Analysis of nitrated polynuclear aromatic hydrocarbons

A derivatization-gas chromatography/electron capture detector (GC/ECD) method has been developed for the measurement of trace nitrated polynuclear aromatic hydrocarbons (NPAHs) in air. The method involves first the derivatization of parent nitro-PAHs to their corresponding fluorinated derivatives, followed by GC/ECD analysis. The sensitivity of the method is an order of magnitude higher than those of direct GC/ECD analysis of NPAHs themselves. The method is simple and robust and thus ideally suited for the routine monitoring of NPAHs in air samples. The sensitivity and reproducibility of GC/negative ion chemical ionization MS (NICIMS) for the measurement of NPAHs after derivatization has been evaluated. The method has sensitivity comparable to GC/ECD, but is less reproducible in quantification. The method is therefore suitable for method validation and NPAHs peak confirmation rather than routine operations.     

Mobility of polychlorinated aromatic compounds in soils contaminated with wood-preserving oil

Greater understanding of the mobility of polychlorinated aromatic compounds in soils is needed to investigate contamination and design suitable remediation strategies for sites contaminated with wood-preserving oil. The objectives of this study were (1) to develop a suitable aqueous batch extraction method for soil containing wood-preservative residues; (2) to determine partition coefficients for the primary contaminants [pentachlorophenol (PCP), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFS)] in oil, soil, and aqueous phases; and (3) to evaluate the potential soil migration of the primary contaminants. In a three-phase oil-soil-water mixture, PCP, PCDDs, and PCDFs were partitioned to the greatest extent in the oil phase. These results suggest that the migration of contaminants can occur in a saturated subsurface soil zone containing an oil phase at a wood-preserving site. In the absence of a free oil phase, PCDDs and PCDFs were highly partitioned onto soil and were considered non-leachable in the aqueous phase. However, PCP was considered highly leachable from contaminated soil containing only an aqueous liquid phase. Results from this study indicate that removal of any free oil phase present in subsurface soil should have highest priority during the cleanup of contaminated wood-preserving sites.     

Removal of aqueous-phase polynuclear aromatic hydrocarbons using aspen wood fibers

Roadway runoff derived polynuclear aromatic hydrocarbons (PAHs) impact the quality of surface and ground water. Inexpensive aspen wood fibers have been investigated as a means to remove dissolved PAH under laboratory conditions. Our isotherm experiments demonstrated that the uptake of naphthalene, fluorene, anthracene, and pyrene required up to 12.5 days to reach equilibrium. Aspen wood-water sorption coefficients, Kww, were linearly correlated to octanol-water partition coefficients and the molecular weight of the studied PAH compounds. The correlation between Kww and molecular weight was the most significant. Column experiments were carried out to study the sorption and desorption of fluorene, anthracene, and pyrene under dynamic conditions. The results indicate linear sorption, but non-linear desorption behavior. The degree of desorption was inversely correlated to a compound's hydrophobicity. Flow interruption experiments showed that sorption and desorption was rate limited. A mass balance of the sorption and desorption tests indicated that sorptive uptake exceeded desorptive release over a given number of pore volumes. Further, absolute mass-removal efficiency increased with the molecular weight and hydrophobicity of the PAH compound. Batch and column studies demonstrated that aspen wood has the potential to become an effective remedial agent for PAH in stormwater runoff or other PAH contaminated waters.     

Unavailability of polynuclear aromatic hydrocarbons from coal particles to the eastern oyster

The accumulation by oysters of polycyclic aromatic hydrocarbons (PAH) from coal dust entering the estuarine environment has been postulated in the vicinity of coal transfer operations. Oysters Crassostrea virginica were exposed to coal dust plus 15 day leachate at concentrations of 10 mg litre(-1) and 1 mg litre(-1) coal dust for 28 days in a flow-through test system. Potential effects of the exposures were measured by comparing the uptake of PAH and the growth of the exposed animals versus control groups. Oysters sampled at 7, 14 and 28 days did not exhibit an increase in PAH body burden over control animals provided the guts were first purged of particulates. Even at the high test concentrations (10 mg litre(-1)), no effect of the exposure on shell growth was observed.     

炼油污水深度处理研究

炼油污水经生化处理后虽能达标排放 ,但仍对水体造成污染。若再经深度处理使水质达到地面水Ⅳ级标准 ,循环用于工业生产 ,则具有重大经济效益和环境效益。     

Phase distribution and artifact formation in ambient air sampling for polynuclear aromatic hydrocarbons

Laboratory and field sampling experiments were conducted to determine the phase-distribution of polynuclear aromatic hydrocarbons (PAH) in the ambient atmosphere and to determine the potential for artifact formation due to volatilization and ozone (O₃) reaction during normal sampling conditions. The study was conducted in two segments to investigate both summer and winter ambient temperature effects. The winter measurements reflect stronger association of PAH with the particulate phase than the summer data, but data from both seasons show appreciable filter losses due to volatilization of phenanthrene, anthracene, fluoranthene, benz(a)anthracene and chrysene. No evidence was found for volatilization of the heavier PAH, including benzo(e)pyrene, benzo(a)pyrene, indeno(l,2,3-c,d)pyrene, benzo(g,h,i)perylene and coronene. Although O₃ reacted readily with particulate matter that was freshly spiked with PAH in the laboratory experiments, no evidence was found for reaction of O₃ with particulate matter during the field sampling experiments.     

