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1.
Ambient air samples were collected at two different locations between 2011 and 2012 in Zhengzhou, China in order to assess the concentration level, health risks, as well as the sources of polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM2.5). The mean annual levels of PM2.5 observed at industry site and residential site were 172?±?121 and 160?±?72 μg m?3, respectively, which were about five times the annual value of proposed PM2.5 standard (35 μg m?3) in China. The PM2.5 in all daily samples (n?=?47) exceeds the proposed PM2.5 standard in China (75 μg m?3) at both industrial and residential sites. Seasonal variations of PM2.5 showed a clear trend of winter?>?autumn?>?spring?>?summer at both sites. The total concentrations of 16 PM2.5-associated PAHs ranged from 61?±?51 to 431?±?281 and 38?±?25 to 254?±?189 ng m?3, with mean value of 176?±?233 and 111?±?146 ng m?3 at industry and residential sites, respectively. The major species were fluoranthene, pyrene, chrysene, benzo[b]fluoranthene and benzo[k]fluoranthene, and the concentration levels of PAHs in PM2.5 were higher in winter than those of other seasons at both sites. The annual mean values of toxicity equivalency concentrations of ∑16PAHs in PM2.5 were 22.8 and 13.5 ng m?3 in industry and residential area, respectively. In this study, the risk level of adult citizens through inhalation exposure to PAHs was calculated. The average estimates of lifetime inhalation cancer risks were approximately 8.9?×?10?7 and 6.3?×?10?7 for industry and residential sites, respectively. The main sources of 16 PAHs from both diagnostic ratios and principle component analysis identified as vehicular emissions and coal combustion.  相似文献   

2.
The temporal and spatial trends in the variability of PM10 and PM2.5 from 2010 to 2015 in the metropolitan area of Lima-Callao, Peru, are studied and interpreted in this work. The mean annual concentrations of PM10 and PM2.5 have ranges (averages) of 133–45 μg m?3 (84 μg m?3) and 35–16 μg m?3 (26 μg m?3) for the monitoring sites under study. In general, the highest annual concentrations are observed in the eastern part of the city, which is a result of the pattern of persistent local winds entering from the coast in a south-southwest direction. Seasonal fluctuations in the particulate matter (PM) concentrations are observed; these can be explained by subsidence thermal inversion. There is also a daytime pattern that corresponds to the peak traffic of a total of 9 million trips a day. The PM2.5 value is approximately 40% of the PM10 value. This proportion can be explained by PM10 re-suspension due to weather conditions. The long-term trends based on the Theil-Sen estimator reveal decreasing PM10 concentrations on the order of ?4.3 and ?5.3% year?1 at two stations. For the other stations, no significant trend is observed. The metropolitan area of Lima-Callao is ranked 12th and 16th in terms of PM10 and PM2.5, respectively, out of 39 megacities. The annual World Health Organization thresholds and national air quality standards are exceeded. A large fraction of the Lima population is exposed to PM concentrations that exceed protection thresholds. Hence, the development of pollution control and reduction measures is paramount.  相似文献   

3.
Air quality in Hyderabad, India, often exceeds the national ambient air quality standards, especially for particulate matter (PM), which, in 2010, averaged 82.2?±?24.6, 96.2?±?12.1, and 64.3?±?21.2 μg/m3 of PM10, at commercial, industrial, and residential monitoring stations, respectively, exceeding the national ambient standard of 60 μg/m3. In 2005, following an ordinance passed by the Supreme Court of India, a source apportionment study was conducted to quantify source contributions to PM pollution in Hyderabad, using the chemical mass balance (version 8.2) receptor model for 180 ambient samples collected at three stations for PM10 and PM2.5 size fractions for three seasons. The receptor modeling results indicated that the PM10 pollution is dominated by the direct vehicular exhaust and road dust (more than 60 %). PM2.5 with higher propensity to enter the human respiratory tracks, has mixed sources of vehicle exhaust, industrial coal combustion, garbage burning, and secondary PM. In order to improve the air quality in the city, these findings demonstrate the need to control emissions from all known sources and particularly focus on the low-hanging fruits like road dust and waste burning, while the technological and institutional advancements in the transport and industrial sectors are bound to enhance efficiencies. Andhra Pradesh Pollution Control Board utilized these results to prepare an air pollution control action plan for the city.  相似文献   

