Ozone influence on native vegetation in the Jizerske hory Mts. of the Czech Republic: results based on ozone exposure and ozone-induced visible symptoms

Ozone levels in the Jizerske hory Mts. measured at 13 sites by diffusive samplers during the 2006 and 2007 vegetation seasons are presented. A significant ozone gradient (5.4 ppb in 2006 and 4.0 ppb in 2007) per 100 m difference in altitude between 370 and 1,100 m a.s.l. was recorded. High-resolution maps of phytotoxic potential were developed. The AOT40 threshold (5 ppm h) was exceeded over the entire area with the highest levels exceeding this threshold by 12 times in the upper portions of the mountains. Ozone visible injury was evaluated at four of the monitoring sites on seven native plant and tree species. Four species showed ozone-like symptoms, two of which (Rubus idaeus and Fagus sylvatica) were confirmed as ozone-induced. Our results indicate that ambient ozone is likely to have a much lower impact on the Jizerske hory Mts. vegetation than expected, considering the measured ambient ozone exposures and favourable environmental conditions for ozone uptake.     

Prediction of extreme ozone levels in Barcelona, Spain

Barcelona is one of the most polluted cities in Western Europe, although our levels of air pollution are within the World Health Organisation air quality guidelines. However, high concentrations of air pollution have not been studied yet. Ground ozone levels is a topic of considerable environmental concern, since excessive level of ozone are taken as indicative of high pollution. In terms of the air quality guidelines ozone levels higher than 100 µg m^–3 can start to be health-hazards for human health. Our objective is to report a detailed analysis of ozone data exceeding the thresholds established by the air quality guidelines. Data analysed were collected in two measurement stations in Barcelona, for the reference period 1991–1996. Applying statistical techniques commonly used in the analysis of extreme values, mainly the Peak Over Threshold method was used for in this study. The analysis reveal that the ozone threshold values for the protection of human health has exceeded many times in both stations. The estimated return values for 3, 10, and 40 yr exceed the threshold value for information to the public of almost once in both stations, also it seems to be unlikely that the threshold value for warning to the public will be exceeded in 40 yr.     

Variations and trends of ground-level ozone and AOT40 in the rural areas of Lithuania

The analysis of data of the ground-level ozone concentration and accumulated ozone exposure over a threshold of 40 ppb (AOT40) in the rural areas of Lithuania is presented. Trends in the annual ozone mean, 95{th} and 25{th} percentiles were determined as statistically not significant at Preila and Rugsteliskes sites during the 1994hbox{–}2004 period. Trends in the ozone concentration and its percentiles in the air masses arriving to Preila station in “polluted” and “unpolluted” sectors have been examined. Statistically significant changes in the ozone annual mean and 25th percentile were found in air masses in both “polluted” and “unpolluted” sectors in the 1988hbox{–}2002 period. The trend analysis in the ozone monthly mean and percentiles for each month of the year revealed the main changes in the ozone level in both sectors during January-May. Insignificant downward trends in monthly 95th percentile in “unpolluted” sector and upward trends in “polluted” sector were found during summer months. Values of AOT40 for the protection of forests as well as crops and semi-natural vegetation were determined during the 1994–2004 period. The estimated AOT40 values for the protection of forests were lower than the critical level at Lithuanian rural sites but AOT40 values for the protection of crops and semi-natural vegetation were found to be higher than the critical level at both sites.     

Why Should We Calculate Complex Indices of Ozone Exposure? Results from Mediterranean Background Sites

While moving towards a flux-based approach, exposure-based ozone metrics are still a practical measure for summarising ambient air quality. Ozone hourly concentrations for the period 2000–2004 from sites in the Mediterranean Italy (≤600 m a.s.l.) were examined to define the O₃ summary statistic in the area, and to determine how O₃ exposure indices correlate to each other. Thirty-four of the most common O₃ exposure metrics were calculated. The results show that background O₃ pollution in Italy exceeds the European and North American standards. The exceedances of the target value, information and alert thresholds set by the 2002/3/CE Directive should encourage Italy to take the appropriate measures to reduce the risk. All the O₃ exposure indices, except the maximum permissible ozone concentration (MPOC) for forests, point to the potential for negative effects on vegetation and human health across Italy. As indices evaluated significantly correlated with each other, we suggest use of the most biologically meaningful metric when summarizing air quality information.     

