Formation of polycyclic aromatic hydrocarbons in northern and middle taiga soils

An integrated study of the qualitative and quantitative composition of polycyclic aromatic hydrocarbons (PAHs) in the atmospheric precipitation-soil-lysimetric water system was performed using high performance liquid chromatography. It was shown that the accumulation of low-molecular PAHs (phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, and chrysene) in soils is due to the transformation of organic matter and the regional transport and deposition of PAHs with atmospheric precipitation on the underlying surface. High-molecular polyarenes (benz[b]fluoranthene, benz[k]fluoranthene, benz[a]pyrene, dibenz[a,h]anthracene, benzo[ghi]perylene, and indeno[1,2,3-cd]pyrene) mainly result from the decomposition of soil organic matter.     

Contamination of soils in the urbanized areas of Belarus with polycyclic aromatic hydrocarbons

The content of polycyclic aromatic hydrocarbons (PAHs) in the soils of urbanized areas, including the impact zones of Belarus, were studied. The concentrations of 16 PAHs in the soils were determined for individual and high-rise building zones, forests, and forest parks of Belarus. The levels of the PAH accumulation in the soils of different industrial enterprises and boiler stations were analyzed. Possible sources of soil contamination with PAHs were considered, and the structure of the PAHs in the soils was shown. The levels of the soil contamination were determined from the regulated parameters for individual compounds and the sum of 16 PAHs.     

生物表面活性剂强化微生物修复多环芳烃污染土壤的初探

通过温室盆栽实验,单独或联合接种多环芳烃专性降解菌(DB)和添加生物表面活性剂-鼠李糖脂(RH),研究了生物表面活性剂强化微生物修复多环芳烃(PAHs)长期污染土壤的效果。结果表明,添加RH和接种DB能明显促进土壤中PAHs总量和各组分PAHs的降解。经过90 d培养后,添加RH、DB和RH+DB处理的PAHs的降解率分别为21.3%、32.6%、36.0%,较对照分别提高了333.0%、563.3%、633.0%。此外,随着苯环数的增加,土壤中15种PAHs平均降解率逐渐降低。同时也发现DB、RH+DB处理土壤中脱氢酶活性、多酚氧化酶活性和PAHs降解菌数量显著高于CK、RH处理,但是CK与RH处理没有显著差异,说明DB、RH在促进土壤中PAHs的降解方面有不同的机制。     

湛江市区不同利用类型土壤的PAHs污染特征和来源

首次对湛江市表层土壤PAHs污染进行研究,并根据利用类型对其进行分类讨论。虽然湛江市的环境质量在全国名列前茅,但研究显示随着重化工业的快速发展,湛江市土壤已受到一定程度的PAHs污染,∑PAHs的平均含量达491.1ng.g-1,低于珠三角的发达城市,而高于中等城市,特别是某些工业区污染严重,超过荷兰相关标准;与其它城市一样,湛江市土壤PAHs的组分构成以4环和5环为主,占∑PAHs的65.1%。∑PAHs的变化趋势为旧厂址>市区工业区>交通>郊区工业区>休闲>农业,市区>郊区;3环组分比重随市中心距离的增大而增加,4环和5环则相反,6环差异较小。农业和郊区工业高比重的3环组分可能与市区石油源PAHs的大气输送有关。已搬迁工厂高含量∑PAHs表明PAHs在土壤的积累影响是长期的,而休闲区178.7 ng.g-1的∑PAHs则表明解决PAHs的污染问题必须解决污染源问题。利用4种PAHs比值判断湛江市土壤PAHs的来源主要是石油源、石化燃烧和煤、柴等生物燃烧源的混合源,与湛江市社会经济情况相符。     

Concentrations and composition of polycyclic aromatic hydrocarbons in the granulodensimetric fractions of soils in Moscow parks

A comprehensive study of the contents and composition of 15 compounds from the group of polycyclic aromatic hydrocarbons in granulodensimetric fractions of soddy-podzolic soils was performed. The specificity of the accumulation of these substances in the clay (heavy-weight) and light-weight soil fractions was investigated. The levels of the soil contamination in Moscow parks with polyarenes were determined, and the assessment of changes in the degree of the soil contamination over a long period of time was made.     