4.
A new kinetic method has been developed for the determination of iodine in water samples. The method is based on the catalytic effect of I? with the oxidation of Indigo Carmine (IC) by KBrO3 in the sulfuric acid medium. The optimum conditions obtained are 0.16 M sulfuric acid, 1?×?10?3 M of IC, 1?×?10?2 M KBrO3, reaction temperature of 35°C, and reaction time of 80 s at 612 nm. Under the optimized conditions, the method allowed the quantification of I? in a range of 12–375 ng/mL with a detection limit of 0.46 ng/mL. The method was applied to the determination of iodine in river and city water samples with the satisfactorily results.  相似文献   

5.
Trace amounts of bismuth(III) and uranium(VI) can be simultaneously determined in a single scan by adsorptive cathodic stripping voltammetry in the presence of cupferron as a complexing agent. Optimal conditions were found to be: 0.1 mol?L?1 acetate buffer (pH 5.3), 5?×?10?5?mol?L?1 cupferron, accumulation potential of ?0.25 V, and accumulation time of 30 s. The linear range of Bi(III) and U(VI) was observed over the concentration range from 2?×?10?9 to 2?×?10?7?mol?L?1 and from 1?×?10?8 to 5?×?10?7?mol?L?1, respectively. The influence of the main components of real water samples such as foreign ions and organic substances (surface active substances, humic substances) was precisely investigated. The method was applied to the simultaneous measurements of bismuth and uranium in natural water samples.  相似文献   

6.
Daily and hourly average data from nine air-quality monitoring stations distributed across central Taiwan, which include ten items (i.e., PM10, PM2.5, wind direction, wind speed, temperature, relative humidity, SO2, NO2, NO, and CO), were collected from 2005 to 2009. Four episode types: long-range transport with dust storms (DS), long-range transport with frontal pollution (FP), river dust (RD), and stagnant weather (SW), and one mixed type of episode were identified. Of these four episode types, the SW was the dominant type, averaging about 70 %. The mean ratio of PM2.5/PM10 was the lowest during the RD episodes (0.42), while the mean ratio of PM2.5/PM10 was the highest during the SW episodes (0.64). Fine aerosol (PM2.5) and coarse aerosol (PM10–2.5) samples were collected by high-volume samplers for chemical composition analysis, from only three stations (Douliou, Lunbei, and Siansi) during the days of SW, RD, DS, and FP. The concentrations of PM2.5 and three ionic species (NH4 +, NO3 ?, and SO4 2?) all showed significant differences among the four episode types. The highest levels of NO3 ? (12.1 μg/m3) and SO4 2? (20.5 μg/m3) were found during the SW and FP episodes, respectively. A comparison on the spatial similarity of aerosol compositions among the episodes and/or non-episodes (control) was characterized by the coefficient of divergence (CD). The results showed higher CD values in PM10–2.5 than in PM2.5, and the CD values between RD episodes and the other three episodes were higher than those between two types of episode for the other three episodes. The ratios of SOR (sulfur oxidation ratio), SO4 2?/EC (elemental carbon), NOR (nitrogen oxidation ratio), and NO3 ?/EC showed that sulfate formation was most rapid during the FP, while nitrate formation was most rapid during the SW.  相似文献   

7.
A colorimetric assay method is described for the environmental detection of 2-mercaptobenzimidazole (MBI) using surface plasmon resonance of gold nanoparticles (AuNPs). Stable and dispersed AuNPs with intensified plasmon resonance were prepared in situ using a simple, rapid, and eco-friendly procedure by applying ascorbic acid as a reducer and cetyltrimethylammonium bromide as a stabilizer. The presence of MBI has a strong effect on the plasmon absorbance of AuNPs, which was employed for the detection of MBI. The calibration curve was linear in the range of 1.0?×?10?6–5.5?×?10?5 mol/L of MBI; the detection limit was 8.4?×?10?7 mol/L. The relative standard deviations for eight replicate measurements of 3.0?×?10?6 and 5?×?10?5 mol/L MBI were 3.9 and 1.4 %, respectively. The method was successfully applied to the determination of MBI in tap, river, sea, and heat exchanger cooling water samples.  相似文献   

