Atmospheric transport and outflow of polycyclic aromatic hydrocarbons from China

A potential receptor influence function (PRIF) model, based on air mass forward trajectory calculations, was applied to simulate the atmospheric transport and outflow of polycyclic aromatic hydrocarbons (PAHs) emitted from China. With a 10 day atmospheric transport time, most neighboring countries and regions, as well as remote regions, were influenced by PAH emissions from China. Of the total annual PAH emission of 114 Gg, 92.7% remained within the boundary of mainland China. The geographic distribution of PRIFs within China was similar to the geographic distribution of the source regions, with high values in the North China Plain, Sichuan Basin, Shanxi, and Guizhou province. The Tarim basin and Sichuan basin had unfavorable meteorological conditions for PAH outflow. Of the PAH outflow from China (8092 tons or 7.1% of the total annual PAH emission), approximately 69.9% (5655 tons) reached no further than the offshore environment of mainland China and the South China Sea. Approximate 227, 71, 746, and 131 tons PAHs reached North Korea, South Korea, Russia-Mongolia region, and Japan, respectively, 2-4 days after the emission. Only 1.4 tons PAHs reached North America after more than 9 days. Interannual variation in the eastward PAH outflow was positively correlated to cold episodes of El Ni?o/Southern Oscillation. However, trans-Pacific atmospheric transport of PAHs from China was correlated to Pacific North America index (PNA) which is associated with the strength and position of westerly winds.     

Emission of polycyclic aromatic hydrocarbons in China

Emission of 16 polycyclic aromatic hydrocarbons (PAHs) listed as U.S. Environmental Protection Agency (U.S. EPA) priority pollutants from major sources in China were compiled. Geographical distribution and temporal change of the PAH emission, as well as emission profiles, are discussed. It was estimated that the total PAH emission in China was 25,300 tons in 2003. The emission profile featured a relatively higher portion of high molecular weight (HMW) species with carcinogenic potential due to large contributions of domestic coal and coking industry. Among various sources, biomass burning, domestic coal combustion, and coking industry contributed 60%, 20%, and 16% of the total emission, respectively. Total emission, emission density, emission intensity, and emission per capita showed geographical variations. In general, the southeastern provinces were characterized by higher emission density, while those in western and northern China featured higher emission intensity and population-normalized emission. Although energy consumption in China went up continuously during the past two decades, annual emission of PAHs fluctuated depending on the amount of domestic coal consumption, coke production, and the efficiency of energy utilization.     

Emission of polycyclic aromatic hydrocarbons in China by county

Quantitative relationships among social, economic, and climate parameters, and energy consumption for Chinese provinces, provide data for regression models' estimated rates of energy consumption and emission of polycyclic aromatic hydrocarbons (PAHs) by county. A nonlinear model was used for domestic coal combustion with total population and annual mean temperature as independent variables. Linear regression models were utilized for all other types of fuel consumption. Monte Carlo simulation demonstrated that emission factors, rather than the regression modeling, constitute the main source of uncertainty in prediction. Models were validated using available energy data of several northern and southern counties of China from the literature. The total PAHs produced by each county is approximately equivalent to the sum of the total emission from energy, coke, and aluminum production.     

食品中多环芳烃及卤代多环芳烃的研究进展

综述了多环芳烃及卤代多环芳烃的性质、毒性及国内外食品中的污染情况和研究现状,并对目前的分析测定方法进行了介绍,希望为我国开展食品领域内多环芳烃和卤代多环芳烃的研究提供参考。     

Atmospheric gas-particle partitioning of polycyclic aromatic hydrocarbons in high mountain regions of Europe

