Anaerobic degradation of five polycyclic aromatic hydrocarbons from river sediment in Taiwan

This study investigated the anaerobic degradation of five polycyclic aromatic hydrocarbons (PAHs) from Erren River sediment in southern Taiwan. The degradation rates of PAH were in the order: acenaphthene > fluorene > phenanthrene > anthracene > pyrene. The degradation rate was enhanced when the five compounds were present simultaneously in river sediment. Comparison of the PAH degradation rates under three reducing conditions showed the following order: sulfate-reducing conditions > methanogenic conditions > nitrate-reducing conditions. The addition of electron donors (acetate, lactate and pyruvate) enhanced PAH degradation under methanogenic and sulfate-reducing conditions. However, the addition of acetate, lactate or pyruvate inhibited PAH degradation under nitrate-reducing conditions. The addition of heavy metals, nonylphenol and phthalate esters (PAEs) inhibited PAH degradation. Our results show that sulfate-reducing bacteria, methanogen and eubacteria are involved in the degradation of PAH; sulfate-reducing bacteria constitute a major microbial component in PAH degradation. Of the microorganism strains isolated from the sediment samples, we found that strain ER9 expressed the greatest biodegrading ability.     

混合表面活性剂-浊点萃取法测定沉积物中多环芳烃的含量

以混合型表面活性剂（十二烷基硫酸钠（SDS）和对叔辛基苯基聚己二醇醚（Triton X-114））为萃取剂,采用浊点萃取法萃取沉积物中的15种多环芳烃（PAHs）,并利用HPLC技术测定15种PAHs的含量。实验结果表明,当混合型表面活性剂的加入量 3％（w）、混合型表面活性剂中SDS含量 50%（φ）、Na2SO4含量 8％（w）、萃取温度 60 ℃、超声萃取时间 10 min 时,15种PAHs的线性关系良好,r=0.998 9~0.999 7,检出限0.4~8.2 μg/L,加标回收率71.22%~97.36%,相对标准偏差0.92%~4.36%（n=6）。     

Metabolism of nC11 fatty acid fed to Trichoderma koningii and Penicillium janthinellum II: Production of intracellular and extracellular lipids

Abstract

Little is known about the fungal metabolism of nC₁₀ and nC₁₁ fatty acids and their conversion into lipids. A mixed batch culture of soil fungi, T. koningii and P. janthinellum, was grown on undecanoic acid (UDA), a mixture of UDA and potato dextrose broth (UDA+PDB), and PDB alone to examine their metabolic conversion during growth. We quantified seven intracellular and extracellular lipid classes using Iatroscan thin-layer chromatography with flame ionization detection (TLC-FID). Gas chromatography with flame ionization detection (GC-FID) was used to quantify 42 individual fatty acids. Per 150 mL culture, the mixed fungal culture grown on UDA+PDB produced the highest amount of intracellular (531 mg) and extracellular (14.7 mg) lipids during the exponential phase. The content of total intracellular lipids represented 25% of the total biomass-carbon, or 10% of the total biomass dry weight produced. Fatty acids made up the largest class of intracellular lipids (457 mg/150 mL culture) and they were synthesized at a rate of 2.4 mg/h during the exponential phase, and decomposed at a rate of 1.8 mg/h during the stationary phase, when UDA+PDB was the carbon source. Palmitic acid (C_16:0), stearic acid (C_18:0), oleic acid (C_18:1), linoleic acid (C_18:2) and vaccenic acid (C_18:1) accounted for >80% of the total intracellular fatty acids. During exponential growth on UDA+PDB, hydrocarbons were the largest pool of all extracellular lipids (6.5 mg), and intracellularly they were synthesized at a rate of 64 μg/h. The mixed fungal species culture of T. koningii and P. janthinellum produced many lipids for potential use as industrial feedstocks or bioproducts in biorefineries.     

Charcoal burning as a source of polyaromatic hydrocarbons in waterpipe smoking

Polyaromatic hydrocarbons (PAH) content from seven commercial waterpipe charcoals were determined during the smoking process to estimate how much PAHs would not be trapped by the water trap and could reach the lungs of the smokers. Naphthalene, 2-methylnaphthalene, acenaphthylene, acenaphthene, phenanthrene and fluoranthene were the most abundant PAH compounds produced during smoking. Naphthalene was the highest in all of the smoke contents and levels of 5 to 405 μg/15 minutes could be inhaled by the smoker. The amounts of PAHs produced during the smoking events in absence of tobacco varied greatly among different brands of charcoal. The amount and composition of the emitted PAH were not related to the amount and composition of the original chemicals in the charcoal prior to burning. Our findings suggest that public health agencies should regulate smoked charcoal products alongside tobacco.     

