Comparison of ozone levels between working days and weekends in Athens,Greece

Athens has a major problem of ozone air pollution due to its climate which is dominated by hot and dry summers with intensesunshine. As a result there is a high violation of the air quality limits of ozone. By comparing ozone air pollution betweenweekdays and weekends it is possible to estimate the effect of the reduction of primary pollutants causing the formation ofozone on the levels of this pollutant. Thus it was estimated thatwhile during the weekends the concentrations of the ozone precursors (nitrogen oxides and volatile organic compounds) werereduced by the order of 10–20%, the effect on ozone levels was lower.     

Measurements of Ozone Concentrations in Zagreb

Ozone concentrations were measured in Zagreb at four sites from May 1999 to April 2001 in order to categorize the air quality with respect to ozone. In the summer of 2000, the ozone measurements were also extended to four sites in the suburbs of Zagreb. Methods of active and passive sampling with nitrite ion as a reagent were used. In the northern part of the town ozone was analyzed by an automatic device. Automatic device measurements in the years 1999 and 2000 showed that hourly averages of ozone concentrations did not exceed the Croatian recommended value of the 98th percentile (180 g m^–3). Over the two-year period, 24-h averages occasionally exceed 110 g m^–3 in city center and in the northern part of the town. Regardless of these isolated examples, ozone was well within acceptable concentrations. Ozone concentrations measured in summer 2000 were higher in the suburbs of Zagreb than in the city. The 98th percentile values higher than 110 g m^–3 were recorded at three sites.     

Extreme Nitrogen Oxide and Ozone Concentrations in Athens Atmosphere in Relation to Meteorological Conditions

In the present study, we investigate the variation of NO _x (NO + NO₂) and O₃ concentrations and the relation between the extreme events (episodes) of NO _x and O₃ concentrations and the relevant meteorological conditions in the urban atmosphere of the Athens basin. Hourly data of NO, NO₂ and O₃ concentrations from 10 representative monitoring sites located in the Athens basin were used, covering the 10-year time period from 1994 to 2003. The results of our analysis show that the concentrations of air pollutants differ significantly from one monitoring site to another, due to the location and proximity of each station to the emission sources. For each site, there are also significant differences in NO _x and O₃ concentrations from day to day, as well as from month to month and/or from season to season. The annual and seasonal variations show higher NO values in winter and lower in summer. On the contrary, NO₂ and O₃ values are higher in summer (photochemical production of O₃) and lower in winter. These differences are attributed, to a large extent, to the prevailing synoptic and meteorological conditions, the most important between them being the wind direction and speed as well as the atmospheric pressure. Our analysis of the identified 179 extreme NO _x air pollution events shows that most of them took place under anticyclonic conditions, associated with calm or weak winds (speed <2.5 ms⁻¹) of mostly southern to southwestern directions, as well as with low air temperatures and intense stable surface atmospheric conditions. There exists a significant decreasing tendency in NO _x air pollution episodic events over the 10-year study period, resulting in very few to none events in the period from 2000 to 2003. As far as it concerns the extreme O₃ concentrations, 34 air pollution events were identified, occurring under high air temperatures, variable weak winds and intense solar irradiation. The trends of O₃ concentrations are stronger in suburban sites than in urban ones.     

Air pollution in Athens basin and health risk assessment

An inventory of air pollution sources within the Athens basin is carried out for the years 1989, 1992 and 1998 and the results areinputted in a climatological model for predicting ambient concentrations. Despite of the significant growth in the numberof road vehicles and the deteriorating traffic, the emissions andambient concentrations of fine particulates, CO, NO_x and VOCappear to remain reasonably constant over for the period 1989 to 1998, while these of SO₂ and Pb are reduced, mainly due to the renewal of vehicle fleet, the use of catalytic technologies and the improved quality of the used fuel. The results further indicate that for CO, NO_x and VOC the major source is road traffic, while for PM_2.5 and SO₂ both space heating andtraffic share responsibility. The air pollutant concentrations monitored by the network of 11 stations are reviewed and statistics related to air quality guidelines are presented. As fine particulate levels are not monitored, approximate PM_2.5and PM₁₀ concentrations are derived from black smoke ones on basis of experimentally determined conversion factors. The computed and monitored air pollution levels are compared and found in reasonable agreement. The results of the above analysisshow that the levels of all `classical' pollutants, with the exception of SO₂ and Pb, exceed significantly the WHO guidelines and are thus expected to exert a significant healthimpact. The latter could be quantified in relation to the PM_2.5 or PM₁₀ levels on the basis of risk assessment information developed by the World Health Organization (WHO). The results show that the existing levels of fine particle concentrations in Athens increase significantly the mortality and morbidity, and reduce the average longevity of the entirepopulation from 1.3 to 1.7 years.     

Spatial and Temporal Variation of Ozone Concentrations at High Altitude Monitoring Sites in Germany

The present study deals with the characterisation and interpretation of hourly taken maximum ozone concentrations of each day at various high altitude monitoring sites in Germany and contributes to the understanding of ozone transport processes. The relation between long range transport of ozone as well as its precursors and high ozone concentrations is of special interest. Aim of this paper is to investigate the influence and importance of large scale meteorological circulation and source regions of anthropogenic ozone precursors to local ozone concentrations using 2-dimensional backward trajectories. Further, reasons for the spatial and temporal variation of ozone concentration levels will be shown. Investigating numerous cases a similar origin of air masses causing high ozone concentrations in Germany and uniform patterns at various sites could be identified.     