多环芳烃污染土壤的植物-微生物联合修复初探

在温室盆栽条件下,通过种植紫花苜蓿单独或联合接种菌根真菌(Glomus caledonium L.)(AM)和多环芳烃专性降解菌(DB),研究了利用植物-微生物强化修复多环芳烃(PAHs)长期污染土壤的效果。试验结果表明,接种菌根真菌和PAHs专性降解菌能促进紫花苜蓿的生长和土壤中PAHs的降解。经过90天修复试验,种植紫花苜蓿接种AM、DB和DB+AM处理的PAHs的降解率分别为47.9%、49.6%、60.1%,均高于只种植紫花苜蓿的对照处理(CK)(21.7%)。另外,随着PAHs苯环数的增加,其平均降解率逐渐降低,但是接种PAHs专性降解菌能够提高4环和5环PAHs的降解率。同时也发现土壤中脱氢酶活性和PAHs降解菌数量越高的处理,土壤PAHs的降解率也越高,这也是种植紫花苜蓿接种微生物能够有效促进土壤PAHs降解的原因。     

Polycyclic aromatic hydrocarbons in soils of Moscow

The contents of polycyclic aromatic hydrocarbons (PAHs) in the upper horizons of Moscow soils range up to 1400 mg/kg for individual compounds and up to 10000 mg/kg for their sum. The concentration coefficients of PAHs in the soil vary from 0.7 to 200 depending on individual polyarene properties and land use. The heavy polynuclear structures of technogenic origin have the highest concentration coefficients. The highest accumulation of PAHs is observed for the soils of dumping sites, residential-transport areas, and industrial zones. According to the state sanitary norms set in the Russian Federation for the content of benzo[a]pyrene in soils, more than one-third of the urban soils studied are classified as pure, and about half soils are classified as acceptable.     

Distribution of polycyclic aromatic hydrocarbons in the soil-plant system

The content and composition of the polycyclic aromatic hydrocarbons (PAHs) in the conjugated systems of [arable soil]-[above-ground plant organs] in background (reference) and contaminated regions were studied. The coefficients of the biological uptake of PAHs by plants (K _bPAH) were determined for different PAH concentrations in the soil. Correlations of the PAH accumulation rate in plants with the physicochemical properties of the PAHs—the solubility, hydrophobicity, volatility, and chemical activity (polarizability and ionization potential)—were revealed. The high accuracy, sensitivity, and information value of the standardized parameters K _b were shown (with K _bPAH as an example) for the quantitative study of the accumulation mechanisms of substances by plants compared to the average arithmetic values of their concentrations in the plants.     

Phytotoxicity of polycyclic aromatic hydrocarbons to willow trees

The toxicity of PAH to willow trees(Salix alba, S. viminalis, S. viminalis x schwerinii) was investigated. Willow cuttings were grown in PH-saturated hydroponic solution (naphthalene NAP, phenanthrene PHEN and benzo(a)pyrene BaP). Toxicity was related to aqueous solubility and was highest for NAP. PHEN did not show significant effects, except in one case. Exposure of trees to BaP showed no effect in two cases, but increased transpiration and growth in two others. High dosages of NAP were fatal for the trees, the lowest dosage significantly stimulated growth. Soil samples were taken from several PAH contaminated sites, among them gas works sites and a former sludge basin. The PAH contents ranged from 1.76 mg/kg to 1451 mg/kg. None of the soils was lethally toxic to the trees, and difference between growth in control soils and growth in PAH contaminated soils was not apparent. Growth and water use efficiency were positively, but not significantly correlated to the PAH content of the soils. Outdoor growth of willows and poplars on the former sludge basin in Valby was monitored, with willows growing faster than poplars(Fopulus trichocarpa). Phytotoxic effects could be observed at some willows at the Valby sludge basin, but it is not sure whether these effects can be contributed to PAH.     

