Polychlorinated biphenyls (PCBs) in soils of the Moscow region: concentrations and small-scale distribution along an urban-rural transect

In soils of the Moscow region, we examined PCB concentrations in bulk samples and aggregate fractions. Topsoils under grassland and forest at five locations along a southeast-bound transect from Moscow and at a northeastern background location (grassland only) were analysed. We collected aggregates >1 cm and fractionated them into interior and exterior portions and also analysed the remaining soil without the aggregates >1 cm. The concentrations of the sum of 17 PCBs (sigma17PCBs) in 35 bulk soil samples ranged from 3.1 to 42 microg kg(-1). This was 48-61% of the sigma33PCBs determined in 23 selected samples. The congeners 138(+158), 101 and 52 were most abundant. All PCB concentrations and the degree of chlorination declined with increasing distance from Moscow. The PCBs were accumulated in the aggregate exterior (on average 146% of the sigma17PCBs in bulk soil). We conclude that the ecotoxicological risk of PCBs in soils may not be properly assessed with the conventional bulk soil analysis.     

Passive air sampler as a tool for long-term air pollution monitoring: Part 1. Performance assessment for seasonal and spatial variations

The potential of passive air sampling devices (polyurethane foam disks) to assess the influence of local sources on the quality of the surrounding environment was investigated. DEZA Valasske Mezirici, a coal tar and mixed tar oils processing plant, and Spolana Neratovice, a chemical factory with the history of high production of organochlorinated pesticides (OCPs), were selected as the point sources of PAHs, and OCPs, respectively. Levels of PCBs, OCPs and PAHs were determined for all sampling sites and sampling periods. The study brought useful data about the air concentrations of POPs in the investigated regions. More important, it provided information on the transport and fate of POPs in the vicinity of local sources of contamination useful for the estimation of their influence. Very good capability of passive samplers to reflect temporal and spatial fluctuation in concentrations of persistent organic pollutants in the ambient air was confirmed which makes them applicable for monitoring on the local scale.     

Polybrominated diphenyl ethers (PBDEs) in soils along a rural-urban-rural transect: sources, concentration gradients, and profiles

This study reports concentrations of PBDEs in surface soil samples collected along a 140 km transect across Kuwait to assess the role of urban centers as sources of persistent organic pollutants to the surrounding environment. The ΣPBDE concentrations varied by a factor of ∼250 and ranged from 289 to 80,078 pg g⁻¹ d.w. The concentrations of PBDEs in Kuwait City were significantly higher (p < 0.01) than those collected from sites outside the city supporting the hypothesis that urban centers are sources of PBDEs. The congener profiles were dominated by BDE-209, accounting for 93% of the PBDEs in the soil samples. The concentrations of all congeners (except BDE-209) were highly correlated with percent organic carbon (%OC) (p > 0.05) when the data from Kuwait City was omitted from the analysis. These findings suggest that soil concentrations outside the urban centers were close to equilibrium with the atmosphere.     

Mercury in the Mediterranean,part I: spatial and temporal trends

The present paper provides an overview of mercury studies performed in the Mediterranean Sea region in the framework of several research projects funded by the European Commission and on-going national programmes carried out during the last 15 years. These studies investigated the temporal and spatial distribution of mercury species in air, in the water column and sediments, and the transport mechanisms connecting them. It was found that atmospheric concentrations of Hg compounds, particularly oxidised Hg species observed at five coastal sites in the Mediterranean Sea Basin, are significantly higher compared with those recorded at five coastal sites distributed across N Europe, most probably due to natural emissions. Hg levels in water are comparable to other oceans. Anthropogenic and natural point sources show locally limited enrichments, while natural diffusive sources influence Hg speciation over larger areas. Results and statistic comparison of mercury species concentrations within Mediterranean compartments will be presented and discussed.     