Atmospheric concentrations and gas-particle partitioning of polycyclic aromatic hydrocarbons (PAH) have been determined at three remote mountain areas in Europe. Gas-phase mean concentrations of total PAH (20 individual compounds) were very similar at all sites, ranging from 1.3-2.6 ng m(-3) in the Pyrenees (Spain) to 2.7-3.7 ng m(-3) in the Alps (Austria) and Caledonian mountains (Norway). A seasonal variability was observed, with the highest levels found in winter. The seasonal differences were reflected better in the particle-associated PAH, showing the increase of PAH emissions in the colder months and a temperature dependence of the gas-particle partitioning. Significant geographical differences were also observed for particulate PAH, indicating a greater influence of regional sources than in the gas phase. Partitioning of PAH between gas and particulate phases was well-correlated with the subcooled liquid vapor pressure in all samples, but with slopes significantly steeper than the expected value of -1. These steeper slopes may reflect the occurrence of a nonexchangeable PAH fraction in the aerosols, likely associated to the soot carbon phase. Comparison of absorption to organic matter and soot carbon using the octanol-air (Koa) and soot-air (Ksa) partitioning coefficients shows that, despite uncertainties on estimated organic matter and soot carbon contents in the sampled aerosols, Koa underpredicts aerosol PAH concentrations by a factor of 0.6-2 log units. In contrast, predicted and measured high mountain aerosol PAH differ by 0.2-0.6 log units when Ksa is considered. The results point to soot carbon as the main transport medium for the long-range distribution of aerosol-associated PAH.     

Trophic dilution of polycyclic aromatic hydrocarbons (PAHs) in a marine food web from Bohai Bay, north China

Trophic transfer of polycyclic aromatic hydrocarbons (PAHs) in aquatic ecosystems is an important criterion for assessing their ecological risk. This study analyzed 18 PAHs in phytoplankton/seston, zooplankton, five invertebrate species, five fish species, and one seabird species collected from Bohai Bay, and trophic transfer of the PAHs was determined in the food web, of which the length was approximately 4 on the basis of stable nitrogen isotope values. The concentrations of PAHs (2-64.5 ng/g wet weight) in the marine ecosystem were moderate compared with other marine organisms worldwide, and the PAH compositions exhibited species-specific profiles that were related to trophic levels in some organisms. Significant negative relationships were also found between trophic levels and lipid-normalized concentrations for 10 PAH compounds (acenaphthylene, anthracene, fluoranthene, pyrene, chrysene, benz[a]anthracene, benzo[b]fluoranthene + benzo[k]fluoranthene, benzo[e]pyrene, benzo[a]pyrene, and perylene), and their trophic magnification factors (TMFs) ranged from 0.11 for fluoranthene to 0.45 for acenaphthylene. These results confirm that PAHs undergo trophic dilution in the marine food web, which is likely to be the combined results of low assimilation efficiencies and efficient metabolic transformation at higher trophic levels.     

食品中多环芳烃的研究进展

简述了近年来关于食品中多环芳烃的形成机理、分析方法及控制措施的研究进展,以期为解决食品中多环芳烃的污染问题提供依据。     

Outflow of polycyclic aromatic hydrocarbons from Guangdong, southern China

The atmospheric outflow of polycyclic aromatic hydrocarbons (PAHs) from Guangdong, China, a region of high PAH emission, was modeled using a potential receptor influence function (PRIF) probabilistic model which was based on a spatially resolved PAH inventory and air mass forward-trajectory calculations. Photochemical degradation and deposition (dry and wet) of PAHs during atmospheric transport were taken into consideration. On average, 48% of the PAHs (by mass) remained in the atmosphere for a transport period of 5 days, staying within the boundary of the source region. The medium molecular weight PAHs (four rings) were predicted to travel longer distances in the atmosphere than the low (three rings) or high molecular weight PAHs (five rings) because they are less photodegradable than the lower molecular weight, gas-phase PAHs and less likelyto undergo wet and dry depositions than the higher molecular weight, particulate phase PAHs. Under the strong influence of the East Asian monsoons in winter, the predominant outflow pattern of PAHs from Guangdong was to the South China Sea and Southeast Asian countries. In summer, PAHs were transported primarily to northern mainland China. Under particular weather conditions in winter, the PAH-containing air masses were lifted by cold fronts or convection and transported toward the Pacific Ocean by westerly winds. In addition to the distinct seasonality in PAH dispersion and outflow, interannual long-term variation in the outflow is likely influenced by El Ni?o and southern oscillation.     

