High-ring Polycyclic Aromatic Hydrocarbons Research Articles

Distribution and transfer rules of polycyclic aromatic hydrocarbons in soil-wheat ecosystems in China.

The translocation and accumulation patterns of polycyclic aromatic hydrocarbons (PAHs) in the soil-crop system have important implications for the fate of PAHs and human health. This study summarized the concentrations of 16 priority PAHs in the soils and various parts of mature winter wheat in China, sourced from a screening of previous literature in English and Chinese databases. The study analyzes the distribution characteristics, transfer patterns, and human health risks of PAHs in sites studied in Shaanxi, Henan, and Shandong provinces. The results showed that the concentrations of Σ16 PAHs in the rhizosphere soil of wheat ranged from 10.30 to 893.68 ng/g, in descending order of Shaanxi > Henan > average > Shandong. In sites with mild to moderate contamination (200 < Σ16 PAHs < 600 ng/g; i.e., Henan and Shaanxi), the concentration of Σ16 PAHs in the roots was higher than that in the stems or the grains, while in contamination-free sites (Σ16 PAHs < 200 ng/g; i.e., Shandong), the highest concentration of Σ16 PAHs was found in the stems. Generally, the concentrations of PAHs increased in the order of roots-stems-grains. The predominant PAHs in each part of wheat were 2- or 3-ring compounds, with five- or six-ring PAHs being more prevalent in wheat from Shanghe, Shandong. The bioaccumulation factors of different wheat parts from Shaanxi and Henan were consistently smaller than 1, and low- and medium-ring (2-4 rings) PAHs had bigger bioconcentration factors than high-ring (5-6 rings) PAHs. However, the accumulation of PAHs in the aboveground parts of wheat was larger than that in the underground parts of the Shandong sites. The linear regression relationship between the octanol-water partition coefficient and root concentration factor (RCF) of PAHs reflected that low and medium-ring PAHs were more easily absorbed by wheat roots than high-ring PAHs in Shaanxi and Henan. Our assessment of the health risks of oral wheat intake in adults and children by the incremental lifetime cancer risk (ILCR) model found a potential carcinogenic risk for both age groups in each province, with higher risks in adults than in children.

Analysis of PAHs content, source and risk assessment in surface sediments from Laizhou Bay and Bohai Bay

To understand the levels of PAHs and ecological risks to the marine environment in Laizhou Bay and Bohai Bay, 33 sediment samples were collected in the region for analysis. PAH concentrations ranged from 98.22 ng·g−1 (dw) to 239.01 ng·g−1 (dw). PAHs in the region are at low to medium pollution levels compared to studies worldwide. Diagnostic ratios and PCA indicate that PAHs are primarily sourced from fuel combustion. PAHs carried into the Bohai Sea by means of river water and sediment are more likely to settle to the seafloor as opposed to diffuse. This results in a slightly higher proportion of low-ring PAHs than high-ring PAHs. Low-ring PAHs accounted for 56 % of the total. Low-ring PAHs are key contributors to ecosystem risk. The SQGs and RQ∑PAHs show that PAHs do not pose a considerable ecological danger within the region.

Insights into the effects of hydrogen peroxide and Fenton oxidation on PAHs removal and indigenous microorganisms in a coking-contaminated soil

Polycyclic aromatic hydrocarbons (PAHs) are typical persistent organic pollutants in the coking-contaminated soil, however, the effects of chemical oxidation on PAHs removal and the responses of indigenous microorganisms in slurry system has not been studied. In this study, the removal efficiency of PAHs and the responses of indigenous microorganisms treated by hydrogen peroxide (H2O2) and Fenton oxidation under different liquid-to-solid (L/S) ratio were investigated. The results showed that the highest removal efficiency of Σ PAHs treated by H2O2 oxidation was at the L/S ratio of 4:1. At such condition, the order of PAHs removal efficiency from high to low was 3-ring PAHs (69.7%–99.9%), followed by high ring PAHs (4-6 rings, 54.5%–95.5%), and 2-ring PAHs (38.1%–52.4%). However, Fenton oxidation had insignificantly increased the removal efficiency of PAHs, partly because the high content of metal cations (i.e., Fe2＋ and Mn2+) in coking contaminated soil. The number of soil microorganisms changed slightly during H2O2 and Fenton oxidation treatments (∼10 8 copies/g), while the bacterial diversity increased significantly. Microbial function analysis suggested that the carbohydrate metabolism, xenobiotics biodegradation and metabolism mainly contributed to the degradation of PAHs. Moreover, the function genes and pathways (i.e., amino sugar metabolism and citrate cycle) that involved in PAHs biodegradation increased, which can further promote the biological degradation of PAHs by indigenous microorganisms.

