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Environmental persistent free radicals (EPFRs), as emerging contaminants in environment, can induce oxidative stress causing severe adverse health outcomes. The formation of EPFRs is thought to be associated with the transformation of aromatic compounds like polycyclic aromatic hydrocarbons (PAHs). Herein this study firstly evaluated EPFRs in industrial soils being highly polluted by PAHs, and explored its associated with PAHs, with the modification of soil organic matter content. Soil EPFRs from two industrial plants were 4.1 × 10 16 and 4.5 × 10 16 spins/g, respectively, that were significantly higher than the levels in the surrounding areas. Carbon-centered EPFRs account for approximately 80% inside the plant, but outside the plants, nearly 50-70% of EPFRs were carbon-centered with adjacent heteroatoms. As one important precursor of EPFRs, PAHs exhibited a significantly positive correlation with EPFRs in industrial soils (p < 0.05), explaining 40%-60% of the variation in EPFRs concentration in the present study. The relationship between soil organic matter and EPFRs concentration normalized by PAHs forms an inverted V-shape, suggesting an inhibition effect of soil organic matter on the EPFR formation potentials from PAHs, that is worthy to be further examed in future laboratory and field experiments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Some Polycyclic Aromatic Compounds (PACs) such as nitrated-PAHs (NPAHs), oxygenated-PAHs (OPAHs) and methyl-PAHs (MPAHs) have attracted significant concern due to derivatives have greater potential to be more toxic at low environmental concentrations compared to their PPAHs, particularly in petrochemical industrial region and its surrounding areas surface soils in China. Hence, this article provides an insight into the fate, sources, impacts, and relevance to the external environment of PAH-derivatives based on important emissions source. Moreover, prospective health risk due to their exposure has also been discussed. In this study, the concentration (10 -3  ng/g) of Ʃ18PPAHs, Ʃ11MPAHs, Ʃ12NPAHs, and Ʃ4OPAHs in the park were 9.67 ± 1.40, 3.24 ± 0.54, 0.03 ± 0.02 and 0.19 ± 0.65, respectively, which were 4.47, 3.89, 2.04 and 1.17 times than of them surrounding the region. A decreasing trend of the low molecular weight (2-4Rings) contribution to the total amount of PAHs, while the fraction of high molecular weight (5-6Rings) species showed the opposite trend. According to the principal component analysis (PCA) and diagnostic ratios indicated PAHs in the soil samples have mixed sources from industrial activities, solid fuel combustion, and heavy traffic. Despite the high concentrations of MPAHs and OPAHs, the toxicity equivalency quotients (TEQs) of them were not calculated due to the lack of toxic equivalent factors (TEF), thus current studies on PAH and derivatives could have underestimated their exposure risks. The quality and sustainable management of soils are crucial for human health and sustainable development, while there is lack of public awareness of the severe issue of soil pollution. It is recommended to conduct more intensive monitoring and regional assessments in the future., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The rapid growth of maritime traffic, transportation, and fishery activities has increased shipping emissions and degraded the air quality in coastal areas. As a result, controlling ocean-based pollution sources have become increasingly important. This study investigated the real-world emission characteristics of oxygenated polycyclic aromatic hydrocarbons (OPAHs, a group of highly toxic semi-volatile organic compounds) from five types of offshore ships using diesel oil: small and medium fishing ships, tug boats, ferry, and engineering ships, under various driving mode. Both gaseous and particle emission factors (EF) of four specific OPAHs were determined in our study. Among the OPAHs species emitted from ships, 9-fluorenone (9FO; 72%) and anthrathrace-9,10-quinone (ATQ; 25%) were the most abundant. The arithmetic mean of the sum of gaseous OPAHs EFs for all ships in this study was 2.5 ± 4.4 mg/kg fuel burned, and the mean particulate OPAHs EF was 4.7 ± 7.9 mg/kg. Small fishing ships had the highest total OPAHs EFs (31.0 ± 17.0 mg/kg). Apart from small fishing ships, there was no significant difference in the total EF of OPAHs for the other four types of ships. The emissions of the four OPAHs are predominantly in the particulate phase. There were no significant differences in the emissions of the four OPAHs under different driving mode. According to estimates, the annual OPAH emissions from the four types of ships in Hainan in 2017 were approximately 4.2 (range: 2.7-7.0) tons, dwarfing the OPAH emissions from diesel-powered on-road vehicles in China (23.5 kg)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants associated with various health risks including lung cancer. Indoor exposure to PAHs, particularly from the indoor burning of fuels, is significant; however, long-term large-scale assessments of indoor PAHs are hampered by high costs and time-consuming in field sampling and laboratory experiments. A simple fuel-based approach and statistical regression models were developed as a trial to predict indoor BaP, as a typical PAH, in China, and consequently spatiotemporal variations in indoor BaP and indoor exposure contributions were discussed. The results show that the national population-weighted indoor BaP concentration has decreased substantially from 46.1 ng/m 3 in 1992 to 6.60 ng/m 3 in 2017, primarily due to the increased use of clean energies for cooking and heating. Indoor BaP exposure contributed to > 70% of the total inhalation exposure in most cities, particularly in regions where solid fuels are widely utilized. With limited experimental observation data in building statistical models, quantitative results of the study are associated with high uncertainties; however, the study undoubtedly supports effective countermeasures on indoor PAHs from solid fuel use and the importance of promoting clean household energy usage to improve household air quality., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Polycyclic aromatic hydrocarbons (PAHs) derivatives such as oxygenated PAHs (oPAHs) and nitrated PAHs (nPAHs), are receiving raising concerns due to their high toxic potential. Incomplete solid fuel combustion can release large quantities of PAHs derivatives, especially in low-efficiency domestic stoves. In this study, field measurements were conducted in rural Chinese homes to determine emissions of nPAHs and oPAHs from solid fuel combustion. A total of 12 fuel-stove combinations including cooking and space heating activities were investigated. Emission factors (EFs) of total nPAHs and oPAHs were in the range of 1.0-682.1 μg/kg and 0.01-131.7 mg/kg, respectively, with arithmetic means and stand deviations of 53.5 ± 72.5 μg/kg and 13.9 ± 24.4 mg/kg, respectively. The EFs of nPAHs and oPAHs for coal combustion (including honeycomb briquette, coal chunk, and peat tested in this study) were 30.2 ± 28.1 μg/kg and 1.5 ± 2.9 mg/kg, respectively, much lower than that for biomass burning (p < 0.05). The combustion phase could significantly affect the PAHs derivative emissions with higher emissions at initial phase than that at stable phase. Fuel type was found to affect the EFs, composition profiles, and ratios of PAHs derivatives to parent PAHs. This study tries to have an insight of PAHs derivative emissions from various solid fuel combustion, which would be useful in understanding the atmospheric PAHs derivative pollutions in China., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Soil polycyclic aromatic hydrocarbons (PAHs) generated from industrial processes are highly spatially heterologous, with limited quantitative studies on their main influencing factors. The present study evaluated the soil PAHs in three types of industrial parks (a petrochemical industrial park, a brominated flame retardant manufacturing park, and an e-waste dismantling park) and their surroundings. The total concentrations of 16 PAHs in the parks were 340-2.43 × 10 3 , 26.2-2.63 × 10 3 , and 394-2.01 × 10 4  ng/g, which were significantly higher than those in the surrounding areas by 1-2 orders of magnitude, respectively. The highest soil PAH contamination was observed in the e-waste dismantling park. Nap can be considered as characteristic pollutant in the petrochemical industrial park, while Phe in the flame retardant manufacturing park and e-waste dismantling park. Low molecular weight PAHs (2-3 rings) predominated in the petrochemical industrial park (73.0%) and the surrounding area of brominated flame retardant manufacturing park (80.3%). However, high molecular weight PAHs (4-6 rings) were enriched in the other sampling sites, indicating distinct sources and determinants of soil PAHs. Source apportionment results suggested that PAHs in the parks were mainly derived from the leakage of petroleum products in the petroleum manufacturing process and pyrolysis or combustion of fossil fuels. Contrarily, the PAHs in the surrounding areas could have been derived from the historical coal combustion and traffic emissions. Source emissions, wind direction, and local topography influenced the PAH spatial distributions., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Halogenated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) have received tremendous attention due to their high toxicity. To identify the emission pattern of Cl/Br-PAHs from various industrial productions, understand the formation mechanisms and the influence on the surroundings, this study investigated the surface soils of three typical industrial parks. Generally, traces of Cl-PAHs were much lower than Br-PAHs. The mean Cl-PAH concentrations followed the trend of petrochemical industrial park (3.12 ng/g), brominated flame retardant (BFR) manufacturing park (1.48 ng/g), and electronic waste dismantling park (0.26 ng/g). However, the BFR manufacturing park had the highest mean Br-PAH concentration (21.6 ng/g), significantly higher than the other two parks. Generally, higher levels of the chemicals were found in the parks than in their surroundings, except for the electronic waste dismantling park. The massive addition of chlorine additives in crude oil and its by-products, plus the enormous quantity of brominated brines used in BFR productions, favor Cl/Br-PAH formation. Analyzing the homolog compositions of Cl/Br-PAHs suggested that 3- or 4-ring Cl/Br-PAHs were typically come from the petrochemical industrial park and electronic waste dismantling park. Contrarily, 4- or 5-ring Cl/Br-PAHs were predominantly come from the BFR manufacturing activity. This study provides fingerprints to trace the Cl/Br-PAH emissions during industrial production and analyzes the formation mechanism., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A portable emission sampling system was used to perform on-site measurements of the emission factors (EFs; quantities of pollutants emitted per unit of energy consumed) of 29 polycyclic aromatic hydrocarbons (PAHs) for five types of marine vessels using light diesel in Hainan Province, China. Both gaseous- and particulate-phase PAHs from vessel emissions were sampled and measured using gas chromatography coupled with mass spectrometry (GC-MS), and the PAH EFs were calculated based on the carbon mass balance method. The average EFs of gaseous- and particulate-phase PAHs were 6.2 ± 7.8 and 17 ± 26 mg/kg, with naphthalene (NAP) and phenanthrene (PHE) dominating the gaseous- and particulate-phase PAH emissions, respectively. Among the five types of vessels, the EFs for small fishing boats were significantly higher than those for other types of vessels, and the lowest EFs were found for tug boats. Composition profiles and typical isomer ratios of PAHs were calculated for five types of vessels. Particulate-phase PAHs accounted for 63 ± 16% of the total emissions of 29 PAH species, and the particulate/gaseous-phase partitioning of PAHs was dominated by organic carbon (OC) absorption rather than black carbon (BC) adsorption. Emission factors of PAHs under different activity conditions were measured and calculated, and relatively higher EFs were found in the maneuvering mode for medium fishing boats and in the operating mode for engineering vessels. No significant differences were found among the PAH composition profiles under different activity conditions., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