Updating federal standards for toxicants: n-Hexane as the model

Regulatory agencies commonly set standards for a myriad of chemical and physical hazards, with a special focus on carcinogens. This focus can obscure the need to update previously set standards for non-carcinogenic hazards in response to new scientific data. This paper considers n-hexane as a representative chemical hazard: the occupational standard of 500 ppm over an 8 hr time weighted average for a 40 hr week as set in 1948. In the last 12 yr, n-hexane has been shown to cause adverse effects on the peripheral and central nervous systems, the eye, and the respiratory tract. Yet, these new data have not, as yet, been incorporated into a revised standard for n-hexane. The lack of scientific data on the carcinogenicity of n-hexane may be an underlying reason explaining the failure of regulatory agencies to revise their standards. Perhaps, the most troubling problem to regulatory agencies is the sheer magnitude of the chemical regulatory burden. Research should proceed on developing meaningful categories or groupings both for the initial setting of standards and for revising existing standards.     

Errors in ozone risk assessment using standard conditions for converting ozone concentrations obtained by passive samplers in mountain regions

Passive samplers are often employed to measure ozone concentrations in remote areas such as mountain forests. The potential ozone risk for vegetation is then assessed by calculating the AOT40 exposure index (accumulated hourly ozone concentration exceedances above 40 ppb, i.e. AOT40 = Σ([O(3)] - 40)Δt for any hourly ozone concentration [O(3)] > 40 ppb). AOT40 is customary calculated on the basis of ozone concentrations expressed as a volumetric mixing ratio, while lab sheets normally report ozone concentrations from passive samplers in mass units per cubic metre. Concentrations are usually converted from mass units to ppb using a standard conversion factor taking SATP (Standard Ambient Temperature and Pressure) conditions into account. These conditions, however, can vary considerably with elevation. As a consequence, the blanket application of a standard conversion factor may lead to substantial errors in reporting and mapping ozone concentrations and therefore in assessing potential ozone risk in mountain regions. In this paper we carry out a sensitivity analysis of the effects of uncertainties in estimations of air temperature (T) and atmospheric pressure (P) on the concentration conversion factor, and present two examples from two monitoring and mapping exercises carried out in the Italian Alps. We derived P and T at each site from adiabatic lapse rates for temperature and pressure and analysed the magnitude of error in concentration estimations. Results show that the concentration conversion is much more sensitive to uncertainties in P gradient estimation than to air temperature errors. The concentration conversion factor (cf) deviates 5% from the standard transformation at an elevation of 500 m asl. As a consequence, the standard estimated AOT40 at this elevation is about 13% less than the actual value. AOT40 was found to be underestimated by an average between 25% and 34% at typical elevations of mountain forest stands in the Italian Alps when a correct conversion factor for transforming ozone concentrations from μg m(-3) to ppb is not applied.     

Is PM10 mass measurement a reliable index for air quality assessment? An environmental study in a geographical area of north-eastern Italy

The aim of this study was to measure the concentration of some metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Ti) in PM(10) samples collected in one urban and one industrial site and to assess that PM(10) total mass measurement may be not sufficient as air quality index due to its complex composition. Metals were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and differential pulsed anodic stripping voltammetry (DPASV). The measured concentrations were used to calculate the content of metals in the PM(10) total mass, and to estimate the enrichment factors and the correlations between PM(10), metal concentrations and meteorological data for the two sites. The mean PM10 concentration during the sampling period in the urban site exceeded the annual European Union (EU) standard (40 microg/m(3)) and, for some sampling days, the daily EU standard (50 microg/m(3)) was also exceeded. In opposite, both EU standards were never exceeded in the industrial site. The overall metal content was nearly double in the industrial site compared to the urban one, and the mean Ni concentration exceeded the EU annual limit value (10 ng/m(3)). The metals with the highest enrichment factor were Cd, Cu, Ni and Pb for both sites, suggesting a dominant anthropogenic source for these metals. Metal concentrations were very low and typical of rural background during Christmas holidays, when factories were closed. PM(10) total mass measurement is not a sufficient air quality index since the metal content of PM(10) is not related to its total mass, especially in sites with industrial activities. This measurement should be associated with the analysis of toxic metals.     