丛枝菌根作用下土壤中多环芳烃的残留及形态研究

采用盆栽试验方法,以苊为多环芳烃(PAHs)代表物,研究了丛枝菌根(AM)作用下土壤中 PAHs 的残留及形态.供试污染土壤中苊的起始浓度为 35.0 mg/kg.结果表明,AM作用下土壤中苊总残留量明显降低;接种摩西球囊霉菌Glomus mosseae或幼套球囊霉菌Glomus etunicatum后,供试两个污染土样中苊总残留降解率达32.7%～45.2%,比未接种对照高 6.8%～9.8%.有机溶剂提取态是土壤中苊残留的主要部分,AM 作用促进了苊各形态之间的转化;接种AM后土壤 1、2 中苊可脱附态和有机溶剂提取态残留量分别比对照降低了17.0%～37.8% 和 5.4%～26.6%,而结合态残留量比对照增加了12.2%～89.5%.AM 作用能降低土壤中苊可提取态残留含量;但培养55 天后土壤中仍有 65.7%～81.7% 苊属于可提取态残留,对生物有毒害风险.     

Sorption of polycyclic aromatic hydrocarbons to mineral surfaces

Minerals contribute crucially to the retention of polycyclic aromatic hydrocarbons (PAHs) in subsurface environments. To investigate the sorption behaviour to mineral surfaces batch sorption experiments were conducted using three PAHs (phenanthrene, pyrene, benzo(a)pyrene) and three mineral sorbents that were representative of subsurface materials (quartz, goethite‐coated quartz, quartz‐montmorillonite mixture). Sorption kinetics showed an instantaneous, considerable PAH sorption to all minerals, except for phenanthrene sorption to quartz at small aqueous‐phase concentrations. Apparent sorption equilibrium was achieved after 4 hours of contact time. The sorption characteristics were fitted to six isotherm models by applying Monte Carlo simulation and nonlinear regression. Best‐fit models were obtained by a model discrimination approach. Phenanthrene and pyrene sorption were best described by the Freundlich isotherm model, with the exception of phenanthrene sorption to quartz (linear isotherm). Good fit results for quartz were also obtained for the combined linear‐Freundlich isotherm. Benzo(a)pyrene sorption to all minerals followed linear high‐affinity isotherms. In the case of phenanthrene and pyrene, the Monte Carlo simulations resulted in mean values with small standard deviations for the isotherm parameters, indicating a negligible influence of the experimental uncertainties on the accuracy of the fitted parameters. For phenanthrene, (i) linear isotherms to quartz and goethite‐coated quartz and (ii) a nonlinear concave‐shaped isotherm to quartz–montmorillonite, assuming a pore‐filling process to micropores formed by clay aggregates, were confirmed. For pyrene, nonlinear convex‐shaped isotherms to the mineral surfaces were assessed. A specific sorption affinity of pyrene to the goethite surface indicated a non‐covalent cation‐π interaction. Small sorption affinities to quartz–montmorillonite support an unfavourable partitioning into the adjacent water.     

多环芳烃微生物降解机理研究进展

主要阐述了微生物降解PAHs的机理,比较了典型微生物种类芽孢杆菌(Bacillus)和分支杆菌(M.vanbaalenii PYR-1)对同种PAHs菲的代谢过程不同之处,并分析了分支杆菌(M.vanbaalenii PYR-1)对菲和芘的代谢机理,指出微生物氧化降解PAHs主要从其K区和湾区开始,而K区氧化是有毒PAHs降解的主要可能途径,资料显示真菌比细菌对苯并[a]芘的降解能力更强,同时给出了微生物代谢菲、芘和苯并[a]芘的降解图,以便做进一步研究。     

Extraction of polycyclic aromatic hydrocarbons from spiked soil

A homogenization method was evaluated for extracting polycyclic aromatic hydrocarbons (PAHs) from soils. Fifteen PAHs were spiked and recovered from 2 soils at concentrations ranging from 1 to 1000 micrograms/g, using the homogenization method and a Soxhlet extraction method. Each extraction method performed well in removing the 15 PAHs from both soils over a broad range of concentrations. In general, Soxhlet extraction yielded slightly but significantly (P less than 0.05) higher recoveries than did the homogenization method. The homogenization method, however, was easy to use, and the extraction step turnaround time was less than 15 min/sample. The method should be suitable for other applications requiring the extraction of hydrophobic organic compounds from soils.     

