Enhanced degradation of bioremediation residues in petroleum-contaminated soil using a two-liquid-phase bioslurry reactor

A study was performed to determine the potential of two-liquid-phase (TLP) bioslurry reactors using silicon oil as solvent for degradation of residual contaminants in petroleum-contaminated soil. The residues were characterized by gas chromatography–mass spectrometry and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. This allowed for the identification of a mixture of residual biomarkers, metabolic byproducts, oxygenated and hetero-polynuclear aromatic hydrocarbons in the contaminated soil. The removal amount of total extractable organics (TEO) was 15 900 mg kg⁻¹ soil in the TLP reactor within 12 weeks. However, TEO remained intact in the bioslurry reactor without the addition of silicon oil for the duration of the experiment, due to high toxicity of metabolites to the microorganisms. The availability of TEO was calculated using a mild extraction with Triton X-100, and the amount of TEO extracted was in accord with the amount of biodegraded TEO. Significantly reduced toxicity in soil was observed at week 12 through TLP remediation. Dehydrogenase activity in the bioslurry reactor was strongly suppressed. Fluorescein diacetate was significantly hydrolyzed by the composition of bioremediation residues in the contaminated soil. Microbial adhesion to the solvent was revealed by the determination of microbial activity in the water-immiscible-liquid.     

Comparison of atmosphere/aquatic environment concentration ratio of volatile chlorinated hydrocarbons between temperate regions and Antarctica

For the purpose of understanding the transport and deposition mechanisms and the air–water distribution of some volatile chlorinated hydrocarbons (VCHCs), their atmosphere/aquatic environment concentration ratio was evaluated. In addition, for the purpose of differentiating VCHC behaviour in a temperate climate from its behaviour in a polar climate, the atmosphere/aquatic environment concentration ratio evaluated in matrices from temperate zones was compared with the concentration ratio evaluated in Antarctic matrices.In order to perform air samplings also at rigid Antarctic temperatures, the sampling apparatus, consisting of a diaphragm pump and canisters, was suitably modified.Chloroform, 1,1,1-trichloroethane, tetrachloromethane, 1,1,2-trichloroethylene and tetrachloroethylene were measured in air, water and snow using specific techniques composed of a purpose-made cryofocusing-trap-injector (for air samples) and a modified purge-and-trap injector (for aqueous samples) coupled to a gas chromatograph with mass spectrometric detection operating in selected ion monitoring mode. The VCHCs were retrieved in all the investigated matrices, both Italian and Antarctic, with concentrations varying from tens to thousands of ng m⁻³ in air and from digits to hundreds of ng kg⁻¹ in water and snow.The atmosphere/aquatic environment concentration ratios were always found to be lower than 1. In particular, the Italian air/water concentration ratios were smaller than the Antarctic ones, by reason of the higher atmospheric photochemical activity in temperate zones. On the other hand, the Antarctic air/snow concentration ratios proved to be largely in favour of snow with respect to the Italian ratios, thus corroborating the hypothesis of a more efficient VCHC deposition mechanism and accumulation on Antarctic snow.     

Modelling the risk of Pb and PAH intervention value exceedance in allotment soils by robust logistic regression

Soils of allotments are often contaminated by heavy metals and persistent organic pollutants. In particular, lead (Pb) and polycyclic aromatic hydrocarbons (PAHs) frequently exceed legal intervention values (IVs). Allotments are popular in European countries; cities may own and let several thousand allotment plots. Assessing soil contamination for all the plots would be very costly. Soil contamination in allotments is often linked to gardening practice and historic land use. Hence, we predict the risk of IV exceedance from attributes that characterize the history and management of allotment areas (age, nearby presence of pollutant sources, prior land use). Robust logistic regression analyses of data of Swiss allotments demonstrate that the risk of IV exceedance can be predicted quite precisely without costly soil analyses. Thus, the new method allows screening many allotments at small costs, and it helps to deploy the resources available for soil contamination surveying more efficiently.     