京津冀区域臭氧污染趋势及时空分布特征

为研究京津冀区域的臭氧(O_3)污染情况及其时空分布特征,对2013—2015年京津冀区域13个城市80个国家环境空气监测点位的监测数据进行了统计分析。结果表明:2013—2015年,京津冀区域O_3污染状况整体呈加重趋势,其中2014年污染状况最为严重。13个城市中O_3污染最严重的城市为北京和衡水,连续3年均超标,且处于上升态势中。区域内不同城市O_3污染趋势并不相同。京津冀区域O_3浓度变化呈明显的季节变化特征,春末和夏季的O_3污染最严重。O_3-8 h(臭氧日最大8 h均值)年均值的高值区主要分布在北京中北部、承德和衡水等,2013—2015年第90百分位O_3-8 h的高值区均集中分布在北京。O_3的浓度峰值时间要晚于NOx2~5 h。O_3在春、夏季呈单峰分布,白天15:00左右出现最大值,在秋、冬季浓度较低,全天波动不大。     

Ambient ozone injury to forest plants in Northeast and North Central USA: 16?years of biomonitoring

The US Forest Service administers a long-term, nationwide ozone biomonitoring program in partnership with other state and federal agencies to address national concerns about ozone impacts on forest health. Biomonitoring surveys begun in 1994 in the East and 1998 in the West provide important regional information on ozone air quality and a field-based record of ozone injury unavailable from any other data source. Surveys in the Northeast and North Central subregions cover 450 field sites in 24 states where ozone-sensitive plants are evaluated for ozone-induced foliar injury every year. Sites are typically large, undisturbed openings (>3 acres in size) close to forested areas where >3 bioindicator species are available for evaluation. Over the 16-year sampling period, injury indices have fluctuated annually in response to seasonal ozone concentrations and site moisture conditions. Sites with and without injury occur at all ozone exposures but when ambient concentrations are relatively low, the percentage of uninjured sites is much greater than the percentage of injured sites; and regardless of ozone exposure, when drought conditions prevail, the percentage of uninjured sites is much greater than the percentage of injured sites. Results indicate a declining trend in foliar injury especially after 2002 when peak ozone concentrations declined across the entire region.     

Trends analysis of ambient 8 hour ozone and precursor monitoring data in the south central U.S

For the south central U.S., lower tropospheric ozone pollution has been a persistent and challenging problem. This paper provides long-term trends analyses of the ozone and precursor monitoring data collected over the past 20 years in four south central U.S. cities. The results of these analyses should be useful to air quality scientists, managers, planners, and modelers in assessing the effectiveness of ozone pollution control strategies being implemented or being planned for the future. Results of the data analyses show that all areas have monitored significant decreases in ozone and precursor concentrations over the past 20 years, especially in El Paso, Texas. Continuing challenges include the reduction of the percentage of time that monitors record 8 hour ozone concentrations over the U.S. 8 hour ozone standard, and the future control of highly reactive volatile organic compounds.     

