Global atmospheric emission inventory of polycyclic aromatic hydrocarbons (PAHs) for 2004

The global atmospheric emissions of the 16 polycyclic aromatic hydrocarbons (PAHs) listed as the US EPA priority pollutants were estimated using reported emission activity and emission factor data for the reference year 2004. A database for emission factors was compiled, and their geometric means and frequency distributions applied for emission calculation and uncertainty analysis, respectively. The results for 37 countries were compared with other PAH emission inventories. It was estimated that the total global atmospheric emission of these 16 PAHs in 2004 was 520 giga grams per year (Gg y^?1) with biofuel (56.7%), wildfire (17.0%) and consumer product usage (6.9%) as the major sources, and China (114 Gg y^?1), India (90 Gg y^?1) and United States (32 Gg y^?1) were the top three countries with the highest PAH emissions. The PAH sources in the individual countries varied remarkably. For example, biofuel burning was the dominant PAH source in India, wildfire emissions were the dominant PAH source in Brazil, while consumer products were the major PAH emission source in the United States. In China, in addition to biomass combustion, coke ovens were a significant source of PAHs. Globally, benzo(a)pyrene accounted for 0.05% to 2.08% of the total PAH emission, with developing countries accounting for the higher percentages. The PAH emission density varied dramatically from 0.0013 kg km^?2 y in the Falkland Islands to 360 kg km^?2 y in Singapore with a global mean value of 3.98 kg km^?2 y. The atmospheric emission of PAHs was positively correlated to the country's gross domestic product and negatively correlated with average income. Finally, a linear bivariate regression model was developed to explain the global PAH emission data.     

Source apportionment of polycyclic aromatic hydrocarbons in surface soil in Tianjin, China

Principal component analysis and multiple linear regression were applied to apportion sources of polycyclic aromatic hydrocarbons (PAHs) in surface soils of Tianjin, China based on the measured PAH concentrations of 188 surface soil samples. Four principal components were identified representing coal combustion, petroleum, coke oven plus biomass burning, and chemical industry discharge, respectively. The contributions of major sources were quantified as 41% from coal, 20% from petroleum, and 39% from coking and biomass, which are compatible with PAH emissions estimated based on fuel consumption and emission factors. When the study area was divided into three zones with distinctive differences in soil PAH concentration and profile, different source features were unveiled. For the industrialized Tanggu-Hangu zone, the major contributors were cooking (43%), coal (37%) and vehicle exhaust (20%). In rural area, however, in addition to the three main sources, biomass burning was also important (13%). In urban-suburban zone, incineration accounted for one fourth of the total.     

乌鲁木齐市大气可吸入颗粒物中多环芳烃的污染特征及来源解析

在乌鲁木齐市南、北设置2个采样点,从2011年3-12月采集可吸入颗粒物(PM2.5、PM2.5-10)样品,分析了美国环境保护署优控的13种多环芳烃(PAHs)的浓度,采用比值法、主成分分析法和多元线性回归法对乌鲁木齐市大气PM2.5、PM2.5-10中PAHs的来源进行了分析。结果表明,科学院站PM2.5中13种PAHs的总质量浓度平均值为247.2ng/m3,变动范围为1.14~2 113.33ng/m3;新大站PAHs的总质量浓度平均值为240.84ng/m3,变动范围为4.96~1 359.41ng/m3。而科学院站PM2.5-10中13种PAHs的总质量浓度平均值为57.78ng/m3,变动范围为1.18~519.87ng/m3;新大站的总质量浓度平均值为49.18ng/m3,变动范围为1.38~412.52ng/m3。比值法分析结果表明,所采集样品的2/3来自煤和生物质的燃烧排放;主成分分析法和多元线性回归分析法结果表明,采暖期汽油和煤源对PM2.5中总PAHs的贡献率为46%,而非采暖期混合源的贡献率高达85%。采暖期汽油和柴油源对PM2.5-10中总PAHs的贡献率为66%,而非采暖期混合源的贡献率为78%。     

