Polycyclic aromatic hydrocarbons in soils in the vicinity of Nanjing, China

The occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in vegetable soils from five vegetable fields (including: Liuhe, Xixia, Pukou, Jianye and Yuhua districts) in Nanjing outskirt were investigated with high performance liquid chromatography (HPLC) equipped with fluorescence detector. The total concentrations of 15 priority PAHs in 126 soil samples ranged from 21.91 to 533.84ngg(-1) dry weight, and the sum of seven carcinogenic PAHs concentrations varied from 1.48 to 236.19ngg(-1) dry weight. Statistical analysis of the PAHs concentrations showed that the highest PAHs concentration was observed in Liuhe, and the lowest PAHs concentrations were found in Xixia among the five districts. The ratios of fluoranthene to sum of fluoranthene and pyrene concentrations (Flt/(Flt+Pyr)) were more than 0.5 in 99% of vegetable soil samples, showing that the PAHs in soils were generally derived from straw and coal combustion sources. The results from principal component analysis (PCA) further indicated that extensive combustion activities affected the PAHs distribution in Nanjing vegetable soils.     

Removal of sorbed polycyclic aromatic hydrocarbons from soil, sludge and sediment samples using the Fenton's reagent process

The use of the Fenton's reagent process has been investigated for the remediation of environmental matrices contaminated by polycyclic aromatic hydrocarbons (PAHs). Laboratory experiments were first conducted in aqueous solutions, to study the kinetics of oxidation and adsorption of PAHs. Benzo[a]pyrene was more rapidly degraded than adsorbed, while only partial oxidation of fluoranthene occurred. In the case of benzo[b]fluoranthene, its adsorption prevented its oxidation. Besides competition effects between PAHs were found, with slower oxidation of mixtures as compared to single PAH solutions. Apparition of some by-products was observed, and a di-hydroxylated derivative of benzo[a]pyrene could be identified under our conditions. Consequently, application to solid environmental matrices (soil, sludge and sediment samples) was performed using large amounts of reagents. The efficiency of the Fenton treatment was dependent on the matrix characteristics (such as its organic carbon content) and the PAH availability (correlated to the date and level of contamination). However, no pH adjustment was required, as well as no iron addition due to the presence of iron oxides in the solid matrices, suggesting the potential application of Fenton-like treatment for the remediation of PAH-contaminated environmental solids.     

Occurrence and assessment of polycyclic aromatic hydrocarbons in soils from vegetable fields of the Pearl River Delta, South China

Surface soil (0-20 cm) samples from nine representative vegetable fields located in Guangzhou, Shenzhen, Zengcheng and Huadu within the Pearl River Delta, South China were collected and analyzed for 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography coupled to mass spectrometry (GC-MS). Total concentrations of 16 PAHs (Sigma(PAHs)) ranged from 160 to 3700 microg kg(-1). Large variations were observed also between concentrations of individual PAHs from different vegetable fields and within the site as well. Acenapthylene, benzo[b]fluoranthene, fluoranthene, benzo[a]pyrene and benzo[k]fluoranthene were consistently the most prevalent individual PAHs. The values of PAH isomer ratios [anthracene/(anthracene+phenanthrene) and fluoranthene/(fluoranthene+pyrene)] indicate that combustion processes are the major sources of PAHs. Concentrations of PAHs were poorly correlated with organic carbon concentrations of soils, suggesting different sources and also indicating that the PAH pollution of this area is recent. The same outcome is confirmed by the predominance of PAHs with fewer rings (相似文献   

Distributions and concentrations of PAHs in Hong Kong soils

Surface soil (0-10 cm) samples from 53 sampling sites including rural and urban areas of Hong Kong were collected and analyzed for 16 EPA priority polycyclic aromatic hydrocarbons (PAHs). Total PAH concentrations were in the range of 7.0-410 microg kg(-1) (dry wt), with higher concentrations in urban soils than that in rural soils. The three predominant PAHs were Fluoranthene, Naphthalene and Pyrene in rural soils, while Fluoranthene, Naphthalene and Benzo(b + k)fluoranthene dominated the PAHs of urban soils. The values of PAHs isomer indicated that biomass burning might be the major origin of PAHs in rural soils, but vehicular emission around the heavy traffic roads might contribute to the soil PAHs in urban areas. A cluster analysis was performed and grouped the detectable PAHs under 4 clusters, which could be indicative of the PAHs with different origins and PAHs affected by soil organic carbon contents respectively.     

Treatment system for solid matrix contaminated with fluoranthene. II--Recirculating photodegradation technique.