紫外光(UV)光解油田采出水中多环芳烃

为了探讨紫外光光解人工模拟油田采出水中多环芳烃的降解效率,利用自制反应装置对油田采出水中多环芳烃(PAHs)的紫外光光解做了一个初步研究。研究结果证明,紫外光光解对油田采出水中的多环芳烃萘和芴有显著的降解能力。实验室的测试表明,与紫外UVA(365 nm)、UVB(308 nm)的光照相比,紫外UVC(254 nm)在光照60 min的条件下,2种多环芳烃各自的去除率都近似达到了99%。可见,在光解效力和暴露时间两方面,紫外UVC对采出水中萘和芴的去除具有相对稳定和比较高的效率。     

Modelling of iron cycling and its impact on the electron balance at a petroleum hydrocarbon contaminated site in Hnevice, Czech Republic

Over a period of several decades multiple leaks of large volumes from storage facilities located near Hnevice (Czech Republic) have caused the underlying Quaternary aquifer to be severely contaminated with nonaqueous phase liquid (NAPL) petroleum hydrocarbons. Beginning in the late 1980's the NAPL plume started to shrink as a consequence of NAPL dissolution exceeding replenishment and due to active remediation. The subsurface was classified geochemically into four different zones, (i) a contaminant-free zone never occupied by NAPL or dissolved contaminants, (ii) a re-oxidation zone formerly occupied by NAPL, (iii) a zone currently occupied by NAPL, and (iv) a lower fringe zone between the overlying NAPL and the deeper underlying contaminant-free zone. The study investigated the spatial and temporal variability of the redox zonation at the Hnevice site and quantified the influence of iron-cycling on the overall electron balance. As a first step inverse geochemical modelling was carried out to identify possible reaction models and mass transfer processes. In a subsequent step, two-dimensional (forward) multi-component reactive transport modelling was performed to evaluate and quantify the major processes that control the geochemical evolution at the site. The study explains the observed enrichment of the lower fringe zone with ferrihydrite as a result of the re-oxidation of ferrous iron. It suggests that once the NAPL zone started to shrink the dissolution of previously formed siderite and FeS by oxygen and nitrate consumed a significant part of the oxidation capacity for a considerable time period and therefore limited the penetration of electron acceptors into the NAPL contaminated zone.     

Toxic Environmental Releases from Medical Waste Incineration: A Review

Toxic releases from medical waste incineration comprising organic emissions such as polychlorinated dibenzo-dioxin/furan (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs), inorganic emissions and ashes containing toxic metals have been reviewed. Attempts made by various investigators to reduce/eliminate emissions have also been included. Legislations concerning emission standards for medical waste incinerators have been discussed.     

Lead and polycyclic aromatic hydrocarbons (PAHs) in surface soil from day care centres in the city of Bergen, Norway

Surface soil (0-2cm) quality in 87 day care centres in the city of Bergen, Norway has been studied. Approximately 45% of the day care centres contained Pb and PAH values above recommended action levels. There are clear variations between different areas of the city. The old central part of the city hosts most of the contaminated day care centres. In suburban areas most of the day care centres have Pb and PAH concentrations below action levels. City fires, gas work emission, lead-based paint, and traffic are probably important anthropogenic contamination sources, together with uncontrolled transportation of soil from contaminated to clean areas. Geological or other natural sources are probably not an important contributor to the high levels of lead and PAH.     

Linking chemical extraction to microbial degradation of 14C-hexadecane in soil

Chemical extractions have been shown to measure the biodegradable fraction of aromatic contaminants in soil; however, there is little research on the chemical prediction of aliphatic hydrocarbon degradation. The aim of this study was to investigate the potential for cyclodextrin extractions to predict hexadecane biodegradation in soil. Soils were amended with 10 or 100 mg kg⁻¹ of a model alkane n-hexadecane and 100 Bq g⁻¹¹⁴C-n-hexadecane. Correlations between the extents of mineralisation and extractions of the ¹⁴C-contaminant were determined. Solvent shake extractions and aqueous CaCl₂ extractions were poor predictors of hexadecane bioaccessibility. However, the novel HP-α-CD shake extraction showed close correlation (r² = 0.90, n = 36, p < 0.05) to the mineralisation data. This novel extraction technique has the potential to be used to assess the biodegradable aliphatic hydrocarbon fraction in contaminated soils.     

Estimation of the annual scavenged amount of polycyclic aromatic hydrocarbons by forests in the Pearl River Delta of Southern China

Leaves of six main tree species from the Pearl River Delta (PRD) in Southern China were collected to identify the interspecific variability, the spatial variability and the seasonal variations of polycyclic aromatic hydrocarbons' (PAHs) concentrations, and to calculate the amount of PAHs removed by leaves. PAHs concentrations in pine needles were much higher than in broad-leaves and leaves from urban/industrial areas (Baiyunshan and Heshan) exhibited two times greater concentrations than leaves from the rural area (Dinghushan). Seasonal variations of PAHs in leaves occurred with lesser concentrations in September. Leaves in PRD scavenged 3.7 ± 0.9 t PAHs y⁻¹, accounting for about 10% of the total amount emitted in this region. This result suggests that forests play an important role in the fate of PAHs.