The persistence of polynuclear aromatic hydrocarbons (PAHs) in sewage sludge amended agricultural soils

In 1968, five metal enriched sewage sludges containing different concentrations of polynuclear aromatic hydrocarbons (PAHs) were applied to different plots on field soils at two experimental sites, Luddington and Lee Valley, in the UK. This resulted in substantial increases in the total PAH soil concentrations in all plots. Since application, losses have occurred, with the high molecular weight PAHs being more persistent. Calculated half-lives range from under 2 years for naphthalene to over 9 years for benzo[ghi]perylene and coronene. The losses of PAH compounds in these field experiments can be related, in part, to their physico-chemical properties, notably the octanol: water partition coefficient.     

Anaerobic decomposition of halogenated aromatic compounds

Halogenated compounds constitute one of the largest groups of environmental pollutants, partly as a result of their widespread use as biocides, solvents and other industrial chemicals. A critical step in degradation of organohalides is the cleavage of the carbon?halogen bond. Reductive dehalogenation is generally the initial step in metabolism under methanogenic conditions, which requires a source of reducing equivalents, with the halogenated compound serving as an electron acceptor. Dehalogenation is greatly influenced by alternate electron acceptors; e.g. sulfate frequently inhibits reductive dehalogenation. On the other hand, a number of halogenated aromatic compounds can be degraded under different electron-accepting conditions and their complete oxidation to CO(2) can be coupled to processes such as denitrification, iron(III)-reduction, sulfate reduction and methanogenesis. Reductive dehalogenation was the initial step in degradation not only under methanogenic, but also under sulfate- and iron(III)-reducing conditions. Dehalogenation rates were in general slower under sulfidogenic and iron-reducing conditions, suggesting that dehalogenation was affected by the electron acceptor. The capacity for dehalogenation appears to be widely distributed in anoxic environments; however, the different substrate specificities and activities observed for the halogenated aromatic compounds suggest that distinct dehalogenating microbial populations are enriched under the different reducing conditions. Characterization of the microbial community structure using a combination of biomolecular techniques, such as cellular fatty acid profiling, and 16 S rRNA fingerprinting/sequence analysis, was used to discern the distinct populations enriched with each substrate and under each electron-accepting condition. These combined techniques will aid in identifying the organisms responsible for dehalogenation and degradation of halogenated aromatic compounds.     

Bioremediation of soil contaminated with polynuclear aromatic hydrocarbons (PAHs): a review

Polynuclear aromatic hydrocarbons (PAHs) constitute a group of priority pollutants which are present at high concentrations in the soils of many industrially contaminated sites. Criteria established for the removal or treatment or both of soils contaminated with PAHs vary widely within and between nations. The bioremediation of contaminated soils with in-situ, on-site, and bioreactor techniques is reviewed, together with the factors affecting PAH degradation. Current in-situ remediation techniques are considered ineffective for the removal of most PAHs from contaminated soil. On-site 'landforming' methods have been used successfully (and within a reasonable period of time) to degrade only those PAHs with three or fewer aromatic rings. Bioreactors have proved most effective for soil remediation, since conditions for enhanced degradation can be achieved most readily. However, bioreactors are still at the development stage, and further research is required to optimise their efficiency and economy for routine use. Degradation of the more recalcitrant high-molecular-weight PAHs is contaminated soil has not been particularly successful to date. Further research needs are identified to help develop bioremediation into a most cost-effective technology. The importance of full site assessments and treatability studies for successful application in the field is emphasised.     

Accumulation of polycyclic aromatic hydrocarbons in crankcase oil

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in automotive crankcase oils. PAHs were not detected in the new oil; however, concentrations increased rapidly with usage in the gasoline engine of an automobile. The PAH distributions found were dominated by alkylated two- and three-ring compounds. The concentrations of these compounds increased until about 4000 miles and then levelled out. Four-ring compounds continually increased with miles driven, and the five-ring benzopyrenes were only detected in the oil used for the longest distance (about 5800 miles).     