China has been famous for its porcelains for millennia, and the combustion processes of porcelain production emit substantial amounts of air pollutants, which have not been well understood. This study provided firsthand data of air pollutant emissions from biomass porcelain kilns. The emission factor of PM 2.5 was 0.95 ± 1.23 g/kg during the entire combustion cycle, lower than that of biomass burning in residential stoves and coal burning in brick kilns, attributed to the removal effects of the long-distance transport in dragon kilns. The temporal trend of particle pollutants, including particulate matters (PMs) and particulate polycyclic aromatic hydrocarbons (PAHs) (low at ignition phase and high at the end) again indicated the removal effects of the special structure, while gaseous pollutants, such as gaseous PAHs, exhibited the opposite result. The GWC 100 was estimated as 1.4 × 10 6 and 0.5 × 10 6  kg CO 2 e/yr for the scenarios in which 50% and 100% of the wood was renewable, respectively. The GWC 100 of dragon kilns is nearly equal to that of 745 households using wood-fueled stoves. These results indicate the necessity of pollution controls for biomass porcelain kilns to estimate the emission inventory and climate change., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Residential solid fuel combustion (RSFC) is a key cause of air pollution in China. In these serial studies, field measurements of RSFC from 166 rural households in eastern China were conducted to update the database of emission factors (EFs) and chemical profiles of gaseous and particulate organic pollutants, and the present study focuses on the intermediate volatile organic compounds (IVOCs), which are precursors of secondary organic aerosol (SOA). The results show that the averaged EFs of IVOCs (EF IVOC ) for crop straw, fuelwood, and coal are 550.7 ± 397.9, 416.1 ± 249.5, and 361.9 ± 308.0 mg/kg, respectively, which are among the EF IVOC of gasoline vehicle, diesel vehicle, non-road machinery, and heavy fuel oil vessel, and are significantly affected by fuel, stove, and combustion efficiency. The percentages of normal alkanes ( n -alkanes), branched alkanes ( b -alkanes), polycyclic aromatic hydrocarbons (PAHs), and unresolved complex mixture from RSFC are 3.5 ± 1.6, 8.0 ± 3.7, 17.6 ± 6.7, and 70.9 ± 8.1%, respectively, and the compositions are featured by lower b-alkanes and higher PAHs than those of vehicle sources. The proportions of some individual n-alkanes and PAHs (such as n -C 12 - n -C 15 , naphthalene, and its alkyl substituents) can be used as indicators to differentiate RSFC from vehicle sources, while methoxyphenols can be used to distinguish biomass burning from coal combustion. Based on China's energy statistics, the total IVOC emissions from RSFC in 2014 were 175.9 Gg. These data will help to update the IVOC emission inventory and improve the estimates of SOA production in China.