Development of an Ozone Forecasting Model for Non-Attainment Areas in the State of Ohio

Ground level ozone is responsible for the formation ofsmog, and for a variety of adverse effects on bothhuman and plant life. High concentrations of groundlevel ozone occur during the summer months. This paperdescribes the development of a model to forecast themaximum daily concentration of ozone as a function ofthe maximum surface temperature, for ozonenon-attainment regions in Ohio. The model wasdeveloped by statistical analysis of existing data.Site-specific models were developed initially. Theverification and evaluation of the performancecriteria of the model at each site were explored bycomparing the model with an independent datasetcollected from that site. A generalized statewidemodel was developed from the site-specific models. Theperformance criteria of this model were verified andevaluated by employing the same independent datasetsemployed for the site-specific models. An exceedencemodel to predict the occurrence of ozone exceedencesover 100 ppb has also been presented.     

The Seasonal Variation of the Concentrations of Ozone, Sulfur Dioxide, and Nitrogen Oxides in Two Nigerian Cities

A combination of multivariate statistical methods including factor analysis, principal component analysis, principal component regression, and multiple linear regression (MLR) were employed to evaluate the influence of seasons on the concentrations of ozone, sulfur (IV) oxide, and oxides of nitrogen in ambient air of Nigerian cities of Lagos and Ilorin. The former city is located in the coastal area, and it is highly congested with a high intensity of marine, vehicular, and industrial activities, and the latter city is a medium size town, located in the central guinea savannah zone of Nigeria. Samples were collected using a high-volume sampler from near the ground at various sites of diverse human and industrial activities, during wet and dry seasons from 2003 to 2006. The PCA reveals three distinct groupings during the day for all data, which is a reflection of different factors contributing to the atmospheric chemistry of these cities. The predicted ozone concentration values by MLR agree fairly well with the measured data. The dependence of ozone on meteorological parameters including relative humidity, air temperature, and sun exposure and the precursor pollutants depends on weather and the anthropogenic activities. The results for the two cities indicate that reduction in the level of NO₂ is accompanied by an increase in the level of ozone, suggesting the interconversion between the two via photochemical activity.     

PM10 Chemical Model Simulations Over Northern Italy in the Framework of the CityDelta Exercise

Within the framework of CityDelta open model inter-comparison exercise, two different atmospheric chemical transport models, comprehensive air quality model with extension and transport chemical aerosol model, have been applied over a domain centred on Milan (North of Italy) as a result of a cooperation of five Italian groups. The two models have shared the same input fields for yearly PM10 simulations. The paper illustrates the analysis of the particulate matter-simulated concentrations and the comparison with the available experimental data.     

Analysis of the Daily Variations of Wintertime Air Pollution Concentrations in the City of Graz, Austria

Measured air pollution concentrations in a city reflect the influence of different kinds of sources as well as varying meteorological conditions. In the city of Graz in southern Austria, frequent stagnant meteorological conditions can cause elevated levels of air pollution although emission levels are not exceptionally high. With the aid of a detailed emission inventory and an array of sodars and tethersondes as well as lidar systems supplementing the routine meteorological and air chemistry network during a field experiment in January 1998, the daily variations of air pollution concentrations of selected components within the complex topography of the city of Graz are explained. Main results show the almost linear dependence of the morning maximum concentrations on the predicted emission rates. Throughout the day the rising of the well mixed layer reduces concentrations considerably. Concerning NO_X the fast reaction from NO to NO₂ is important due to the down-mixing of O₃ from the residual layer. The maximum in the afternoon is influenced by emission rates and pollution transport due to the mountain wind.     

Calculating losses of crops in Denmark caused by high ozone levels

In order to help guide air pollution legislation at the European level, harmful air pollution effects on agriculture crops and the consequent economic implications for policy have been studied for more than a decade. Ozone has been labeled as the most serious of the damaging air pollutants to agriculture, where growth rates and consequently yields are dramatically reduced. Quantifying the effects has formed a key factor in policymaking. Based on the widely held view that AOT40 (Accumulated exposure Over Threshold of 40 ppb) is a good indicator of ozone-induced damage, the Danish Eulerian Model (DEM) was used to compute reduced agriculture yields on a 50 km×50 km grid over Europe. In one set of scenarios, a ten year meteorological time series was combined with realistic emission inventories. In another, various idealized emission reduction scenarios are applied to the same meteorological time series. The results show substantial inter-annual variability in economic losses, due in most part to meteorological conditions which varied much more substantially than the emissions during the same period. It is further shown that, taking all uncertainties into account, estimates of ozone-induced economic losses require that a long meteorological record is included in the analysis, for statistical significance to be improved to acceptable levels for use in policy analysis. In this study, calculations were made for Europe as a whole, though this paper presents results relevant for Denmark.     

