Previous studies of the size distribution of individual elements in the atmospheric aerosol have ... more Previous studies of the size distribution of individual elements in the atmospheric aerosol have been limited to particle sizes up to 20 Ixm (Davidson and Osborne, 1987). These studies show a sharp decline in the metal mass concentration for sizes larger than 10 ~tm. There are limited data about the chemical speciation of large particles (e.g. Eleftheriadis, 1993) due to the relative lack of importance of these particles to long-range transport studies and human lung deposition.
SAMS is an infrared limb-scanning radiometer designed to measure atmospheric temperature and chem... more SAMS is an infrared limb-scanning radiometer designed to measure atmospheric temperature and chemical composition from 15 to 150 km, using the pressure modulation technique. The molecular species, the spectral bands selected for the system, and the height ranges over which measurements can be made, are summarized. Initial data analysis concentrated on calibrating the instrument and perfecting the attitude and temperature
The impact of bioaerosol emissions from urban, agricultural and industrial environments on local ... more The impact of bioaerosol emissions from urban, agricultural and industrial environments on local air quality is of growing policy concern. Yet the risk exposure from outdoor emissions is difficult to quantify in real-time as microbial concentration in air is low and varies depending on meteorological factors and land use types. While there is also a large number of sampling methods in use, there is yet no standardised protocol established. In this review, a critical insight into chemical fingerprint analysis of microbial volatile organic compounds (MVOC) is provided. The most suitable techniques for sampling and analysing MVOCs in outdoor environments are reviewed and the need for further studies on MVOCs from outdoor environments including background levels is highlighted. There is yet no rapid and portable technique that allows rapid detection and analysis of MVOCs on site. Further directions towards a portable GCeMS coupled with SPME or an electronic nose are discussed.
The effects of meteorology on ambient aerosol concentrations and aerosol transport, within the Gr... more The effects of meteorology on ambient aerosol concentrations and aerosol transport, within the Greater Athens Area during the summer period, was investigated. Measurements of size fractionated anions and cations were made at two sites (inland at Ag. Stefanos and on the coast at Pireas) within the Greater Athens Area. The wind regime exhibited a distinct influence such that the sea-breeze circulation strongly enhanced the formation of secondary aerosols. For sulphate the difference in concentration between the two sites was, on average, 8 times greater on sea-breeze days compared with Etesian days (warm days with NE winds). During 'normal' days, any differences in concentrations were possibly due to local emissions. Elevated concentrations in the fine mode were detected at both sites during the sea-breeze days. The sea-breeze circulation enhances the development of secondary aerosols which was clearly shown at the inland site. Nitrous acid, hydrochloric acid and particulate nitrate, sulphate and ammonium increase during sea-breeze days. Elevated levels of nitrate, 4 µm diameter, were particularly observed on the days with a strong sea-breeze circulation. Sulphate was well correlated with both sulphur dioxide and ammonium suggesting the production of NH 4 HSO 4 /(NH 4) 2 SO 4 aerosols, formed through the neutralisation of NH 3 with sulphuric acids. Ammonium sulphate was found to be the major ammonium component in Athens.
Metallic copper nanoparticles (Cu NPs) are widely used in industry and released in a large quanti... more Metallic copper nanoparticles (Cu NPs) are widely used in industry and released in a large quantity to the environment. They cause harmful effect on animal and bacterial cells starting from approximately 100 mg l-1. Here, we have examined the toxicity and possible mechanisms of toxic action of Cu NPs (38 ± 5 nm) on plant cells using standardised cultures of whole Arabidopsis thaliana plants. Arabidopsis root growth dramatically decreased when 2.5 mg L-1 Cu NPs (29.6±4.8% decrease of the root elongation rate) was added to the Phytogel growth media. Complete blockage of root growth has been observed at 15 mg L-1 Cu NPs. Bulk and supernatant were significantly less toxic agents. Cu NPs (same concentrations) also affected leaf expansion rate. 2.5-15 mg l-1 Cu NPs activated key plant stress reactions, such as elevation of cytosolic free Ca 2+ , production of reactive oxygen species (ROS) and inhibition of photosynthetic efficiency (measured by high resolution PAM). To our knowledge such extreme sensitivity of plants (or any other living organism) to Cu NPs has not been reported previously. Thus, pollution by Cu NPs and potential harmful effects on flora require serious attention by environmentalists.
