Risk assessment of polycyclic aromatic hydrocarbons (PAHs) in sediments from a mixed-use reservoir

Although reservoirs in China are of great significance, very few studies on risk assessment have been reported for reservoirs. This study investigated distribution characteristics, cancer and ecological risks, and source diagnosis of 16 priority polycyclic aromatic hydrocarbons (PAHs) in sediments from Shitou Koumen Reservoir in Jilin Province, China. A total of 12 sediment samples were collected from the reservoir in August (wet season) 2014. Total PAH concentrations in sediment samples ranged from 1294.51 ng/g to 2755.35 ng/g with a mean concentration of 1757.54 ng/g. For individual PAHs, average concentration of Nap was the highest, 800.56 ng/g, while Acy, Fla, BkF, and DahA were undetected in sediment samples. Light PAHs (2–3 rings) accounting for 74.21% was a dominant PAH compositional pattern. Pearson correlation analysis was carried out; results showed that total PAHs was strongly correlated with the highly enriched sedimentary PAHs, and pH was a major factor in controlling PAH distribution. Lifetime cancer risk was employed to assess cancer risk; results indicated that the fish-culturing area was exposed to cancer risk. The molecular diagnostic ratios of isomeric PAHs were applied to identify possible PAH sources; primary PAH sources were identified as oil-related activities, burning agricultural wastes, vehicular emissions, and industrial discharges.     

微生物降解多环芳烃(PAHs)的研究进展

从多环芳烃(PAHs)的降解菌株的筛选、降解机制以及PAHs污染的生物修复等方面介绍了微生物降解PAHs的最新研究进展。     

Uncertainty-based dynamic multimedia human health risk assessment for polycyclic aromatic hydrocarbons (PAHs) in a land oil exploitation area

With the increasing development of the petrochemical industry and the growing demand for oil, polycyclic aromatic hydrocarbons (PAHs) pollutions in the environment, especially in petroleum exploitation areas, are caused by the discharge of waste from the petroleum extraction process into an environmental system. This study aims to develop a new health risk assessment approach based on interval dynamic multimedia fugacity (IDMF) model and uncertainty analysis that could analyze the human exposure risk level for PAH contamination. The developed IDM health risk assessment (IDMHRA) approach is applied to assess previous, current, and future risks at a case study site in Daqing, Heilongjiang, China, from 1985 to 2020 for model validation. The human health risk assessment results show that 11 PAHs (NAP, ANT, FLA, PYR, BaA, CHR, BbF, BkF, BaP, IPY, and DBA) in the study site require further remediation efforts in terms of their unacceptable non-carcinogenic and carcinogenic risk. The results of risk source analysis reveal that soil media is the main risk pathway as compared with other exposure pathways. It can be seen that remediation process for soil contamination in the study site is urgently demanded. The assessment results demonstrate that the developed IDMHRA approach provides an effective tool for decision-makers and environmental managers to make remediation decisions in contaminated sites.     

Multispecies and monoculture rhizoremediation of polycyclic aromatic hydrocarbons (PAHs) from the soil

In this study, we investigated the potential of multispecies rhizoremediation and monoculture rhizoremediation in decontaminating polycyclic aromatic hydrocarbon (PAH) contaminated soil Plant-mediated PAH dissipation was evaluated using monoplanted soil microcosms and soil microcosms vegetated with several different grass species (Brachiaria serrata and Eleusine corocana). The dissipation of naphthalene and fluorene was higher in the "multispecies" vegetated soil compared to the monoplanted and nonplanted control soil. The concentration of naphthalene was undetectable in the multispecies vegetated treatment compared to 96% removal efficiencies in the monoplanted treatments and 63% in the nonplanted control after 10 wk of incubation. Similar removal efficiencies were obtained for fluorene. However, there was no significant difference in the dissipation of pyrene in both the mono- and multispecies vegetated treatments. There also was no significant difference between the dissipation of PAHs in the monoplanted treatments with different grass species. Principle component analysis (PCA) and cluster analysis were used to evaluate functional diversity of the different treatments during phytoremediation of PAHs. Both PCA and cluster analysis revealed differences in the metabolic fingerprints of the PAH contaminated and noncontaminated soils. However, the differences in metabolic diversity between the multispecies vegetated and monoplanted treatments were not clearly revealed. The results suggest that multispecies rhizoremediation using tolerant plant species rather than monoculture rhizoremediation have the potential to enhance pollutant removal in moderately contaminated soils.     