8.
We assessed the incidence of faecal-indicator bacteria in Tyume River over a 12-month period between August 2010 and July 2011. Total coliforms, faecal coliforms and enterococci were determined by the membrane filtration method. Total coliforms were detected in counts ranging from 2.1?×?102 to 3.4?×?104?CFU/100 ml. Faecal coliform counts ranged from 1?×?102 to 1.6?×?104?CFU/100 ml while enterococci counts were in the range of 3.3?×?101 to 5.1?×?103?CFU/100 ml. Indicator bacteria counts increased from upstream to downstream sampling sites. Counts of indicator bacteria at all sites were significantly affected by seasonal changes. The bacteriological qualities of the river water were poor, exceeding the guideline of 200 CFU/100 ml and 33 CFU/100 ml for faecal coliforms and enterococci, respectively, for recreational water. Faecal coliform counts also exceeded the 1,000 CFU/100 ml guideline for water used in fresh produce irrigation. Microbial source tracking results showed that faecal pollution was predominantly of human origin during spring at all sampling sites. During other seasons, human faecal pollution was largely confined to midstream and downstream sampling sites. Generally, the presence of faecal-indicator bacteria in the river water samples suggests faecal pollution of this freshwater resource, raising the possibility of the presence of pathogenic microorganisms in the water and a threat to public health.  相似文献   

9.
A new spectrophotometric method is reported for the determination of nanomolar level of malachite green in surface water samples. The method is based on the catalytic effect of silver nanoparticles on the oxidation of malachite green by hexacyanoferrate (III) in acetate–acetic acid medium. The absorbance is measured at 610 nm with the fixed-time method. Under the optimum conditions, the linear range was 8.0?×?10?9–2.0?×?10?7?mol?L?1 malachite green with a correlation coefficient of 0.996. The limit of detection (S/N?=?3) was 2.0?×?10?9?mol?L?1. Relative standard deviation for ten replicate determinations of 1.0?×?10?8?mol?L?1 malachite green was 1.86 %. The method is featured with good accuracy and reproducibility for malachite green determination in surface water samples without any pre-concentration and separation step.  相似文献   

10.
Continuous aerosol measurements were made at a regional background station (Mukteshwar) located in a rural Himalayan mountain terrain from December 2005 to December 2008 for a period of 3 years. The average concentrations of particulate matter less than or equal to 10 μm (PM10), particulate matter less than or equal to 2.5 μm (PM2.5) and black carbon (BC) are 46.0, 26.6 and 0.85 μg/m3 during the study period. Majority of the PM10 values lie below 100 μg/m3 while majority of the PM2.5 values lie below 30 μg/m3. It is further seen that during the monsoon months, especially July and August, the average values are comparatively low. It is also noted that the PM2.5/PM10 ratios between 0.50 and 0.75 have the maximum frequency distribution in the data set. Furthermore, the monthly mean ratio of BC to PM2.5 mass lies between 3.0 and 7.5 % during the study period. Though the average PM10 and PM2.5 concentrations during the study period are less than the respective Indian ambient air quality standards, however, they are still above the WHO guidelines and would have adverse health impacts. This shows that even in rural/background regions that are far away from major pollution sources or urban areas, the aerosol concentrations are significant and require long-term monitoring, source quantification and aerosol model simulations.  相似文献   