南昌市夏季PM_(2.5)中多环芳烃来源解析

在南昌市设立了5个不同功能区采样点,分别为居民区、工业区、商业区、交通干线区以及郊区,于2008年夏季进行PM2.5采样,对样品进行测定和分析后,通过因子分析法判断PM2.5中多环芳烃(PAHs)的主要污染源,再利用多元线性回归法确定各主要污染源对PAHs的贡献率。结果表明,南昌市夏季PM2.5中PAHs的主要污染源为车辆排放源、高温加热源、燃煤污染源,它们对PAHs的贡献率分别为37.9%、28.2%和22.0%;要控制南昌市夏季PM2.5中的PAHs,主要是要对机动车尾气排放量进行控制,并加强机动车尾气治理工作。     

Long-term atmospheric bulk deposition of polycyclic aromatic hydrocarbons (PAHs) in rural areas of Southern Germany

A novel passive sampling technique using a funnel–adsorber–cartridge device was adopted and validated in the field during a long-term monitoring program on the atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in three rural regions of southern Germany. Apart from seasonal variations, fairly stable annual deposition rates around 200 μg m⁻² yr⁻¹ for the sum of PAHs were obtained. The time-integrating passive samplers showed that spatial variability due to topography was negligible and differences between open-field and forest deposition were within a factor of 2. Based on correlations with ambient temperature, advection was identified as the most important factor that controls the atmospheric deposition of PAHs. Gas-adsorption contributes significantly to the deposition of the semivolatile compounds in forests, but particle deposition seems to be the major pathway for all PAHs.     

Source apportionment of polycyclic aromatic hydrocarbons in surface sediments of the Bohai Sea, China

A total of 112 surface sediment samples covering virtually the entire Bohai Sea were analyzed for polycyclic aromatic hydrocarbons (PAHs), in order to provide the extensive information of recent occurrence levels, distribution, possible sources, and potential biological risk of these compounds in this area. Surface sediment samples were collected from the Bohai Sea using a stainless steel grab sampler. Sixteen PAHs were determined by a Finnigan TRACE DSQ gas chromatography/mass spectrometry. Diagnostic ratios, cluster analysis, and principal component analysis (PCA) with multivariate linear regression (MLR) were performed to identify and quantitatively apportion the major sources of sedimentary PAHs in the Bohai Sea. Concentrations of total PAHs in the Bohai Sea ranged widely from 97.2 to 300.7 ng/g (mean, 175.7?±?37.3 ng/g). High concentrations of PAHs were found in the vicinity of Luan River Estuary-Qinhuangdao Harbor, Cao River Estuary-Bohai Sea Center, and north of the Yellow River Estuary. The three-ring PAHs were most abundant, accounting for about 37?±?5 % of total PAHs. The four-ring and five-ring PAHs were the next dominant ones comprising approximately 29?±?7and 23?±?3 % of total PAHs, respectively. Concentrations of acenaphthylene, acenaphthene, and dibenz[a,h]anthracene are higher than Canadian interim marine sediment quality guideline values at most of the sites in the study area. Contamination levels of PAHs in the Bohai Sea were low in comparison with other coastal sediments in China and developed countries. The distribution pattern of PAHs and source identification implied that PAH contamination in the Bohai Sea mainly originates from petrogenic and pyrogenic sources. Further PCA/MLR analysis suggested that the contributions of spilled oil products (petrogenic), coal combustion, and traffic-related pollution were 39, 38, and 23 %, respectively. Pyrogenic sources (coal combustion and traffic-related pollution) contributed 61 % of anthropogenic PAHs to sediments, which indicates that energy consumption could be a dominant factor in PAH pollution in this area. Acenaphthylene, acenaphthene, and dibenz[a,h]anthracene are the three main species of PAHs with more ecotoxicological concern in the Bohai Sea.     