Vertical ozone characteristics in urban boundary layer in Beijing

Vertical ozone and meteorological parameters were measured by tethered balloon in the boundary layer in the summer of 2009 in Beijing, China. A total of 77 tethersonde soundings were taken during the 27-day campaign. The surface ozone concentrations measured by ozonesondes and TEI 49C showed good agreement, albeit with temporal difference between the two instruments. Two case studies of nocturnal secondary ozone maxima are discussed in detail. The development of the low-level jet played a critical role leading to the observed ozone peak concentrations in nocturnal boundary layer (NBL). The maximum of surface ozone was 161.7 ppbv during the campaign, which could be attributed to abundant precursors storage near surface layer at nighttime. Vertical distribution of ozone was also measured utilizing conventional continuous analyzers on 325-m meteorological observation tower. The results showed the NBL height was between 47 and 280 m, which were consistent with the balloon data. Southerly air flow could bring ozone-rich air to Beijing, and the ozone concentrations exceeded the China’s hourly ozone standard (approximately 100 ppb) above 600 m for more than 12 h.     

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.     

Impact of changed trophic status on the zooplankton composition in six water bodies of Dharwad district, Karnataka state (South India)

Morgan Island, located within the ACE Basin National Estuarine Research Reserve in South Carolina, is home to the only free-ranging colony of rhesus monkeys (Macca mulatta) in the continental United States. The purpose of this study was to assess environmental impacts of the monkey colony on water quality in adjacent tidal creeks and on island vegetation. Three tidal creeks were sampled: Morgan Creek, adjacent to the monkey colony; Back Creek, on Morgan Island not adjacent to the colony; and Rock Creek, on a nearby island unoccupied by monkeys. Temperature, salinity, pH, dissolved oxygen, nutrients and fecal coliform bacteria were measured six times at three sites in each of these creeks, and vegetation change analysis was conducted in a geographic information system using satellite imagery. Results showed elevated fecal coliform concentrations in the Morgan Creek site immediately adjacent to the colony, though no samples exceeded the standard set for recreational water use. Ribotyping reconnaissance matched four Escherichia coli isolates from Morgan and Back Creeks to the monkeys, identifying the colony as one source of fecal coliform bacteria, though relative source loadings could not be quantified. Significant differences were not observed between ammonia or orthophosphate levels in Morgan Creek relative to the other creeks tested; and vegetation change analysis showed a 35% increase in canopy cover between 1979 and 1999. Overall, these results suggest that the rhesus colony’s environmental impacts are localized and minimal. Results from this study provide baseline data on Morgan Island and may be useful in management decisions regarding the future of the monkey colony.     

乌鲁木齐市大气PM2.5中重金属元素含量和富集特征

利用PM2.5／PM10便携式采样器采集了乌鲁木齐市5个功能区PM2.5，样品，用TAS-990石墨炉原子吸收光谱仪检测了PM2.5样品中Cd、Cu、Ni、Pb、Mn的含量。结果表明，乌鲁木齐大气PM2.5质量浓度变化趋势是冬季采暖盛期〉秋季采暖初期〉春季停暖初期〉夏季停暖期。参照《环境空气质量标准》（GB3095—2012）中的二级标准，采样期间卡子湾水泥厂区样品全部超标，其余4个采样点样品在冬季采暖盛期也全部超标，部分样品在非采暖期超标。富集因子法分析表明，乌鲁木齐市5个采样区PM2.5样品中Ni、Cu、Cd、Pb污染主要来自于人类活动，Mn则来源于地壳物质。     

Monitoring ammonia in urban, inner alpine and pre-alpine ambient air

Passive samplers were used to monitor ammonia concentrations at rural inner alpine and pre-alpine, as well as urban, sites in Austria and Bavaria. Elevated concentrations were measured both at farms (up to 36 microg NH3 m(-3)) and at urban locations (up to 28 microg NH3 m(-3)). At urban locations a linear relationship between the traffic density and the NH3 concentration was found, but there was no marked seasonal trend. The highest ammonia concentrations were measured in a traffic tunnel (up to 78 microg NH3 m(-3)). The presence of livestock breeding or small scale alpine pastures resulted in elevated concentrations at the rural sites (8.1-12 and 2.5-4.6 microg NH3 m(-3), respectively), compared to the surrounding areas (3.1 and 0.9 microg NH3 m(-3)). Agriculture related sources are usually limited either spatially or seasonally. As the emissions were moderate in our case, a rapid removal and dilution of ammonia was possible and therefore the NH3 burden was only local. Sources related to traffic are more evenly distributed both geographically and seasonally. The WHO guideline, annual average concentration of 8 microg m(-3) for the protection of vegetation, was only exceeded at farms, at the urban station with the heaviest traffic and in the Tauerntunnel.     