Sorption of polycyclic aromatic hydrocarbons to soils enhanced by heavy metals: perspective of molecular interactions

Purpose

Combined pollution by polycyclic aromatic hydrocarbons (PAHs) and heavy metals are commonly found in industrial soils. This study aims to investigate the effect of the coexistence of heavy metals on the sorption of PAHs to soils. We focused specifically on the relationship of the sorption capacity with the estimation of the binding energy between PAHs and heavy metals.

Materials and methods

The sorption of typical PAHs (naphthalene, phenanthrene, and pyrene) to soils coexisting with heavy metals (Cu(II), Pb(II), and Cr(III)) was characterized in batch sorption experiments. The binding energy between PAHs and heavy metals in aqueous solution was estimated by quantum mechanical (QM) method using density functional theory (DFT) at the M06-2x/def2svp level of theory.

Results and discussion

Sorption capacity and nonlinearity of the PAHs to the soils were enhanced by the coexisting heavy metals. The extent of increment was positively associated with the hydrophobicity of the PAHs and the electronegativity and radius of the metal cations: Cr(III)?>?Pb(II)?>?Cu(II). The cation-π interaction was revealed as an important noncovalent binding force. There was a high correlation between the binding energies of the PAHs and K _f ′ (K _f adjusted after normalizing the equilibrium concentration (C _e) by the aqueous solubility (C _s)) (R ²?>?0.906), indicating the significant role of the cation-π interactions to the improved PAH sorption to soils.

Conclusions

In the presence of heavy metals, the sorption capacities of naphthalene, phenanthrene, and pyrene to soils were enhanced by 21.1–107 %. The improved sorption capacity was largely contributed from the potent interactions between PAHs and heavy metals.

     

Distribution of polycyclic aromatic hydrocarbons (PAHs) in floodplain soils of the Mosel and Saar River

Background, Aim and Scope  Polycyclic aromatic hydrocarbons (PAHs) have gained serious attention in the scientific community due to their persistence and toxic potential in the environment. PAHs may pose a risk to ecosystem health. Along the Mosel River/Germany, a tributary of the river Rhine, PAHs were found at significantly high concentrations (> 20 mg kg⁻¹, German national guideline value Z2, LAGA 1998). These high concentrations were detected during the construction of a storm water retention basin, in which the contaminated soils had to be removed and treated as hazardous waste. This resulted in higher construction costs for implementing flood prevention measures, but did not address the origin of these PAHs and its distribution along Mosel River. Hence, for future flood prevention projects, it is necessary to estimate the extent of PAH contamination along the Mosel River. The aim of the study is to determine the extent of PAH contamination in soils collected along Mosel and Saar River, and to obtain a first insight into the origin of the PAH contamination in this region. Materials and Methods  In total twenty seven sample sites were investigated. Forty two single samples were collected along a 167 km distance of Mosel River and six samples were collected along a 20 km distance of Saar River. Soil samples were collected at a depth of 0 to 2 m with a stainless steel corer (▫ 8 cm). Each 2 m sample was further separated into two sub-samples (0–1 m and 1–2 m). The sixteen EPA PAHs and three additional PAHs (1methylnaphthalene, 2methylnaphthalene and perylene) were analysed with gas chromatography mass spectrometry (GC-MS). For soil characterisation, total organic carbon (TOC), grain size, microscope and X-ray diffraction (XRD) analysis were performed. Results  Grain size for all soil samples was classified as a mixture of sand and silt. XRD analysis showed that all samples were dominated by quartz. Some clay minerals, such as illite and montmorillonite and feldspars, i.e. anorthoclase and orthoclase, were found in minor quantities. TOC ranged from 0.1% to 13%. Microscope analysis showed black coal particles in the majority of the soils collected from the Saar River and part of the Mosel River (downstream of the confluence of Saar and Mosel River). The black particles were not found further upstream along Mosel River. The sum of nineteen PAHs in the soil samples was up to 81 mg kg⁻¹ dry weight (dw). Most soil samples showed a relationship between the presence of coal particles and PAH concentrations. Discussion  Elevated PAH concentrations were found in all soil samples collected from Saar River and downstream Mosel River. Due to former coal mining activities in the Saarland, Germany, there is a strong evidence that the majority of the PAH contamination in the soils downstream Mosel River are linked to these mining activities. Upstream Mosel River coal particles were hardly found although PAH concentrations were high. Therefore another PAH source has to be responsible for these concentrations. PAH distribution patterns indicate a pyrogenic PAH input upstream Mosel River and a mixed input (petrogenic and pyrogenic) downstream Mosel River. Conclusions  Due to PAH distribution patterns, the contamination along the upstream of the Mosel River is probably linked to atmospheric depositions and other sources not linked to coal mining activities. Downstream Mosel River the PAH distribution patterns reflect former coal mining activities. We could corroborate for the first time that coal mining resulted in a serious problem of an extensive PAH contamination at Saar and Mosel River floodplain soils. Recommendations and Perspectives  Coal mining activities have a strong impact on the neighbouring regions (Johnson and Bustin 2006, Short et al. 1999, Stout et al. 2002). It is known that coals exhibit relative high PAH concentrations, especially in the low molecular weight PAHs (Chapman et al. 1996, Radke et al. 1990). However, PAHs in coals are hardly bioavailable (Chapman et al. 1996) and hence may have less adverse effects on exposed biota. They can act as sink for other hydrophobic contaminants. For the assessment of the environmental impact, a detailed study of the sorption and desorption behaviour of PAHs linked to coal particles should be carried out. ESS-Submission Editor: Dr. Ralph Portier (rportie@lsu.edu)     