Occurrence and Release Behavior of PAHs Accumulated in Road Sediment in Urban-Rural Fringe in Beijing, China

ABSTRACT Due to the rapid expansion of cities, the impermeable area has increased. This exacerbated the accumulation of pollutants in road particles and made the road sediment one of the most widely distributed pollution carriers in the urban area. Urban-rural fringe is the frontier of urban expansion and the most dynamic area in the urban region, but less knowledge was available on the pollution status of the region. In this study, the occurrence, release behavior, and environmental risk of polycyclic aromatic hydrocarbons (PAHs) accumulated in road sediment in urban-rural fringe were systematically studied and compared with five other urban functional areas (i.e., commercial area, industrial park, residential area, traffic area, and leisure area) in Beijing, china. The concentration of ∑16PAHs in the road sediment followed in the order of petrol station (2.223 mg/kg)>crossroad (1.506 mg/kg)>main road (0.949 mg/kg)>university gate (0.841 mg/kg)>bus station (0.839 mg/kg). The PAHs concentration in the road sediment with different land use followed in the order of traffic area (3.030 mg/kg)>urban-rural fringe (1.338 mg/kg)>commercial area (0.946 mg/kg)>residential area (0.866 mg/kg)>industrial park (0.673 mg/kg)>leisure area (0.316 mg/kg). The cancer risk in the urban-rural fringe was second only to the traffic area. PAHs with low ring numbers were easier to release into the water, as indicated by that 20–95% nap could be released from the road sediment to runoff. In contrast, high-ring PAHs were more likely to accumulate in the particulate matter as <18.3% of PHE, FLA, and PYR (corresponding to 0.002–0.010 mg/kg) could be released into the water phase, which means that the removal of road sediment plays an important role in reducing pollution. Overall, this study reveals that pollution in the urban-rural fringe cannot be ignored and provides scientific data to support pollution control and risk assessment, especially for urban-rural areas.

Kill two birds with one stone: Ceramisite production using organic contaminated soil

Disposal of organic-contaminated soil through ceramsite production can not only generate ceramsite with acceptable properties but also completely remediate the organic-contaminated soil owing to high treatment temperature. However, the removal mechanism of organic pollutants and the gas-solid phase distribution of the pollutants remain unclear. In this study, coking contaminated soils with high concentrations of polycyclic aromatic hydrocarbons (PAHs) and petroleum hydrocarbon (PHC) were used to prepare ceramsite at 1160 °C. The quality of ceramsite met the required product standard when the disposal ratio of contaminated soil was up to 60%. The concentration of PAHs and PHC in the soil was 57.7 mg kg-1 and 255 mg kg-1. After the experiment, almost no PAHs and PHC were found in the ceramsite. High-ring PAHs were dominant in the flue gas when using model soil spiked with PAHs. Computed tomography scanning indicated that cracks developed in the ceramsite when the temperature was higher than 200 °C. High-temperature in-situ thermal analysis showed that when the temperature was increased to 400 °C, the pollutant from the interior of ceramsite would flow into the flue gas with the released volatile matter. Thermal desorption and degradation of PAHs were the main mechanisms of pollutant removal.