The unique aromatic catabolic genes in sphingomonads degrading polycyclic aromatic hydrocarbons (PAHs)

Many members of the sphingomonad genus isolated from different geological areas can degrade a wide variety of polycyclic aromatic hydrocarbons (PAHs) and related compounds. These sphingomonads such as Sphingobium yanoikuyae strain B1, Novosphingobium aromaticivorans strain F199, and Sphingobium sp. strain P2 have been found to possess a unique group of genes for aromatic degradation, which are distantly related with those in pseudomonads and other genera reported so far both in sequence homology and gene organization. Genes for aromatics degradation in these sphingomonads are complexly arranged; the genes necessary for one degradation pathway are scattered through several clusters. These aromatic catabolic gene clusters seem to be conserved among many other sphingomonads such as Sphingobium yanoikuyae strain Q1, Sphingomonas paucimobilis strain TNE12, S. paucimobilis strain EPA505, Sphingobium agrestis strain HV3, and Sphingomonas chungbukensis strain DJ77. Furthermore, some genes for naphthalenesulfonate degradation found in Sphingomonas xenophaga strain BN6 also share a high sequence homology with their homologues found in these sphingomonads. On the other hand, protocatechuic catabolic gene clusters found in fluorene-degrading Sphingomonas sp. strain LB126 appear to be more closely related with those previously found in lignin-degrading S. paucimobilis SYK-6 than the genes in this group of sphingomonads. This review summarizes the information on the distribution of these strains and relationships among their aromatic catabolic genes.     

Biodegradation of selected UV-irradiated and non-irradiated polycyclic aromatic hydrocarbons (PAHs)

Biodegradation of UV-irradiated anthracene, pyrene,benz[a]anthracene,and dibenz[a,h]anthracene was comparedto that of the non-irradiated samples, individuallyand in synthetic mixtures with enrichment cultures.Combined treatment was repeated for individual anthraceneand for the PAH mixture with Sphingomonas sp.strain EPA 505 and Sphingomonas yanoikuyae.Enrichment culture studies were performed on the PAHmixtures in the presence of the main photoproduct ofanthracene, pure 9,10-anthracenedione. Photochemicallypretreated creosote solutions were also subjected tobiodegradation and the results were compared tothose of the non-irradiated solutions. The primaryinterest was on 16 polycyclic aromatic hydrocarbons(PAHs) listed as priority pollutants by European Union(EU) and the United States Environmental ProtectionAgency (USEPA). Irradiation accelerated thebiodegradation onset for anthracene, pyrene, andbenz[a]anthracene when they were treatedindividually. The biodegradation of irradiatedpyrene started with no lag phase andwas complete by 122 h whereas biodegradation of thenon-irradiated sample had a lag of 280 h andresulted in complete degradation by 720 h. Biodegradation ofPAHs was accelerated in synthetic mixtures, especiallyin the presence of pure 9,10-anthracenedione.In general, irradiation had no effect on the biodegradation of PAHsincubated in synthetic mixtures or with pure cultures. Undercurrent experimental conditions, the UV-irradiation invariablyreduced the biodegradation of PAHs in creosote. Based onthe results of the present and previous photochemical-biologicalstudies of PAHs, the influence of the photochemical pretreatmenton the biodegradation is highly dependent on the compoundsbeing treated and other process parameters.     

Sorption of polycyclic aromatic hydrocarbons (PAHs) by dietary fiber extracted from wheat bran

The unintentional ingestion of carcinogenic xenobiotic substances leads to the high risk of cancer. Dietary fiber (DF) may protect against cancer by sorbing such chemicals. To this end, the sorption of four polycyclic aromatic hydrocarbons (PAHs) to DF extracted from wheat bran (WB) was studied. The strong affinity of PAHs to DF and WB indicated the effective binding of PAHs, and their distribution coefficients (K_d) positively increased with the increase in hydrophobicity of the PAHs. The DF had much higher K_d values for all PAHs compared to those of the unprocessed WB. The DF extraction process removed hydrophilic residues, such as starch, from WB, and increased the roughness of DF surface. Loss of hydrophilic components from WB to DF led to much higher affinity of DF with PAHs than WB. The results indicate that the DF can effectively sorb and remove xenobiotics, thereby having the potential to lower carcinogenic risk to humans.     