Metallic silver nanoparticles (Ag NPs) are the most widely used nanomaterial (25-30% of all produ... more Metallic silver nanoparticles (Ag NPs) are the most widely used nanomaterial (25-30% of all products containing nanoparticles, 2012). Studies conducted over last two decades have shown that levels of engineered Ag NPs in US soils reached 1-8 mg L-1. This shows that Ag NPs have become an important environmental contaminant. Here, we have examined mechanisms of Ag-NP-induced toxic action on flora using model plants of Arabidopsis thaliana. Ag NPs (d = 40±5 nm; 50-10000 mg L-1) inhibited root and leaf elongation and leaf growth as measured in standardised tests of sterile whole plant culture. Ag NPs induced transient elevation of cytosolic free Ca 2+ (major stress signalling second messenger) and generation of reactive oxygen species (ROS, measured by Amplex Red system). Ag NPs inhibited photosynthetic efficiency and caused accumulation of Ag in plant tissues up to 1 g kg-1 fresh weight. In all tests, NPs showed stronger effect than bulk. Using electron paramagnetic resonance spectroscopy, we have found that Ag NPs can interact with Lascorbic acid (major plant antioxidant). This reaction probably leads to ROS accumulation and oxidative stress. Overall, these data show that Ag NPs are toxic to higher plants and their emission to the biosphere should be controlled.
ABSTRACT One of the most important environmental concerns of today is the negative impact of poll... more ABSTRACT One of the most important environmental concerns of today is the negative impact of pollution on human health. The air we breathe and the water we drink are essential ingredients for a healthy life. Unfortunately polluted water and air are common throughout the world. Over a day a healthy adult will consume between 2 and 3 l of fluid and inhale around 11 m3 of air. While exposure to pollutants in air is via inhalation that for water may occur via the ingestion, dermal absorption and inhalation routes. In this chapter we review the sources and concentrations of various air pollutants before considering drinking water quality. For the latter we concentrate on the potentially harmful disinfection by-products.
Background arctic aerosol properties generally observed during the summer were studied at Ny-Åles... more Background arctic aerosol properties generally observed during the summer were studied at Ny-Ålesund, Svalbard in a six-week campaign where the aerosol size distribution and chemical composition were measured. The results presented here demonstrate the marked difference between the background arctic aerosol composition in comparison to the aged aerosol arriving in the area by long-range transport from southern latitudes. It is found that sulphate is the major water-soluble component of background aerosol followed by sea salt. Aged aerosol arriving in the Arctic from polluted areas is recognised by an increase in black carbon and in the refractory aerosol fraction.
Photochemical pollution refers to the complex formation of chemical oxidants (mainly ozone-O3) re... more Photochemical pollution refers to the complex formation of chemical oxidants (mainly ozone-O3) resulting from the interaction of high solar irradiation levels with the precursor substances of nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs). NOx and CO are produced by combustion processes and are emitted by vehicles and industries; VOCs are both anthropogenic and biogenic hydrocarbons (BVOCs). The main BVOCs are isoprene and monoterpenes.
