Characterization of an episode with elevated ozone concentrations.

A detailed analysis has been made of a seven day period in 1973, during which elevated ozone levels were observed at Ottawa. In addition to the ozone data, results are also presented for oxides of nitrogen, carbon monoxide, methane, total hydrocarbons and particulate matter. The particulates were analyzed for seven constituents, including the cations ammonium, calcium, sodium, potassium and lead and the anions sulfate and nitrate. Also measured were several other properties of the particulates, including the size distribution. It was found that none of the other gaseous pollutants showed any increase in concentration when high ozone levels were present. In contrast, the particulate matter did increase and several constituents, notably ammonium and sulfate, showed a dramatic rise. A comparison with ozone data from Toronto and upper New York state showed that the high ozone concentrations were widespread. A meteorological analysis showed that elevated ozone levels were associated with a Tropical air mass with a moderate southwesterly flow of air. Trajectory calculations were carried out to show the origin of the air over Ottawa before, during and after the period of increased ozone.     

Analysis of high level ozone concentrations using nonparametric methods

Controlling emissions of air pollutants and establishing air quality objectives to improve and protect ambient air quality are very important tasks of Governments. Ozone (O₃), one of those pollutants of concern, is not emitted directly into the atmosphere, but is a secondary pollutant produced by reaction between nitrogen dioxide (NO₂), hydrocarbons and sunlight. High levels of ozone can produce harmful effects on human health and the environment in general. Therefore, the study of extreme values of ozone represents an important topic of research in environmental problems. Classical extreme value theory has been usually used in air-pollution studies. It consists of fitting a parametric generalized extreme value (GEV) distribution to a data set of extreme values and using the estimated distribution to compute quantities like the probability of exceedance, the quantiles, the return levels or the mean return periods. In this paper, we propose nonparametric methods to estimate those quantities. Additionally, nonparametric estimators of the trends of very high values of ozone are proposed. The nonparametric estimators are applied to real samples of maximum ozone values obtained from several monitoring stations belonging to the Automatic Urban and Rural Network (AURN) from the UK. Results show that nonparametric estimators work satisfactorily, generally outperforming the behaviour of classical parametric estimators.     

Ground level ozone concentrations at a rural location in northern Spain

A systematic analysis of surface ozone observations at a rural area of the upper Spanish plateau is presented. A near four-year study of ozone concentrations was carried out between February 2000 and October 2003. Diurnal and monthly variations of ozone are studied. The peak concentration levels are obtained between 13:00 and 15:00 GMT and the lowest levels at 4:00 and 5:00 GMT. The highest values together with a slight increase in data variability are found from April to August, when spring and summer maxima are appreciated. The relationship between synoptic-scale atmospheric transport patterns and the maximum ozone concentrations was also examined. Analysis of the 500-hPa synoptic weather patterns revealed that the highest values occur during continental and Atlantic ridges in summer and, to a lesser extent, during troughs in the east-northeast of the Iberian Peninsula in spring. Our approach entailed calculating 3-day isobaric backward air mass trajectories at the observational site sorted on the following main origins: European continent, African continent, Atlantic Ocean and local. The assessment of the results showed the influence of local conditions on the daily maximum ozone concentrations. Moreover, continental air masses provide certain evidence of long-range transport added to the local or regional contribution of the main cities affecting the sampling site. Conversely, Atlantic trajectories show the least contribution to ozone levels.     

Some factors affecting the ambient ozone concentrations measured at Ottawa

The concentration of ozone was measured from June 1972 to February 1973 at a location just outside the centre of Ottawa. Average monthly ozone levels were found to fall on a smooth curve with a maximum concentration in early summer and a minimum concentration in November. The daily ozone concentration profiles showed a consistent pattern, with a significant difference, however, between weekdays and weekends. The strong morning minimum found on weekdays could be attributed to anthropogenic effects. Measurements of NO and NO₂ concentrations appear to confirm the role of NO as the pollutant primarily responsible for the destruction of ozone.     

The impact of anthropogenic and biogenic emissions on surface ozone concentrations in Istanbul

Surface ozone concentrations at Istanbul during a summer episode in June 2008 were simulated using a high resolution and urban scale modeling system coupling MM5 and CMAQ models with a recently developed anthropogenic emission inventory for the region. Two sets of base runs were performed in order to investigate for the first time the impact of biogenic emissions on ozone concentrations in the Greater Istanbul Area (GIA). The first simulation was performed using only the anthropogenic emissions whereas the second simulation was performed using both anthropogenic and biogenic emissions. Biogenic NMVOC emissions were comparable with anthropogenic NMVOC emissions in terms of magnitude. The inclusion of biogenic emissions significantly improved the performance of the model, particularly in reproducing the low night time values as well as the temporal variation of ozone concentrations. Terpene emissions contributed significantly to the destruction of the ozone during nighttime. Biogenic NMVOCs emissions enhanced ozone concentrations in the downwind regions of GIA up to 25 ppb. The VOC/NO_x ratio almost doubled due to the addition of biogenic NMVOCs. Anthropogenic NO_x and NMVOCs were perturbed by ± 30% in another set of simulations to quantify the sensitivity of ozone concentrations to the precursor emissions in the region. The sensitivity runs, as along with the model-calculated ozone-to-reactive nitrogen ratios, pointed NO_x-sensitive chemistry, particularly in the downwind areas. On the other hand, urban parts of the city responded more to changes in NO_x due to very high anthropogenic emissions.     