多环芳烃(PAHs)对油菜生长的影响及其积累效应

多环芳烃(PAHs)是持久性有机污染物(POP)之一, 通过大气沉降和污水灌溉能被植物吸收, 对食品生产安全和人类生命健康具有极大威胁。为探究PAHs对蔬菜作物的生长影响及毒害机理, 采用盆栽试验研究了不同浓度的荧蒽(FLU)和苯并[a]芘(B[a]P)单独胁迫下对油菜(Brassica chinensis)生长、生理和品质的影响及在油菜茎叶内的积累。结果表明: FLU和B[a]P在油菜茎叶内的积累量随着土壤中施加浓度的升高而增加, FLU胁迫下各处理间差异显著(p < 0.05), B[a]P胁迫下5.0和10.0 mg·kg^-1时积累量与对照(CK)相比显著(p < 0.05)增加, 10.0 mg·kg^-1时油菜茎叶内的最大B[a]P积累量没有超过我国食品安全标准; FLU和B[a]P对油菜叶长、叶宽和地上生物量的影响都是低浓度促进高浓度抑制; FLU和B[a]P胁迫下与CK相比株高和光合速率(P_n)值都显著(p < 0.05)降低; 对叶绿素含量的影响是低浓度促进高浓度抑制; 从总体来看, FLU胁迫对还原性维生素C (Vc)具有抑制作用, 5.0 mg·kg^-1时Vc含量最低, 而B[a]P胁迫下变化不规律, 在0.5 mg·kg^-1胁迫时与CK相比略有增加, 5.0 mg·kg^-1时含量最低。     

土壤－植物系统中多环芳烃和重金属的行为研究

对土壤中多环芳烃和重金属的行为研究表明,与对照相比,０—２０ｃｍ以上表土层存在多环芳烃和重金属积累,２０ｃｍ以下土层未发现积累;与春、秋两次采样结果相比,土壤中多环芳烃的含量有所下降,表明土壤微生物对多环芳烃有一定降解作用,且其降解程度与土壤－植物系统的生态结构有关．菲在地下水中检出浓度较高,表明这一污染物有向下迁移的可能性．此外,柳树对土壤中重金属Ｃｄ的积累有明显的削减与净化作用．本研究表明,严格限制污水中多环芳烃和重金属的污染负荷以及设计合理的生态结构是避免多环芳烃和重金属在土壤中积累的关键．     

土壤,植物样品中多环芳烃（PAHs）分析方法研究

土壤、植物和籽实样品分别用四氢呋喃、甲醇、乙酸乙酯以超声技术提取。提取液经旋转浓缩蒸发仪浓缩,经硅胶柱净化后,由高效液相色谱（ＨＰＬＣ）分离,萤光检测分析。对于土壤、植物和籽实样品,其方法回收率根据各个ＰＡＨ化合物的理化性质不同分别为４５．６８－９３．４２、７７．５９－１０８．１３和７９．１１－９８．９６％,结果表明,二氯甲烷、四氢呋喃适合作为土壤样品的提取剂;甲醇、乙酸乙酯分别适合于植物和籽实样     

Cumulative exposure assessment for trace-level polycyclic aromatic hydrocarbons (PAHs) using human blood and plasma analysis

Humans experience chronic cumulative trace-level exposure to mixtures of volatile, semi-volatile, and non-volatile polycyclic aromatic hydrocarbons (PAHs) present in the environment as by-products of combustion processes. Certain PAHs are known or suspected human carcinogens and so we have developed methodology for measuring their circulating (blood borne) concentrations as a tool to assess internal dose and health risk. We use liquid/liquid extraction and gas chromatography–mass spectrometry and present analytical parameters including dynamic range (0–250 ng/ml), linearity (>0.99 for all compounds), and instrument sensitivity (range 2–22 pg/ml) for a series of 22 PAHs representing 2–6-rings. The method is shown to be sufficiently sensitive for estimating PAHs baseline levels (typical median range from 1 to 1000 pg/ml) in groups of normal control subjects using 1-ml aliquots of human plasma but we note that some individuals have very low background concentrations for 5- and 6-ring compounds that fall below robust quantitation levels.     

Molecular biology approaches for understanding microbial polycyclic aromatic hydrocarbons (PAHs) degradation

The known or suspected hazards of polycyclic aromatic hydrocarbons (PAHs) have provoked enormous concentration and endeavours to relieve or eliminate these precarious compounds from miscellaneous environments including soil, water and air. Among various interventions, biodegradation is an appealing approach for its comparative high efficiency and preferable safety. Microorganisms played crucial role in biodegradation of PAHs. Traditional access mainly including culture-dependent procedures has discovered and isolated PAHs-degrading microorganisms which could be subsequently applied to specific contaminated locus. Although certain progress has been achieved owing to traditional methods, much details in PAHs bioremedation leave pending because of the complexity nature of this process. As the rapid development of biology, molecular techniques such as PCR, fingerprinting technique (mainly DGGE), DNA hybridization technique and gene reporters technique have been intensively applied to gain further insight into the mechanism of PAHs degradation. These techniques not only proved the existence and role of uncultivable microorganisms in the whole population of PAHs degrading related microbials, but also made it possible to revealed the otherwise undetectable complex relationships between multi-microorganism concerned in PAHs biodegradation. Application of such techniques in the field of PAHs biodegradation were reviewed in this article.     