Aqueous photodegradation of polycyclic aromatic hydrocarbons

Photodegradation of 12 polycyclic aromatic hydrocarbons was studied in aerated pure water, solutions of Suwannee River fulvic acid, and natural waters using polychromatic light (>290 nm). Quantum yields in pure water varied from 3.2 x 10(-5) to 9.2 x 10(-3). No obvious relationships were evident among the quantum yields and molecular properties. Photodegradation rate constants in solutions of Suwannee River fulvic acid or natural waters were largely unchanged compared to rate constants in pure water. Estimates of PAH photodegradation rates in natural waters can thus be obtained employing the quantum yields in pure water, PAH absorption, and solar irradiance. Calculated rate constants for photodegradation in surface waters during the summertime at mid-latitude varied from 3.2 x 10(-3) to 7.6 h(-1).     

Atmospheric concentrations and deposition of polycyclic aromatic hydrocarbons to the Mid-Atlantic East Coast region

Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured at urban/industrial, suburban, coastal, and rural areas in New Jersey as part of the New Jersey Atmospheric Deposition Network. Concentrations of 36 PAH compounds were measured in the gas and particle phases in air and in precipitation at nine sites at regular intervals from October 1997 through May 2001. Gas-phase and particle-phase sigma36PAH concentrations ranged from 0.45 to 118 ng m(-3) and from 0.046 to 172 ng m(-3), respectively, and precipitation concentrations ranged from 11 to 16200 ng L(-1). PAH concentrations vary spatially across the region, with the highest concentrations occurring at the most heavily urban and industrial locations. Average gas absorption deposition ranged from 0.004 (naphthacene) to 5040 (methylphenanthrenes) ng m(-2) d(-1), and dry particle deposition PAH fluxes ranged from 0.11 (naphthacene) to 300 (benzo[b+k]fluoranthene) ng m(-2) d(-1) at the nine sites. Average atmospheric wet deposition PAH fluxes at the seven sites ranged from 0.40 (cyclopenta[cd]pyrene) to 140 (methylphenanthrenes) ng m(-2) d(-1). These represent the first comprehensive estimates of PAH deposition to New Jersey and the Mid-Atlantic East Coast.     

Atmospheric deposition and marine sedimentation fluxes of polycyclic aromatic hydrocarbons in the Eastern Mediterranean Basin

Atmospheric input was studied and found to be the major source of PAHs in the eastern Mediterranean open marine ecosystem. Dry and wet atmospheric deposition, air-sea exchange, and sediment trap fluxes of polycyclic aromatic hydrocarbons (PAHs) in the eastern Mediterranean basin were estimated from November 2000 to July 2002. Seven dry and four wet deposition samples were analyzed in total and PAH concentrations were determined. Airsea exchange fluxes based on air-water concentration gradientwere drawn from five air and water samples collected concurrently from a coastal area in the eastern Mediterranean. Total annual average deposition fluxes of dry, wet, and air-sea exchange sigma35PAHs were 58.0, 165.7, and -706.4 microg m(-2) y(-1), respectively. Only 1.1 and 0.7% of the total atmospheric deposition flux of PAHs was measured in the sediment traps at 280 and 1440 m depth, respectively.     

