relevant agency in forecast, monitor, and mitigate the level of O3 in the ambient environment, especially in the Sarawak Region.

Spartium junceum (Spanish broom).

2021 ◽  
Author(s):  
Julissa Rojas-Sandoval
Keyword(s):  
South Africa ◽  
Water Immersion ◽  
Urban Pollution ◽  
Early Spring ◽  
Hot Water ◽  
Late Winter ◽  
Severe Drought ◽  
Sulfuric Acid Treatment ◽  
Morphological Adaptations ◽  
Perennial Shrub

Abstract Genetics: The chromosome number reported for S. junceum varies from 2n = 48, 2n = 52, 2n = 54 to 2n = 56 (Afzal-Rafii et al., 1986). Reproductive Biology: S. junceum is a fast-growing, perennial shrub that can live for up to 30 years. Its flowers are hermaphroditic, zygomorphic, yellow in colour and borne in terminal clusters or racemes. It is predominantly a xenogamous (outcrossed) species and its flowers are pollinated by insects, particularly bees (López et al., 1999; Zouhar, 2005). S. junceum begins to produce seeds when plants are two to three years old. This species is a prolific seeder with the potential to produce between 7000 and 10,000 seeds per plant in just one season (Zouhar, 2005; Silva et al., 2008). Under natural conditions, germination rates are approximately 70%. Scarification treatments, such as hot water immersion, dry heat, sulfuric acid treatment and water soak, effectively break seed dormancy and increase germination rates to between 78% and 92% (Travlos et al., 2007). This species produces large seed banks and seeds can remain viable in the soil for up to 30 years (DiTomaso and Kyser, 2013; Geerts et al., 2013; USDA-NRCS, 2017). Physiology and Phenology: S. junceum has a range of xerophytic adaptations. The stem is adapted to reduce the effects of overheating through the profiled positioning of the vegetative parts of the plant. The species has small leaves, which it loses before summer to reduce transpiration and to increase its tolerance to drought stress. The grass-shaped stem helps to reduce the total exposed area of the plant, whereas the root is well developed and ramified. The leaves of S. junceum have thick cuticles with a waxy layer and the plant produces oils that reduce evapotranspiration, which also reduces the temperature of the plant's microenvironment (Bezić et al., 2003).In California, shoots of S. junceum begin to grow in late winter and early spring. They elongate quickly and produce leaves with long internodes by March, with the most rapid growth occurring in May. Leaf longevity is four months or less, although stem photosynthesis occurs all year. Flowers are produced in May and pods mature in late June and early July (Nilsen et al., 1993; Zouhar, 2005). In South Africa, it has been recorded flowering from August to November, while in Lebanon it flowers from May to August (Invasive Species South Africa, 2017). In Europe, S. junceum has been recorded in flower from June to September, and in fruit from August to October (PFAF, 2017). AssociationsS. junceum has a symbiotic relationship with soil bacteria that form nodules on its roots and fix atmospheric nitrogen (PFAF, 2017). Environmental RequirementsS. junceum can grow on poor, dry and stony limestone soils. It is well adapted to rocky or sandy soils, clays, loams and sandy loams with a pH in the range of 5.5 to 7.5; it is also adapted to soils with high salt concentrations. This species has morphological adaptations to xerophytic conditions that allow it to endure severe drought. It thrives in full sun and can tolerate urban pollution, salt-laden winds near the coast and temperatures as low as -10°C (Bezić et al., 2003; Zouhar, 2005; Silva et al., 2008; DiTomaso and Kyser, 2013; Geerts et al., 2013).

Characterizing two distinct biomass burning regimes over Southeast Asia and their impacts on regional air quality

2020 ◽  
Author(s):  
Margaret Marvin ◽  
Paul Palmer ◽  
Fei Yao ◽  
Barry Latter ◽  
Richard Siddans ◽  
...  
Keyword(s):  
Air Quality ◽  
Southeast Asia ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Agricultural Waste ◽  
Critical Evaluation ◽  
Dry Season ◽  
Mitigation Strategies ◽  
Atmospheric Composition ◽  
Regional Air Quality