Indoor biomass burning produces large amounts of small particles and hazardous contaminants leading to severe air pollution and potentially high health risks associated with inhalation exposure. Personal samplers provide more accurate estimates of inhalation exposure. In this study, inhalation exposure to size-segregated particles and particulate polycyclic aromatic hydrocarbons (PAHs) for the biomass user was studied by deploying personal samplers. The study found that daily PM 2.5 inhalation exposure level was as high as 121 ± 96 μg/m 3 , and over 84% was finer PM 1.0 . For PAHs, the exposure level was 113 ± 188 ng/m 3 , with over 77% in PM 1.0 . High molecular weight PAHs with larger toxic potentials enriched in smaller particles resulting in much high risks associated with PAHs inhalation exposure. Indoor exposure contributed to ~80% of the total inhalation exposure as a result of high indoor air pollution and longer residence spent indoor. The highest exposure risk was found for the male smoker who conducted cooking activities at home., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Indoor biomass burning is a major contributor to the emission of PAHs (polycyclic aromatic hydrocarbons) in China. To date, estimates of PAH emissions from the burning of biomass have involved considerable uncertainty, mostly from the lack of real-world measurements of emission factors. In this study, we conducted a comprehensive evaluation on PAH emissions from biomass burning in real-world cooking stoves in three Chinese provinces. PAH emission factors, in both particle- and gas-phase, from 11 fuel-stove combinations were measured and the provincial emissions were estimated based on the measured emission factors and fuel consumption. The measured PAH 28 emission factors (including 16 US EPA priority PAHs and 12 non-priority PAHs) ranged from 42 mg/kg to 370 mg/kg, with an order of magnitude difference, which was mostly affected by fuel type. The emission factors measured in this study were generally higher than those reported in laboratory studies and were comparable with field studies. The gas-particle distribution indicated that the absorption of PAHs by organic carbon in particulate matter (PM) was the dominant sorption mechanism in gas-particle distribution. The composition profile was different from previous studies, especially for non-priority PAHs, which are highly toxic and should be given more attention. Following the disparities in composition profiles, our study suggests that source apportionment based on single- or multi-diagnostic ratios may lead to large bias and uncertainties. It appears that the toxicity potential of PAHs in northern China emitted from combustion of crop residues is greater than that in southern China where PAHs are mainly emitted from wood combustion., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Emissions of polycyclic aromatic hydrocarbons (PAHs) in China remain at a high level compared to those in developed countries. The Yangtze River Delta (YRD) is an economic and industrial center in China with an extremely large population. The potentially high emissions and excess cancer risk from human exposure in this region cannot be neglected. This study applied a multimedia model to estimate the concentrations of 16 US EPA priority PAHs in the environment in the YRD with a well-developed PAH-emission inventory for 2014. The model predicted that the average concentrations of ΣPAHs were 274 ng/m 3 in the air, 255 ng/g in the soil, 15 ng/g in vegetation, 147 ng/L in freshwater and 144 ng/g in sediment, as well as 99 ng/L and 80 ng/g in seawater and sediment, respectively. Soil is the PAH sink in this region, and the net flux of the total PAHs is always from air to soil for each isomer. A deterministic assessment observed that the ELCR (excess lifetime cancer risk) ranged from 2.5 × 10 -6 to 3.0 × 10 -5 for exposure by air inhalation and from 3.5 × 10 -7 to 7.9 × 10 -6 for exposure by soil ingestion. The probabilistic results did not find any probability of ELCR >10 -4 by exposure via soil ingestion in the YRD. The probabilistic ELCR induced by inhalation exposure varied from 8.1 × 10 -7 to 3.1 × 10 -4 in the YRD. This study provided a comprehensive overview of PAHs occurrence in natural environments and of the relevant human health risks. The information presented in this study could help authorities to enact a strategy regarding emission reduction and pollution control relevant to PAHs., Capsule: Multimedia modeling predicted distributions and compositions of PAHs in different environmental compartments, and deterministic and probabilistic ELCRs induced by air inhalation and soil ingestion were also provided., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Under great efforts in fighting against serious haze problem of China since 2013, decreasing of air pollutants especially for fine particles (PM 2.5 ) has been revealed for several key regions. This study tried to answer whether the reduction of PM 2.5 -bound polycyclic aromatic hydrocarbons (PAHs) was coincident with PM 2.5 because of long-term pollution control measures (PCM), and to assess source-oriented health risks associated with inhalation exposure to PAHs. Field measurements were carried out before and after the publishing of local air pollution protection plan for Nanjing, a mega-city in east China. Results indicated that the air quality was substantially improving, with a significant reduction in annual average PM 2.5 by 34%, and moreover, PM 2.5 -bound PAHs significantly reduced by 63% (p < 0.001). The remarkable reduction was mainly attributable to the change of emission sources, compared to the influence of atmospheric circulation patterns, surface meteorological conditions, and atmospheric chemical reaction. Four PAHs sources including coal combustion (CC), petroleum and oil burning (PO), wood burning (WB) and vehicle emission (VE) were identified. On an annual basis, contributions to ambient PM 2.5 -PAHs from WB, PO, CC and VE sources in the period before the action of control measures were 2.26, 2.20, 1.96 and 5.62 ng m -3 , respectively. They reduced to 1.09, 0.37, 1.31 and 1.77 ng m -3 for the four source types, with the reduction percentages as 51, 83, 33 and 68%, respectively. The estimated reduction in lifetime lung cancer risk was around 61%. The study that firstly assessed the health effects of PAHs reduction as a co-benefit raised by air PCM sustained for a long period is believed to be applicable and referential for other mega-cities around the world for assessing the benefits of PCM., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) in agricultural soils, eastern China, were studied through a collection of surface samples at 109 sites. The study covered US EPA priority pollutants but also several non-priority isomers including some dibenzopyrenes which are expected to have higher toxic potentials. The total PAH concentrations varied extensively from 8.8 to 3880 μg/kg, with a geometric mean of 158 μg/kg. There were significant differences in both the concentrations and composition profiles between the south and the north regions. The overall geographical distribution pattern was strongly influenced by both the per capita gross domestic product and soil organic carbon (SOC) content. The former is an indicator of anthropogenic emissions while soil SOC content is associated with the accumulative capacities of the soils. The sequestration mechanism is an important process controlling fates of PAHs in agricultural soil.