The combined UAM-AERO/RAMS modeling system has been applied to study the dynamics of photochemica... more The combined UAM-AERO/RAMS modeling system has been applied to study the dynamics of photochemical gaseous species and particulate matter processes in the eastern Mediterranean area between the Greek mainland and the island of Crete. In particular, the modeling system is applied to simulate atmospheric conditions for two periods, i.e., 13-16 July 2000 and 26-30 July 2000. The spatial and temporal distributions of both gaseous and particulate matter pollutants have been extensively studied together with the identification of major emission sources in the area. New pre-processors were developed for the UAM-AERO model for evaluating detailed emission inventories for biogenic compounds, resuspended dust and sea salt. Comparison of the modeling results with measured data was performed and satisfactory agreement was found for a number of gaseous species. However, the model underestimates the PM 10 measured concentrations during summer. This is mainly due to the considerable underestimation of particulate matter emissions and in particular dust resuspension, the effect of forest fire emissions and the contribution of Saharan dust episodes.
It has recently been estimated that 4 million deaths each year are associated with air pollution ... more It has recently been estimated that 4 million deaths each year are associated with air pollution originating from household solid fuel use. Interventions to reduce biomass fuel-related emissions can yield a diverse stream of benefits including improved public health, socio-economic development, reduced land degradation and climate change mitigation. This study investigates the use of indigenous knowledge to inform interventions to combat indoor air pollution at a rural site in the Punjab province of Pakistan. The results indicate that the majority of people using biomass fuel had knowledge of its ill health effects. A range of methods were utilised to reduce indoor smoke including cooking in open spaces, use of chimneys, better ventilation and use of dry fuel. Education and housing type showed a statistically significant relationship with awareness of methods to reduce indoor exposure to biomass smoke. These findings lend support to the notion that communities have indigenous knowledge and their own methods to reduce exposure to indoor smoke from biomass fuels; this knowledge can be used as tool to design and implement sustainable intervention strategies to reduce the risk of exposure to indoor air pollution. It is recommended that a community based intervention focusing on locally manufactured improved stoves and better designed cooking spaces would be a suitable intervention in this region.
Nutrient and N 2 O concentrations in the nutrified English rivers and estuaries were much higher ... more Nutrient and N 2 O concentrations in the nutrified English rivers and estuaries were much higher than those in the Welsh rivers. N 2 O concentrations and % saturation in the estuaries were significantly correlated with nitrate, nitrite and ammonium concentrations in the water. The strongest correlation was with nitrite (r 2 = 0.56, p < 0.01), suggesting that nitrite was the most significant factor among the different nutrients in regulating N 2 O concentration in the estuaries. N 2 O concentrations in the English rivers and estuaries were supersaturated throughout the year with annual averages from 186.9 to 992.9%, indicating that these rivers and estuaries were sources of atmospheric N 2 O, whereas in the Welsh rivers N 2 O concentrations were much lower with annual averages from 113.6 to 137.4% saturation. Although the estuarine area in the Colne was almost the same as that in the Conwy, the annual N 2 O emission from the Colne was much higher (937498 mol N yr −1) than in the Conwy (23020 mol N yr −1). On the east coast, riverine emissions of N 2 O were only 0.5-12.5% of the total emission from rivers and estuaries. Thus rivers were negligible, but estuaries were significant contributors to the UK N 2 O inventory.
Extensive aerosol and trace gas measurements were conducted at Ny-Ålesund (Svalbard) before and a... more Extensive aerosol and trace gas measurements were conducted at Ny-Ålesund (Svalbard) before and after Arctic sunrise in 2001 (NICE Dark and Light intensive campaigns) in order to study the possible role of aerosols in the renoxification mechanism. This study reports aerosol physical measurements over a continuous 3-month period. Arctic and sub-Arctic air masses dominated the measurement period and were characterized by low number (N ∼ 275 and 590 cm -3 respectively) and surface area (S ∼ 39 and 28 µm 2 cm -3 ) concentrations (measured range d = 14-740 nm) except for two Arctic haze events with high concentrations in springtime (N ∼ 1140 cm -3 and ∼ 125 µm 2 cm -3 ). Excluding these events, aerosol volatility measurements indicated no significant variation in the volatile (∼0.40), semi-volatile (∼0.32) or refractory (∼0.28) volume fractions which are commonly attributed to H 2 SO 4 , (NH 4 ) 2 SO 4 /NH 4 HSO 4 and soot/dust/sea-salt aerosol.