新型菌株法检测典型环境雌激素类物质

相对于化学检测方法,生物法检测环境雌激素类污染物具有简便快捷等优点。利用本实验室已建立的环境雌激素类污染物的基因工程菌检测技术,对17-β-雌二醇(17-β-(o)estradiol)的雌激素活性进行了检测,绘制了标准曲线,确定其检测限为ng/L。并且利用该菌株法分别对艹屈(chrysene)、芘(pyrene)和苯并(a)蒽(benz(a)anthracene)3种不同结构的多环芳烃的雌激素活性进行了检测。结果显示,3种物质的雌激素活性差异明显,具有不同的检测限。此外,对污水和污泥样品中的麝香含量进行了检测,结果显示其活性变化趋势与化学法检测结果基本一致。因此,利用该基因工程菌检测技术可对环境样品中一定的雌激素活性进行快速有效地筛选;进一步对比17-β-雌二醇的标准曲线,可实现对雌激素类物质的初步定量。     

Persistent organic pollutants in plastic marine debris found on beaches in San Diego, California

Plastic debris were collected from eight beaches around San Diego County, California. Debris collected include: pre-production pellets and post-consumer plastics including fragments, polystyrene (PS) foam, and rubber. A total of n = 2453 pieces were collected ranging from <5 mm to 50 mm in size. The plastic pieces were separated by type, location, and appearance and analyzed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its breakdown products, and chlordanes. PAH concentrations ranged from 30 ng g⁻¹ to 1900 ng g⁻¹, PCBs from non-detect to 47 ng g⁻¹, chlordanes from 1.8 ng g⁻¹ to 60 ng g⁻¹, and DDTs from non-detect to 76 ng g⁻¹. Consistently higher PAH concentrations found in PS foam samples (300-1900 ng g⁻¹) led us to examine unexposed PS foam packaging materials and PS virgin pellets. Unexposed PS foam contained higher concentrations of PAHs (240-1700 ng g⁻¹) than PS virgin pellets (12-15 ng g⁻¹), suggesting that PAHs may be produced during manufacturing. Temporal trends of debris were investigated at one site, Ocean Beach, where storm events and beach maintenance were found to be important variables influencing debris present at a given time.     

Dechlorination of chlorinated hydrocarbons by bimetallic Ni/Fe immobilized on polyethylene glycol-grafted microfiltration membranes under anoxic conditions

In this study, the dechlorination of chlorinated hydrocarbons including trichloroethylene (TCE), tetrachloroethylene (PCE) and carbon tetrachloride (CT) by bimetallic Ni/Fe nanoparticles immobilized on four different membranes was investigated under anoxic conditions. Effects of several parameters including the nature of membrane, initial concentration, pH value, and reaction temperature on the dechlorination efficiency were examined. The scanning electron microscopic images showed that the Ni/Fe nanoparticles were successfully immobilized inside the four membranes using polyethylene glycol as the cross-linker. The agglomeration of Ni/Fe were observed in poly(vinylidene fluoride), Millex GS and mixed cellulose ester membranes, while a relatively uniform distribution of Ni/Fe was found in nylon-66 membrane because of its hydrophilic nature. The immobilized Ni/Fe nanoparticles exhibited good reactivity towards the dechlorination of chlorinated hydrocarbons, and the pseudo-first-order rate constant for TCE dechlorination by Ni/Fe in nylon-66 were 3.7-11.7 times higher than those in other membranes. In addition, the dechlorination efficiency of chlorinated hydrocarbons followed the order TCE > PCE > CT. Ethane was the only end product for TCE and PCE dechlorination, while dichloromethane and methane were found to be the major products for CT dechlorination, clearly indicating the involvement of reactive hydrogen species in dechlorination. In addition, the initial rate constant for TCE dechlorination increased upon increasing initial TCE concentrations and the activation energy for TCE dechlorination by immobilized Ni/Fe was 34.9 kJ mol⁻¹, showing that the dechlorination of TCE by membrane-supported Ni/Fe nanoparticles is a surface-mediated reaction.     