Sixteen U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) and eleven non-priority isomers including some dibenzopyrenes were analyzed to evaluate health risk attributable to inhalation exposure to ambient PAHs and contributions of the non-priority PAHs in a megacity Nanjing, east China. The annual average mass concentration of the total 16 EPA priority PAHs in air was 51.1 ± 29.8 ng/m 3 , comprising up to 93% of the mass concentration of all 27 PAHs, however, the estimated Incremental Lifetime Cancer Risk (ILCR) due to inhalation exposure would be underestimated by 63% on average if only accounting the 16 EPA priority PAHs. The risk would be underestimated by 13% if only particulate PAHs were considered, though gaseous PAHs made up to about 70% of the total mass concentration. During the last fifteen years, ambient Benzo[a]pyrene decreased significantly in the city which was consistent with the declining trend of PAHs emissions. Source contributions to the estimated ILCR were much different from the contributions for the total mass concentration, calling for the introduce of important source-oriented risk assessments. Emissions from gasoline vehicles contributed to 12% of the total mass concentration of 27 PAHs analyzed, but regarding relative contributions to the overall health risk, gasoline vehicle emissions contributed 45% of the calculated ILCR. Dibenzopyrenes were a group of non-priority isomers largely contributing to the calculated ILCR, and vehicle emissions were probably important sources of these high molecular weight isomers. Ambient dibenzo[a,l]pyrene positively correlated with the priority PAH Benzo[g,h,i]perylene. The study indicates that inclusion of non-priority PAHs could be valuable for both PAH source apportionment and health risk assessment., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are an important class of water pollutants because of their known ecological and human toxicity. Electrocoagulation (EC) is a promising technology for mitigating industrial wastewater pollution, but the removal and transformation of PAHs during EC treatment has not yet been understood. Therefore, a paper-making wastewater effluent (PMWW) was employed in this study to investigate the relationship between PAHs' removal and transformation during EC treatment. The results show that 86% of PAHs were effectively removed not only by the electro-oxidation reactions, but also by adsorption onto Fe hydroxide flocs. The removal and transformation of PAHs were related to the number of rings in their structures. Some PAHs composed of two aromatic rings (e.g., naphthaline and dimethylnaphthalene) were produced from humic acid-like and fulvic acid-like organics in PMWW, while PAHs with three to four rings were degraded, thus being removed efficiently. Therefore, PAH transformation during EC treatment exerted double-sided effects on the removal of PAHs; the net effect appeared to be positive. Overall, this study revealed the existence and importance of PAH transformation during EC treatment and provided useful guidance for pulp and paper mills to improve the design and operation of wastewater treatment facilities., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Residential solid fuels are widely consumed in rural China, contributing to severe household air pollution for many products of incomplete combustion, such as polycyclic aromatic hydrocarbons (PAHs) and their polar derivatives. In this study, concentrations of nitrated and oxygenated PAH derivatives (nPAHs and oPAHs) for household and personal air were measured and analyzed for influencing factors like smoking and cooking energy type. Concentrations of nPAHs and oPAHs in kitchens were higher than those in living rooms and in outdoor air. Exposure levels measured by personal samplers were lower than levels in indoor air, but higher than outdoor air levels. With increasing molecular weight, individual compounds tended to be more commonly partitioned to particulate matter (PM); moreover, higher molecular weight nPAHs and oPAHs were preferentially found in finer particles, suggesting a potential for increased health risks. Smoking behavior raised the concentrations of nPAHs and oPAHs in personal air significantly. People who cooked food also had higher personal exposures. Cooking and smoking have a significant interaction effect on personal exposure. Concentrations in kitchens and personal exposure to nPAHs and oPAHs for households using wood and peat were significantly higher than for those using electricity and liquid petroleum gas (LPG)., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Polycyclic aromatic hydrocarbons (PAHs) derivatives like nitrated and oxygenated PAHs are of growing concerns because of considerably higher toxicity and important roles during atmospheric chemical reactions. Residential solid fuel combustion is likely to be one large primary source of these pollutants in developing countries. In this study, inhalation exposure to nitrated and oxygenated PAH derivatives was evaluated among rural residents using carried samplers. The exposure levels of individual nitrated PAHs ranged from 4.04 (9-nitrated phenanthrene) to 89.8 (9-nitrated anthracene) pg/m(3), and of oxy-PAHs were 0.570 (benzo[a]anthracene-7, 12-dione) to 7.99 (Benzanthrone) ng/m(3), generally higher in wood user than that in anthracite user. A majority of derivatives in particle presented in PM2.5 (80% for nitrated naphthalene and over 90% for other targets) and even fine PM1.0. Mass fractions of PAH derivatives in fine and ultra-fine particles were significantly higher than the fractions of corresponding parent PAHs, indicating more adverse health outcomes induced by these derivatives. The inhalation exposure levels for residents adopting wood gasifier burners was significantly lower than the documented results for those burning wood in typical built-in brick stoves, and comparable to those using LPG and electricity, which provided vital information for clean stove development and intervention programs., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are a group of pollutants of widespread concerns. Gaseous and size-segregated particulate-phase PAHs were collected in indoor and outdoor air in rural households. Personal exposure was measured and compared to the ingestion exposure. The average concentrations of 28 parent PAHs and benzo(a)pyrene (BaP) were 9000 ± 8390 and 131 ± 236 ng/m(3) for kitchen, 2590 ± 2270 and 43 ± 95 ng/m(3) for living room, and 2800 ± 3890 and 1.6 ± 0.7 ng/m(3) for outdoor air, respectively. The mass percent of high molecular weight (HMW) compounds with 5-6 rings contributed 1.3% to total 28 parent PAHs. Relatively higher fractions of HMW PAHs were found in indoor air compared to outdoor air. Majorities of particle-bound PAHs were found in the finest PM0.25 , and the highest levels of fine PM0.25 -bound PAHs were in the kitchen using peat and wood as energy sources. The 24-h personal PAH exposure concentration was 2100 ± 1300 ng/m(3) . Considering energies, exposures to those using wood were the highest. The PAH inhalation exposure comprised up to about 30% in total PAH exposure through food ingestion and inhalation, and the population attributable fraction (PAF) for lung cancer in the region was 0.85%. The risks for inhaled and ingested intakes of PAHs were 1.0 × 10(-5) and 1.1 × 10(-5) , respectively., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Dietary intake is one of the major exposure pathways of polycyclic aromatic hydrocarbons (PAHs), especially in Chinese people because foods are often prepared with grilling and/or frying that would produce high levels of PAHs. In this paper, we assessed daily dietary intakes (DDI) of PAHs, using a "duplicate plate method", among 100 Chinese urban residents. The DDI of benzo(a)pyrene ranged from 0.06 µg per day to 13.5 µg per day with a median of 0.69 µg per day, varying largely across subjects. The median Incremental Lifetime Cancer Risk (ILCR) attributable to PAH dietary intake was 6.65 × 10(-5) (4.41 × 10(-5) to 1.02 × 10(-4) as inter-quartile range). The contribution of several high-PAH containing foods like barbecued, smoked or deep-fried meats to the overall DDIs was about 13%. The use of raw foods may underestimate dietary intake of PAHs and associated exposure risk considerably. Results from foods sampled in different seasons suggested that seasonal variability within an individual may contribute notably to overall variability measured in a population and more future studies with longer-term investigation on food ingestion and pollutant exposure are needed. The study indicates that measuring actually consumed foods is more appropriate for dietary intake exposure assessment, and intra-individual variance should be taken into account during study design and data analysis., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Application of biochar-based fertilizers is increasingly being considered for its potential agronomic and environmental benefits. However, biochar may contain residues of polycyclic aromatic hydrocarbons (PAHs) as a result of its production by pyrolysis. The strong adsorption of PAHs to biochar makes extraction and analysis of biochar-based fertilizers difficult. This study optimizes the extraction of PAHs in biochar-based fertilizer samples by using an ultrasonic bath for quantification by gas chromatography-mass spectrometry. Among 12 solvents, acetone-cyclohexane (1:1) mixture was selected as the optimum solvent for extraction. Three variables affecting the extraction were studied by Box-Behnken design. The optimum conditions were 57 °C extraction temperature, 81 min extraction time, and two extraction cycles, which were validated by assessing the linearity of analysis, LOD, LOQ, recovery, and levels of PAHs in real biochar-based fertilizer samples. Results revealed that the 16 U.S. EPA PAHs had good linearity, with squared correlation coefficients greater than 0.99. LODs were low, ranging from 2.2 ng g(-1) (acenaphthene) to 23.55 ng g(-1) (indeno[1,2,3-cd]perylene), and LOQs varied from 7.51 ng g(-1) to 78.49 ng g(-1). The recoveries of 16 individual PAHs from the three biochar-based fertilizer samples were 81.8-109.4 %. Graphical Abstract Use of RSM to optimize UAE for extraction of the PAHs in biochar-based fertilizer.