11.
The objective of this study was to estimate the potential of organic municipal solid waste generated in an urban setting in a tropical climate to produce biogas. Five different categories of wastes were considered: fruit waste, food waste, yard waste, paper waste, and mixed waste. These fractions were assessed for their efficiency for biogas production in a laboratory-scale batch digester for a total period of 8 weeks at a temperature of 15–30 °C. During this period, fruit waste, food waste, yard waste, paper waste, and mixed waste were observed to produce 0.15, 0.17, 0.10, 0.08, and 0.15 m3 of biogas per kilogram of volatile solids, respectively. The biogas produced and caloric value of each feedstock was in the range of 1.25?×?10?3 m3 (17 kWh)/cap/day (paper waste) to 15?×?10?3 m3 (170 kWh)/cap/day (mixed waste). Paper waste produced the least (<1×10?3(<17.8 kWh)/cap/day), and mixed waste produced the highest methane yield (10?×?10?3 m3 (178 kWh)/cap/day). Thus, mixed waste was found to be more efficient than other feedstocks for biogas and methane production; this was mainly related to the better C/N ratio in mixed waste. Taking the total waste production in Jimma into account, the total mixed organic solid waste could produce 865?×?103 m3 (5.4 m3/capita) of biogas or 537?×?103 m3 (3.4 m3/capita) of methane per year. The total caloric value of methane production potential from mixed organic municipal solid waste was many times higher than the total energy requirement of the area.  相似文献   

12.
The effective determination of heavy metals from environmental media is among the most important issues for many industrialized countries. The interaction between RS-N, as novel heavy metal probe, and metal ions was studied. RS-N shows selective color change from colorless to pink in the presence of Hg2+ in methanol/water solvent and the UV–Vis study shows peak at 560 nm. Fluorescence data revealed that the fluorescence enhance of RS-N by Hg2+ dramatically was the result of the formation of [Hg2+]RS-N complex. The effective association constants (K a ) were 3.97?×?105 and 0.204?×?105 M?1 for Hg2+ and Cu2+ to RS-N, respectively. The thermodynamic parameters, enthalpy change (ΔH 0) and entropy change (ΔS 0), were calculated to be ?6.431?±?0.226 kJ/mol and ?0.129?±?0.008 J/K/mol, respectively, according to van’t Hoff equation on the basis of Gibbs free energy (ΔG 0) ranged from ?33.8326 to ?28.5389 kJ/mol.  相似文献   

13.
New forest management and planning approaches are designed to optimize forest structure. Optimal forest structure was determined using newly established growth models while considering primary timber production objectives as well as non-timber objectives for inaccessible areas and social and political pressures on land management. With currently planned management the forests of the Ormanüstü Planning Unit (OPU) in the Black Sea region of northern Turkey are likely to become an important C sink. To quantify this potential C sink and understand its implication to the regional carbon budget and future forest management, we estimated the changes in the OPU between 1973 and 2006. Based on four periods of data for the OPU forests obtained from the Forest Management and Planning Office of Turkey, we used allometric biomass and C regression equations along with biomass expansion factors to estimate the forest biomass carbon pool for each of four inventory years 1973, 1984, 1997, and 2006. Since 1973, OPU forests have accumulated 110.2?×?103 tons of C as a result of forest expansion and the growth of extant forests, increasing by 50.8 % from 217?×?103 tons in 1973 to 327.2?×?103 tons C in 2006. Hardwood and softwood forests accounted for 44 and 56 % of carbon accumulation during this period, respectively. From 1973 through 2006, forest C accumulated at a rate of 3.3?×?103 tons C year?1. Carbon density of the OPU forests in the Black Sea region increased by 48.2 % from 5,679 to 8,419 tons/ha.  相似文献   

14.
A large variety of ornamental and decorative items are manufactured from bone waste by various unorganized sectors in India. An initial survey indicated that workers were exposed at various phases of final product. The subjects (12 industrial units) were tested for total suspended particulate matter (TSPM), particulate matter <10  $\upmu $ m (PM10), and particulate matter <2.5  $\upmu $ m (PM2.5). Prevalent levels of TSPM ranged between 2.90 and 5.89 mg m???3. Respirable fractions of occupational dust as PM10 and PM2.5 were found in the range of 0.30?C2.08 and 0.26?C0.50 mg m???3, respectively. Cytotoxicity study was conducted using hemolysis as a sensitive marker. In an in vitro study, rat RBCs were exposed to the concentration of 25?C1,000  $\upmu $ g/ml for 15?C120 min. A considerable variation was observed in the hemolytic activity of samples collected from different areas. At 500  $\upmu $ g/ml concentration, the hemolytic activity (12 h) was found to be in the range of 18?C25%. Due to limitation in sample mass of respirable fractions, only one concentration (100  $\upmu $ g/ml/2 h) was used for comparative study on hemolysis of RBCs caused by PM10 and PM2.5. Interestingly, the hemolytic activity was more at PM2.5 than PM10 and TSPM. These results suggest that the respirable particles are capable of reaching deep into the respiratory system. The finding is significant notably when there are no standards available in occupationally exposed populations. This is the first such study. Data could be of importance to policy makers and regulators.  相似文献   