A laboratory-scale solar reactor and photodegradation technique were developed to enhance the degradation process of fluoranthene. Fluoranthene was used in this study to represent toxic polycyclic aromatic hydrocarbons (PAHs) that are persistent in the environment. The extracted fluoranthene from soil in organic solvent (EFOS) and hydrogen peroxide (H2O2) were pumped from a 100 ml vessel into a solar glass cell coated with titanium dioxide (TiO2) at 80 microl min(-1). This work compares the efficiency of the developed photocatalytic degradation technique with the conventional batch process. The degradation efficiency of the developed technique was assessed at different initial concentrations of fluoranthene and percentages of H2O2 in the extract using different flow rates. Preliminary results indicated that the developed technique degraded 99% of fluoranthene from EFOS in the presence of H2O2 and 83% without H2O2. There was no significant difference between fluoranthene degradation rates by the developed technique and the batch method. The developed technique however, treated double the volume of solution that was treated by the batch reactor method which was time consuming and required continuous attention.     

Polycyclic aromatic hydrocarbons in the sediments of the South China Sea

Sixteen sediment samples, collected from the South China Sea, were analyzed for 11 parent polycyclic aromatic hydrocarbons (PAHs) using gas chromatography and gas chromatography-mass spectrometry. Total concentrations of the 11 PAHs studied in the sediments ranged from 24.7 to 275.4 ng/g with a mean of 145.9 ng/g dry sediment. PAH concentrations displayed a consistent distribution trend with the sediment organic carbon content. The linear regression analysis showed that the total concentration of PAHs in the sediment was significantly correlated to the sediment organic carbon content with a correlation coefficient of 0.735 (n=16). Special PAH compound ratios, such as phenanthrene/anthracene and fluoranthene/pyrene, were calculated to evaluate the relative importance of different origins. The collected data showed that pyrolytic input from anthropogenic combustion processes was predominant at almost all the stations investigated. Only one station, located in the proximity of oil wells, appeared to be contaminated predominantly by petrogenic input. Three anthropogenic PAHs, i.e. pyrene, benzo[a]pyrene and benzo[e]pyrene, exhibited similar distribution patterns in the studied area, implying that these compounds possess identical sources. However, perylene did not entirely follow the distribution trend of the three PAHs, suggesting that the sediment perylene probably derived from other sources such as in situ biogenic origins. Dibenzothiophene, a sulfur heterocyclic aromatic compound, was also measured in this study.     

Benzo[b]fluoranthene,a Potential Alternative to Benzo[a]pyrene as an Indicator of Exposure to Airborne PAHs in the Vicinity of Söderberg Aluminum Smelters

ABSTRACT

Benzo[b]fluoranthene (B[b]F) was used in relative abundance ratios (RARs), a parameter obtained by dividing the concentration of individual polycyclic aromatic hydrocarbons (PAHs) found in a given sample by the concentration of B[b]F in the same sample. The B[b]F RARs were derived for PAH concentrations measured at stacks and sampling stations in the vicinity of two Söderberg aluminum horizontal stud smelters (HSSs). The samples collected were analyzed by high-performance liquid chromatography using UV and fluorescence detection. A total of 15 PAHs were analyzed, but, due to the inefficiency of the sampling method used in collecting gaseous PAHs, only particulate PAHs were considered. Comparisons between the B[b]F RARs obtained simultaneously at the source (stack) and those obtained at sampling stations at the two smelters showed that B[b]F degrades more slowly than or at the same rate as most other particulate PAHs monitored. Twenty-three months of urban sampling in the vicinity of one of the aluminum HSSs are also presented, and the results indicate that B[b]F is more stable than all other particulate PAHs investigated. Sampling conducted during a smelter shutdown period confirmed that B[b]F was a much better marker of this source than was benzo[a]pyrene (B[a]P), the usual indicator. The remarkable stability of the benzo[k]fluoranthene (B[k]F)/B[b]F ratio is also discussed.     