Comparison of atmospheric polycyclic aromatic hydrocarbons (PAHs) over six years at a CAWNET background site in central China: Changes of seasonal variations and potential sources

Total suspended particles (TSP) and gaseous samples were collected by using a high-volume sampler from March 2012 to March 2013 and January 2018 to January 2019 at a background site (Jinsha, JSH) in central China to study the chemical characteristics, seasonal variations, and potential sources of polycyclic aromatic hydrocarbons (PAHs). The average concentrations of ∑15PAHs were 24.55 ± 9.19 ng m−3 in 2012/2013 and 20.98 ± 9.77 ng m−3 in 2018/2019. Low-ring PAHs were more concentrated in gas phase while high-ring PAHs were prone into particle phase. The concentrations of PAHs in the two sampling years were high in winter but low in summer and autumn. The relationships between the gas concentrations of PAHs and temperature indicated that most PAHs were influenced by long-range atmospheric transport (LRAT) in 2012/2013 and in 2018/2019, excluding anthracene (Ant) and pyrene (Pyr) were partially affected by air-surface re-volatilization in 2012/2013. The source of atmospheric PAHs at JSH was similar in 2012/2013 and 2018/2019,which was mainly due to the LRAT of PAHs emitted from biomass/fossil fuel combustion in the northern area of JSH. From 2012/2013 to 2018/2019, there was no significant difference between the concentrations of PAHs in spring and winter, whereas the concentrations of PAHs decreased from 2012/2013 to 2018/2019 in summer. In all, the control of PAHs at the source region was partially effective from 2012/2013 to 2018/2019.

Concentrations of the 16 US EPA PAHs in 86 Vegetable Oil Samples

A wide survey of the distributions of polycyclic aromatic hydrocarbons (PAHs) in vegetable oils (n = 86) for human consumption from manufacturers and retail shops in China were conducted by GC-MS following extraction with acetonitrile and purification using silica gel solid phase. Levels of BaP and PAH4 in 37 and 34 samples, respectively, were not in line with maximum permitted limit set by EU regulations. The three-ring and four-ring PAH compounds were predominant in vegetable oils, followed by 2 rings, which may be attribute to the truth that low molecular weight PAHs are prone assimilated by plant roots than high-ring PAHs, and are mainly produced under low temperature (<200 °C) processing conditions. The level of PAHs contamination found in this study in oil products should prompt a suitable intervention strategy to meet the health needs of consumers. Considering the vegetable oil categories, the levels of 16 PAHs in peanut and sesame oil were higher than other oils. This may be related to the two oils mostly extracted from roasted seeds for the development of flavor or aromatic in China. To hold the flavor of the crude oils, they were not refined. The health risk assessment of PAHs showed that there was a potential carcinogenic risk for the vegetable oil intake in China, but it has not yet reached the priority risk level.

Fate of PAHs in treated wastewater reused as irrigation water: Environmental risks in water-soil-ryegrass multimedia system

The main aim of this study was to determine the fate, bio-metabolism and environmental risk of low-ring and high-ring polycyclic aromatic hydrocarbons (PAHs) in a water-soil-ryegrass multi-media system, under long-term irrigation condition with micro-polluted treated wastewater. Field experiments were carried out to simulate garden irrigation using treated wastewater containing typical representative low-ring naphthalene (Nap) and high-ring benzo[a]pyrene (BaP). The results showed that BaP's vertical attenuation rate and adsorption accumulation rate were 1.7 and 1.2 times higher than Nap's, respectively. The adsorption, biodegradation, and the rhizosphere effect were responsible for 40.7%, 28.4%, 21.6%, and 30.5%, 36.6%, 17.7%, respectively, of the attenuation of BaP and Nap. The major metabolic pathways of Nap and BaP are hydroxylation, ring opening cleavage, and decarboxylation, with the metabolic chain of BaP being longer than that of Nap due to more ring cleaving reactions. Pseudomonas, Mycobacterium, and Sphingomonas were the functional microorganisms with PAHs degradation capacity that were positively correlated with PAHs degradation, particularly in the rhizosphere. After ten years of irrigation with treated wastewater, the prediction of environmental risk revealed that there were few potential risks. Thus, the results of this feasibility study demonstrated that using treated wastewater for garden irrigation was a relatively safe and effective strategy.

Removal Performance and Mechanism of Benzo(b)Fluorathene Using MnO2 Nanoflower/Graphene Oxide Composites.