There is wide concern about polycyclic aromatic hydrocarbons (PAHs) because of their carcinogenic and mutagenic potential. The coking industry is an important source of PAHs. In this study, 36 arable soil samples, a sensitive medium from the perspective of food safety and health, were collected from one of the largest coke production bases in China. The concentration of total 21 PAHs ranged from 294 to 1665 ng g(-1), with a mean of 822±355 ng g(-1). Approximately 60% of the soil samples were heavily polluted with the level higher than 600 ng g(-1). Particularly high abundances of high molecular weight PAHs were found, and the calculated BaPeq was as high as 54.3 ng g(-1). Soil PAH levels were positively correlated with soil organic matter content. The soil PAHs were from complex mixture sources, and high-temperature pyrogenic sources were most likely responsible for the heavy PAH contamination. Effective control strategies and probable remediation approaches should be proposed to improve soil quality., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The agronomic benefit of biochar has attracted widespread attention to biochar-based fertilizers. However, the inevitable presence of polycyclic aromatic hydrocarbons in biochar is a matter of concern because of the health and ecological risks of these compounds. The strong adsorption of polycyclic aromatic hydrocarbons to biochar complicates their analysis and extraction from biochar-based fertilizers. In this study, we optimized and validated a method for determining the 16 priority polycyclic aromatic hydrocarbons in biochar-based fertilizers. Results showed that accelerated solvent extraction exhibited high extraction efficiency. Based on a Box-Behnken design with a triplicate central point, accelerated solvent extraction was used under the following optimal operational conditions: extraction temperature of 78°C, extraction time of 17 min, and two static cycles. The optimized method was validated by assessing the linearity of analysis, limit of detection, limit of quantification, recovery, and application to real samples. The results showed that the 16 polycyclic aromatic hydrocarbons exhibited good linearity, with a correlation coefficient of 0.996. The limits of detection varied between 0.001 (phenanthrene) and 0.021 mg/g (benzo[ghi]perylene), and the limits of quantification varied between 0.004 (phenanthrene) and 0.069 mg/g (benzo[ghi]perylene). The relative recoveries of the 16 polycyclic aromatic hydrocarbons were 70.26-102.99%., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Twelve nitro-PAHs (nPAHs) and four oxy-PAHs (oPAHs) were measured in air samples for 12 months at 18 sites in urban settings, rural villages, or rural fields in northern China. The nPAH concentrations were higher in urban areas (1.3 ± 1.3 ng/m(3)), and nPAH/parent PAH ratios were higher (suggesting important contributions from motor vehicles and secondary formation) in urban sites than in rural villages. oPAHs are primarily emitted from solid fuel combustion and motor vehicles, and similar oPAH concentrations were found in urban areas (23 ± 20 ng/m(3)) and rural villages (29 ± 24 ng/m(3)). The high numbers of motor vehicles in Beijing and intensive industrial activity in Taiyuan and Dezhou caused higher nPAH concentrations. No spatial trend in oPAH concentrations was found in the rural villages, because similar oPAH mixtures are emitted from solild fuel combustion. The nPAH and oPAH concentrations were higher in the winter, and correlated with residential energy consumption and precipitation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Smoked meat is widely consumed in many areas, particularly in rural southwest China. High concentrations of polycyclic aromatic hydrocarbons (PAHs) in smoked meat could lead to adverse dietary exposure and health risks. In this study, 27 parent PAHs (pPAHs), 12 nitrated PAHs (nPAHs), and 4 oxygenated PAHs (oPAHs) were measured in coal- and wood-smoked meats. The median concentrations of pPAHs, nPAHs, and oPAHs were as high as 1.66 × 10(3), 4.29, and 20.5 ng/g in the coal-smoked meat and 2.54 × 10(3), 7.32, and 9.26 ng/g in the wood-smoked meat, respectively. Based on the relative potency factors of individual PAHs, the calculated toxic equivalent (TEQ) values of all pPAHs were 22.1 and 75.1 ng TEQ/g for the wood- and coal-smoked meats, respectively. The highest concentrations of PAHs can be found in the surface layer of skin and decrease exponentially with depth. Surface PAH concentrations correlated with concentrations of PAHs in household air and with the concentration in emission exhaust. Migration of PAHs from surface to interior portions of meat is faster in lean than in fat or skin, and oPAHs and pPAHs can penetrate deeper than pPAHs. The penetration ability of PAHs is negatively correlated with the molecular weight.