GC/MS analysis of polynuclear aromatic hydrocarbons in sediment samples from the Niger Delta region

Thirteen sediment samples from different locations in the Niger Delta region of Nigeria were analyzed for the presence of 16 polynuclear aromatic hydrocarbons (PAHs) via gas chromatography/mass spectrometry. The specific target compounds for this study included naphthalene, acenaphthylene, acenaphthene, flourene, phenanthrene, anthracene, flouranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]flouranthene, benzo[a]pyrene, benzo[ghi]perylene, dibenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene. Four isotopically labeled polynuclear aromatic hydrocarbons (acanaphthene-d10, phenanthrene-d10, chrysene-d12 and perylene-d12) were used for internal standardization. All 16 PAHs were found in most of the thirteen samples with concentration ranging from 0.1 microg/kg to 28 microg/kg. It was also found that the 5 and 6-ring PAHs were present in higher concentrations than all the other compounds, indicating their high resistance to microbial degradation.     

Prediction of seawater solubility of aromatic compounds

The salting-out effect by seawater constituents on the water solubilities of 11 aromatic compounds, anthracene, pyrene, phenanthrene, biphenyl, naphthalene, p-nitrotoluene, p-toluidine, o-nitrophenol, m-nitrophenol, p-nitrophenol and phenol was investigated. A best fit equation (r = 0.965) for the salting-out parameters, K, and distilled water solubilities, S_o, at 20°C was found to be K = ?0.0298 log S_o + 0.114. Seawater solubilities, S, predicted for solutions of ionic strength, I, using the equation log S = (0.0298 I + 1) log S_o ? 0.114 I were in agreement with observed values within 13 % (average 4.8 %) and there were no significant differences between values from the Pacific Ocean seawater and those from 35 o/oo NaCl solutions. It was concluded that dissolved organic matter in seawater had an insignificant effect for the test chemicals.     

Oxygenated fuel induced cosolvent effects on the dissolution of polynuclear aromatic hydrocarbons from contaminated soil

The cosolvent-induced dissolution of polynuclear aromatic hydrocarbons (PAHs) from contaminated soil caused by oxygenated fuel spills was studied. Oxygenated fuel induces a solvent flushing effect on the contaminated soil due to the high content of oxygenated compounds (i.e., methanol, ethanol, and methyl tert butyl ether (MTBE)). The miscible displacement techniques were applied to evaluate the increased potential for secondary contamination in an impacted site. Significant solubility enhancement of the 18 PAHs monitored during fuel spill simulation and cosolvent flushing is clearly evident when compared to normal water dissolution. The breakthrough concentration profile for each PAH constituent was integrated over the cumulative effluent volume (i.e., the zeroth moment) to determine the total PAH mass removed during the experiment. The removal efficiency of PAHs ranges from 46.6% to 99.9% in three oxygenated fuels (i.e., M85, E85, and oxygenated gasoline) during the fuel spill. Several factors including hydrophobicity of compounds, nonequilibrium dissolution due to nonuniform coal tar distribution, and heterogeneous media properties affect the oxygenated compound-induced dissolution process. This study provides a basis to predict the facilitated transport of hydrophobic organic compounds from subsurface environment due to the cosolvent effects of oxygenated fuels.     

Polynuclear aromatic compounds in the ambient air of Stockholm

The abundance of 15 polynuclear aromatic compounds (PAC) in the ambient air in Stockholm have been monitored over a period of four years. Correlation was made between the concentrations of PAC and other simultaneously measured parameters.     

岩溶区多环芳烃的研究进展

多环芳烃(PAHs)是一类持久性有机污染物(POPs),普遍存在于环境介质中,其主要来自有机物的不完全燃烧或高温处理以及石油泄漏。PAHs进入大气后通过沉降和雨洗等途径进入地表和地下,在土壤和地下河沉积物中富集,因其难以转化,岩溶地下空间可能成为其最终归宿,成为潜在污染源,危害岩溶生态和人类健康。针对岩溶区的特殊性和脆弱性,综述了国内外对岩溶区PAHs的研究状况,并分析了中国岩溶区PAHs的污染水平,以期让中国岩溶区已遭受有机污染的事实引起关注和重视。     

石油炼化废水组成对厌氧氨氧化-反硝化细菌混培物的影响

为了探究石油炼化废水中COD和毒性物质对厌氧氨氧化-反硝化细菌混培物的影响,利用已具有高效脱氮性能的细菌混培物建立生物脱氮反应器进行连续驯化实验,实现进水COD和毒性物质比例的增加,并结合MPN-PCR技术对驯化前后两类菌群数量进行检测。结果发现,驯化前后厌氧氨氧化细菌数目由7.549×1014个·g-1减为8.212×108个·g-1,脱氮生化活性仍保持在40.2%左右;反硝化细菌数目由3.523×106个·g-1增为4.693×1016个·g-1,脱氮生化活性增加了5.76倍左右。结果表明,厌氧氨氧化细菌和反硝化细菌混培脱氮体系的脱氮生化活性未与细菌数目呈正相关性变化,COD和毒性物质对体系产生了不同程度的影响;厌氧氨氧化细菌比反硝化细菌对石油炼化废水毒性的作用更敏感;混培脱氮体系在一定程度上可以有效地抵抗石油炼化废水高浓度COD、高毒性物质对厌氧氨氧化生理生化脱氮过程的负面影响。