Assessment of honey contamination with polycyclic aromatic hydrocarbons

The aim of this study was to assess honey contamination by polycyclic aromatic hydrocarbons. Six species of honey were examined, as well as rape blossom and soil from villages P?czerzyno and Przybys?aw in West Pomerania, Poland. The instrumental analysis was performed using a HP 6890 gas chromatograph coupled to a HP 5973 mass spectrometer with selected ion monitoring (SIM). Quantification was done by gas chromatography-mass spectrometry (GC-MS) using perdeuterated internal standards. Both soil samples showed high levels of all 23 PAHs, whereas honey contained mostly non-carcinogenic PAHs of low molecular weight. The most contaminated honey from P?czerzyno contained 0.24 μg kg-1 benzo[a]pyrene. Moreover, despite low contamination of honey, a positive correlation was found between PAH content in honey, blossom and soil.     

Assessing contamination of smoked sprats (Sprattus sprattus) with polycyclic aromatic hydrocarbons (PAHs) and changes in its level during storage in various types of packaging

The analysis of material used in this study demonstrated that the amount of polycyclic aromatic hydrocarbons (PAHs) in smoked sprats varies from the level below the lowest detection limit in muscles up to 9.99 µg kg^?1 of benzo[a]pyrene (BaP) in fish skin. Such a high level of PAHs in skin was reported only in one of six batches of sprats, while mean BaP level was at 1.69 µg kg^?1. Regardless such a high BaP level in skin, its concentration in muscles did not exceed the maximum acceptable level. The study objective was to assess to what extent packaging materials adsorb PAH compounds from food. Changes in the PAH levels were monitored in fish during their storage in packages made of various materials. The storage time was from 0 to 168 hours. The obtained results varied considerably, therefore their scatter did not allow to confirm unequivocally the preliminary hypothesis about the reduction of PAHs due to their migration to packaging material. However, analysis of the packaging used in this study demonstrated a significant increase in the level of total 16 PAHs. When high-density polyethylene (HDPE) packaging was analysed, a six-fold increase in the total 16 PAHs was observed comparing to the blank sample.     

Partitioning and source diagnostics of polycyclic aromatic hydrocarbons in rivers in Tianjin, China

Water, suspended particulate matter (SPM), and sediment samples were collected from ten rivers in Tianjin and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), dissolved organic carbon (DOC), particulate organic carbon (POC) in SPM and total organic carbon (TOC) in sediment. The behavior and fate of PAHs influenced by these parameters were examined. Generally, organic carbon was the primary factor controlling the behavior of the 16 PAH species. Partitioning of PAHs between SPM and water phase was studied, and K(OC) for some PAH species were found to be significantly higher than the predicted values. The source of PAHs contamination was diagnosed by using PAH isomer ratios. Coal combustion was identified to be a long-term and prevailing contamination source for sediment, while sewage/wastewater source could reasonably explain a short-term PAHs contamination of SPM.     

Spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments from Daya Bay, South China

The spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in Daya Bay, China. The total concentration of the 16 USEPA priority PAHs in surface sediments ranged from 42.5 to 158.2 ng/g dry weight with a mean concentration of 126.2 ng/g. The spatial distribution of PAHs was site-specific and combustion processes were the main source of PAHs in the surface sediments. Total 16 priority PAH concentration in the cores 8 and 10 ranged from 77.4 to 305.7 ng/g and from 118.1 to 319.9 ng/g respectively. The variation of the 16 PAH concentrations in both cores followed the economic development in China very well and was also influenced by input pathways. Some of the PAHs were petrogenic in core 8 while pyrolytic source was dominant in core 10. In addition, pyrolytic PAHs in both cores were mainly from the coal and/or grass and wood combustion.     

Accumulation and distribution of polycyclic aromatic hydrocarbons in rice (Oryza sativa)

Various tissues of rice plants were sampled from a PAH contaminated site in Tianjin, China at different growth stages of the ripening period and analyzed for PAHs. PAHs were much higher in roots than in the exposed tissues. Grains and internodes accumulated much smaller amounts of PAHs than leaves, hulls or ear axes. No specific gradient trends along roots, stem, ear axes, and grains were observed, suggesting that systematic translocation among them is unlikely. Over the ripening period, PAH concentrations were increased in rice roots and decreased in most above-ground tissues. Significant correlations between PAH and lipid contents can only be observed during full mature stage. The spectra of individual PAH compounds in rice organs including roots were similar to those in air, rather than those in soil. There was also a significant correlation between bioconcentration factor (BCF, plant over air) and octanol/air partitioning coefficient (Koa).     