Sorption of polycyclic aromatic hydrocarbons (PAHs) on glass surfaces

Sorption of polycyclic aromatic hydrocarbons (PAHs) to glass commonly used in laboratories was studied. Sorption coefficients (K_d) of five selected PAHs to borosilicate glass surfaces were measured using column chromatography. A linear relationship between log K_d and the corresponding water solubility of the subcooled liquid (log S_w) of the investigated PAHs was observed. Based on the determined sorption coefficients our data revealed that mass loss caused by sorption on glass walls strongly depends on the ratio of solution volume to contacted surface area (V/S). The influence of solution chemistry such as ionic strength, solution pH, presence of cosolvent, and the influence of temperature on the sorption process were investigated. In the presence of ionic strength, sorption coefficients concurrently increased but less than a factor of 2 up to 0.005 M calcium chloride concentration. However, further increasing ionic strength had no influence on K_d. The cosolvent reduced sorption at a concentration of methanol in water above 0.5% (v/v); however, for benzo[a]pyrene even with 10% (v/v) methanol the mass loss would be still higher than 10% (with a V/S ratio less than 0.25). Significant effects of the solution pH and temperature were not observed. These results suggest that van der Waal’s forces dominate the sorption process. In the analysis of highly hydrophobic PAHs in aqueous samples, mass loss due to sorption on glass walls should be accounted for in the final result if untreated glass is used. The presented relationship between log K_d and log S_w may help to decide if such a correction is necessary. Furthermore, the frequently used silanization of glass surfaces may not be sufficient to suppress sorption for large PAHs.     

Persistence of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge-amended soil

The application of sewage sludge as a fertilizer is a common method used to improve soil properties. However, sewage sludge may contain various organic pollutants including polycyclic aromatic hydrocarbons. In the present study, the persistence of PAHs in soils fertilized with different sewage sludge doses was compared in relation to the sewage sludge dose applied (30, 75, 150, 300 and 600 Mgha(-1)) and the content of the polycyclic aromatic hydrocarbons in them. The experiment was carried out in two blocks of experimental plots divided according to the type of plants grown: field plants and perennial-willow. Sewage sludge addition to soils resulted in an increase in the content of polycyclic aromatic hydrocarbons in these soils. This increase was proportional to the quantity of sewage sludge applied. The results obtained showed that during a 42/54-month period, more than half of the individual PAHs introduced into the soil with sewage sludge were degraded. The scope of dissipation depended on the sewage sludge dose and the use to which the area was put. In the experiment with the willow only in the case of the highest sludge dose was a decrease in the PAH content above 50% noted; whereas in the case of the experiment with the field plants, it was higher by 50% for all sewage sludge doses. In experiment with field plants the highest scope of individual PAH disappearance was observed in the soil with the sewage sludge dose amounting to 300 Mgha(-1). In experiment with willow a relatively high dissipation of individual PAHs (>50%) was found in the treatment with the highest sludge dose (600 Mgha(-1)). A wider PAH dissipation range in the experiment with field plants was conditioned by the more favourable conditions created as a result of the breeding treatments applied. Agrotechnical treatments clearly increased the disappearance of the PAHs in those soils fertilized with the lowest sewage sludge doses (30 and 75 Mgha(-1)). The results obtained showed that the preferred method of treating a light soil fertilised with sewage sludges should be a one-year system, with a sludge application of 75 Mgha(-1).     

Seasonal variation of polycyclic aromatic hydrocarbons (PAHs) emissions in China

A regression model based on the provincial energy consumption data was developed to calculate the monthly proportions of residential energy consumption compared to the total year volume. This model was also validated by comparing with some survey and statistical data. With this model, a PAHs emission inventory with seasonal variation was developed. The seasonal variations of different sources in different regions of China and the spatial distribution of the major sources in different seasons were also achieved. The PAHs emissions were larger in the winter than in the summer, with a difference of about 1.3-folds between the months with the largest and the smallest emissions. Residential solid fuel combustion dominated the pattern of seasonal variation with the winter-time emissions as much as 1.6 times as that in the summer, while the emissions from wild fires and open fire straw burning was mainly concentrated during the spring and summer.     