Passive air sampler as a tool for long-term air pollution monitoring: Part 2. Air genotoxic potency screening assessment

The capability of passive air sampling to be employed in the evaluation of direct genotoxicity of ambient air samples was assessed. Genotoxic effects of the total extracts from the polyurethane foam filters exposed for 28 days during a regional passive air sampling campaign were investigated. Twenty sampling sites were selected in Brno city on the area of approximately 20x20 km in October and November 2004. Brno is the second largest city of the Czech Republic, highly industrialized with approximately 370,000 of permanent inhabitants. The levels of PAHs, PCBs, and chlorinated pesticides were determined in all samples. Fraction of each extract was also assayed in the bacterial genotoxicity test using Escherichia coli sulA::lacZ. Complete dose-response relationships of the air extracts were determined. The statistical analysis showed significant correlation between observed biological effects and PAHs concentrations in samples.     

Determining temporal and spatial variations in ozone air quality

Unless the change in emissions is substantial, the resulting improvement in ozone air quality can be easily masked by the meteorological variability. Therefore, the meteorological and chemical signals must be separated in examining ozone trends. In this paper, we discuss the use of the Kolmogorov-Zurbenko filter in evaluating the temporal and spatial variations in ozone air quality utilizing ozone concentration data from several monitoring locations in the northeastern United States. The results indicate a downward trend in the ozone concentrations during the period 1983-1992 at most locations in the northeastern United States. The results also reveal that ozone is a regional-scale problem in the Northeast.     

Performance of a thermally desorbable type-tube diffusive sampler for very low air concentrations monitoring

Perkin-Elmer tubes packed with Tenax TA have been tested for the monitoring of low concentrations of aromatic compounds and linear alkanes using diffusive sampling. The uptake rates have been investigated for different exposure doses. A particular hexane and benzene behaviour has been observed: their uptake rates decrease rapidly in the lower exposure doses and so follow an exponential curve. The uptake rates of heavier compounds adopt another tendency: a slow decrease with time following a linear profile. The relative humidity influence has been studied too, and no water perturbation has been recorded.     

Contamination and source differentiation of Pb in park soils along an urban-rural gradient in Shanghai

Urban soil Pb contamination is a great human health risk. Lead distribution and source in topsoils from 14 parks in Shanghai, China were investigated along an urban-rural gradient. Topsoils were contaminated averagely with 65 mg Pb kg⁻¹, 2.5 times higher than local soil background concentrations. HCl-extracts contained more anthropogenic Pb signatures than total sample digests as revealed by the higher ^207/206Pb and ^208/206Pb ratios in extracts (0.8613 ± 0.0094 and 2.1085 ± 0.0121 versus total digests 0.8575 ± 0.0098 and 2.0959 ± 0.0116). This suggests a higher sensitivity of HCl-extraction than total digestion in identifying anthropogenic Pb sources. Coal combustion emission was identified as the major anthropogenic Pb source (averagely 47%) while leaded gasoline emission contributed 12% overall. Urbanization effects were observed by total Pb content and anthropogenic Pb contribution. This study suggests that to reduce Pb contamination, Shanghai might have to change its energy composition to clean energy.     

Neural network forecasting of air pollutants hourly concentrations using optimised temporal averages of meteorological variables and pollutant concentrations

The new method for the forecasting hourly concentrations of air pollutants is presented in the paper. The method was developed for a site in urban residential area in city of Zagreb, Croatia, for four air pollutants (NO₂, O₃, CO and PM₁₀). Meteorological variables and concentrations of the respective pollutant were taken as predictors. A novel approach, based on families of univariate regression models, was employed in selecting the averaging intervals for input variables. For each variable and each averaging period between 1 and 97 h, a separate model was built. By inspecting values of the coefficient of correlation between measured and modelled concentrations, optimal averaging periods for each variable were selected. A new dataset for building the forecasting model was then calculated as temporal moving averages (running means) of former variables. A multi-layer perceptron type of neural networks is used as the forecasting model. Index of agreement, calculated for the entire dataset including the data for model building, ranged from 0.91 to 0.97 for the respective pollutants. As suggested by the analysis of the relative importance of the input variables, different agreements for different pollutants are likely due to different sources and production mechanisms of investigated pollutants. A comparison of the new method with more traditional method, which takes hourly averages of the forecast hour as input variables, showed similar or better performance. The model was developed for the purpose of public-health-oriented air quality forecasting, aiming to use a numerical weather forecast model for the prediction of the part of input data yet unknown at the forecasting time. It is to expect that longer term averages used as inputs in the proposed method will contribute to smaller input errors and the greater accuracy of the model.     