Comparative study of different exposure routes on the biotransformation and genotoxicity of PAHs in the flatfish species, Scophthalmus maximus

In this study, laboratory experiments were carried out in order to come to a better understanding of the fate of polycyclic aromatic hydrocarbons (PAHs) in the marine environment and especially on their bioaccumulation, biotransformation and genotoxic effects in fish. Juveniles of turbot (Scophthalmus maximus) were exposed to PAHs through different routes via (1) a mixture of dissolved PAHs, (2) a PAH-polluted sediment and (3) an oil fuel elutriate. Fish were exposed 4 days followed by a 6-day depuration period. In each experiment, PAH concentrations in the seawater of the tanks were analysed regularly by gas chromatography coupled with mass spectrometry. Muscle and liver samples were also analysed for parent PAH levels and PAH bioconcentration factors were calculated. Biotransformation was evaluated by measuring the levels of PAH metabolites in fish bile. Genotoxicity was assessed by the alkaline comet assay. Regardless of exposure route, the parent PAH concentrations in the liver and muscle showed a peak level 1 day after the beginning of the exposure, followed by a decrease up to the background level towards the end of the experiment, except for the exposure to dissolved PAHs for which levels were relatively low throughout the study. As a consequence, no bioaccumulation was observed in fish tissues at the end of the experiment. In contrast, regardless of exposure routes, a rapid production of biliary metabolites was observed throughout the whole exposure experiment. This was especially true for 1-hydroxypyrene, the major metabolite of pyrene. After 6 days of recovery in clean water, a significant decrease in the total metabolite concentrations occurred in bile. Fish exposed through either route displayed a significant increase in DNA strand breaks after 4 days of exposure, and significant correlations were observed between the level of biliary PAH metabolites and the level of DNA lesions in fish erythrocytes. Overall results indicate that exposure to either a mixture of dissolved PAHs, a PAH-contaminated sediment or a dispersed oil fuel elutriate leads to biotransformation and increase in DNA damage in fish. The quantification of PAH metabolites in bile and DNA damage in erythrocytes appear to be suitable for environmental monitoring of marine pollution either in the case of accidental oil spills or sediment contamination.     

A directional passive air sampler for monitoring polycyclic aromatic hydrocarbons (PAHs) in air mass

A passive air sampler was developed for collecting polycyclic aromatic hydrocarbons (PAHs) in air mass from various directions. The airflow velocity within the sampler was assessed for its responses to ambient wind speed and direction. The sampler was examined for trapped particles, evaluated quantitatively for influence of airflow velocity and temperature on PAH uptake, examined for PAH uptake kinetics, calibrated against active sampling, and finally tested in the field. The airflow volume passing the sampler was linearly proportional to ambient wind speed and sensitive to wind direction. The uptake rate for an individual PAH was a function of airflow velocity, temperature and the octanol-air partitioning coefficient of the PAH. For all PAHs with more than two rings, the passive sampler operated in a linear uptake phase for three weeks. Different PAH concentrations were obtained in air masses from different directions in the field test.     

Biomonitoring seasonal variation of urban air polycyclic aromatic hydrocarbons (PAHs) using Ficus benghalensis leaves

Temporal and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) concentrations in leaves of Ficus benghalensis were investigated in Varanasi city (India). Leaf samples were collected from six sites from urban area of Varanasi and from a control site. PAH extraction was done by sonication in dichloromethane-acetone and quantification by GC-MS. In January total leaf PAHs concentrations at all the urban sites were twice higher as compared to other season's viz. summer and rainy. In contrast, at the control site leaf PAHs concentrations showed lower values than urban sites. The maximum concentrations of total PAHs in winter were due to the medium molecular weight PAHs which increases with respect to both low and high molecular weight PAHs. The temporal variation of medium molecular weight PAHs was similar both at the urban and remote sites. These results support biomonitoring ability of Ficus benghalensis leaves to temporal variations in PAHs contamination.     