15.
大气污染物排放清单是了解大气污染特征和控制对策的前提。根据排放因子方法,建立了2018年西宁市金属(包括黑色和有色金属)冶炼和压延加工业PM2.5、PM10大气污染物的排放清单,并对其时空分布特征和清单不确定性进行了分析。结果表明:西宁市黑色金属冶炼和压延加工业PM2.5、PM10的总排放量分别是4.88×103、8.37×103 t;该行业对PM2.5、PM10排放量贡献率最大的是城北区,分别为58.36%、49.61%。有色金属冶炼和压延加工业PM2.5、PM10的总排放量分别是1.85×103、2.78×103 t,该行业对PM2.5、PM10贡献率最大的是大通县,分别为53.51%、56.99%。黑色金属冶炼和压延加工业对PM2.5、PM10<...  相似文献   

16.
The present study proposed to investigate the atmospheric distribution, sources, and inhalation health risks of polycyclic aromatic hydrocarbons (PAHs) in a tropical megacity (Delhi, India). To this end, 16 US EPA priority PAHs were measured in the inhalable fraction of atmospheric particles (PM10; aerodynamic diameter, ≤10 μm) collected weekly at three residential areas in Delhi from December 2008 to November 2009. Mean annual 24 h PM10 levels at the sites (166.5–192.3 μg m?3) were eight to ten times the WHO limit. Weekday/weekend effects on PM10 and associated PAHs were investigated. Σ16PAH concentrations (sum of 16 PAHs analyzed; overall annual mean, 105.3 ng m?3; overall range, 10.5–511.9 ng m?3) observed were at least an order of magnitude greater than values reported from European and US cities. Spatial variations in PAHs were influenced by nearness to traffic and thermal power plants while seasonal variation trends showed highest concentrations in winter. Associations between Σ16PAHs and various meteorological parameters were investigated. The overall PAH profile was dominated by combustion-derived large-ring species (85–87 %) that were essentially local in origin. Carcinogenic PAHs contributed 58–62 % to Σ16PAH loads at the sites. Molecular diagnostic ratios were used for preliminary assessment of PAH sources. Principal component analysis coupled with multiple linear regression-identified vehicular emissions as the predominant source (62–83 %), followed by coal combustion (18–19 %), residential fuel use (19 %), and industrial emissions (16 %). Spatio-temporal variations and time-evolution of source contributions were studied. Inhalation cancer risk assessment showed that a maximum of 39,780 excess cancer cases might occur due to lifetime inhalation exposure to the analyzed PAH concentrations.  相似文献   

17.
The Fine Resolution Atmospheric Multi-pollutant Exchange Model was used to calculate the spatial distribution and chemical composition of PM10 concentrations for two geographically remote countries in Europe—the UK and Poland—for the year 2007. These countries are diverse in terms of pollutant emissions as well as climate conditions. Information on the contribution of natural and anthropogenic as well as national and imported particles in total PM10 concentrations in both countries is presented. The paper shows that the modelled national annual average PM10 concentrations, calculated for the entire country area, are similar for the UK and Poland and close to 12 μg m?3. Secondary inorganic aerosols dominate the total PM10 concentrations in Poland. Primary particulate matter has the greatest contribution to total PM10 in the UK, with large contribution of base cations. Anthropogenic sources predominate (81 %) in total PM10 concentrations in Poland, whereas natural prevail in the UK—hence, the future reduction of PM10 air concentrations by emissions reduction could be more difficult in the UK than in Poland.  相似文献   