Atmospheric PCBs and organochlorine pesticides in Birmingham,UK: concentrations,sources, temporal and seasonal trends

Concentrations of individual PCBs and DDT, DDE, α- and γ-HCH were recorded in 62 air samples of 24 h duration taken every 1–2 weeks at an urban location in Birmingham, UK between April 1999 and July 2000. Concentrations of PCBs 31/28, 52, 49, 47, 105, 149, 153, 138/164, 174, and 180 were significantly lower (p<0.05) than those recorded at the same site in 1997–1998. While DDT concentrations and DDT:DDE ratios were much lower than those recorded in southern England in 1992–1993; no such decline was observed in concentrations of α- and γ-HCH, or the α:γ-HCH ratio. These data are consistent with declining European usage of DDT, but continuing UK use of γ-HCH, and overseas use and subsequent atmospheric transport of “technical” HCH. γ-HCH concentrations displayed two non-temperature dependent peaks in spring and late summer/early autumn, consistent with agricultural use patterns. Multiple linear regression analysis was used to elucidate the relative influence of temperature, wind direction and a variety of other meteorological variables on atmospheric concentrations of PCBs. When all samples were considered, concentrations of most PCB congeners were influenced by a combination of reciprocal temperature, wind direction, and wind speed. Plotting the ratio of the Beta weightings for the regression coefficients for reciprocal temperature and sine (or cosine) of wind direction against chlorine number, revealed a general increase in the relative influence of temperature compared to wind direction with increasing chlorine number. However, when the 31 samples for which the wind speed <4.4 m s⁻¹ were analysed; only temperature and atmospheric relative humidity were influential for most congeners. This absence of influence of wind direction under relatively calm atmospheric conditions, suggests that it is medium-to-long range transport rather than local sources that exerts the greatest influence on PCB concentrations at our site.     

Passive sampling of ambient, gaseous air pollutants: an assessment from an ecological perspective

During some past two decades there has been a growing interest among air pollution-vegetation effects-scientists to use passive sampling systems for quantifying ambient, gaseous air pollutant concentrations, particularly in remote and wilderness areas. On the positive side, excluding the laboratory analysis costs, passive samplers are inexpensive, easy to use and do not require electricity to operate. Therefore, they are very attractive for use in regional-scale air quality assessments. Passive samplers allow the quantification of cumulative air pollutant exposures, as total or average pollutant concentrations over a sampling duration. Such systems function either by chemical absorption or by physical adsorption of the gaseous pollutant of interest onto the sampling medium. Selection of a passive sampler must be based on its known or tested characteristics of specificity and linearity of response to the chemical constituent being collected. In addition, the effects of wind velocity, radiation, temperature and relative humidity must be addressed in the context of absorbent/adsorbent performance and sampling rate. Because of all these considerations, passive samplers may provide under- or overestimations of the cumulative exposures, compared to the corresponding data from co-located continuous monitors or active samplers, although such statistical variance can be minimized by taking necessary precautions. On the negative side, cumulative exposures cannot identify short-term (相似文献   

Changes in sulphate retention, soil chemistry and drainage water quality along an upland soil transect

Soils sampled along an altitudinal transect in an upland area of North East Scotland have been used to investigate downslope changes in the capacity of soils to retain sulphate. Simulated laboratory experiments involving the leaching of reconstituted cores with 'rainfall' containing low (1.85 mg litre(-1) and high (51.90 mg litre(-1) concentrations of sulphate indicate that soils developed on upper slopes have a limited capacity to adsorb sulphate, whereas soils on lower slopes have a much greater sulphate adsorption capacity. Soil drainage water, produced from 'sensitive' upper slope soils may therefore be significantly modified by physico-chemical reactions in lower slopes before reaching watercourses.     