Distribution of polycyclic aromatic hydrocarbons in soils at Guiyu area of China, affected by recycling of electronic waste using primitive technologies

The concentration, distribution, profile and possible source of polycyclic aromatic hydrocarbons (PAHs) in soil were studied in Guiyu, an electronic waste (E-waste) recycling center, using primitive technologies in Southeast China. Sixteen USEPA priority PAHs were analyzed in 49 soil samples (0-10 cm layer) in terms of individual and total concentrations, together with soil organic matter (SOM) concentrations. The concentrations of a sum of 16 PAHs ranged from 44.8 to 3206 microgkg(-1) (dry weight basis), in the descending order of E-waste open burning sites (2065 microgkg(-1))>areas near burning sites (851microgkg(-1))>rice fields (354 microgkg(-1))>reservoir areas (125microgkg(-1)). The dominant PAHs were naphthalene, phenanthrene and fluoranthene, which were mainly derived from incomplete combustion of E-waste (e.g. wire insulations and PVC materials), and partly from coal combustion and motorcycle exhausts. All individual and total PAH concentrations were significantly correlated with SOM except for naphthalene and acenaphthylene. Principal component analysis was performed, which indicated that PAHs were mainly distributed into three groups in accordance with their ring numbers and biological and anthropogenic source. In conclusion, PAH concentrations in the Guiyu soil were affected by the primitive E-waste recycling activities.     

Benzo[b]fluoranthene, a potential alternative to benzo[a]pyrene as an indicator of exposure to airborne PAHs in the vicinity of Söderberg aluminum smelters

Benzo[b]fluoranthene (B[b]F) was used in relative abundance ratios (RARs), a parameter obtained by dividing the concentration of individual polycyclic aromatic hydrocarbons (PAHs) found in a given sample by the concentration of B[b]F in the same sample. The B[b]F RARs were derived for PAH concentrations measured at stacks and sampling stations in the vicinity of two S?derberg aluminum horizontal stud smelters (HSSs). The samples collected were analyzed by high-performance liquid chromatography using UV and fluorescence detection. A total of 15 PAHs were analyzed, but, due to the inefficiency of the sampling method used in collecting gaseous PAHs, only particulate PAHs were considered. Comparisons between the B[b]F RARs obtained simultaneously at the source (stack) and those obtained at sampling stations at the two smelters showed that B[b]F degrades more slowly than or at the same rate as most other particulate PAHs monitored. Twenty-three months of urban sampling in the vicinity of one of the aluminum HSSs are also presented, and the results indicate that B[b]F is more stable than all other particulate PAHs investigated. Sampling conducted during a smelter shutdown period confirmed that B[b]F was a much better marker of this source than was benzo[a]pyrene (B[a]P), the usual indicator. The remarkable stability of the benzo[k]fluoranthene (B[k]F)/B[b]F ratio is also discussed.     

Chemical characterization and source identification of polycyclic aromatic hydrocarbons in aerosols originating from different sources

To obtain the characteristic factors or signatures of particulate polycyclic aromatic hydrocarbons (PAHs) to help identify the sources of particulate PAHs in the atmosphere, different carbonaceous aerosols were generated by burning different fossil fuels and biomass under different conditions in the laboratory, and the chemical characteristics of 14 PAHs were studied in detail. The results showed that (1) carbonaceous aerosols derived from domestic burning of coal, diesel fuel, and gasoline have much higher concentrations of PAHs than those derived from domestic burning of biomass; (2) carbonaceous aerosols derived from domestic burning of diesel fuel/gasoline have similar PAH components as those derived from high-temperature combustion of diesel fuel/gasoline, although the former have much higher concentrations of PAHs than the latter, suggesting that the burning temperature obviously affects the emitting amount of particulate PAHs, but only slightly influences the PAHs components; and (3) the ratios of benzo[b]fluoranthene/acenaphthylene, benzo[b]fluoranthene/fluorene, dibenzo[a,h]anthracene/acenaphthylene, dibenzo[a,h]anthracene/fluorine, and benzo[b]fluoranthene/benzo[k]fluoranthene in carbonaceous aerosols are sensitively dependent on their sources, indicating that these ratios are suitable for use as characteristic factors or signatures of particulate PAHs in the atmosphere.     

Structural characterisation of humic acid-bound PAH residues in soil by 13C-CPMAS-NMR-spectroscopy: evidence of covalent bonds

The fate of 13C-labelled phenanthrene and fluoranthene in different soil systems during biodegradation was studied. The soil humic acid fraction was isolated followed by structural characterisation using 13C-cross polarisation magic angle spinning nuclear magnetic resonance spectroscopy (13C-CPMAS-NMR). It could be demonstrated that especially the ratio between the concentrations of polycyclic aromatic hydrocarbons (PAHs) and soil humus matrix limits the usefulness of this analytical tool. Based on these results a ratio of 13C-activity(PAH)/13C-activity(soil) approximately 1.5/1.0 in the test material was suggested. The chemical transformation of a PAH and its bound residue formation in a soil system detected by changes of chemical shifts in the 13C-NMR spectrum was proven for the first time. Structural information obtained by NMR spectra were verified by alkaline hydrolysis of PAH/humus-associations and following identification of cleavage products. Ester-bound phenanthrene metabolites such as 1-hydroxy-2-naphthoic acid, ortho-phthalic acid and 3,4-dihydroxybenzoic acid were detected. Additional structural assignments indicated the presence of ether-bound phenanthrene derivatives as well. Using isotopic labelling techniques a quantitative evaluation of bound residue distribution was undertaken. Fifty to seventy percent of phenanthrene metabolites which could be related to the added 13C(1)-phenanthrene were ester bound via their carboxyl groups.     