18.
The bioaccumulation and toxicity of arsenate (arsenic (As)(V)) was studied using three cultures of cyanobacterial species—Oscillatoria tenuisa, Anabaena affinis, and Microcystis aeruginosa—that were isolated from a eutrophic reservoir. The As(V) uptake depended on the cyanobacterial species, the growth phase of the cyanobacteria, the duration of exposure, and the initial concentration of As(V). The specific growth rates of the three cultures immediately following the logarithmic phase were 0.033–0.041 L/day when the initial concentration of As(V) was 50 mg/L. These rates were 2.3–3.6 times less than those in the original culture medium without As(V). The rate of intake of As(V) in the logarithmic phase cultures greatly exceeded that in the stationary cultures. The accumulation of As(V) by the three cultures increased rapidly within 1 week from the initial value of 3.23?×?10?2–5.40?×?10?2 to 5.06?×?10?1–6.73?×?10?1 ng/cell in the logarithmic phase. The effective concentrations (EC50) of As(V) for inhibiting the growth of the three cyanobacterial species growth of at 72 h followed the order Oscillatoria tenuisa (3.8 mg/L)?>?A. affinis (2.6 mg/L)?>?M. aeruginosa (1.2 mg/L). The cyanobacterial species that was most sensitive to As(V) was M. aeruginosa. Preliminary results from SEM-map studies suggest most of the As(V) in Microcystis aeruginosa accumulated in the cytoplasm (intercellular), while in O. tenuisa and A. affinis, a large proportion of As(V) bound to the cell wall (extracellular). These differences were understood with reference to the variation among the metabolic properties and morphological characteristics of the cyanobacterial species.  相似文献   

19.
The aim of this study was to provide improved information on the long-term transfer of global nuclear weapons 137Cs fallout to cow’s milk in Iceland many years after deposition. The spatial variation in deposition was confirmed to be explained by precipitation. Soil samples showed a significant difference in 137Cs deposition density between the main agricultural areas, with the South having the highest values, then the West and North and the lowest in the Northeast. There was no significant difference between the effective half-lives in 137Cs activity concentrations in milk and milk powder from the main dairies in Iceland based on data for milk from 1990 to 2007 and for milk powder from 1986 to 2007. There was, however, a significant difference between the effective half-lives obtained for these two regions, 13.5?years for the Northern and 10.5?years for the Southern regions. These half-lives for global fallout are longer than those previously reported for similar time periods in other Arctic areas. The transfer of 137Cs to cow’s milk was quantified for different agricultural regions using aggregated transfer coefficients (T ag) for the period of peak global fallout soil inventory in 1965–1967. The values ranged from 2.8?×?10?3 to 10.6?×?10?3?m2?kg?1. By 2001–2004, the T ag values had only declined, in the main agricultural areas, to 0.6?×?10?3–1.0?×?10?3?m2?kg?1. Long-term transfer rates to milk many years after deposition were high in Iceland compared with most other reported data. The transfer is potentially relevant for some of the contaminated areas around the Fukushima Nuclear Power Plant after the accident in March 2011 since limited information is available on uptake from Andosols and associated effective half-lives.  相似文献   

20.
The relationship between indoor and outdoor particulate air pollution was investigated at an urban background site on the Payambar Azam Campus of Mazandaran University of Medical Sciences in Sari, Northern Iran. The concentration of particulate matter sized with a diameter less than 1 μm (PM1.0), 2.5 μm (PM2.5), and 10 μm (PM10) was evaluated at 5 outdoor and 12 indoor locations. Indoor sites included classrooms, corridors, and office sites in four university buildings. Outdoor PM concentrations were characterized at five locations around the university campus. Indoor and outdoor PM measurements (1-min resolution) were conducted in parallel during weekday mornings and afternoons. No difference found between indoor PM10 (50.1 ± 32.1 μg/m3) and outdoor PM10 concentrations (46.5 ± 26.0 μg/m3), indoor PM2.5 (22.6 ± 17.4 μg/m3) and outdoor PM2.5 concentration (22.2 ± 15.4 μg/m3), or indoor PM1.0 (14.5 ± 13.4 μg/m3) and outdoor mean PM1.0 concentrations (14.2 ± 12.3 μg/m3). Despite these similar concentrations, no correlations were found between outdoor and indoor PM levels. The present findings are not only of importance for the potential health effects of particulate air pollution on people who spend their daytime over a period of several hours in closed and confined spaces located at a university campus but also can inform regulatory about the improvement of indoor air quality, especially in developing countries.  相似文献   

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