Dietary intake of polycyclic aromatic hydrocarbons in a Spanish population

The objective of the present study was to estimate the dietary intake of polycyclic aromatic hydrocarbons (PAHs), particularly benzo[a]pyrene (B[a]P), as well as to identify the principal dietary sources of such compounds in the Spanish adult population. The study included 40,690 subjects aged 35 to 64 years from five regions of Spain that were included in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Spain cohort. Usual food intake was estimated by personal interview through a computerized version of a dietary history questionnaire. The estimations of B[a]P and total PAHs were made, taking into account the country where the determinations of content of these compounds in the foods came from and the year of publication. The mean intake of B[a]P in the population was 0.14 microg/day, and the mean intake of total PAHs was 8.57 microg/day. Both for B[a]P and total PAHs, women had a significantly lower mean intake than men, and older people consumed lesser amounts than younger people. Furthermore, the intake was higher in the northern regions. There were no significant differences by smoking status. The food groups of meat and meat products, cereals, and oils and fats contribute 55.5% to the total B[a]P intake, while cereals and meat and meat products contribute 61% to the total PAH consumption. Our estimations of B[a]P intake were lower than in the United Kingdom and The Netherlands, were similar to those found in other studies from Spain and Italy, and were higher than those in the United States and Norway.     

Atmospheric occurrence and deposition of polycyclic aromatic hydrocarbons in the northeast tropical and subtropical Atlantic Ocean

Atmospheric transport and deposition of polycyclic aromatic hydrocarbons (PAHs) over tropical oceans has not yet been studied even though tropical oceans account for 35% of the global oceans. Here we show the results from measurements of gas- and aerosol-phase PAHs and dry deposition samples in the NE tropical Atlantic Ocean atmosphere, a region between 26 degrees and 21 degrees N, off shore of the Saharan desert. The results show that PAHs concentrations are high at the coastal ocean (15-20 ng m(-3) for sum of 27 gas-phase individual PAHs) and decrease by a factor of 2-3 at open ocean (26 degrees W). The spatial variability observed is consistent with dilution, reaction, and deposition during transport. Atmospheric dry deposition velocities ranged between 0.1 and 0.3 cm s(-1) with higher deposition velocities for the more volatile PAHs. Outbreaks of Saharan Dust significantly increase the deposition rates of PAHs. The occurrence and deposition of PAHs in tropical regions is complex and results from the interplay of a number of processes, such as wind speed, aerosol loads, important sources from West Africa, processes controlling the diurnal variability, and sequestration driven by high primary productivity regions. The measured average atmospheric residence times of gas- and aerosol-phase PAHs are 3.7 and 3.5 days, respectively.     

高脂食品中多环芳烃研究

多环芳烃具有非极性强特点,易在脂质含量丰富食品中造成污染。该文对富脂肉类等高脂肪食品中多环芳烃来源、形成及污染现状、检测方法等进行概述,并对控制其中多环芳烃污染方法进行总结和讨论。     

Occurrence of polycyclic aromatic hydrocarbons in smoked cheese

The presence of polycyclic aromatic hydrocarbons (PAH) in smoked cheeses of different origin was studied. The samples were subjected to an initial extraction of fat and an alkaline treatment, extracted with cyclohexane, cleaned up by means of solid-phase extraction tubes, and analyzed by gas chromatography/mass spectrometry (GC/MS) operating in selective ion-monitoring mode (SIM). The results revealed the presence of numerous polycyclic aromatic hydrocarbons in the exterior zone of the samples, some of them with methyl groups. In all cases, the concentrations of compounds of low molecular weight were much higher than those of high molecular weight. Polycyclic aromatic hydrocarbons with varying degrees of carcinogenicity were identified, including benzo(a)pyrene in concentrations, which, although they did not exceed the limit established for this compound in the rind of ripened cheeses, do exceed the limit of 0.03 microg/kg fixed for other foods smoked with smoke flavorings. Significant differences in the number and concentration of PAH in smoked cheese also were observed from rind to interior, the rind being the most contaminated zone.     

食用油中多环芳烃的研究进展

多环芳烃(PAHs)是指2个或2个以上苯环以稠环形式相连的一类化合物,具有基因毒性和致癌性.对食用油中PAHs的来源、检测方法及控制和脱除方法进行了详尽的阐述,并指出PAHs前处理方法和控制、脱除方法是未来的研究方向.