耶路撒冷宽容博物馆

一座博物馆就是一部物化的发展史,人们通过文物与历史对话,穿过时空的阻隔,俯瞰历史的风风雨雨。与2010年主题"博物馆——为社会和谐而在"(Museums for Social Harmony)相呼应,这座宽容博物馆在扮演重要文化角色的同时,也让人们开始关     

Problems of reunified Jerusalem

The reunification of Jerusalem following the war between Israel and Jordan in 1967 has not solved many of the most difficult problems facing the city. More than 20 years later the same difficulties persist here as in the West Bank.     

Surface ozone concentrations and ecosystem health: past trends and a guide to future projections

This paper reviews current understanding of the sources and sinks of ozone in the troposphere, recent studies of long-term trends, and the factors which have to be taken into consideration when constructing and interpreting future models of ozone concentration. The factors controlling surface O₃ concentrations are discussed initially to provide a basis for the ensuing discussion, followed by a summary of the evidence for recent trends in ground-level ozone concentrations, i.e. over the past 3 decades, which have shown a significant increase in the annual average in ‘background’ air typical of the unpolluted northern hemisphere. Closer to precursor sources, although urban winter concentrations have increased, rural peak spring and summer concentrations during ozone ‘episodes’ have decreased markedly in response to emissions reductions. In order to determine whether such trends are meaningful, the statistical techniques for determining temporal trends are reviewed. The possible causes of long-term trends in ozone are then discussed, with particular reference to the use of chemistry-transport models to interpret past trends. Such models are also used to make predictions of future trends in surface ozone concentrations, but few are comprehensive in integrating future climate changes with changes in land use and in emissions of ozone precursors. Guidance is given on the likely effects of climate/precursor/chemistry interactions so that model predictions can be judged.     

Trends of phosphorus,nitrogen and chlorophyll a concentrations in Finnish rivers and lakes in 1975-2000

During recent decades the amounts of nutrients discharged to Finnish surface waters have markedly decreased. This has been achieved by considerable investments in water protection, which were made mainly to improve municipal and industrial wastewater purification. We investigated whether these water protection measures have decreased phosphorus and nitrogen concentrations in Finnish rivers and lakes. In addition, possible trends in chlorophyll a concentrations in lakes were studied. The data consisted of a total of over 68000 monitoring results of 22 rivers and 173 lakes (or sub-basins of lakes) with different types of catchment areas. The study period covered the years 1975-2000 and the non-parametric Kendall Tau b and Seasonal Kendall tests were applied for detecting trends. Decreasing nutrient concentration trends were typical in many lakes and rivers earlier polluted by municipal and industrial wastewaters. Increasing nutrient concentration trends were common in smaller rivers and lakes receiving diffuse loading from agriculture. The results show that the investments directed towards wastewater purification have effectively improved the quality of Finnish inland waters. However, no clear effects of decreasing non-point loading were found. Thus, more effective measures should be directed towards decreasing non-point source loading.     

Integrating monitoring networks to obtain estimates of ground-level ozone concentrations --a proof of concept in Tuscany (central Italy)

Prior to 2000 a network of conventional ozone (O3) analysers existed in the Province of Firenze (Tuscany, central Italy). Between 2000 and 2004 the network was extended to incorporate a newly designed bioindicator network of tobacco plants (Nicotiana tabacum Bel W3). The objective was to set-up an integrated monitoring system to obtain estimates of ground-level O3 concentrations over the whole study area (3513 km2) in order to fill data gaps and cover reporting requirements. The existing conventional monitors were purposefully located mainly in urban areas. A total of 45 biomonitoring sites were selected using a systematic design to cover the target area. Two to five additional biomonitoring sites were co-located with conventional O3 analysers for calibration purposes, and five more sites for independent validation of modelled O3 concentrations. Visible Leaf Injury Index (LII) on the tobacco plants was significantly correlated (P: 0.018/0.0014) with a series of O3 exposure variables (mean of weekly 1-hour maxima, M1; mean of 7-hour means, M7; 24-hour mean, M24; and weekly AOT40). LII was found to be a significant predictor of weekly means of the O3 exposure variables with a standard error of estimates between 13.6 and 24.3 microg m(-3) (absolute values). LII was mapped with an ad-hoc spatial model over the study area at a 22 km grid resolution, and mapped values were used to predict O3 concentrations by means of a first order linear model. Results showed that high estimates of O3 (up to 188 microg m(-3) as mean of weekly maxima, M1) occurred more frequently in hilly and mountainous areas, with a spatial pattern changing on an annual basis. Predicted O3 concentrations were not significantly different from the measured concentrations (P: 0.34), although marked differences were observed for individual sites and years. The study provided evidence that integration of monitoring networks using different methods can be a viable option to obtain estimates of O3 concentrations over large areas.     