UV-Fenton催化氧化法对采油废水中多环芳烃的处理效果

针对采油废水中含有多环芳烃种类多且较难去除的特点,采用UV-Fenton技术对采油废水中多环芳烃的处理效果进行了研究,通过正交实验和单因素实验,研究了在254 nm波长紫外光照射下,Fe2+投加量、H2O2投加量、pH值和光照时间对水样中多环芳烃中的菲和芴处理效果的影响。实验结果显示,处理初始浓度为1 000μg/L的菲、芴时,反应的最佳工艺条件为:Fe2+浓度为1.8 mmol/L、H2O2投加量为0.15 mmol/L、pH值为4、光照时间1.25 h。在此条件下,菲和芴的去除率可达71.9%。     

红三叶草根际区石油降解菌的筛选及降解性能

从石油污染的土壤红三叶草（nifoliumrepensLinn）根际修复区中分离筛选得到4株以原油作为惟一碳源和能源进行生长繁殖的高效石油降解菌。通过菌落形态、显微镜个体形态观察、生理生化鉴定以及菌株16SrDNA序列分析,初步鉴定4株优势降解菌分别为动性杆菌、藤黄微球菌、蜡状芽孢杆菌和短小芽孢杆菌。采用气相色谱／质谱（GC／MS）法分析4株混合菌对石油烃的降解性能。结果表明：在摇床培养条件下,混合菌54d对总石油烃的生物降解率达到90．50％,较对照高67．72％。随着生物降解时间的延长,石油组分中的正构烷烃、异构烷烃及环烷烃相对总量均呈减小趋势,而芳香烃和其他醇类、醛和酸类的相对含量则有所增加。     

Spatio-Temporal Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Atmospheric Air of Tamil Nadu,India, and Human Health Risk Assessment

This study analyzed the seasonal distribution and the possible sources of polycyclic aromatic hydrocarbons (PAHs) in the atmospheric environment of Tamil Nadu, India. Passive air sampling was performed at 32 locations during the period from April 2009 to January 2010, and PAHs were quantified using a gas chromatograph-mass spectrometer. Analysis showed that the concentrations of PAHs were in the range of 5–47.5 ng/m³ with uniform distribution in urban areas in all seasons. Pre-monsoon season showed the highest cumulative concentration of PAHs in both agricultural and coastal areas. Among PAHs, phenanthrene, fluoranthene, and pyrene levels were found to be predominant in all the samples, contributing up to 36%, 35.5%, and 24.5% of total PAHs, respectively. The signature of the PAHs obtained through diagnostic ratio and principal component analysis revealed that diesel emissions was the probable source of PAHs in all locations. Based on Word Health Organization guidelines, the human lung cancer risk due to observed level of PAH concentration (i.e., PAHs exposure) is meager. However, the risk is predicted to be more in the coastal area during summer (18 individuals among 0.1 million people). To the knowledge of these authors, this report is the first on the seasonal analysis of PAHs using passive air sampling in India.     

石油污染土壤胶体特征及其稳定性

采集辽河油田石油污染土壤样品并用离心法提取胶体,定性和定量研究了石油污染土壤胶体的主要物理化学性质,通过间歇实验研究了不同p H(p H=4~9)、不同价态阳离子(Na+、Ca2+和Fe3+)和不同价态阴离子(NO-3、SO2-4和PO3-4)存在下的胶体稳定性,比较了阳离子存在下石油污染土壤胶体和未受污染土壤胶体稳定性。研究结果表明,该石油污染土壤胶体总石油烃含量为123.24 mg/g,石油烃主要为直链烷烃和环烷烃。相同p H条件下石油污染土壤胶体Zeta电位负值比未受污染土壤胶体Zeta电位负值高。石油污染土壤胶体稳定性随p H值增加而增加,随着阳离子价数升高而减小,随阴离子价数升高而增大。Ca2+和Cu2+存在下,石油污染土壤胶体比未受污染土壤胶体稳定性更小。Na+和Fe3+存在下,石油污染土壤胶体比未受污染土壤胶体稳定性更大。