Successful Treatment of Low PAH-Contaminated Sewage Sludge in Aerobic Bioreactors (7 pp) *

Background, Aims and Scope Polycyclic Aromatic Hydrocarbons (PAHs) are known for their adverse and cumulative effects at low concentration. In particular, the PAHs accumulate in sewage sludge during wastewater treatment, and may thereafter contaminate agricultural soils by spreading sludge on land. Therefore, sludge treatment processes constitute the unique opportunity of PAH removal before their release in the environment. In this study, the ability of aerobic microorganisms to degrade light and heavy PAHs was investigated in continuous bioreactors treating trace-level PAH-contaminated sludge. Methods Several aerobic reactors were operated under continuous and perfectly mixed conditions to simulate actual aerobic sludge digesters. Three sterile control reactors were performed at 35°C, 45°C or 55°C to assess PAH abiotic losses under mesophilic and thermophilic conditions. Three biological reactors were also operated at 35°C, 45°C or 55°C. Furthermore, 250 mM methanol were added in an additional mesophilic reactor (35°C). All reactors were fed with long-term PAH-contaminated sewage sludge, and PAH removal was assessed by inlet/outlet mass balance. In this study, PAH compounds ranged from 2 to 5-unsubstituted aromatic rings, i.e. respectively from Fluorene to Indeno(123cd)pyrene. Results and Discussion Significant abiotic losses were observed for the lightest PAHs (fluorene, phenanthrene and anthracene), while biodegradation occurred for all PAHs. More than 80% of the lightest PAHs were removed. Biodegradation rates inversely correlated with the increasing molecular weight, and seemed limited by the low bioavailability of the heaviest PAHs (only 50% of removal). The enhancement of PAH bioavailability by increasing the process temperature or adding methanol was tested. A temperature increase from 35°C to 45°C and then to 55°C significantly enhanced the biodegradation of the heaviest PAHs from 50% to 80%. However, high abiotic losses were observed for all PAHs at 55°C, which was attributed to volatilization. Optimal conditions were found at 45°C considering the low abiotic losses and the high PAH biodegradation rates. Similar performances were achieved by addition of methanol in the sludge. It was concluded that increasing temperatures or addition of methanol favored PAH diffusion from solids to an aqueous compartment, and enhanced their bioavailability to PAH-degrading microorganisms. Conclusion In this study, the use of long-term acclimated aerobic ecosystems showed the high potential of aerobic microorganisms to degrade a wide range of PAHs at trace levels. However, PAH biodegradation was likely controlled by their low bioavailability. Two aerobic processes have been finally proposed to achieve efficient decontamination of sewage sludge, at 45°C or in the presence of methanol. The PAH concentrations in reactor outlet were lower than the French requirements, and allow the treated sludge to be spread on agricultural land. Recommendations and Outlook The two proposed aerobic processes used physical or chemical diffusing agents. The global ecological impact of using the latter agents for treating trace level contamination must be considered. Since methanol was completely removed during the process, no additional harm is expected after treatment. However, an increase of temperature to 45°C could drastically increase the energy demand in full-scale plants, and therefore the ecological impact of the process. Moreover, since bioavailability controls PAH biodegradation, efficiency of the processes could also be influenced by the hydraulic parameters, such as mixing and aeration rates. Further experimentations in a pilot scale are therefore recommended, as well as a final assessment of the global environmental benefit of using such aerobic processes in the bioremediation of trace level compounds. - Abbreviations (PAHs): Ant – anthracene; B(a)A – benzo(a)anthracene ; B(b)F – benzo(b)fluoranthene; B(k)F – benzo(k)fluoranthene; B(ghi)P – benzo(g,h,i)perylene; B(a)P – benzo(a)pyrene; Chrys – chrysene; DB – dibenzo(a,h)anthracene; Fluor – fluoranthene; Fluo - fluorene; Ind – indeno(1,2,3-c,d)pyrene; Phe - phenanthrene; Pyr – pyrene - * The basis of this peer-reviewed paper is a presentation at the 9th FECS Conference on 'Chemistry and Environment', 29 August to 1 September 2004, Bordeaux, France.     