Irrigation Efficiency and Quality of Irrigation Return Flows in the Ebro River Basin: An Overview

The review analysis of twenty two irrigation efficiency (IE) studies carried out in the Ebro River Basin shows that IE is low (average IE)_avg(= 53%) in surface-irrigated areas with high-permeable and shallow soils inadequate for this irrigation system, high (IE)_avg(= 79%) in surface-irrigated areas with appropriate soils for this system, and very high (IE)_avg(= 94%) in modern, automated and well managed sprinkler-irrigated areas. The unitary salt (total dissolved solids) and nitrate loads exported in the irrigation return flows (IRF) of seven districts vary, depending on soil salinity and on irrigation and N fertilization management, between 3–16 Mg salt/ha⋅ year and 23–195 kg NO)₃ ⁻-N/ha⋅ year, respectively. The lower nitrate loads exported from high IE districts show that a proper irrigation design and management is a key factor to reduce off-site nitrogen pollution. Although high IE’s also reduce off-site salt pollution, the presence of salts in the soil or subsoil may induce relatively high salt loads (≥14 Mg/ha⋅ year) even in high IE districts. Two important constrains identified in our revision were the short duration of most surveys and the lack of standards for conducting irrigation efficiency and mass balance studies at the irrigation district level. These limitations {emphasize the need for the establishment of a permanent and standardized network of drainage monitoring stations for the appropriate off-site pollution diagnosis and control of irrigated agriculture.     

徐州市区空气中有机污染现状与变化规律

通过建立和完善空气中有机污染物的分析方法,对徐州市区空气中的有机污染物开展了全面详细的探查,弄清了市区空气中有机污染物的污染现状及时空变化规律,填补了徐州市空气监测数据中的有机污染物的空白,为开展空气有机污染物的调查和监测奠定了一定的基础。     

The Radial Increment and Stemwood Element Concentrations of Scots Pine in the Area Influenced by the Narva Power Plants in Northeast Estonia

Soil is an important component of a watershed. Understanding soils and their interactions with the other components are, thus, considered to be critical and essential for conservation of resources and management of the watershed. Development of soil sampling and analysis programs are crucial for these purposes. Site-specific soil data are needed to identify current soil characteristics, as well as to validate datasets gathered for watershed-scale modelling of non-point sources (NPS) of pollutants arising from various land-use activities, hydrodynamics and water quality. The Koycegiz Lake–Dalyan Lagoon watershed, located in the southwest of Turkey along the Mediterranean Sea Coast, was selected as the study area for watershed modelling purposes. Development of soil sampling plans, their practical optimization, soil analyses and interpretation are presented in this article. The soil analyses conducted include physical, chemical and specific soil characteristics. Within the framework of this study, soil fertility parameters are presented and evaluated. Such an approach used is recommended for especially developing countries where up-to-date data sets are not fully available and/or centrally publicized.     

Climate change, urban air problems and transport policy in the European Union

This paper surveys some recent studies on conventional air pollution and climate change in the transport sector in Europe. Fuel efficiency standards, car emission standards and transport pricing instruments are analysed from an economic perspective taking into account environmental and economic efficiency objectives. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spatio-Temporal Variations of Sulphur Dioxide Patterns with Wind Conditions in Central Taiwan

Sulphur dioxide (SO₂) is one of the main atmospheric pollutants in central Taiwan. This article analyses the SO₂ concentration seasonal variations and spatial distribution using data obtained from ten air quality monitoring stations and the Taiwan Weather Bureau. It reveals that SO₂ concentration is high in winter and low in summer and that high concentration centers are located south of the Taichung coal-fired power plant, the main source of SO₂ emissions in the region.The location of high concentration centers changeswith different prevailing winds. SO₂ variations due towind direction are not unique. During short periods,when meteorological conditions are constant, variationin the pollution sources cause variations in thespatial distribution. This has been deduced byappreciation of Intervention analysis to time seriesof hourly data.     

Collaborative Science, Policy Development and Program Implementation in the Transboundary Georgia Basin/Puget Sound Ecosystem

The transboundary Georgia Basin Puget Sound ecosystem is situated in the southwest corner of British Columbia and northwest comer of Washington State. While bountiful and beautiful, this international region is facing significant threats to its marine and freshwater resources, air quality, habitats and species. These environmental challenges are compounded by rapid population growth and attendant uiban sprawl. As ecosystem stresses amplified and partnerships formed around possible solutions, it became increasingly clear that the shared sustainability challenges in the Georgia Basin and Puget Sound required shared solutions. Federal, state and provincial institutional arrangements were made between jurisdictions, which formalized small scale interest in transboundary management of this ecosystem. Formal agreements, however, can only do so much to further management of an ecosystem that spans international boarders. A transboundary regional research meeting, the 2003 GB/PS Research Conference, opened the doors for large-scale informal cross-boarder cooperation and management. In addition to cooperation, continued efforts to stem toxic pollution, contain urban growth, and protect and restore ecosystems, require a commitment from scientists, educators and policy makers to better integrate research and science with decision-making.Former Director of Planning and of Special Projects in the British Columbia Ministry of Municipal Affairs.