Molecular biology approaches for understanding microbial polycyclic aromatic hydrocarbons (PAHs) degradation

The known or suspected hazards of polycyclic aromatic hydrocarbons (PAHs) have provoked enormous concentration and endeavours to relieve or eliminate these precarious compounds from miscellaneous environments including soil, water and air. Among various interventions, biodegradation is an appealing approach for its comparative high efficiency and preferable safety. Microorganisms played crucial role in biodegradation of PAHs. Traditional access mainly including culture-dependent procedures has discovered and isolated PAHs-degrading microorganisms which could be subsequently applied to specific contaminated locus. Although certain progress has been achieved owing to traditional methods, much details in PAHs bioremedation leave pending because of the complexity nature of this process. As the rapid development of biology, molecular techniques such as PCR, fingerprinting technique (mainly DGGE), DNA hybridization technique and gene reporters technique have been intensively applied to gain further insight into the mechanism of PAHs degradation. These techniques not only proved the existence and role of uncultivable microorganisms in the whole population of PAHs degrading related microbials, but also made it possible to revealed the otherwise undetectable complex relationships between multi-microorganism concerned in PAHs biodegradation. Application of such techniques in the field of PAHs biodegradation were reviewed in this article.     

Aerobic bacterial degradation of polycyclic aromatic hydrocarbons (PAHs) and its kinetic aspects

Aerobic bacterial degradation of PAHs is reviewed. Particular attention is paid to its kinetic aspects (rate and specificity). The general concepts of PAH biodegradation in nature and the role of aerobic bacteria in this process are described. The problem of PAH bioavailability and the mechanism of PAH penetration through bacterial cell wall are discussed. The key role of the reaction of PAH hydroxylation in controlling the rate and specificity of PAH biodegradation process is substantiated. The effects of competitive inhibition, intermediate inhibition, cross induction, and cometabolism are considered. The importance of microbial communities for PAH biodegradation in natural ecosystems is shown. The review contains the list of 138 references.     

Binding of polycyclic aromatic hydrocarbons (PAHs) to teleost aryl hydrocarbon receptors (AHRs)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous, environmental contaminants that pose a potential risk to fish populations. Both field and laboratory studies suggest that exposure of the early life stages of fish to PAH can mimic the embryotoxic effects of the planar halogenated hydrocarbons (PHHs), the most potent of which is 2,3,7,8-tetrachlorodibenzo-p-dioxin. PHH toxicity is mediated by the aryl hydrocarbon receptor (AHR) and PHH potency is predicted by its AHR-binding affinity and CYP1A induction potency. However, the role of the AHR, if any, in mediating the developmental effects of PAH to fish remains unknown. In this study we looked at the AHR binding affinity of a test set of PAH that had been previously ranked for their potency for inducing teleost CYP1A. PAH that induced CYP1A inhibited [3H]TCDD binding to in vitro-expressed AHRs from rainbow trout and the AHR expressed in PLHC-1 fish hepatoma cells. Generally, the relative rank order for AHR binding affinity predicted the rank order of these same PAH for inducing CYP1A reported in other studies. There was a strong, positive relationship between binding to the PLHC-1 AHR (stimulus) and the EC50s for CYP1A induction (response) in whole juvenile trout and in RTL-W1 cells, but EC50s were much higher than expected for a 1:1 stimulus/response relationship. These data show that the ability of PAH to bind to teleost AHR predicts PAH potency for CYP1A induction. If PAH toxicity is receptor-mediated and predicted by induction potencies, we will have a powerful mechanistic-based tool for rapidly assessing the risk of toxicity to fish of PAH from any source.     