Photoenhanced toxicity of a weathered oil onCeriodaphnia dubia reproduction

Traditionally, the toxic effects of petroleum have been investigated by conducting studies in the absence of ultraviolet radiation (UV). Photomediated toxicity is often not considered, and the toxic effects of an oil spill can be grossly underestimated. The toxicity of a weathered oil collected from a monitoring well at an abandoned oil field toCeriodaphnia dubia was examined in the presence of UV. A solar simulator equipped with UVB, UVA, and cool white lamps was used to generate environmentally comparable solar radiation intensities.C. dubia were exposed to six concentrations of water accommodated fractions (WAF) of weathered oil in conjunction with three levels of laboratory simulated UV (Reference = < 0.002 μW/cm²UVB; 3.0 μW/cm² UVA; Low = 0.30 μW/cm² UVB; 75.0 μW/cm² UVA; High = 2.0 μW/cm² UVB; 340.0 μW/cm² UVA) and visible light. Seven day static renewal bioassays were used to characterize WAF/UV toxicity. WAF toxicity significantly (p < 0.05) increased when the organisms were exposed to WAF in the presence of UV. The photoenhanced toxicity of the WAF increased with WAF concentration within each UV regime. Relative to the reference light regime, the average number of neonates from adults exposed to 1.6 mg TPH/L decreased significantly by 20% within the low light regime, and by 60% within the high light regime. These results indicate that organisms exposed to dissolved-phase weathered oil in the presence of environmentally realistic solar radiation, exhibit 1.3–2.5 times greater sensitivity, relative to organisms exposed under traditional laboratory fluorescent lighting.     

Sources of PCDD/Fs, non-ortho PCBs and PAHs in sediments of high and low impacted transboundary rivers (Belgium-France)

PAHs, PCDD/Fs and non-ortho PCBs have been assessed in Yser and Upper-Scheldt river sediments. Higher contamination levels were observed in the Upper-Scheldt sediments: maximum concentrations for the 16 US-EPA PAHs, PCDD/Fs and non-ortho PCBs respectively amount to 8.9 mg kg⁻¹, 12 ng TEQ kg⁻¹ and 5.1 ng TEQ kg⁻¹. Diagnostic PAH ratios in sediments and atmospheric samples suggest that the PAH compounds are from pyrolytic origin, more specifically combustion processes. The huge consumption of coal in cokes-ovens and smelters and its use for house-heating in Northern France, although decreasing during the last decades, are in support of that suggestion. PCDD/F fingerprints in sediments and deposition material indicate that OCDD is the dominant congener. In addition use of pentachlorophenol (PCP) in the past led to a minor contribution of PCDD/Fs in our sediment samples. Non-ortho PCBs form a substantial fraction of the total TEQ concentrations observed in the sediments. Since the 1980s and 1990s a substantial reduction of the PCDD/F sediment concentrations is observed, but this is not the case for the PAHs.     

Contamination of polycyclic aromatic hydrocarbons in surface sediments of mangrove swamps

The concentrations of total polycyclic aromatic hydrocarbons (sigmaPAHs) and 15 individual PAH compounds in 20 surface sediments collected from four mangrove swamps in Hong Kong were analysed. sigmaPAH concentrations ranged from 356 to 11,098 ng g(-1) dry weight with mean and median values of 1992 and 1,142 ng g(-1), respectively. These values were significantly higher than those of marine bottom sediments of Hong Kong harbours, suggesting that more PAHs were accumulated in mangrove surface sediments. The concentrations of sigmaPAHs as well as individual PAH compound varied significantly among mangrove swamps. The swamps heavily polluted by livestock and industrial sewage, such as Ho Chung and Mai Po, had much higher concentrations of total PAHs and individual PAH than the other swamps. The PAH profiles were similar among four mangrove swamps, and were dominated by naphthalene (two-ring PAH), fluorene and phenanthrene (three-ring PAH). The mangrove sediments had higher percentages of low-molecular-weight PAHs. These indicated that PAHs in mangrove sediments might originate from oil or sewage contamination (petrogenic input). Ratio values of specific PAH compounds such as phenanthrene/anthracene and fluoranthene/ pyrene, were calculated to evaluate the possible source of PAH contamination in mangrove sediments. These ratios varied among samples, suggesting that mangrove sediments might have a mixed pattern of pyrolytic and petrogenic inputs of PAHs. Sediments collected from Ho Chung mangrove swamp appeared to be more dominated by pyrolytic input while those from Tolo showed strong petrogenic contamination.     

Photo-induced toxicity of PAHs to Hyalella azteca and Chironomus tentans: effects of mixtures and behavior

In the aquatic environment, polycyclic aromatic hydrocarbon (PAH) contamination can result from several anthropogenic sources such as petroleum runoff, industrial processes, and petroleum spills. When ultraviolet light (UV) is present at sufficient intensity, the acute toxicity of some PAHs to aquatic biota is greatly enhanced. This photo-induced toxicity of PAHs is directly influenced by the amount of PAH and by the level of UV intensity present in the aquatic environment. Thus, behavioral responses and habits that affect an aquatic organism's exposure to UV as well as exposure to PAHs can influence the extent to which damage due to photo-induced toxicity occurs. Experiments demonstrated the effects of photo-induced toxicity of anthracene and fluoranthene on the survival of two benthic macroinvertebrates, the midge Chironomus tentans and the freshwater amphipod Hyalella azteca. This study further investigated the survival and behavior of the test organisms in different substrates (no substrate, a sand monolayer, leaf discs, and sediment) with and without UV. The free-swimming, epibenthic H. azteca avoided the effects of photo-induced toxicity of PAHs to some extent by hiding in leaves when this substrate was available. Results emphasize the importance of organisms' behavior in affecting the photo-induced toxicity of PAHs in the aquatic environment.     