Analysis of temporal and spatial dichotomous PM air samples in the El Paso-Cd. Juarez air quality basin.

This paper presents and discusses the results obtained from the gravimetric and chemical analyses of the 24-hr average dichotomous samples collected from five sites in the El Paso-Cd. Juarez air quality basin between August 1999 and March 2000. Gravimetric analysis was performed to determine the temporal and spatial variations of PM2.5 (particulate matter less than 2.5 microm in diameter) and PM25-10 (particulate matter less than 10 pm but greater than 2.5 microm in diameter) mass concentrations. The results indicate that approximately 25% of the PM10 (i.e., PM25 + PM25-10) concentration is composed of PM2.5. Concurrent measurements of hourly PM concentrations and wind speed showed strong diurnal patterns of the regional PM pollution. Results of X-ray fluorescence (XRF) elemental analyses were compared to similar but limited studies performed by the Texas Natural Resource Conservation Commission (TNRCC) in 1990 and 1997. Major elements from geologic sources-Al, Si, Ca, Na, K, Fe, and Ti-accounted for 35% of the total mass concentrations in the PM2.5-10 fraction, indicating that geologic sources in the area are the dominant PM sources. Levels of toxic trace elements, mainly considered as products of anthropogenic activities, have decreased significantly from those observed in 1990 and 1997.     

Spatial distribution of atmospheric PAHs and PCNs along a north-south Atlantic transect

Ship-board air samples collected between The Netherlands and South Africa in January-February 2001 were analysed for polycyclic aromatic hydrocarbons (PAHs) and polychlorinated naphthalenes (PCNs). The highest PAH concentrations occurred in the European samples, and in samples close to West Africa and South Africa. Consistently low PAH concentrations were measured in the southern hemisphere open ocean samples (190-680 pg/m3). The highest PCN concentrations occurred in the European samples, but high values were also detected off the West African coast, and in the sample taken closest to South Africa. Data are presented for diurnal cycles taken in the remote South Atlantic. The day:night ratios of phenanthrene, 1-methylphenanthrene and fluoranthene were typically approximately 1.5-2.5:1. The mechanism(s) causing this observation is/are not understood at present, but dynamic environmental process(es) is/are implicated.     

Polybrominated diphenyl ethers (PBDEs) and organochlorines in melon-headed whales, Peponocephala electra, mass stranded along the Japanese coasts: maternal transfer and temporal trend

Polybrominated diphenyl ethers (PBDEs) and organochlorine compounds (OCs) were determined in the blubber of 55 melon-headed whales (Peponocephala electra) mass stranded along the Japanese coasts since 1982. DDTs and PCBs were predominant in all the specimens investigated. In whales that died during the latest event in 2006, concentrations of PBDEs (190–510 ng/g lipid wt) were approximately two orders of magnitude lower than DDTs and PCBs, but comparable with HCHs and HCB. Maternal transfer of PBDEs to offspring through the whole reproductive process was estimated to be 85% of the mother's body burden, while that occurring during gestation was much lower (2.6–3.5%). Concentrations of PCBs, DDTs, and HCB were lower in melon-headed whales stranded after the year 2000 than those stranded in 1982, whereas PBDE and CHL levels showed a temporal increase during the past 20 years, suggesting that the peak of their usage and contamination occurred after the year 1982.     

Polybrominated diphenyl ethers (PBDEs) and their methoxylated derivatives in pike from Swedish waters with emphasis on temporal trends, 1967-2000