Invisible city: a Jerusalem in the forest?

The Bielski partisans are perhaps the most famous of the 'Forest Jews' of Belarus, Jews who engaged in active resistance to the Germans in the years between 1941 and 1944 from their hide-outs in the forest. When they escaped to 'partisan country' Jews had to adjust to an entirely new physical and social environment. Persecuted by one of the most technologically advanced armies in the world, and forced by circumstances to join the Soviet-led, communist, anti-religious partisan movement, the Bielski group faced numerous social and cultural dilemmas in establishing the living conditions that ensured their survival. The extreme cold of the Russian winter made circumstances extremely harsh, 'living like animals'1 according to one partisan, although in time life improved sufficiently for many in the Bielski detachment to believe that their final camp had acquired the status of a small town or shtetl. If, however, such military camps have often recalled more established urban settlements, this question requires clarification in the Bielski case, and is the principal focus of this paper. In its examination of the dwellings and settlements constructed by the Bielski group, and how they evolved over time, the study underlines the minimum dimensions of culture that arise in near-survival conditions.     

The 1996 Paso del Norte Ozone Study: analysis of meteorological and air quality data that influence local ozone concentrations

The 1996 Paso del Norte Ozone Study and subsequent data analyses were implemented to develop an understanding of the chemical and physical processes which lead to high concentrations of ozone in the Paso del Norte study area which includes El Paso County, Texas, Sunland Park, New Mexico, and Ciudad Juárez, Mexico. Both the data and data analysis results are being used to support photochemical grid modeling. El Paso County and Sunland Park fail to meet the National Ambient Air Quality Standard (NAAQS) for ozone, and neighboring Ciudad Juárez fails to meet the Mexican ambient standard for ozone. This paper summarizes the measurement campaigns of the 1996 Paso del Norte Ozone Study and the findings and conclusions that arose from subsequent data analyses. Data analyses showed that high ozone concentrations resulted from a combination of conditions, including high surface temperatures, strong sunlight with few clouds, light surface winds and high concentrations of ozone precursors at ground level in the morning, and slow convective boundary layer (CBL) growth. Synoptic-scale meteorological conditions observed during high ozone episodes included an aloft high-pressure system and aloft warming. Aloft carryover of ozone and ozone precursors did not significantly contribute to high concentrations of ozone at the surface.     

Trends of phosphorus, nitrogen and chlorophyll a concentrations in Finnish rivers and lakes in 1975–2000

During recent decades the amounts of nutrients discharged to Finnish surface waters have markedly decreased. This has been achieved by considerable investments in water protection, which were made mainly to improve municipal and industrial wastewater purification. We investigated whether these water protection measures have decreased phosphorus and nitrogen concentrations in Finnish rivers and lakes. In addition, possible trends in chlorophyll a concentrations in lakes were studied. The data consisted of a total of over 68 000 monitoring results of 22 rivers and 173 lakes (or sub-basins of lakes) with different types of catchment areas. The study period covered the years 1975–2000 and the non-parametric Kendall Tau b and Seasonal Kendall tests were applied for detecting trends. Decreasing nutrient concentration trends were typical in many lakes and rivers earlier polluted by municipal and industrial wastewaters. Increasing nutrient concentration trends were common in smaller rivers and lakes receiving diffuse loading from agriculture. The results show that the investments directed towards wastewater purification have effectively improved the quality of Finnish inland waters. However, no clear effects of decreasing non-point loading were found. Thus, more effective measures should be directed towards decreasing non-point source loading.     

“信仰再追寻”——徐则臣小说《耶路撒冷》析论

徐则臣的小说《耶路撒冷》书写了一代人对信仰的"再次追寻"。在这艰苦跋涉的旅途背后,若隐若现着的"信仰"勾连起历史遗留下的心理阴影;而与此同时消费时代里的泥沙俱下又彻底颠覆了过往的种种寄托。作者书写着乡土故里的厚重历史内涵,借助西方宗教文化的思想形式为外衣,最终暗示这群中年人将再次寻得"信仰",并以坚韧笃信的情怀引领下一代。精心设计的结构使得这一旅程处处浸润着生活的辛酸与苦闷。分析《耶路撒冷》中的"信仰再追寻"现象,可窥得近年来文学作品中记述信仰问题的潜在动向,也相信可以为方兴未艾的新世纪文学研究提供一个有益的研究路径。     

Planning illegality: The roots of unauthorised housing in Arab East Jerusalem

This paper investigates the role of Israeli residential policies in the Israeli–Palestinian conflict over East Jerusalem. The focus is specifically on municipal housing policies for Arab neighbourhoods; the thesis is that Arab residential illegality is primarily a direct consequence of Israeli urban policies, and is a tool for achieving the (political) aim of the containment of Arab demographic growth and of Arab urban expansion.     

Trends in product information

Within CIB working commission W 74 on information co-ordination a special ‘Product file’ group monitors developments in this latter area. Here, chairman of the group, Anne Volbeda, deputy director of the Bouwcentrum in the Netherlands, comments on the move towards the data base approach, while presenting the results of an updated survey of some data sheet systems available in different countries at the time of the survey.