... 1984) 87--100 87 Elsevier Science Publishers BV, Amsterdam -- Printed in The Netherlands OZON... more ... 1984) 87--100 87 Elsevier Science Publishers BV, Amsterdam -- Printed in The Netherlands OZONE--SECONDARY AEROSOL--VISIBILITY RELATIONSHIPS IN NORTH-WEST ENGLAND I. COLBECX and ROY M. HARRISON ... Prahm, LP, K. Conradsen and CB Nielson, 1980. ...
The role of urban plumes in the exposure of suburban/rural areas to pollution by ozone is discuss... more The role of urban plumes in the exposure of suburban/rural areas to pollution by ozone is discussed, and literature on direct measurement of ozone within plumes reviewed. There is a virtual absence of reports of ozone destruction within a NOx-rich urban plume and reasons are given for this gap in the current published data. These negative ozone increments are important because the particular air quality problems encountered downwind of a city will depend on its character as a source or sink of ozone. Simple plume reconstruction methods are used to verify and extend data from measurements in the London plume. There is an optimum time for air-parcel release with respect to increased plume ozone, and a change in the typical diurnal variation of ground-level ozone concentrations when the receptor site is situated within an urban plume. On a surface constructed from air parcel emission times and times travelled downwind of London, a major peak in plume ozone increment is observed 6-8 h downwind of a post rush-hour release in the urban centre. A secondary maximum in the surface is also apparent for air parcels 2-3 h after release in the early afternoon. These are not the emission and travel times usually adopted in modelling studies of the urban plume from London. Sites in the urban plume are also found to have a statistically different diurnal variation compared to rural/suburban sites which are not influenced by the plume. This is due to the titration of ozone mixing into the plume from aloft by plume NO.
Previous studies of the size distribution of individual elements in the atmospheric aerosol have ... more Previous studies of the size distribution of individual elements in the atmospheric aerosol have been limited to particle sizes up to 20 Ixm (Davidson and Osborne, 1987). These studies show a sharp decline in the metal mass concentration for sizes larger than 10 ~tm. There are limited data about the chemical speciation of large particles (e.g. Eleftheriadis, 1993) due to the relative lack of importance of these particles to long-range transport studies and human lung deposition.
SAMS is an infrared limb-scanning radiometer designed to measure atmospheric temperature and chem... more SAMS is an infrared limb-scanning radiometer designed to measure atmospheric temperature and chemical composition from 15 to 150 km, using the pressure modulation technique. The molecular species, the spectral bands selected for the system, and the height ranges over which measurements can be made, are summarized. Initial data analysis concentrated on calibrating the instrument and perfecting the attitude and temperature
The impact of bioaerosol emissions from urban, agricultural and industrial environments on local ... more The impact of bioaerosol emissions from urban, agricultural and industrial environments on local air quality is of growing policy concern. Yet the risk exposure from outdoor emissions is difficult to quantify in real-time as microbial concentration in air is low and varies depending on meteorological factors and land use types. While there is also a large number of sampling methods in use, there is yet no standardised protocol established. In this review, a critical insight into chemical fingerprint analysis of microbial volatile organic compounds (MVOC) is provided. The most suitable techniques for sampling and analysing MVOCs in outdoor environments are reviewed and the need for further studies on MVOCs from outdoor environments including background levels is highlighted. There is yet no rapid and portable technique that allows rapid detection and analysis of MVOCs on site. Further directions towards a portable GCeMS coupled with SPME or an electronic nose are discussed.