Spatial distribution,potential risk assessment,and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments of Lake Chaohu,China

Twenty-nine sediment samples were collected from Lake Chaohu, a shallow eutrophic lake in Eastern China, and were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to determine the spatial distribution and exposure risks of PAHs. Three receptor models, the principal component analysis-multiple linear regression (PCA-MLR) model, the positive matrix factorization (PMF) model, and the Unmix model, were used in combination with the PAHs diagnostic ratios to investigate the potential source apportionment of PAHs. A clear gradient in the spatial distribution and the potential toxicity of PAHs was observed from west to east in the sediments of Lake Chaohu. ∑₁₅PAH concentrations and the TEQ were in the range of 80.82-30 365.01 ng g^?1 d.w. and 40.77-614.03, respectively. The highest values of the aforementioned variables were attributed to urban–industrial pollution sources in the west lake region, and the levels decreased away from the river inlets. The three different models yielded excellent correlation coefficients between the predicted and measured levels of the 15 PAH compounds. Similarly, source apportionment results were derived from the three receptor models and the PAH diagnostic ratios, suggesting that the highest contribution to the PAHs was from coal combustion and wood combustion, followed by vehicular emissions. The PMF model yielded the following contributions to the PAHs from gasoline combustion, diesel combustion, unburned petroleum emissions, and wood combustion: 34.49, 24.61, 16.11, 13.01, and 11.78 %, respectively. The PMF model produced more detailed source apportionment results for the PAHs than the PCA-MLR and Unmix models.     

Contribution of sugar-cane harvesting season to atmospheric contamination by polycyclic aromatic hydrocarbons (PAHs) in Araraquara city,Southeast Brazil

In Brazil, sugar-cane crops are burned to facilitate harvesting, and this causes environmental pollution from the large amounts of smoke and soot that are released into the atmosphere. The smoke and soot contain numerous organic compounds such as PAHs. In this study, PM₁₀ and PAH concentrations in the air of Araraquara (SE Brazil, with around 200,000 inhabitants and surrounded by sugar-cane plantations) were determined during the harvest and non-harvest seasons. The sampling strategy included two campaigns in each season, with 20 samples per season. PM₁₀ was collected using a Hi-vol sampler with Teflon? – coated glass fiber filters. PM₁₀ ranged from 41 to 181 μg m^?3 during the harvest season, and from 12 to 47 μg m^?3 during the non-harvest season. The mean total concentration of PAHs was 2.5 ng m^?3 (non-harvest season) and 11.6 ng m^?3 (harvest season). In all sampling periods, the most abundant polycyclic aromatic hydrocarbons were phenanthrene and fluoranthrene, and the least abundant was anthracene. The cluster analysis of the total PAH concentrations for each day of sampling and the corresponding meteorological data suggested that the atmospheric concentration of PAHs was independent of the differences in the weather between the seasons. For both sampling seasons, the statistical treatment (PCA, Varimax rotation and HCA) indicated the presence of vehicle sources (diesel, gasoline, and natural-gas engines); but for the harvest season, the main source was attributed to sugar-cane burning. The data generated by this study indicated the burning of sugar-cane as the main contributor to the high levels of PAHs detected in samples during the sugar-cane harvest season.     

Enrichment of polycyclic aromatic hydrocarbons (PAHs) in mariculture sediments of Hong Kong

Surface and core sediments collected from six fish farms in Hong Kong and from reference sites were investigated for the enrichment and sources of polycyclic aromatic hydrocarbons (PAHs). Moderately high ∑PAH₁₆ levels (123-947 ng g⁻¹, mean: 450 ng g⁻¹) were found in the surface aquaculture sediments. In comparison with the sediments from the reference sites, the average enrichment percentage of total organic carbon (TOC) and PAHs in surface sediments were 21.4 and 43.8%, respectively, and in the core sediments, 24.6 and 73.7%, respectively. Mathematical source apportionment analyses (i.e. isomer ratios, hierarchical cluster analysis, principal components analysis with multiple linear regression analysis) suggested a higher percentage of petrogenic sources in aquaculture sediments. The fish feeds might be the main source of the enriched PAHs in the aquaculture sediments. To our knowledge, this is the first study showing that PAHs in aquaculture sediments could be attributed to human aquaculture activities.     