Levels of persistent organic pollutants in the Neretva River (Bosnia and Herzegovina) determined by deployment of semipermeable membrane devices (SPMD)

The main objective of this study was to determine levels of certain persistent organic pollutants (POPs) in Neretva River, Bosnia and Herzegovina (BiH), which is currently facing implementation of the Stockholm Convention on persistent organic pollutants (POPs) and environmental protection strategies. This is the very first report on the deployment of semipermeable membrane devices (SPMDs) in BiH. SPMDs were used for continuous 3-weeks sampling of POPs at three locations, covering 220 km long stream of the Neretva River. Water concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polybrominated diphenylethers (PBDEs) were calculated using performance reference compounds (PRCs). The total OCP concentrations ranged from 40 to 140 pg L^?1 and most of compounds were detected only in lower course of the river. Total PAH ranged from 160 to 4000 pg L^?1 and show a clear spatial variation. Dominant PAHs were phenanthrene, fluoranthene, fluorene and acenaphthene. Total PCB ranged from undetectable to 120 pg L^?1. From the group of 15 PBDE congeners investigated, only PBDE-47 and PBDE-99 were detected. Since the concentrations of broad spectrum of POPs found in the Neretva River are quite low, future actions should be focused on preservation rather than on sanitation measures. Regular monitoring should anyhow be established.     

Polycyclic aromatic hydrocarbons (PAHs) concentrations and related carcinogenic potencies in soil at a semi-arid region of India

A study of polycyclic aromatic hydrocarbons in surface soil was conducted at selected locations in Agra (semi-arid region of India) for a span of one year in order to ascertain the contamination levels. The concentrations of PAH were measured at four locations in the city of Agra, which covers industrial, residential, roadside and agricultural areas. The samples were extracted with hexane by ultrasonic agitation. The extracts were then fractioned on a silica-gel column and the aromatic fraction was subjected to HPLC. The average concentration of total PAH in all samples was 12.1 microg g(-1) and the range was from 3.1 microg g(-1) to 28.5 microg g(-1). The maximum concentrations of PAHs were found to be in winter season. The concentration of PAH decreased in the order chrysene > benzo(b)fluoranthene > fluoranthene. Factor analysis suggests that the mixed signature of all the sources are intermediate between vehicular and combustion activities.     

Bioaccumulation of cyclopenta[cd]pyrene and benzo[ghi]fluoranthene by mussels transplanted in a coastal lagoon

The bioaccumulation of two isomeric non-alternant non-priority polycyclic aromatic hydrocarbons (PAHs), namely cyclopenta[cd]pyrene and benzo[ghi]fluoranthene, was investigated in caged mussels (Mytilus galloprovincialis) exposed for 30 days in three sites of a coastal lagoon (Pialassa Baiona, Ravenna, Italy) contaminated by pyrogenic PAHs. The concentration of cyclopenta[cd]pyrene and benzo[ghi]fluoranthene increased from undetectable levels in reference mussels withdrawn from the Adriatic sea to 10-30 ng g(-1) dry weight in transplanted mussels. Other contaminants bioaccumulated by caged mussels included pyrene, fluoranthene and mercury. Whilst the isomer concentration ratio pyrene/fluoranthene in biota was comparable to that observed in sediments, the cyclopenta[cd]pyrene/benzo[ghi]fluoranthene ratio was much lower in mussels than in sediments. The lower sediment biota accumulation factor of cyclopenta[cd]pyrene with respect to that of benzo[ghi]fluoranthene was tentatively attributed to the greater biological activity of the former compound, which contains a reactive olefinic bond in the cyclopenta fused ring moiety. Given the higher mutagenic activity of cyclopenta[cd]pyrene with respect to other priority PAHs, its bioaccumulation from contaminated sediments may rise considerably the overall toxicity of PAH residues in exposed biota.     