The effects of meteorology on ambient aerosol concentrations and aerosol transport, within the Gr... more The effects of meteorology on ambient aerosol concentrations and aerosol transport, within the Greater Athens Area during the summer period, was investigated. Measurements of size fractionated anions and cations were made at two sites (inland at Ag. Stefanos and on the coast at Pireas) within the Greater Athens Area. The wind regime exhibited a distinct influence such that the sea-breeze circulation strongly enhanced the formation of secondary aerosols. For sulphate the difference in concentration between the two sites was, on average, 8 times greater on sea-breeze days compared with Etesian days (warm days with NE winds). During 'normal' days, any differences in concentrations were possibly due to local emissions. Elevated concentrations in the fine mode were detected at both sites during the sea-breeze days. The sea-breeze circulation enhances the development of secondary aerosols which was clearly shown at the inland site. Nitrous acid, hydrochloric acid and particulate nitrate, sulphate and ammonium increase during sea-breeze days. Elevated levels of nitrate, 4 µm diameter, were particularly observed on the days with a strong sea-breeze circulation. Sulphate was well correlated with both sulphur dioxide and ammonium suggesting the production of NH 4 HSO 4 /(NH 4) 2 SO 4 aerosols, formed through the neutralisation of NH 3 with sulphuric acids. Ammonium sulphate was found to be the major ammonium component in Athens.
Metallic copper nanoparticles (Cu NPs) are widely used in industry and released in a large quanti... more Metallic copper nanoparticles (Cu NPs) are widely used in industry and released in a large quantity to the environment. They cause harmful effect on animal and bacterial cells starting from approximately 100 mg l-1. Here, we have examined the toxicity and possible mechanisms of toxic action of Cu NPs (38 ± 5 nm) on plant cells using standardised cultures of whole Arabidopsis thaliana plants. Arabidopsis root growth dramatically decreased when 2.5 mg L-1 Cu NPs (29.6±4.8% decrease of the root elongation rate) was added to the Phytogel growth media. Complete blockage of root growth has been observed at 15 mg L-1 Cu NPs. Bulk and supernatant were significantly less toxic agents. Cu NPs (same concentrations) also affected leaf expansion rate. 2.5-15 mg l-1 Cu NPs activated key plant stress reactions, such as elevation of cytosolic free Ca 2+ , production of reactive oxygen species (ROS) and inhibition of photosynthetic efficiency (measured by high resolution PAM). To our knowledge such extreme sensitivity of plants (or any other living organism) to Cu NPs has not been reported previously. Thus, pollution by Cu NPs and potential harmful effects on flora require serious attention by environmentalists.
Metallic silver nanoparticles (Ag NPs) are the most widely used nanomaterial (25-30% of all produ... more Metallic silver nanoparticles (Ag NPs) are the most widely used nanomaterial (25-30% of all products containing nanoparticles, 2012). Studies conducted over last two decades have shown that levels of engineered Ag NPs in US soils reached 1-8 mg L-1. This shows that Ag NPs have become an important environmental contaminant. Here, we have examined mechanisms of Ag-NP-induced toxic action on flora using model plants of Arabidopsis thaliana. Ag NPs (d = 40±5 nm; 50-10000 mg L-1) inhibited root and leaf elongation and leaf growth as measured in standardised tests of sterile whole plant culture. Ag NPs induced transient elevation of cytosolic free Ca 2+ (major stress signalling second messenger) and generation of reactive oxygen species (ROS, measured by Amplex Red system). Ag NPs inhibited photosynthetic efficiency and caused accumulation of Ag in plant tissues up to 1 g kg-1 fresh weight. In all tests, NPs showed stronger effect than bulk. Using electron paramagnetic resonance spectroscopy, we have found that Ag NPs can interact with Lascorbic acid (major plant antioxidant). This reaction probably leads to ROS accumulation and oxidative stress. Overall, these data show that Ag NPs are toxic to higher plants and their emission to the biosphere should be controlled.