High-ring polycyclic aromatic hydrocarbons (PAHs, Benzo[b]fluorathene (BbFA), etc.) are difficult to biodegrade in the water environment. To address this issue, an innovative method for the preparation of MnO2 nanoflower/graphene oxide composite (MnO2 NF/GO) was proposed for adsorption removal of BbFA. The physicochemical properties of MnO2 NF/GO were characterized by SEM, TEM, XRD, and N2 adsorption/desorption and XPS techniques. Results show that the MnO2 NF/GO had well-developed specific surface area and functional groups. Batch adsorption experiment results showed that adsorption capacity for BbFA was 74.07 mg/g. The pseudo-second-order kinetic model and Freundlich isotherm model are fitted well to the adsorption data. These show electron-donor-acceptor interaction; especially π-π interaction and π complexation played vital roles in BbFA removal onto MnO2 NF/GO. The study highlights the promising potential adsorbent for removal of PAHs.

Insights into the removal efficiencies of aged polycyclic aromatic hydrocarbons in humic acids of different soil aggregate fractions by various oxidants

Chemically oxidative removal of polycyclic aromatic hydrocarbons (PAHs) in soil is related to their occurrence state. Whether the heterogeneity of natural organic matter has an effect on the occurrence of PAHs in soil and, if there is an effect, on the oxidative removal efficiency of PAHs remains unknown. In this study, the removal efficiencies of 16 priority PAHs aged in humic acids (HAs) of different soil aggregate fractions by various oxidants were investigated by combining soil fractionation and microreaction experiments. Results showed that the accumulations of PAHs in particulate HA (P-HA) and microaggregate occluded HA (MO-HA) mainly occurred in the early period of the aging time frame. In contrast, PAH accumulation in non-aggregated silt and clay associated HA (NASCA-HA) was relatively slow and tended to saturate in the late period of the aging time frame. The cumulative contents of PAHs throughout the entire aging period in MO-HA and NASCA-HA were significantly greater than that in P-HA. The aged PAHs in P-HA and NASCA-HA exhibited the highest and lowest removal efficiencies, respectively. This ranking was mainly governed by the molecular size and polarity of HAs. Sodium persulfate and potassium permanganate had the highest removal efficiencies in total PAHs in HAs, with average efficiencies of 85.8% and 79.1%, respectively, in P-HA. Hydrogen peroxide had the lowest degradation efficiency in PAHs. In particular, the degradation efficiency of total PAHs in NASCA-HA was lowered to 31.0%. PAH congeners in HAs showed a large difference in oxidative removal efficiency. Low-ring PAH was more easily degraded than medium- and high-ring PAHs, and in most treatments, fluoranthene and pyrene in the medium ring and benzo[a]pyrene in the high ring demonstrated higher efficiencies than other PAHs with the same number of rings. Our findings are useful in promoting the accurate and green remediation of PAH-contaminated soils.

Polydopamine-coated polyethylene sieve plate as an efficient and convenient adsorption sink for the bioaccessibility prediction of PAHs in soils

Bioaccessibility measurements of polycyclic aromatic hydrocarbons (PAHs) in soils are significant for exposure risk assessment. The current physicochemical methods require tedious operation processes, underestimate the actual risks, or are unsuitable for high organic content soils. In this work, an efficient and convenient method based on polydopamine-coated polyethylene sieve plate (PDA@PESP) and hydroxypropyl-β-cyclodextrin (HPCD) was developed to predict the bioaccessibility of PAHs in multi-type soils. The PDA@PESP can be prepared via in situ self-polymerization, allowing to extract PAHs from HPCD solution quantitatively and rapidly. When applied to evaluate the bioaccessibility with PDA@PESP as an adsorption sink and HPCD as a diffusive carrier, the proposed method can significantly improve the extractable fraction of PAHs compared to single HPCD extraction in particular for high organic carbon content soil and high-ring PAHs. The desorption kinetics data indicated that the method can predict the bioaccessible fraction of PAHs. In addition, the method predicted a satisfactory accumulation into earthworms (Eisenia fetida) with a slope statistically approximated to 1. A highly significant linear regression (R2 = 0.95) was also found between the proposed method and Tenax desorption in historically contaminated soils, demonstrating that the method is an efficient and convenient approach for the bioaccessibility prediction of PAHs in soils.