Personal inhalation exposure samples were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) for 126 selected volunteers during heating and non-heating seasons in a typical northern Chinese city, Taiyuan. Measured personal PAH exposure levels for the urban residents in the heating and non-heating seasons were 690 (540-1051) and 404 (266-544) ng/m(3) , respectively, while, for the rural residents, they were 770 (504-1071) and 312 (201-412) ng/m(3) , respectively. Thus, rural residents are exposed to lower PAH contamination in comparison with the urban residents in the non-heating seasons. In the heating season, personal PAH inhalation exposure levels were comparable between the urban and rural residents, in part owing to the large rate of residential solid fuel consumption in the rural area for household cooking and heating. The estimated incremental lifetime cancer risks (ILCR) due to PAH exposure in Taiyuan were 3.36 × 10(-5) and 2.39 × 10(-5) for the rural and urban residents, respectively, significantly higher than the literature-reported national average level, suggesting an urgent need of PAH pollution control to protect human health., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Air pollution in rural China has often been ignored, especially for the less developed west China. Atmospheric polycyclic aromatic hydrocarbons (PAHs) were measured monthly at 11 rural sites (5 rural villages and 6 rural fields) together with 7 urban stations in northern China between April 2010 and March 2011. PAH concentrations at rural village sites were similar to those in urban areas and significantly higher than those in rural fields, indicating severe contamination in rural villages. PAH concentrations in the west were similar to those in the more developed North China Plain, and higher than those along the coast. Such a geographical distribution is mainly caused by the differences in residential energy consumption and meteorological conditions, which can explain approximately 48% of the total variation in PAH concentrations. With heavy dependence on biofuel combustion for heating, seasonality in rural areas is more profound than that in urban areas., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Daily dietary and inhalation exposures to 16 parent polycyclic aromatic hydrocarbons (PAHs) and urinary excretion of 13 monohydroxy metabolites (OHPAHs) were monitored for 12 non-smoking university students in Beijing, China, during a controlled feeding experiment. The relationship between the urinary excretion of OHPAHs and the uptake of PAHs was investigated. The results suggest severe exposure of the subjects to PAHs via both dietary and inhalation pathways. Large increase of most urinary OHPAHs occurred after the ingestion of lamb kabob. Higher concentrations of OHPAHs were observed for female subjects, with the intakes of parent PAHs lower than those by males, likely due to the gender differences in metabolism. It appears that besides 1-PYR, metabolites of PHE could also be used as biomarkers to indicate the short-term dietary exposure to PAHs and urinary 3-BaA may serve as the biomarker for inhalation intake of high molecular weight PAHs., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Field measurements were conducted to measure emission factors of particulate matter (EFPM), organic carbon (EFOC), elemental carbon (EFEC), 28 parent polycyclic aromatic hydrocarbons (EF28pPAHs), and 4 oxygenated PAHs (EF4oPAHs) for four types of crop straws burned in two stoves with similar structure but different ages. The average EFPM, EFOC, EFEC, EF28pPAHs, and EF4oPAHs were 9.1 ± 5.7 (1.8-22 as range), 2.6 ± 2.9 (0.30-12), 1.1 ± 1.2 (0.086-5.5), 0.26 ± 0.19 (0.076-0.96), 0.011 ± 0.14 (1.3 × 10(-4) - 0.063) g/kg, respectively. Much high EF28pPAHs was observed in field compared with the laboratory derived EFs and significant difference in EF28pPAHs was identified among different crop residues, indicating considerable underestimation when laboratory derived EFs were used in the inventory. The field measured EFPM, EFOC, and EFEC were significantly affected by stove age and the EFs of carbonaceous particles for the 15-year old stove were approximately 2.5 times of those for the 1-year old stove., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Emission characterization of polycyclic aromatic hydrocarbons (PAHs) from residential combustion of crop residues, woody material, coal, and biomass pellets in domestic stoves in rural China are compared in term of emission factors (EFs), influencing factors, composition profiles, isomer ratios and phase distributions. The EFs of PAHs vary by 2 orders of magnitude among fuel types suggesting that a detailed fuel categorization is useful in the development of an emission inventory and potential in emission abatement of PAHs by replacing dirty fuels with relatively cleaner ones. The influence of fuel moisture in biomass burning is nonlinear. Biofuels with very low moisture display relatively high emissions as do fuels with very high moisture. Bituminous coals and brushwood yield relatively large fractions of high molecular PAHs. The emission factor of benzo(a)pyrene equivalent quantity for raw bituminous coal is as high as 52 mg/kg, which is 1-2 orders of magnitude higher than the other fuels. For source diagnosis, high molecular weight isomers are more informative than low molecular weight ones and multiple ratios could be used together whenever possible.

Emission factors (EFs) of parent polycyclic aromatic hydrocarbons (pPAHs), nitrated PAHs (nPAHs), and oxygenated PAHs (oPAHs) were measured for indoor corn straw burned in a brick cooking stove under different burning conditions. The EFs of total 28 pPAHs, 6 nPAHs and 4 oPAHs were (7.9 +/- 3.4), (6.5 +/- 1.6) x 10(-3), and (6.1 +/- 1.4) x 10(-1) mg/kg, respectively. Fuel charge size had insignificant influence on the pollutant emissions. Measured EFs increased significantly in a fast burning due to the oxygen deficient atmosphere formed in the stove chamber. In both restricted and enhanced air supply conditions, the EFs of pPAHs, nPAHs and oPAHs were significantly higher than those measured in normal burning conditions. Though EFs varied among different burning conditions, the composition profiles and calculated isomer ratios were similar, without significant differences. The results from the stepwise regression model showed that fuel burning rate, air supply amount, and modified combustion efficiency were the three most significant influencing factors, explaining 72%-85% of the total variations.

Controlled combustion experiments were conducted to investigate the influence of fuel charge size, moisture, air ventilation and feeding rate on the emission factors (EFs) of carbonaceous particulate matter, parent polycyclic aromatic hydrocarbons (pPAHs) and their derivatives from residential wood combustion in a typical brick cooking stove. Measured EFs were found to be independent of fuel charge size, but increased with increasing fuel moisture. Pollution emissions from the normal burning under an adequate air supply condition were the lowest for most pollutants, while more pollutants were emitted when an oxygen deficient atmosphere was formed in the stove chamber during fast burning. The impacts of these factors on the size distribution of emitted particles was also studied. Modified combustion efficiency and the four investigated factors explained 68%, 72%, and 64% of total variations in EFs of PM, organic carbon, and oxygenated PAHs, respectively, but only 36%, 38% and 42% of the total variations in EFs of elemental carbon, pPAHs and nitro-PAHs, respectively.

Global atmospheric emissions of 16 polycyclic aromatic hydrocarbons (PAHs) from 69 major sources were estimated for a period from 1960 to 2030. Regression models and a technology split method were used to estimate country and time specific emission factors, resulting in a new estimate of PAH emission factor variation among different countries and over time. PAH emissions in 2007 were spatially resolved to 0.1° × 0.1° grids based on a newly developed global high-resolution fuel combustion inventory (PKU-FUEL-2007). The global total annual atmospheric emission of 16 PAHs in 2007 was 504 Gg (331-818 Gg, as interquartile range), with residential/commercial biomass burning (60.5%), open-field biomass burning (agricultural waste burning, deforestation, and wildfire, 13.6%), and petroleum consumption by on-road motor vehicles (12.8%) as the major sources. South (87 Gg), East (111 Gg), and Southeast Asia (52 Gg) were the regions with the highest PAH emission densities, contributing half of the global total PAH emissions. Among the global total PAH emissions, 6.19% of the emissions were in the form of high molecular weight carcinogenic compounds and the percentage of the carcinogenic PAHs was higher in developing countries (6.22%) than in developed countries (5.73%), due to the differences in energy structures and the disparities of technology. The potential health impact of the PAH emissions was greatest in the parts of the world with high anthropogenic PAH emissions, because of the overlap of the high emissions and high population densities. Global total PAH emissions peaked at 592 Gg in 1995 and declined gradually to 499 Gg in 2008. Total PAH emissions from developed countries peaked at 122 Gg in the early 1970s and decreased to 38 Gg in 2008. Simulation of PAH emissions from 2009 to 2030 revealed that PAH emissions in developed and developing countries would decrease by 46-71% and 48-64%, respectively, based on the six IPCC SRES scenarios.