Temporal trends of five tetra- to hexabromodiphenyl ethers [BDE47, BDE99, BDE100, BDE153 and BDE154) and two methoxy-tetraBDEs [6-methoxy-2,2',4,4'- tetraBDE (6-MeO-BDE47) and 2'-methoxy-2,3',4,5'- tetraBDE (2'-MeO-BDE68)] in pike from Lake Bolmen for the years 1967-2000, are presented. All BDE congeners show increasing trends up to the mid-1980s (Sigma5PBDE from 60 to 1600 pg/g wet weight in 1989, i.e. a more than 25-fold increase), and then decrease or level off. The decreasing trends of PBDEs after the 1980s were considerably slower in the present study than was found in a study of an environmental matrix from the Baltic Proper covering the same time period. This difference suggests local sources near Lake Bolmen. The MeO-BDEs show initially decreasing concentrations, which for 6-MeO-BDE47 continues until the early 1990s. The concentrations of 6-MeO-BDE47 in herring from five locations along the Swedish coast increased from south to north in the Baltic Sea. No correlation between the concentrations of the BDE congeners and the MeO-BDEs was observed, indicating sources other than PBDEs for these compounds. The presence of MeO-BDEs in fish from lakes with different characteristics suggests a natural production not favoured by eutrophication, or dependent on sampling season and geographical location.     

A prediction-based approach to modelling temporal and spatial variability of traffic-related air pollution in Montreal, Canada

Concentrations of traffic-related air pollution can be highly variable at the local scale and can have substantial seasonal variability. This study was designed to provide estimates of intra-urban concentrations of ambient nitrogen dioxide (NO₂) in Montreal, Canada, that would be used subsequently in health studies of chronic diseases and long-term exposures to traffic-related air pollution. We measured concentrations of NO₂ at 133 locations in Montreal with passive diffusion samplers in three seasons during 2005 and 2006. We then used land use regression, a proven statistical prediction method for describing spatial patterns of air pollution, to develop separate estimates of spatial variability across the city by regressing NO₂ against available land-use variables in each of these three periods. We also developed a “pooled” model across these sampling periods to provide an estimate of an annual average. Our modelling strategy was to develop a predictive model that maximized the model R². This strategy is different from other strategies whose goal is to identify causal relationships between predictors and concentrations of NO₂.Observed concentrations of NO₂ ranged from 2.6 ppb to 31.5 ppb, with mean values of 12.6 ppb in December 2005, 14.0 ppb in May 2006, and 8.9 ppb in August 2006. The greatest variability was observed during May. Concentrations of NO₂ were highest downtown and near major highways, and they were lowest in the western part of the city. Our pooled model explained approximately 80% of the variability in concentrations of NO₂. Although there were differences in concentrations of NO₂ between the three sampling periods, we found that the spatial variability did not vary significantly across the three sampling periods and that the pooled model was representative of mean annual spatial patterns.     

Using experimental and forest soils to investigate the uptake of polycyclic aromatic hydrocarbons (PAHs) along an urban-rural gradient

Spatial and temporal variation in the atmospheric deposition of PAHs to soil was examined by deploying experimental soils for approximately 165 days and conducting a survey of forest soils at several sites along an urban-rural transect extending from downtown Toronto to approximately 80 km north of the city. PAH concentrations decreased with distance from the urban centre-by a factor of 2 and 60 for the experimental and forest soils respectively. The large gradient for the forest soils is generally consistent with air concentrations of PAHs measured using high volume and passive air samplers. The smaller gradient for the experimental soils was due to kinetic limitations of PAH accumulation and the relatively short deployment period of approximately 165 days. Mean effective deposition velocities (gas+particle) for the full range of PAHs for the experimental soils at the urban, suburban, and the rural sites were 2, 31 and 26 cm s(-1), respectively. These were incorporated into a dynamic model that was used to assess the long-term uptake of PAHs in forest soils. Model results indicate that lower molecular weight PAHs may achieve equilibrium and become involved in soil-air exchange whereas higher molecular weight PAHs are accumulated for much longer time periods.     