Spatial and temporal variation of surface ozone,NO and NO2 at urban,suburban, rural and industrial sites in the southwest of the Iberian Peninsula

Surface ozone is one of the most important photochemical pollutants in the low atmosphere, causing damage to human health, vegetation, materials and climate. The weather (high temperatures and high solar radiation), orography (presence of the Guadalquivir valley) and anthropogenic (the cities of Cádiz, Córdoba, Huelva and Seville and two important industrial complexes) characteristics of the southwestern Iberian Peninsula make this region ideal for the formation and accumulation of ozone. To increase the knowledge of ozone behaviour in this area, the monthly, daily and weekly variations of ozone and its precursors, nitrogen oxides (NO_x?=?NO?+?NO₂), were analysed over a 4-year period (2003 to 2006). Using the k-means cluster technique, 12 representative stations of five different areas with different ozone behaviour were selected from a total of 29 monitoring sites. This is the first time that the analysis of these atmospheric pollutants has been carried out for the whole area, allowing therefore a complete understanding of the dynamics and the relationships of these compounds in this region. The results showed an opposite behaviour among ozone and NO and NO₂ concentrations in urban and suburban zones, marked by maximums of ozone (minimums NO_x) in spring and summer and minimums (maximums) in autumn and winter. A seasonal behaviour, with lower amplitude, was also observed in rural and industrial areas for ozone concentrations, with the NO and NO₂ concentrations remaining at low and similar values during the year in rural zones due to the absence of emission sources in their surroundings. The daily cycles of ozone in urban, suburban and industrial sites registered a maximum value in the early afternoon (14:00–17:00 UTC) while for NO_x two peaks were observed, at 7:00–10:00 UTC and 20:00–22:00. In the case of rural stations, no hourly peak of ozone or NO_x was registered. The weekend effect was studied by using a statistical contrast tests (Student’s t). The results indicated that only areas influenced by important traffic emissions presented a weekend effect for NO and NO₂, whereas an ozone weekend effect was not detected in any case.     

Multimedia environmental monitoring: 50 years at Hanford

Environmental monitoring has been an ongoing activity on the U.S. Department of Energy's Hanford Site in southeastern Washington for almost 50 years. Objectives are to detect and assess potential impacts of Site operations on air, surface and ground waters, foodstuffs, fish, wildlife, soil and vegetation. Data from monitoring effects are used to calculate the overall radiological dose to humans working onsite or residing in nearby communities. In 1989, measured Hanford Site perimeter concentrations of airborne radionuclides were below applicable guidelines. Concentrations of radionuclides and nonradiological water quality in the Columbia River were in compliance with applicable standards. Foodstuffs irrigated with river water taken downstream of the Site showed radionuclide levels that were similar to those found in foodstuffs from control areas. Low levels of ¹³⁷Cs and ⁹⁰Sr in most onsite wildlife samples and concentrations of radionuclides in soils and vegetation from on- and offsite locations were typical of those attributable to worldwide fallout. The calculated dose potentially received by a maximally exposed individual (i.e., based on hypothetical, worst-case assumptions for all routes of exposure) in 1989 (0.05 mrem/yr) was similar to those calculated for 1985 through 1988.In addition to monitoring radioactivity in fish and wildlife, population numbers of key species are determined. Chinook salmon (Oncorhynchus tshawytscha) spawning in the Columbia River at Hanford has increased in recent years with a concomitant increase in winter roosting activity of bald eagles (Haliaeetus leucocephalus). An elk (Cervus elaphus) herd, established by immigration in 1972, is also increasing. The Hanford Site currently serves as a refuge for Canada goose (Branta canadensis), great blue heron (Ardea herodias), and various plants and other animals, e.g., mule deer (Odocoileus hemionus), and coyotes (Canis latrans).     