添加剂对堆肥降解多环芳烃的影响

为了研究多环芳烃(PAHs)污染土壤堆肥修复的加速机制,在人工控温的堆肥装置中以芘、菲和芴为研究对象,采用室内模拟实验的方式研究了添加硫酸钙、过磷酸钙、草炭、竹炭、十二烷基硫酸钠(K12)和十二烷基苯磺酸钠(SD-BS)等对锯末高温堆肥降解污染土壤PAHs的影响。研究结果表明,生物堆肥可以有效的去除土壤中PAHs,堆肥7周后所有处理下芘、菲和芴的降解率基本达到80%以上。不同添加剂处理下芘、菲和芴降解率不同,尤其是添加草炭和竹炭处理中芴和菲在第4周的时候就取得90%以上的降解率,芘在第6周也取得80%以上的降解率,而且氮素的损失率也分别下降了42.6%和36.09%,比其他处理的PAHs降解率和保氮效果都要好。分析其原因,一方面可能是添加不同添加剂对堆肥过程中pH值、有机质(SOM)、总氮(TN)和过氧化氢酶(CAT)都有一定的影响,提高了土壤微生物的活性;另一方面可能是由于草炭和竹炭对氨有良好的吸附性,具有良好的保氮效果,同时也能改善了微生物和目标化合物的接触方式,从而提高了PAHs的降解率。     

Leaching characteristics of polycyclic aromatic hydrocarbons (PAHs) from spiked sandy soil

In order to evaluate the factors affecting leachability of hydrophobic organic pollutants (HOPs), we performed leaching tests under a variety of conditions using sandy soil contaminated with phenanthrene and pyrene. The results obtained were: (1) the shaking time, temperature, and dissolved humic matter (DHM, as coexisting matter) increased leachability; (2) ionic strength reduced leachability; and (3) the liquid-to-solid ratio and pH level had no effect on leaching concentration of HOPs. In DHM-added leaching tests assuming equilibrium with HOPs, DHM, and solid matrix, the partitioning (binding) coefficient of HOPs to DHM was accurately calculated with the equations proposed in this study. While we recommend taking into consideration the coexistence of DHM, it is difficult to use universally because its properties differ according to origin and extracting method. It is therefore reasonable to use an alternative reagent having an effect similar to that of DHM.     

燃煤电厂多环芳烃的生成与控制

多环芳烃 (PAHs)对人体健康的危害极大。本文综述了燃煤电厂煤燃烧过程中多环芳烃的生成机理 (直接释放、热解合成和高温缩合机理 )和影响因素 (煤种、温度、锅炉负荷、过剩空气系数、停留时间、钙硫比和一次风 /二次风比 ) ,在此基础上介绍了煤燃烧过程中多环芳烃的各种控制技术和方法     

Seasonal variation of polycyclic aromatic hydrocarbons (PAHs) in Pearl River Delta region,China

A level IV fugacity model was applied to simulate the seasonal variation of polycyclic aromatic hydrocarbons (PAHs) in various bulk media in Pearl River Delta (PRD), China. The predictions were validated against monthly observed concentrations of gaseous and particulate phase PAHs in air and annual mean concentrations of all other bulk media. The uncertainty of the predictions was evaluated using Monte Carlo simulation. The influential parameters were identified using sensitivity analysis on both media concentrations and seasonal variations. The predicted concentrations and the patterns of seasonal variation generally agreed with the field observations. Concentrations of gaseous phase PAHs in air increased in the summer and decreased in the winter while concentrations of particulate phase PAHs in summer were lower than those in the winter. The relative variations of PAHs in the other bulk media were not as profound as those in air and the variation patterns were chemical compound dependent. Temperature and precipitation were the most important parameters leading to the seasonalities of PAH concentrations. Other key parameters included dry precipitation rate, advective water flow from upstream, and solid fractions in air and water.     