ABSTRACT One of the most important environmental concerns of today is the negative impact of poll... more ABSTRACT One of the most important environmental concerns of today is the negative impact of pollution on human health. The air we breathe and the water we drink are essential ingredients for a healthy life. Unfortunately polluted water and air are common throughout the world. Over a day a healthy adult will consume between 2 and 3 l of fluid and inhale around 11 m3 of air. While exposure to pollutants in air is via inhalation that for water may occur via the ingestion, dermal absorption and inhalation routes. In this chapter we review the sources and concentrations of various air pollutants before considering drinking water quality. For the latter we concentrate on the potentially harmful disinfection by-products.
Background arctic aerosol properties generally observed during the summer were studied at Ny-Åles... more Background arctic aerosol properties generally observed during the summer were studied at Ny-Ålesund, Svalbard in a six-week campaign where the aerosol size distribution and chemical composition were measured. The results presented here demonstrate the marked difference between the background arctic aerosol composition in comparison to the aged aerosol arriving in the area by long-range transport from southern latitudes. It is found that sulphate is the major water-soluble component of background aerosol followed by sea salt. Aged aerosol arriving in the Arctic from polluted areas is recognised by an increase in black carbon and in the refractory aerosol fraction.
Photochemical pollution refers to the complex formation of chemical oxidants (mainly ozone-O3) re... more Photochemical pollution refers to the complex formation of chemical oxidants (mainly ozone-O3) resulting from the interaction of high solar irradiation levels with the precursor substances of nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs). NOx and CO are produced by combustion processes and are emitted by vehicles and industries; VOCs are both anthropogenic and biogenic hydrocarbons (BVOCs). The main BVOCs are isoprene and monoterpenes.
The combined UAM-AERO/RAMS modeling system has been applied to study the dynamics of photochemica... more The combined UAM-AERO/RAMS modeling system has been applied to study the dynamics of photochemical gaseous species and particulate matter processes in the eastern Mediterranean area between the Greek mainland and the island of Crete. In particular, the modeling system is applied to simulate atmospheric conditions for two periods, i.e., 13-16 July 2000 and 26-30 July 2000. The spatial and temporal distributions of both gaseous and particulate matter pollutants have been extensively studied together with the identification of major emission sources in the area. New pre-processors were developed for the UAM-AERO model for evaluating detailed emission inventories for biogenic compounds, resuspended dust and sea salt. Comparison of the modeling results with measured data was performed and satisfactory agreement was found for a number of gaseous species. However, the model underestimates the PM 10 measured concentrations during summer. This is mainly due to the considerable underestimation of particulate matter emissions and in particular dust resuspension, the effect of forest fire emissions and the contribution of Saharan dust episodes.
It has recently been estimated that 4 million deaths each year are associated with air pollution ... more It has recently been estimated that 4 million deaths each year are associated with air pollution originating from household solid fuel use. Interventions to reduce biomass fuel-related emissions can yield a diverse stream of benefits including improved public health, socio-economic development, reduced land degradation and climate change mitigation. This study investigates the use of indigenous knowledge to inform interventions to combat indoor air pollution at a rural site in the Punjab province of Pakistan. The results indicate that the majority of people using biomass fuel had knowledge of its ill health effects. A range of methods were utilised to reduce indoor smoke including cooking in open spaces, use of chimneys, better ventilation and use of dry fuel. Education and housing type showed a statistically significant relationship with awareness of methods to reduce indoor exposure to biomass smoke. These findings lend support to the notion that communities have indigenous knowledge and their own methods to reduce exposure to indoor smoke from biomass fuels; this knowledge can be used as tool to design and implement sustainable intervention strategies to reduce the risk of exposure to indoor air pollution. It is recommended that a community based intervention focusing on locally manufactured improved stoves and better designed cooking spaces would be a suitable intervention in this region.