Regional assessment of ozone sensitive tree species using bioindicator plants

Tropospheric ozone occurs at phytotoxic levels in the northeastern and mid-Atlantic regions of the United States. Quantifying possible regional-scale impacts of ambient ozone onforest tree species is difficult and is confounded by other factors, such as moisture and light, which influence the uptake of ozone by plants. Biomonitoring provides an approach to document direct foliar injury irrespective of direct measure ofozone uptake. We used bioindicator and field plot data from theUSDA Forest Service to identify tree species likely to exhibit regional-scale ozone impacts. Approximately 24% of sampled sweetgum (Liquidambar styraciflua), 15% of sampled loblollypine (Pinus taeda), and 12% of sampled black cherry (Prunus serotina) trees were in the highest risk category. Sweetgum and loblolly pine trees were at risk on the coastal plain of Maryland, Virginia and Delaware. Black cherry trees were at riskon the Allegheny Plateau (Pennsylvania), in the Allegheny Mountains (Pennsylvania, West Virginia, and Maryland) as well ascoastal plain areas of Maryland and Virginia. Our findings indicate a need for more in-depth study of actual impacts on growth and reproduction of these three species.     

A study of ground-level ozone pollution, ozone precursors and subtropical meteorological conditions in central Taiwan

Hourly concentrations of ozone (O(3)), 55 volatile organic compounds (VOCs, ozone precursors) and nitrogen oxides (NOx) were measured at an upwind urban site, a downwind suburban site, and a rural site in central Taiwan, from January 2003 to December 2006. VOC and NOx mean concentrations showed a gradient from high to low across the urban (56 ppb and 34 ppb), suburban (38 ppb and 27 ppb) and rural sites (25 ppb and 21 ppb) but a reverse gradient in ozone across these sites (24, 27, and 29 ppb, respectively). Although there was about twice the difference in VOC concentrations between the urban and rural sites, nearly 65% ozone formation potential was contributed to by the same 9 VOCs. Seasonal patterns showed peak ozone levels in autumn and minima in summer at the urban site, but minima in winter at the downwind suburban and rural sites. Ozone precursor levels, on the other hand, were lowest in summer and highest in winter. The diurnal pattern showed that ozone levels peaked one hour later at the rural site than at the urban site. The ethylbenzene to m,p-xylene ratio, an indicator of the age of the air mass, increased from 0.4 at the urban site to 0.6 at the suburban site and 0.8 at the rural site during daily peak ozone times. This finding suggests the transport of ozone and precursors from upwind to downwind producing elevated ozone levels in the suburban and rural areas. Ozone episodes occurred mostly in days with a mean midday UV index of 6.5 (1 UV index=100 J m(-2)) and wind speed at 1.3 m s(-1) at all three sites.     

安徽省臭氧污染特征及气象影响因素分析

基于2016—2018年安徽省68个国控环境空气质量自动监测站点的臭氧(O_3)监测数据,研究分析了安徽省O_3污染特征及其与气象因子的相关性。结果表明:安徽省O_3污染程度呈现逐年加重趋势,并有显著的季节和月度变化特征。2016—2018年,各年度单月O_3日最大8小时滑动平均质量浓度第90百分位数的最大值分别出现在9月、5月、6月。O_3日变化趋势为典型的单峰形,各年度最低值出现在晨间07:00左右,最高值则是在15:00—16:00。全省O_3浓度总体上呈现出北高南低的空间特征。温度、相对湿度与O_3浓度分别呈现显著正相关、负相关,但在不同季节存在一定差异,其中,春秋季温度与O_3浓度的相关性好于夏冬季,夏季相对湿度与O_3浓度的相关性最为显著。O_3浓度在平均风速为2.1～2.2 m/s时更易出现超标。中部和北部城市在东南风的作用下易出现O_3超标并达到O_3浓度高值,而南部地区在风向为西风时更容易出现O_3超标。