Studies on polycyclic aromatic hydrocarbons in two sediment cores from the huaxi reservoir,china: Assessment of levels,sources, and ecological risk

This study investigated the levels, sources and ecological risks of 16 polycyclic aromatic hydrocarbons (PAHs) in two sediment cores that were collected along the Huaxi Reservoir. The spatial distributions and residue levels of the 16 priority PAHs in the sediments from the Huaxi Reservoir were analyzed for their potential ecological risk, source apportionment and contribution to the total PAH residue. The concentration level of the total PAHs (TPAHs) was in the range 1805 ng·g^?1 to 20023 ng·g^?1 based on dry weight, and the content of PAHs in the Huaxi Reservoir exhibited a gradual upward trend. The PAH congener ratios fluoranthene/(fluoranthene + pyrene) and indeno[1, 2, 3-cd]pyrene/(indeno[1, 2, 3-cd]pyrene + benzo[g, h, i]perylene) were used to identify the source. The main source of the low molecular weight PAHs was wood and coal combustion, whereas the high molecular weight PAHs were primarily from petroleum combustion sources. The results of an ecological risk assessment demonstrated that ACE poses a potential ecological risk, while FLU, NAP, ANT, BaP, DBA, PHEN and PYR can have serious ecological risks.     

Concentrations, sources and spatial distribution of polycyclic aromatic hydrocarbons in soils from Beijing, Tianjin and surrounding areas, North China

The concentrations, profiles, sources and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) were determined in 40 surface soil samples collected from Beijing, Tianjin and surrounding areas, North China in 2007, and all sampling sites were far from industrial areas, roadsides and other pollution sources, and across a range of soil types in remote, rural villages and urban areas. The total concentrations of 16 PAHs ranged from 31.6 to 1475.0 ng/g, with an arithmetic average of 336.4 ng/g. The highest PAH concentrations were measured in urban soils, followed by rural village soils and soils from remote locations. The remote-rural village-urban PAH concentration gradient was related to population density, gross domestic product (GDP), long-range atmospheric transport and different types of land use. In addition, the PAH concentration was well correlated with the total organic carbon (TOC) concentration of the soil. The PAH profile suggested that coal combustion and biomass burning were primary PAH sources.     

Hydrocarbon pollution fixed to combined sewer sediment: a case study in Paris

Over a period of two years (2000-2001), sediment samples were extracted from 40 silt traps (STs) spread through the combined sewer system of Paris. All sediment samples were analysed for physico-chemical parameters (pH, organic matter content, grain size distribution), with total hydrocarbons (THs) and 16 polycyclic aromatic hydrocarbons (PAHs) selected from the priority list of the US-EPA. The two main objectives of the study were (1) to determine the hydrocarbon contamination levels in the sediments of the Paris combined sewer system and (2) to investigate the PAH fingerprints in order to assess their spatial variability and to elucidate the PAH origins. The results show that there is some important inter-site and intra-site variations in hydrocarbon contents. Despite this variability, TH and PAH contamination levels (50th percentile) in the Parisian sewer sediment are estimated at 530 and 18 microg g(-1), respectively. The investigation of the aromatic compound distributions in all of the 40 STs has underlined that there is, at the Paris sewer system scale, a homogeneous PAH background pollution. Moreover, the study of the PAH fingerprints, using specific ratios, suggests the predominance of a pyrolytic origin for those PAHs fixed to the sewer sediment.     

Analysis of polycyclic aromatic hydrocarbons (PAHs) in airborne particles by direct sample introduction thermal desorption GC/MS

The technique of thermal desorption (TD)–GC/MS was evaluated for measuring airborne, 4–6 ring polycyclic aromatic hydrocarbons (PAHs) collected onto quartz filters. TD provides a more readily automated and sensitive alternative to traditional solvent extraction, decreasing the time/cost of analysis and reducing the risk of analyte loss or sample contamination. The developed method was successfully applied to the analysis of PAH standard solutions loaded on sorbent tubes packed with quartz wool and the graphitized carbon black sorbent Carbograph2. The optimized method showed high desorption efficiency over the whole range of target PAHs with good precision, linearity and sensitivity. The proposed method was verified on an urban dust Standard Reference Material (SRM 1649a); the experimentally determined concentrations agreed with the certified ranges (95% confidence limit) for all target compounds except benzo[a]anthracene, which fell just outside the narrow certified range. The desorption efficiency and the reproducibility of the method was evaluated by analysing pieces of real sample filters sampled from urban air for a period of 24 h. The results confirmed the homogeneity of the filter and showed high recovery efficiencies for all target PAHs.     