<p>Mainland and maritime Southeast Asia is home to more than 655 million people, representing nearly 10% of the global population. The dry season in this region is typically associated with intense biomass burning activity, which leads to a significant increase in surface air pollutants that are harmful to human health, including ozone (O<sub>3</sub>) and fine (radii smaller than 2.5 microns) particulate matter (PM<sub>2.5</sub>). Latitude-based differences in dry season timing and land use distinguish two regional biomass burning regimes: (1) agricultural waste burning on the peninsular mainland from February through April and (2) coastal peat burning across the equatorial islands in September and October. The type and amount of material burned determines the chemical composition of emissions and subsequently their impact on regional air quality. Understanding the individual and collective roles of these biomass burning regimes is a crucial step towards developing effective air quality mitigation strategies for Southeast Asia. Here, we use the nested GEOS-Chem atmospheric chemistry transport model (horizontal resolution of 0.25° x 0.3125°) to simulate fire-atmosphere interactions over Southeast Asia during March and September of 2014, when emissions peak from the two regional burning seasons. Based on our analysis of model output, we report how these two distinct biomass burning regimes impact the photochemical environment over Southeast Asia and what the resulting consequences are for surface air quality. We will also present a critical evaluation of our model using ground-based and satellite observations of atmospheric composition across the region.</p>

scholarly journals Evaluation of regional simulation of surface ozone over Southeast Asia using ground-based observation at two existing Global Atmospheric Watch stations

2021 ◽  
Vol 880 (1) ◽  
pp. 012006
Author(s):  
Didin Agustian Permadi ◽  
Nguyen Thi Kim Oanh
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Emission Inventory ◽  
Surface Ozone ◽  
Wrf Model ◽  
Ambient Air ◽  
Quality Standard ◽  
Ozone Pollution ◽  
Ozone Precursors ◽  
Remote Sites

Abstract High level of ground level ozone concentrations was found in most of Southeast Asian (SEA) large cities and often exceeded the national ambient air quality standard. Ozone and PM10 are among of the critical air quality parameters that cause the unhealthy air quality index. Effort to mitigate ozone pollution is greatly complicated due to the photochemistry processes therefore photochemical smog modelling has been widely used. Surface ozone simulation in SEA was done using CHIMERE and weather research forecast (WRF) model. Emission inventory of ozone precursors was done for three countries in the domain, i.e. Indonesia, Thailand and Cambodia. Modelling performance evaluation for meteorological parameters and ozone at the SEA big cities was done in another study. This paper focused on the model evaluation conducted at the two remote sites represented by 2 (two) global atmospheric watch (GAW) remote stations of Bukit Kototabang (BKT) and Danum Valley (DNV). Evaluation result showed an overestimation of observed ozone in BKT while a contradictive result was seen in DNV station which was due to the ozone chemistry and inaccurate estimation of emissions (both anthropogenic and biogenic emission). The evaluation conducted at the remote sites was not even better than that conducted previously at the urban areas. Statistically, only mean normalized gross error and unpaired peak accuracy values that satisfy the criteria for surface ozone modelling suggesting major improvement required for ozone precursors emission inventory data.

scholarly journals Gridded global surface ozone metrics for atmospheric chemistry model evaluation

2015 ◽  
Vol 8 (2) ◽  
pp. 603-647 ◽  
Author(s):  
E. D. Sofen ◽  
D. Bowdalo ◽  
M. J. Evans ◽  
F. Apadula ◽  
P. Bonasoni ◽  
...  
Keyword(s):  
Air Quality ◽  
Atmospheric Chemistry ◽  
Model Evaluation ◽  
Climate Model ◽  
Surface Ozone ◽  
Quality Monitoring ◽  
Air Quality Monitoring ◽  
Monitoring Networks ◽  
Chemistry Research ◽  
Consistent Manner

Abstract. The concentration of ozone at the Earth's surface is measured at many locations across the globe for the purposes of air quality monitoring and atmospheric chemistry research. We have brought together all publicly available surface ozone observations from online databases from the modern era to build a consistent dataset for the evaluation of chemical transport and chemistry-climate (Earth System) models for projects such as the Chemistry-Climate Model Initiative and Aer-Chem-MIP. From a total dataset of approximately 6600 sites and 500 million hourly observations from 1971–2015, approximately 2200 sites and 200 million hourly observations pass screening as high-quality sites in regional background locations that are appropriate for use in global model evaluation. There is generally good data volume since the start of air quality monitoring networks in 1990 through 2013. Ozone observations are biased heavily toward North America and Europe with sparse coverage over the rest of the globe. This dataset is made available for the purposes of model evaluation as a set of gridded metrics intended to describe the distribution of ozone concentrations on monthly and annual timescales. Metrics include the moments of the distribution, percentiles, maximum daily eight-hour average (MDA8), SOMO35, AOT40, and metrics related to air quality regulatory thresholds. Gridded datasets are stored as netCDF-4 files and are available to download from the British Atmospheric Data Centre (doi:10.5285/08fbe63d-fa6d-4a7a-b952-5932e3ab0452). We provide recommendations to the ozone measurement community regarding improving metadata reporting to simplify ongoing and future efforts in working with ozone data from disparate networks in a consistent manner.

Sign in / Sign up

Export Citation Format

Share Document