Using Radiocarbon to Apportion Sources of Polycyclic Aromatic Hydrocarbons in Household Soot

To determine whether polycyclic aromatic hydrocarbons (PAHs) in household soot were derived from the combustion of scrap wood or creosote that was impregnated in the wood (or some combination of both), the molecular composition and radiocarbon ( 14 C) content of the total carbon and several PAHs in the soot was investigated. The 5730-year half-life of 14 C makes it an ideal marker for identifying creosote-derived PAHs ( 14 C-free) versus those derived from the combustion of wood (contemporary 14 C). The 14 C abundance of phenanthrene, fluoranthene, pyrene, and retene was determined by accelerator mass spectrometry after solvent extraction and purification by preparative capillary gas chromatography. The molecular analysis (presence of retene and 1,7-dimethylphenanthrene) and bulk 14 C content (contemporary) of the soot indicated that wood combustion was a strong source of carbon to the soot. The 14 C of retene in two soot samples was also contemporary, indicating that it was derived from the combustion of the scrap wood. These results are consistent with previous work that has suggested that retene is an excellent marker of wood combustion. However, the 14 C content of phenanthrene, fluoranthene, and pyrene in one soot sample was much lower and revealed that these compounds had a mixed creosote and wood source. Using an isotopic mass balance approach, we estimate that 40 to 70% of phenanthrene, fluoranthene, and pyrene were derived from the combustion of the scrap wood. The results of this study show that molecular marker and bulk 14 C analysis can be potentially misleading in apportioning sources of every PAH, and that molecular-level 14 C analysis of PAHs can be a powerful tool for environmental forensics.     

Pinus nigra and Pinus pinaster needles as passive samplers of polycyclic aromatic hydrocarbons

Nine polycyclic aromatic hydrocarbons (PAHs) were analysed in pine needles of different ages (from 6 to 30 months) collected from two species, Pinus nigra and Pinus pinaster, in seven sites located along a transect from a suburban to a rural area of Genoa (Italy). In all sites and for both species, concentrations of more volatile PAHs (phenanthrene, anthracene, fluoranthene, pyrene) were higher than those for other less volatile PAHs, which are preferentially sorbed to airborne particulates (benzo[a]anthracene, chrysene, benzofluoranthenes, benzo[a]pyrene). Concentrations of total PAHs found in P. nigra in the rural sites were, on the average, 2.3 times higher than those in P. pinaster growing nearby. In both pine species, concentrations of volatile PAHs increased according to needle age. Annual trends of other PAHs were more variable, with a general decrease in older needles. P. pinaster needles are shown to be more reliable passive samplers, since they are more resistant to plant diseases, and considerable variation in PAH concentration was observed in P. nigra needles with moulds and fungi.     

The effect of soil organic matter on fate of polycyclic aromatic hydrocarbons in soil: A microcosm study

A microcosm study was conducted to address the influences of air-soil partition and sequestration on the fate of polycyclic aromatic hydrocarbons (PAHs) in soil. Sterilized and unsterilized soils with soil organic carbon (SOC) content ranging from 0.23 to 7.06% were incubated in a chamber with six PAHs supplied through air. After 100 d of incubation when the system approached pseudo-steady state, the PAHs concentrations in the unsterilized soils still correlated with SOC significantly, while the association did not exist for those sterilized. The lower degradation rate in the soil with higher SOC was likely the major reason for the association between SOC and PAHs concentrations, while the decreased surface porosity likely suppressed such correlation for the sterilized samples. The results indicated that the sequestration was likely the major mechanism for the accumulation of PAHs in soils, while both of the soil porosity and PAHs properties had observed influences.     

Complexation-flocculation of organic contaminants by the application of oxyhumolite-based humic organic matter

Control of hazardous organic micropollutants is a challenging water quality issue. Dissolved humic organic matter (DOM) isolated from oxyhumolite coal mined in Bohemia was investigated as a complexation agent to remove polycyclic aromatic hydrocarbons (PAHs) and functionalized phenols from water by a two-stage process involving complexation and flocculation. After the formation of humic-contaminant complexes, ferric salts were added resulting in the precipitation and flocculation of the DOM and the associated pollutants. Flocculation experiments with ferric ion coagulants indicated that precipitation of oxyhumolite DOM together with the complexed contaminants occurred at lower ferric ion concentrations than with the reference DOM in acidic environments (pH approximately 3.5). The complexation-flocculation removal rates for non-reactive PAHs characterized by small localization energies of pi-electrons correlated well with the complexation constants. On the other hand, the combined complexation-flocculation removal rates for activated PAHs including trans-stilbene, anthracene and 9-methyl anthracene, as well as functionalized polar phenols, were higher than predicted from the complexation coefficients. Methodological studies revealed for the first time that the ferric ion coagulant contributed to enhanced removal rates, most probably due to ferric ion-catalyzed pollutant degradation resulting in oxidized products.