Pollution survey of polycyclic aromatic hydrocarbons in surface water of Hangzhou, China

The concentrations of 10 polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured for five times (July and November 1999–2002) in four water bodies of Hangzhou, China. To investigate possible sources of PAH contamination, sediments, soils, runoff water and atmospheric particles of the region were also analyzed for their PAH contents. The maximum levels of PAHs in the water bodies (34.4–67.7 μg/l) were found in July, while significantly lower PAH concentrations (4.7–15.3 μg/l) were measured in November. The contamination is substantial and it may have resulted in acute toxic effects on aquatic organisms. The measured PAH concentrations in sediments and soils (224–4222 ng/g), runoff water (8.3 μg/l) and air particles (2.3 μg/m³) are discussed in relation to concentrations and patterns found in the surface water bodies. Comparison of PAH levels in sediments and soils led to the conclusion that the erosion of soil material does not contribute significantly to the contamination of sediments. The atmospheric PAH deposition to water bodies in the city area of Hangzhou was estimated to be 530 tons/a, while the contribution of surface runoff water was estimated to be 30.7 tons/a. The ratios of selected PAH were then used to illuminate the possible origin of PAHs in the examined samples (petrogenic, pyrogenic).     

Dissolution and removal of PAHs from a contaminated soil using sunflower oil

This study reports on the feasibility of remediation of polycyclic aromatic hydrocarbon (PAH) contaminated soils using sunflower oil, an environmentally-friendly solvent. Batch experiments were performed to test the influence of oil/soil ratio on the remediation of PAH contaminated soil, and to test the mass transfer behaviors of PAHs from soil to oil. An empirical model was employed to describe the kinetics of PAH dissolution and to predict equilibrium concentrations of PAHs in oil. PAH containing oil was regenerated using active carbon. Results show that dissolution of PAHs from a Manufactured Gas Plant (MGP) soil at oil/soil ratios of one or two were almost the same. Nearly all PAHs (81-100%) could be removed by sunflower oil dissolution. Mass transfer coefficients for low molecular PAHs namely fluoranthene, phenanthrene and anthracene were one or two orders of magnitude higher than those for high molecular PAHs with 4-6 rings. Ninety milliliters of PAH containing oil could be regenerated by 10 g active carbon in a batch reactor. Such a remediation procedure indicates that sunflower oil is a promising agent for the removal of PAHs from MGP soils. However, further research is required before the method can be used for in situ remediation of contaminated sites.     

Polycyclic aromatic hydrocarbons in the surface sediments from Yellow River, China

Fourteen surface sediment samples were collected from Lanzhou Reach of Yellow River, China in July 2005. The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography equipped with a mass spectrometry detector (GC-MS). Total concentrations of the PAHs ranged from 464 to 2621 ng/g dry weight. Sediment samples with the highest PAH concentrations appeared at the downstream of Lanzhou City, where there was the biggest wastewater discharge pipeline from Lanzhou Oil Refinery Factory and Lanzhou Chemical Industry Company. Municipal sewage also contributed to the PAH contamination in the sediments. A correlation existed between the sediment organic carbon content (f(oc)) and the total PAH concentrations (r(2)=0.57), suggesting that sediment organic carbon content played an important role in controlling the PAHs levels in the sediments. According to the observed molecular indices, PAHs contamination in Lanzhou Reach of Yellow River originated both from the high-temperature pyrolytic processes and from the petrogenic source, showing a mixed PAH input pattern, which was also confirmed by the results of a principal component analysis (PCA). According to the numerical effect-based sediment quality guidelines (SQGs) of the United States, the levels of PAHs at most studied sites in Lanzhou Reach of Yellow River should not exert adverse biological effects. Although at some sites (such as S10, S12, etc.) one PAH may exceed the effects range low (ERL), individual PAH did not exceed the effects range median (ERM). The results indicated that sediments in all sites should have potential biological impact, but should have no impairment.