Nutrient and N 2 O concentrations in the nutrified English rivers and estuaries were much higher ... more Nutrient and N 2 O concentrations in the nutrified English rivers and estuaries were much higher than those in the Welsh rivers. N 2 O concentrations and % saturation in the estuaries were significantly correlated with nitrate, nitrite and ammonium concentrations in the water. The strongest correlation was with nitrite (r 2 = 0.56, p < 0.01), suggesting that nitrite was the most significant factor among the different nutrients in regulating N 2 O concentration in the estuaries. N 2 O concentrations in the English rivers and estuaries were supersaturated throughout the year with annual averages from 186.9 to 992.9%, indicating that these rivers and estuaries were sources of atmospheric N 2 O, whereas in the Welsh rivers N 2 O concentrations were much lower with annual averages from 113.6 to 137.4% saturation. Although the estuarine area in the Colne was almost the same as that in the Conwy, the annual N 2 O emission from the Colne was much higher (937498 mol N yr −1) than in the Conwy (23020 mol N yr −1). On the east coast, riverine emissions of N 2 O were only 0.5-12.5% of the total emission from rivers and estuaries. Thus rivers were negligible, but estuaries were significant contributors to the UK N 2 O inventory.
Extensive aerosol and trace gas measurements were conducted at Ny-Ålesund (Svalbard) before and a... more Extensive aerosol and trace gas measurements were conducted at Ny-Ålesund (Svalbard) before and after Arctic sunrise in 2001 (NICE Dark and Light intensive campaigns) in order to study the possible role of aerosols in the renoxification mechanism. This study reports aerosol physical measurements over a continuous 3-month period. Arctic and sub-Arctic air masses dominated the measurement period and were characterized by low number (N ∼ 275 and 590 cm -3 respectively) and surface area (S ∼ 39 and 28 µm 2 cm -3 ) concentrations (measured range d = 14-740 nm) except for two Arctic haze events with high concentrations in springtime (N ∼ 1140 cm -3 and ∼ 125 µm 2 cm -3 ). Excluding these events, aerosol volatility measurements indicated no significant variation in the volatile (∼0.40), semi-volatile (∼0.32) or refractory (∼0.28) volume fractions which are commonly attributed to H 2 SO 4 , (NH 4 ) 2 SO 4 /NH 4 HSO 4 and soot/dust/sea-salt aerosol.
... 1984) 87--100 87 Elsevier Science Publishers BV, Amsterdam -- Printed in The Netherlands OZON... more ... 1984) 87--100 87 Elsevier Science Publishers BV, Amsterdam -- Printed in The Netherlands OZONE--SECONDARY AEROSOL--VISIBILITY RELATIONSHIPS IN NORTH-WEST ENGLAND I. COLBECX and ROY M. HARRISON ... Prahm, LP, K. Conradsen and CB Nielson, 1980. ...
The role of urban plumes in the exposure of suburban/rural areas to pollution by ozone is discuss... more The role of urban plumes in the exposure of suburban/rural areas to pollution by ozone is discussed, and literature on direct measurement of ozone within plumes reviewed. There is a virtual absence of reports of ozone destruction within a NOx-rich urban plume and reasons are given for this gap in the current published data. These negative ozone increments are important because the particular air quality problems encountered downwind of a city will depend on its character as a source or sink of ozone. Simple plume reconstruction methods are used to verify and extend data from measurements in the London plume. There is an optimum time for air-parcel release with respect to increased plume ozone, and a change in the typical diurnal variation of ground-level ozone concentrations when the receptor site is situated within an urban plume. On a surface constructed from air parcel emission times and times travelled downwind of London, a major peak in plume ozone increment is observed 6-8 h downwind of a post rush-hour release in the urban centre. A secondary maximum in the surface is also apparent for air parcels 2-3 h after release in the early afternoon. These are not the emission and travel times usually adopted in modelling studies of the urban plume from London. Sites in the urban plume are also found to have a statistically different diurnal variation compared to rural/suburban sites which are not influenced by the plume. This is due to the titration of ozone mixing into the plume from aloft by plume NO.
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