Vertical Distribution Characteristics of PAHs in Soils with Different Land Use Types During Rapid Urbanization

To study the vertical distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) in the soils from different land use types during urbanization, three land use types (urban land, cultivated land, and woodland) were selected in the eastern part of Shenyang, where urbanization is occurring rapidly. In each case, five soil samples were obtained from different depths (0-1 m). Change in the concentrations of PAHs, vertical migration factors, and the distribution and sources of PAHs were analyzed in the vertical soil profiles. Total concentrations of PAHs in the different soil type were ordered as follows:city 1 (513.19-12689.04 μg·kg-1); dry field (36.18-7196.10 μg·kg-1); paddy field (70.92-747.53 μg·kg-1); city 2 (19.39-636.47 μg·kg-1); and woodland (4.79-349.24 μg·kg-1). PAHs were mainly trapped in shallow soils in urban and forest land, but can migrate deeper into the soil profile in cultivated land. High-ring PAHs were abundant at depths of 0-30 cm, while low-ring PAHs were abundant deeper in the soil profiles. SOM had a significant effect on the vertical distribution of PAHs, and the physical and chemical properties of PAHs had a significant influence on their migration ability. However, combustion sources from industrial activities and transportation in the region are still considered the main sources of PAHs despite the fact that some low-ring PAHs derive from petroleum product inputs.

Occurrence, sources and health risk of polycyclic aromatic hydrocarbons in soils around oil wells in the border regions between oil fields and suburbs

The Yellow River Delta (YRD) is a typical region where oil fields generally overlap cities and towns, leading to complex soil contamination from both the oil fields and human activities. To clarify the distribution, speciation, potential sources and health risk of polycyclic aromatic hydrocarbons (PAHs) in soils of border regions between oil fields and suburbs of the YRD, 138 soil samples (0–20 cm) were collected among 12 sampling sites located around oil wells with different extraction histories. The 16 priority control PAHs (16PAHs), as selected by the United States Environmental Protection Agency (USEPA), were extracted via an accelerated solvent extraction and detected by GC-MS. The results showed that soils of the study area were generally polluted by the 16PAHs. Among these pollutions, chrysene and phenanthrene were the dominant components, and 4-ring PAHs were the most abundant. A typical temporal distribution pattern of the 16PAHs was revealed in soils from different sampling sites around oil wells with different exploitation histories. The concentrations of total 16PAHs and high-ring PAHs (HPAHs) both increased with the extraction time of the nearby oil wells. Individual PAH ratios and PCA method revealed that the 16PAHs in soil with newly developed oil wells were mainly from petroleum pollutants, whereas PAHs in soils around oil wells with a long exploitation history were probably from petroleum contamination; combustion of petroleum, fuel, and biomass; and degradation and migration of PAHs from petroleum. Monte Carlo simulation was used to evaluate the health risks of the 7 carcinogenic PAHs and 9 non-carcinogenic PAHs in the study area. The results indicated that ingestion and dermal contact were the predominant pathways of exposure to PAH residues in soils. Both the carcinogenic and non-carcinogenic burden of the 16PAHs in soils of the oil field increased significantly with exploitation time of nearby oil wells.

Wood-Biochar-Supported Magnetite Nanoparticles for Remediation of PAH-Contaminated Estuary Sediment

In this study, we investigated the ability of a magnetic wood biochar (WB)-based composite catalyst (Fe3O4–WB) to catalyze sodium persulfate (PS) for the remediation of estuary sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). The effects of various critical parameters, including the catalyst dose and initial pH, were investigated. The degradation of the PAHs was found to be related to the number of rings in their structure. The results showed that Fe3O4–WB is an efficient catalyst for the removal of high-ring PAHs (HPAHs), with the highest degradation rates for the 6-, 5-, and 4-ringed PAHs being 90%, 84%, and 87%, respectively, for a PS concentration of 2 × 10−5 M, catalyst concentration of 3.33 g/L, and pH of 3.0. That the reduction rate of the HPAHs was greater than that of the low-ring PAHs can be attributed to the strong affinity of the HPAHs for biochar derived from wood biomass. Overall, this study revealed that the WB-mediated electron transfer catalysis of the surface functional groups in a wide range of pH in the Fe3O4–WB/PS system and potentially application in the remediation of sediments contaminated with PAHs.