Emissions of polycyclic aromatic hydrocarbons (PAHs) from the pyrolysis of scrap tires

This work investigated the PAHs generated in a waste-tire pyrolysis process and the PAHs removal by a wet scrubber (WSB) and a flare. IND, DBA, and BaP were found to dominate in the powders of scrap tires before the pyrolysis. The PAHs in the carbon blacks formed in the pyrolysis were mainly 2-, 3-, 6-, and 7-ring PAHs. Nap was the most predominant water-phase PAH in the WSB effluent. About 40% of the water-phase total-PAHs in the WSB effluent were contributed by nine carcinogenic PAHs. NaP, IND, and COR displayed higher mean gas- and particulate-phase concentrations than the other PAHs in the flare exhaust. The mean removal efficiencies of individual PAHs, total-PAHs, and high carcinogenic BaP+IND+DBA were 39.1–90.4%, 76.2%, and 84.9%, respectively for the WSB. For the flare, the mean removal efficiencies of gaseous, particulate, and combined (gaseous+particulate) total-PAHs were 59.8%, 91.2%, and 66.8%, respectively, whereas the removal efficiencies were 91.0%, 80.1%, and 89.1%, respectively for the total-BaPeq. However, the gaseous BaA displayed a negative mean removal efficiency. The total PAH emission rate and factor estimated for the scrap tire pyrolysis plant were 42.3 g d⁻¹ and 4.00 mg kg-tire⁻¹, respectively.     

Accumulation of weathered polycyclic aromatic hydrocarbons (PAHs) by plant and earthworm species

Experiments were conducted to assess the bioavailability of polyclycic aromatic hydrocarbons (PAHs) in soil from a Manufactured Gas Plant site. Three plant species were cultivated for four consecutive growing cycles (28 days each) in soil contaminated with 36.3 microg/g total PAH. During the first growth period, Cucurbita pepo ssp. pepo (zucchini) tissues contained significantly greater quantities of PAHs than did Cucumis sativus (cucumber) and Cucurbita pepo ssp. ovifera (squash). During the first growth cycle, zucchini plants accumulated up to 5.47 times more total PAH than did the other plants, including up to three orders of magnitude greater levels of the six ring PAHs. Over growth cycles 2-4, PAH accumulation by zucchini decreased by 85%, whereas the uptake of the contaminants by cucumber and squash remained relatively constant. Over all four growth cycles, the removal of PAHs by zucchini was still twice that of the other species. Two earthworm species accumulated significantly different amounts of PAH from the soil; Eisenia foetida and Lumbricus terrestris contained 0.204 and 0.084 microg/g total PAH, respectively, but neither species accumulated measurable quantities 5 or 6 ring PAHs. Lastly, in abiotic desorption experiments with an aqueous phase of synthetically prepared organic acid solutions, the release of 3 and 4 ring PAHs from soil was unaffected by the treatments but the desorption of 5-6 ring constituents was increased by up to two orders of magnitude. The data show that not only is the accumulation of weathered PAHs species-specific but also that the bioavailability of individual PAH constituents is highly variable.     

Bulk deposition of polycyclic aromatic hydrocarbons (PAHs) in an industrial site of Turkey

Ambient air and deposition samples were collected in the period of July 2004-May 2005 in an industrial district of Bursa, Turkey and analyzed for polycyclic aromatic hydrocarbon (PAH) compounds. The overall average of fourteen bulk deposition fluxes for PAHs was 3300+/-5100 ng m(-2) d(-1). PAH depositions showed a seasonal variation and they were higher in winter months. This was probably due to increases in residential heating activities and decreases in atmospheric mixing layer levels. Ambient air samples, measured with a high volume air sampler, were collected from the same site. The average total concentration including gas and particulate phase was about 300+/-420 ng m(-3) and it was in the range of previously reported values. Some of the ambient air and bulk deposition samples were collected simultaneously in dry periods. Both concurrently measured values were used to calculate the dry deposition velocities whose overall average value was 0.45+/-0.35 cm s(-1).