白洋淀土壤中多环芳烃的分布特征及来源

采用气相色谱质谱联用仪检测了白洋淀表层(0～20 cm)和亚表层(20～30或农田30～40 cm)土壤中16种多环芳烃的含量。结果表明：表层土壤中多环芳烃总量的变化范围为146.0～645.9 ng·g^-1,平均含量为417.4 ng·g^-1;亚表层土壤中多环芳烃总量的变化范围为43.0～394.5 ng·g^-1,平均含量为152.4 ng·g^-1。表层土壤中多环芳烃含量与有机碳含量相关性不显著,亚表层土壤中多环芳烃含量与有机碳含量呈显著正相关(P<0.01),这可能表明了土壤埋藏改造过程中PAHs与土壤有机相结合程度不断加强,以及土壤中不同环数多环芳烃的环境行为差异,总体上看,与高环(≥4环)多环芳烃相比,萘、菲等低环(2～3环)多环芳烃更容易向下层迁移。PAHs的源解析分析表明,白洋淀表层土壤的多环芳烃表现出显著的以生物质和煤燃烧为主的源特征,这与淀区的人为活动,如秸秆燃烧等相关。     

Effectiveness of phytoremediation as a secondary treatment for polycyclic aromatic hydrocarbons (PAHs) in composted soil

A greenhouse study was conducted over a 12-month period to investigate the fate of polycyclic aromatic hydrocarbons (PAHs) in soil using phytoremediation as a secondary treatment. The soil was pretreated by composting for 12 weeks, then planted with tall fescue (Festuca arundinacea), annual ryegrass (Lolium multiflorum), and yellow sweet clover (Melilotus officinalis). Two sets of unvegetated controls also were evaluated, one fertilized and one unfertilized. Total PAH concentrations decreased in the tall fescue, annual ryegrass, and yellow sweet clover treatments by 23.9%, 15.3%, and 9.1%, respectively, whereas the control was reduced by less than 5%. The smaller two- and most of the three-ringed compounds--naphthalene, acenaphthylene, acenaphthene, fluorene, and anthracene--were not found in detectable concentrations in any of the treatments. The most probable number analysis for microbial PAH degraders did not show any statistically significant differences among treatments. There were significant differences among treatments (p < 0.05) for the residual concentrations of five of the target PAHs. Root surface area measurements indicated that tall fescue and annual ryegrass both had significantly higher root surface area than yellow sweet clover, although the two species were not significantly different from each other. The tall fescue treatment resulted in the highest root and shoot biomass, followed by annual ryegrass and yellow sweet clover, and also had the highest percent of contaminant removal after 12 months. These results imply a positive relationship between plant biomass development and PAH biodegradation.     

Health risk assessment of atmospheric polycyclic aromatic hydrocarbons over the Central Himalayas

Carcinogenic risk assessments of polycyclic aromatic hydrocarbons (PAHs) in four sites from the Central Himalayas (Bode, Lumbini, Pokhara, and Dhunche) were performed. Lifetime Average Daily Dose (LADD), Lifetime lung cancer risk (LLCR) and Incremental lifetime cancer risk (ILCR) were calculated in order to evaluate the cancer risk. PAHs levels were converted to BaP equivalent concentrations (B[a]Peq), and models of health risk assessment were applied. B[a]Peq concentrations exceeded the standard limited value (1 ng/m³) in all the four sites. The human health risk assessment (HHRA) demonstrated high carcinogenic risk on residents of Bode and Lumbini. Further, LLCR in all sites were over the acceptable range (1.15E-03, 7.90E-04, 1.40E-04 and 9.96E-05, respectively); however, ILCR ranking exhibited acceptable range in Lumbini, Pokhara, and Dhunche (7.10E-06, 1.26E-06, and 8.95E-07). The risk variation among the sites is due to the difference in pollution status. The study shows health risk due to atmospheric PAHs via inhalation prevails all the seasons throughout, differing only seasonally; nevertheless, the concentration and carcinogenic risk decreased remarkably from south-north transect of the central Himalaya. Keeping some uncertainties aside, this study provides noble insights and helps to formulate new advance assessment on the carcinogenic risk of atmospheric PAHs over the Central Himalayas.     

Characterization,source apportionment,and human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in road dust of a small island state in the Caribbean

Sixty-four and fifty-six road dust samples were collected over two seasons from various locations throughout the island of Trinidad and analyzed for the 16 priority PAHs. Total PAH concentrations ranged from 21 ng g^?1 to 4723 ng g^?1 (d.w.) for the rainy season and 36 ng g^?1 to 2428 ng g^?1 (d.w.) for the dry season. The Σ4–6 ring PAHs accounted for 88% and 63% of the 16 PAHs in road dust samples for the rainy and dry seasons, respectively. PAH diagnostic ratios, principal component analysis, and cluster analysis revealed both pyrogenic and petrogenic sources in road dust for the two seasons, with major contributions from vehicular emissions. Contributions from incomplete combustion and petroleum sources were also identified. The estimated Incremental Lifetime Cancer Risk (ILCR) associated with exposure to road dust PAHs in Trinidad for the rainy and dry seasons indicated no potential risk for both children and adults, as denoted by ILCR values lower than 10^?6.