Source identification and ecological impact evaluation of PAHs in urban river sediments: A case study in Taiwan

The Love River and Ho-Jin River, two major urban rivers in Kaohsiung City, Taiwan, are moderately to heavily polluted because different types of improperly treated wastewaters are discharged into the rivers. In this study, sediment and river water samples were collected from two rivers to investigate the river water quality and accumulation of polycyclic aromatic hydrocarbons (PAHs) in sediments. The spatial distribution, composition, and source appointment of PAHs of the sediments were examined. The impacts of PAHs on ecological system were assessed using toxic equivalence quotient (TEQ) of potentially carcinogenic PAHs (TEQcarc) and sediment quality guidelines. The average PAHs concentrations ranged from 2161 ng/g in Love River sediment to 160 ng/g in Ho-Jin River sediment. This could be due to the fact that Love River Basin had much higher population density and pyrolytic activities. High-ring PAHs (4–6 rings) contributed to 59–90% of the total PAHs concentrations. Benzo(a)pyrene (BaP) had the highest toxic equivalence quotient (up to 188 ng TEQ/g). Moreover, the downstream sediments contained higher TEQ of total TPHs than midstream and upstream sediment samples. The PAHs were adsorbed onto the fine particles with high organic content. Results from diagnostic ratio analyses indicate that the PAHs in two urban river sediments might originate from oil/coal combustion, traffic-related emissions, and waste combustion (pyrogenic activities). Future pollution prevention and management should target the various industries, incinerators, and transportation emission in this region to reduce the PAHs pollution.

Concentrations and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Soils and Vegetables influenced by Facility Cultivation

The concentrations, sources, and health risks of 16 United States Environmental Protcction Agency(USEPA) priority polycyclic aromatic hydrocarbons (PAHs) in vegetables (leafy lettuce, amaranth, water spinach, and Shanghai green), in soils inside and outside the vegetable greenhouse, and in wet deposition were investigated by conducting an experiment on facility cultivation. The results showed that the average concentrations of total PAHs in vegetables and soils were 99.27 ng·g-1and 128.01 ng·g-1 in the greenhouse, and 109.11 ng·g-1 and 173.07 ng·g-1 out of the greenhouse. The concentrations of PAHs in the greenhouse were lower than those outside and the high ring-PAHs were lower than the low ring-PAHs both inside and outside. The PAH concentrations in suspended particular matter in dissolved phases of wet deposition were 2986.49 ng·g-1 and 61.9 ng·L-1, respectively. The low rings were easily enriched by the vegetables based on the shoot concentration factors. PAHs in soils and vegetables mainly originated from oil emissions and grass, wood, and coal combustion, while those in suspended particular matter in wet deposition were from petrogenic sources and the combustion of grass, wood, and coal. Petroleum combustion emissions were the main sources of PAHs in dissolved phases. We used the model of incremental lifetime cancer risks to evaluate the health risk of eating these vegetables. There was a potential risk of cancer for both children and adults for all vegetables except amaranth. The carcinogenic risk of vegetables outside the greenhouse was higher than the risk inside. Amaranth had a low carcinogenic risk with the value of incremental lifetime cancer risk lower than 10-6, while the risk of Shanghai green ranged between 10-4 and 10-6.

Bioremediation of PAH-contaminated farmland: field experiment.

The agricultural soil contaminated by polycyclic aromatic hydrocarbons (PAHs) is gradually emerging and becoming serious in China with the rapid development of economy. To reduce the risk of PAHs in agricultural soil and guarantee the food safety, the biological agent that Mycobacterium gilvum immobilized on modified peanut shell powder enhanced remediation of polycyclic aromatic hydrocarbon-contaminated vegetable farmland was investigated under the conditions of the field experiment. The results indicated that adding biological agent could promote PAH degradation in the soil, especially high-ring PAHs. The degradation rates of PAHs in the soil could be further improved to 16.5-43.5%, respectively, compared with the soil without the biological agent. Adding the biological agent could significantly improve soil dehydrogenase activity and microbial diversity. It also could reduce the enrichment of PAHs in mustard planted in the polluted field, which indicated that the biological treatments might be less ecological risk. The work suggested that adding the biological agent might be a promising in situ bioremediation strategy for PAH-contaminated farmland field.