Recent spatial gradients and time trends in Dhaka,Bangladesh, air pollution and their human health implications

Dhaka, the capital of Bangladesh, is among the most polluted cities in the world. This research evaluates seasonal patterns, day-of-week patterns, spatial gradients, and trends in PM_2.5 (<2.5 µm in aerodynamic diameter), PM₁₀ (<10 µm in aerodynamic diameter), and gaseous pollutants concentrations (SO₂, NO₂, CO, and O₃) monitored in Dhaka from 2013 to 2017. It expands on past work by considering multiple monitoring sites and air pollutants. Except for ozone, the average concentrations of these pollutants showed strong seasonal variation, with maximum during winter and minimum during monsoon, with the pollution concentration of PM_2.5 and PM₁₀ being roughly five- to sixfold higher during winter versus monsoon. Our comparisons of the pollutant concentrations with Bangladesh NAAQS and U.S. NAAQS limits analysis indicate particulate matter (PM_2.5 and PM₁₀) as the air pollutants of greatest concern, as they frequently exceeded the Bangladesh NAAQS and U.S. NAAQS, especially during nonmonsoon time. In contrast, gaseous pollutants reported far fewer exceedances throughout the study period. During the study period, the highest number of exceedances of NAAQS limits in Dhaka City (Darus-Salam site) were found for PM_2.5 (72% of total study days), followed by PM₁₀ (40% of total study days), O₃ (1.7% of total study days), SO₂ (0.38% of total study days), and CO (0.25% of total study days). The trend analyses results showed statistically significant positive slopes over time for SO₂ (5.6 ppb yr^?1, 95% confidence interval [CI]: 0.7, 10.5) and CO (0.32 ppm yr^?1, 95% CI: 0.01, 0.56), which suggest increase in brick kilns operation and high-sulfur diesel use. Though statistically nonsignificant annual decreasing slopes for PM_2.5 (?4.6 µg/m³ yr^?1, 95% CI: ?12.7, 3.6) and PM₁₀ (?2.7 µg/m³ yr^?1, 95% CI: ?7.9, 2.5) were observed during this study period, the PM_2.5 concentration is still too high (~ 82.0 µg/m³) and can cause severe impact on human health.

Implications: This study revealed key insights into air quality challenges across Dhaka, Bangladesh, indicating particulate matter (PM) as Dhaka’s most serious air pollutant threat to human health. The results of these analyses indicate that there is a need for immediate further investigations, and action based on those investigations, including the conduct local epidemiological PM exposure-human health effects studies for this city, in order to determine the most public health effective interventions.     

粤港澳大湾区空气污染物的时空分布及其影响因素

基于粤港澳珠三角洲空气质量监测数据,利用克里金插值法和Spearman秩系数相关法分析了2015—2021年大湾区空气污染物的时空分布特征,利用灰色关联分析法分析了自然、社会因素对空气污染物的影响。结果表明,近7年大湾区的空气质量整体向好,PM10、PM2.5年均值分别为40.32、23.38$ \mathrm{\mu } $g·m−3,均低于新标准二级限值,O3、NO2、SO2年均值分别为51.68、33.45和6.61$ \mathrm{\mu } $g·m−3。其中,SO2质量浓度低于新标准一级限值,CO年均值为0.68$ \mathrm{m} $g·m-3,CO、PM2.5、NO2、PM10和SO2年均质量浓度呈下降趋势,降幅分别为23.67%、39.48%、27.02%、33.75%和41.21%,季节上表现为冬季最高、春秋季次之、夏季最低。O3年均质量浓度呈波浪上升趋势,升幅为14.54%,季节变化为：秋季>春季>冬季>夏季,O3质量浓度升高的原因可能是副热带高气压带和台风外围的大气环流形式等不利气象条件和O3前体物高排放逐渐升高等人为排放因素等共同影响的结果。O3的空间分布表现为东莞、深圳、港澳和江门南部等东部沿海地区高于中西部内陆地区,高值质量浓度达48~70 μg·m−3,其他污染物质量浓度呈“中西—东部”递减趋势。气温、日照时数和风速与CO、NO2、PM10、PM2.5和SO2质量浓度呈负相关,与O3 呈正相关,相对湿度与O3呈负相关,与其他污染物呈正相关,降水量对珠港澳三地污染物质量浓度影响不一。能源消耗、工业生产、人口和机动车数据等是影响大湾区空气质量的主要因素。本研究结果可为粤港澳大湾区在大气污染防治、环保策略制定等方面提供参考。