Air pollutants from residential solid fuel combustion are attracting growing public concern. Field measured emission factors (EFs) of various air pollutants for solid fuels are close to the reality and urgently needed for better emission estimations. In this study, emission factors of particulate matter (PM), organic carbon (OC), elemental carbon (EC), and various polycyclic aromatic hydrocarbons (PAHs) from residential combustions of coal briquette, coal cake, and wood were measured in rural Heshun County, China. The measured EFs of PM, OC, and EC were 8.1-8.5, 2.2-3.6, 0.91-1.6 g/kg for the wood burnt in a simple metal stove, 0.54-0.64, 0.13-0.14, 0.040-0.0041 g/kg for the briquette burned in an improved stove with a chimney, and 3.2-8.5, 0.38-0.58, 0.022-0.052 g/kg for the homemade coal cake combusted in a brick stove with a flue, respectively. EFs of 28 parent PAHs, 4 oxygenated PAHs, and 9 nitro-PAHs were 182-297, 7.8-10, 0.14-0.55 mg/kg for the wood, 14-16, 1.7-2.6, 0.64-0.83 mg/kg for the briquette, and 168-223, 4.7-9.5, 0.16-2.4 mg/kg for the coal cake, respectively. Emissions from the wood and coal cake combustions were much higher than those for the coal briquette, especially true for high molecular weight PAHs. Most EFs measured in the field were higher than those measured in stove combustions under laboratory conditions.

The concentration and composition of PAHs emitted from biomass cooking fuel were characterized in a rural non-smoking household in northern China. Twenty-two parent PAHs (pPAHs), 12 nitro-PAHs (nPAHs), and 4 oxy-PAHs (oPAHs) were measured in the kitchen, bedroom, and outdoors during both summer and winter. The most severe contamination occurred in the kitchen in the winter, where the daily mean concentrations of pPAHs, nPAHs, and oPAHs were 7500 ± 4100, 38 ± 29, and 8400 ± 9200 ng/m(3), respectively. Our results suggest that the nPAHs were largely from secondary formation in ambient air while oPAHs were either from primary emission of biomass burning or secondary formation from pPAHs in the kitchen. The daily mean benzo(a)pyrene equivalent exposure concentration was as high as 200 ± 160 ng/m(3) in the winter for the housewife who did the cooking compared to 59 ± 37 ng/m(3) for the control group that did not cook., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Biomass pellets are emerging as a cleaner alternative to traditional biomass fuels. The potential benefits of using biomass pellets include improving energy utilization efficiency and reducing emissions of air pollutants. To assess the environmental, climate, and health significance of replacing traditional fuels with biomass pellets, it is critical to measure the emission factors (EFs) of various pollutants from pellet burning. However, only a few field measurements have been conducted on the emissions of carbon monoxide (CO), particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs) from the combustion of pellets. In this study, pine wood and corn straw pellets were burned in a pellet burner (2.6 kW), and the EFs of CO, organic carbon, elemental carbon, PM, and PAHs (EF(CO), EF(OC), EF(EC), EF(PM), and EF(PAH)) were determined. The average EF(CO), EF(OC), EF(EC), and EF(PM) were 1520 ± 1170, 8.68 ± 11.4, 11.2 ± 8.7, and 188 ± 87 mg/MJ for corn straw pellets and 266 ± 137, 5.74 ± 7.17, 2.02 ± 1.57, and 71.0 ± 54.0 mg/MJ for pine wood pellets, respectively. Total carbonaceous carbon constituted 8 to 14% of the PM mass emitted. The measured values of EF(PAH) for the two pellets were 1.02 ± 0.64 and 0.506 ± 0.360 mg/MJ, respectively. The secondary side air supply in the pellet burner did not change the EFs of most pollutants significantly (p > 0.05). The only exceptions were EF(OC) and EF(PM) for pine wood pellets because of reduced combustion temperatures with the increased air supply. In comparison with EFs for the raw pine wood and corn straw, EF(CO), EF(OC), EF(EC), and EF(PM) for pellets were significantly lower than those for raw fuels (p < 0.05). However, the differences in EF(PAH) were not significant (p > 0.05). Based on the measured EFs and thermal efficiencies, it was estimated that 95, 98, 98, 88, and 71% reductions in the total emissions of CO, OC, EC, PM, and PAHs could be achieved by replacing the raw biomass fuels combusted in traditional cooking stoves with pellets burned in modern pellet burners.

Indoor solid fuel combustion is a dominant source of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) and the latter are believed to be more toxic than the former. However, there is limited quantitative information on the emissions of OPAHs from solid fuel combustion. In this study, emission factors of OPAHs (EF(OPAH)) for nine commonly used crop residues and five coals burnt in typical residential stoves widely used in rural China were measured under simulated kitchen conditions. The total EF(OPAH) ranged from 2.8 ± 0.2 to 8.1 ± 2.2 mg/kg for tested crop residues and from 0.043 to 71 mg/kg for various coals and 9-fluorenone was the most abundant specie. The EF(OPAH) for indoor crop residue burning were 1-2 orders of magnitude higher than those from open burning, and they were affected by fuel properties and combustion conditions, like moisture and combustion efficiency. For both crop residues and coals, significantly positive correlations were found between EFs for the individual OPAHs and the parent PAHs. An oxygenation rate, R(o), was defined as the ratio of the EFs between the oxygenated and parent PAH species to describe the formation potential of OPAHs. For the studied OPAH/PAH pairs, mean R(o) values were 0.16-0.89 for crop residues and 0.03-0.25 for coals. R(o) for crop residues burned in the cooking stove were much higher than those for open burning and much lower than those in ambient air, indicating the influence of secondary formation of OPAH and loss of PAHs. In comparison with parent PAHs, OPAHs showed a higher tendency to be associated with particulate matter (PM), especially fine PM, and the dominate size ranges were 0.7-2.1 μm for crop residues and high caking coals and <0.7 μm for the tested low caking briquettes.