Source apportionment research of fine particulate matter in the atmosphere by PAHs

Haze weather frequently occurs in many cities in China. Polycyclic aromatic hydrocarbons(PAHs) in fine particulate matter(PM2.5) can adversely affect the environment and human health. In this paper, PM2.5 samples were collected at nine sites in a city in northeastern China from September 2013 to October 2014. Sixteen USEPA(US Evironment Protection Agency) priority PAHs in PM2.5 were analyzed to determine their spatial and temporal distribution characteristics. The source apportionment of PAHs was conducted with the Positive Matrix Factorization(PMF) model. The results indicate that the concentrations of total PAHs(T-PAHs) in PM2.5 are within the range of 0.26 to 72.48 ng/m3. The seasonal variation of T-PAHs is winter>spring>autumn>summer, and the space distribution of PAHs is JZP>DP>BFH>LP> EESA>IPT>CP>HZMC>JYP. In all types of PAHs, three-ring and five-ring PAHs are significantly prominent(62%) in the heating period due to petrogenic sources and traffic emissions. Middle- and high-ring PAHs in the non-heating period are caused by coal combustion and vehicle exhaust, which accounts for 77% of the total emissions. The source apportionment results obtained by the diagnostic ratio of PAHs reflect that coal burning, traffic and other sources have a distinct influence on PAH emissions in this city. Six factors are defined by PMF v5.0, namely, coke oven emissions(7.7%), biomass burning(44.3%), petrogenic sources(10.7%), coal combustion(10.4%), gasoline engine emissions(16.7%), and diesel engine emissions(10.3%). The results indicate that the PAHs in PM2.5 in the city are primarily caused by combustion processes and vehicle exhaust.

Characteristics of Carbon Material Formation on SBA-15 and Ni-SBA-15 Templates by Acetylene Decomposition and Their Bioactivity Effects.

Carbon spheres and tubes were formed from acetylene decomposition on SBA-15 and Ni-SBA-15 at 650–850 °C. At 650 °C, the decomposed carbons covered the surface of the support, and no carbon spheres and filament materials were formed. Carbon sphere formation occurred at 750 °C–850 °C; with diameters ranging from 0.8 μm–1.1 μm. For Ni-SBA-15, the diameters of the spheres and filaments were 0.8 μm and 62 nm, respectively, at 650 °C. At 750 °C, the diameter of the ball carbon materials ranged from 0.7 μm–0.8 μm, the diameter of the carbon tubes formed was 120–130 nm, and their pore diameter was 8.0 nm–11 nm. At 850 °C, the diameters of ball carbon materials and carbon tubes were similar to those of the materials at the formation temperature, 750 °C. Si, O and C were the main constituents of SBA-15; Ni-SBA-15 and carbon material formation supports. High-ring PAHs (such as BaP (five rings); IND (six rings); DBA (five rings) and B[ghi]P (six rings)) exist in carbon materials. SBA-15 revealed insignificant cytotoxicity, but Ni-SBA-15 inhibited the proliferation of human lung cancer cells (A549). Less inhibition on cell viability and reactive oxidative species (ROS) generation on A549 were determined for carbon material formation on the Ni-SBA-15 compared to the Ni-SBA-15.

Exposure to low dose benzo[a]pyrene during early life stages causes symptoms similar to cardiac hypertrophy in adult zebrafish

Growing evidence indicates that polycyclic aromatic hydrocarbons (PAHs) can lead to cardiac hypertrophy and recent research indicates that exposure to low dose crude oil during early embryonic development may lead to impacts on heart health at later life stages. The aim of this study was to evaluate whether exposure during early life stages to low dose benzo[a]pyrene (BaP), as a high-ring PAH, would lead to cardiac hypertrophy at later life stages. Zebrafish were exposed to low dose BaP until 96 hpf, then transferred to clean water and maintained for a year before histological and molecular biological analysis. Our results showed that exposure to low level BaP during early life stages increased heart weight to body weight ratios and deposited collagen in the heart of adult zebrafish. ANP, BNP and c-Myc were also induced in the heart of adult zebrafish by BaP. These results proved that low level BaP exposure during early life stages caused symptoms similar to cardiac hypertrophy in adult zebrafish. Our results displayed an elevated expression of CdC42, RhoA, p-ERK1, 2 and Rac1. Therefore, the mechanism of the cardiac hypertrophy caused by BaP exposure during early life stages may be through inducing the expression of CdC42, RhoA and Rac1, together with activating ERK1, 2.