城市土壤多环芳烃的特征和来源解析研究进展

Polycyclic aromatic hydrocarbons (PAHs) are mainly produced by combustion processes and consist of a number of toxic compounds.They are always emitted as a mixture and have become a major type of pollutants in urban areas.The degree of soil contamination by PAHs is of special concern in areas immediately in proximity to cities with heavy traffic,factories,older buildings,and infrastructure.The accumulation of soil PAHs is also affected by non-anthropogenic factors,such as climate,vegetation,and soil property.This paper reviews three typical source identification techniques,including diagnostic ratios,positive matrix factorization,and principle conrponents analysis.The advantages or disadvantages of these techniques are analyzed.It is recommended that multiple identification techniques be used to determine the sources in order to minimize the weaknesses inherent in each method and thereby to strengthen the conclusions for PAH source identification.     

Pyrogenic polycyclic aromatic hydrocarbons in soils of reserved and anthropogenically modified areas: Factors and features of accumulation

The accumulation features of pyrogenic polycyclic aromatic hydrocarbons (PAHs) in soils were analyzed depending on the type of burning material and the combustion conditions (the temperature, oxygen access, and dispersion of the combustion products). The PAH accumulation features in the soils of three reserved areas of forest, steppe, and peat fires were revealed. The distribution features of the PAHs resulting from the anthropogenic pyrogenic processes (the household combustion of wood and the inflammation of coal dumps) in soils were established. The differences in the qualitative composition of the PAHs arriving to the soils from the different pyrogenic sources were shown.     

Determination of monocyclic and polycyclic aromatic hydrocarbons in fish tissue

An analytical method is presented in which fish tissue is analyzed for neutral monocyclic and polycyclic aromatic hydrocarbons (AHs) and aromatic sulfur heterocycles (ASHs) by capillary column gas chromatography (CGC) with photoionization detection. The sample enrichment procedure includes saponification with aqueous KOH, acidification of the digestates, and extraction of the aromatic compounds into cyclopentane-dichloromethane. Adsorption chromatography on tandem segments of potassium silicate and silica gel removes 99% of the coextracted lipid. Final enrichment by gel permeation chromatography eliminates residual biogenic material and potentially interfering alkanes. Relatively volatile monoaromatics are included among the analytes by virtue of the efficiency of the complementary enrichment steps, the use of small quantities of only low-boiling solvents, and the selectivity of the detector. Most targeted compounds (AHs ranging in size from C3-alkylbenzenes through benzo[g,h,l]perylene and ASHs within the same size range) can be determined in 5 g (wet weight) samples of fish tissue at concentrations as low as 20 ng/g. Comparisons are made of recoveries of selected AHs under ordinary and gold fluorescent lighting conditions.