Air-soil exchange is an important process governing the fate of polycyclic aromatic hydrocarbons (PAHs). A novel passive air sampler was designed and tested for measuring the vertical concentration profile of 4 low molecular weight PAHs in gaseous phase (PAH(LMW4)) in near soil surface air. Air at various heights from 5 to 520 mm above the ground was sampled by polyurethane foam disks held in down-faced cartridges. The samplers were tested at three sites: A: an extremely contaminated site, B: a site near A, and C: a background site on a university campus. Vertical concentration gradients were revealed for PAH(LMW4) within a thin layer close to soil surface at the three sites. PAH concentrations either decreased (Site A) or increased (Sites B and C) with height, suggesting either deposition to or evaporation from soils. The sampler is a useful tool for investigating air-soil exchange of gaseous phase semi-volatile organic chemicals., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Indoor combustion of crop residues for cooking or heating is one of the most important emission sources of polycyclic aromatic hydrocarbons (PAHs) in developing countries. However, data on PAH emission factors (EFs) for burning crop residues indoor, particularly those measured in the field, were scarce, leading to large uncertainties in the emission inventories. In this study, EFs of PAHs for nine commonly used crop residues burned in a typical Chinese rural cooking stove were measured in a simulated kitchen. The measured EFs of total PAHs averaged at 63 ± 37 mg/kg, ranging from 27 to 142 mg/kg, which were higher than those measured in chamber experiments, implying that the laboratory experiment-based emission and risk assessment should be carefully reviewed. EFs of gaseous and particulate phase PAHs were 27 ± 13 and 35 ± 23 mg/kg, respectively. Composition profiles and isomer ratios of emitted PAHs were characterized. Stepwise regressions found that modified combustion efficiency and fuel moisture were the most important factors affecting the emissions. There was 80 ± 6% of PAHs associated with PM2.5, and the mass percentage of PAHs in fine particles increased as the molecular weight increased. For freshly emitted PAHs, absorption into organic carbon, rather than adsorption, dominated the gas-particle partitioning.

Eighty eight surface soil samples were collected from the Qinghai-Tibetan Plateau (QTP) for determination of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs), including dichlorodiphenyltrichloroethane and metabolites (DDXs) and hexachlorocyclohexane isomers (HCHs). The measured concentrations were 51.8 ± 38.5 ng g(-1), 0.329 ± 0.818 ng g(-1), and 0.467 ± 0.741 ng g(-1) as means and standard deviations of PAHs, DDXs, and HCHs, respectively, which were 1-2 orders of magnitude lower than those reported for eastern China. Significant differences were also revealed among four sub-areas within QTP. PAHs detected in the samples from the remote sub-areas of T'ang-ku-la/Hoh Xil Mountains and along the Qinghai-Tibet highway in the west and northwest of QTP were 1 order of magnitude lower than those from Lhasa and east Qinghai. The differences in soil OCPs among the sub-areas were 2-7 times. Soil PAHs were significantly correlated with emission density and soil organic carbon content (SOC), while OCPs were correlated significantly with the population density and SOC. Based on the calculated backward air mass trajectories and geographical distributions of emission and population, it was revealed that PAHs and OCPs accumulated in the soils in the west and northwest QTP were primarily from long-range transport and may represent the background levels of East Asia. This part of QTP can also serve as an important receptor area for regional or even global long-range transport study. The elevated concentrations of PAHs and OCPs in Lhasa and east Qinghai were mainly from local sources, while PAHs from adjacent Lanzhou area also contributed considerably to the accumulation of PAHs in east Qinghai.

Bulk deposition samples were collected in remote, rural village and urban areas of Beijing-Tianjin region, North China in spring, summer, fall and winter from 2007 to 2008. The annually averaged PAHs concentration and deposition flux were 11.81±4.61 μg/g and 5.2±3.89 μg/m2/day respectively. PHE and FLA had the highest deposition flux, accounting for 35.3% and 20.7% of total deposition flux, respectively. More exposure risk from deposition existed in the fall for the local inhabitants. In addition, the PAHs deposition flux in rural villages (3.91 μg/m2/day) and urban areas (8.28 μg/m2/day) was 3.8 and 9.1 times higher than in background area (0.82 μg/m2/day), respectively. This spatial variation of deposition fluxes of PAHs was related to the PAHs emission sources, local population density and air concentration of PAHs, and the PAHs emission sources alone can explain 36%, 49%, 21% and 30% of the spatial variation in spring, summer, fall and winter, respectively., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Five sets of size-fractionated particles were collected in a northern China village in various seasons in order to measure respirable airborne particulates (PM10) and particulate phase polycyclic aromatic hydrocarbons (PAHs) in ambient air. The time-weighted annual mean concentration and standard deviation of PM10 were 358 +/- 107 microg/m3, higher than both the national standard (100 microg/m3) and the levels observed in several contaminated northern Chinese cities. In addition to high levels of PAHs (391 +/- 487 ng/m3), the fraction of higher molecular weight PAHs was higher than most reported in the literature, and the time-weighted annual mean benzo(a)pyrene equivalent concentration was 44.2 +/- 51.4 ng/m3, more than four times the national standard of 10 ng/m3 and 44 times the WHO guideline of 1 ng/m3. Apparently, residents in Donghe suffer from exposure to high levels of both PM10 and particulate phase PAHs. The particle size distribution was centered in the range of Dp < or = 3.3 microm in winter and shifted to the ranges of Dp < or = 2.1 microm and 5.8 microm < Dp < 10 microm in spring and summer respectively. Approximately 90.0% of PAHs were associated with airborne particulates with Dp < or = 2.1 microm.

Actions and interactions between heavy metals (HM)-cadmium, zinc, lead, and polycyclic aromatic hydrocarbons (PAHs)-phenanthrene, fluoranthene, benzo(a)pyrene toward soil urease activity were studied after 7, 14, 21, and 28 days of exposure under controlled conditions. The experimental approach was based on the uniform design. Ten different contamination conditions were studied simultaneously, with 10 concentration levels for each pollutant. Data treatment was essentially based on the multiple regression technique. The results showed that Zn interacted more easily with PAHs than Pb or Cd. On the first 7 days of incubation, zinc alone reduced the urease activity more significantly than any other pollutants and no significant interactions between PAH and HM were observed. From 14 to 21 days of incubation, the interaction between Zn and benzo(a)pyrene decreased the soil urease activity. At 14 days, the interaction between Zn and phenanthrene was antagonistic (less than additive), while at 21 days it was synergistic (more than additive). At 28 days, the interaction between phenanthrene and fluoranthene was synergistic. This study indicated that the combined effect of PAH and HM on soil urease activity depends largely on the incubation time. Uniform design appears to be a good method for investigating the combined effect of PAH and HM.

Actions and interactions of heavy metals (cadmium, zinc and plumbum) and polycyclic aromatic hydrocarbons (PAHs) [phenanthrene, fluoranthene, benzo(a)pyrene] on the soil urease and dehydrogenase activity were studied after 49 days exposure. The experimental approach was based on the uniform design which can cut the experiment time and improve the efficiency of experiments. Data treatment was essentially based on the multiple regression technique. The results showed that the action and interaction between heavy metals and PAHs were strongly dependent on the time of pollution. The dehydrogenase exhibits more sensitive to the combined pollution than urease. The negative interaction between Zn and Cd to hydrogenase activity and the combined stimulatory activity of Phenanthrene and Benzo(a)pyrene (or fluoranthene) to soil enzyme were observed. The interactions between Zn (Cd) and phenanthrene towards urease (dehydrogenase) were positive, and the interaction between Zn and benzo(a)pyrene to urease activity was negative. This study corresponds to exploratory phase in order to reveal interaction effects of heavy metals and PAHs on the soil enzyme and then to set up more in-depth analysis to increase progressively the understanding of the ecotoxicological mechanisms involved.