Degradation of bis(2-ethylhexyl) phthalate constituents under methanogenic conditions

The degradation of bis(2-ethylhexyl) phthalate (DEHP) and its intermediary hydrolysis products 2-ethylhexanol (2-EH) and mono(2-ethylhexyl) phthalate (MEHP) was investigated in a methanogenic phthalic acid ester-degrading enrichment culture at 37°C. 2-Ethylhexanoic acid (2-EHA), a plausible degradation product of 2-EH, was also studied. The culture readily degraded 2-EH via 2-EHA to methane which was formed in stoichiometric amounts assuming complete degradation of 2-EH to methane and carbon dioxide. MEHP was degraded to stoichiometric amounts of methane with phthalic acid as a transient intermediate. DEHP remained unaffected throughout the experimental period (330 days).Abbreviations 2-EH 2-ethylhexyl alcohol - 2-EHA 2-ethylhexanoic acid - BBP butylbenzyl phthalate - Be-CoA benzoyl Coenzyme A - CoA Coenzyme A - DEHP bis(2-ethylhexyl) phthalate - MEHP mono(2-ethylhexyl) phthalate - MSW municipal solid waste - PA phthalic acid - PAE phthalic acid ester - TMS trimethylsilyl derivative     

Anaerobic degradation of xenobiotics by organisms from municipal solid waste under landfilling conditions

The potential for biological transformation of 23 xenobiotic compounds by microorganisms in municipal solid waste (MSW) samples from a laboratory scale landfill reactor was studied. In addition the influence of these xenobiotic compounds on methanogenesis was investigated. All R11, 1,1 dichloroethylene, 2,4,6 trichlorophenol, dimethyl phthalate, phenol, benzoate and phthalic acid added were completely transformed during the period of incubation (> 100 days). Parts of the initially added perchloroethylene, trichloroethylene, R12, R114, diethyl phthalate, dibutyl phthalate and benzylbutyl phthalate were transformed. Methanogenesis from acetate was completely inhibited in the presence of 2,5 dichlorophenol, whereas 2,4,6 trichlorophenol and R11 showed an initial inhibition, whenafter methane formation recovered. No transformation or effect on the anaerobic microflora occurred for R13, R22, R114, 3 chlorobenzoate, 2,4,6 trichlorobenzoate, bis(2 ethyl)hexyl phthalate, diisodecyl phthalate and dinonyl phthalate. The results indicate a limited potential for degradation, of the compounds tested, by microorganisms developing in a methanogenic landfill environment as compared with other anaerobic habitats such as sewage digestor sludge and sediments.Abbreviations BBP benzylbutylphthalate - DEHP bis(2 ethylhexyl) phthalate - 3 CB 3 chlorobenzoate - R22 chlorodifluoromethane - CFC chlorofluorocarbon - R13 chlorotrifluoromethane - cis1,2 DCE cis 1,2 dichloroethylene - DBP dibutyl phthalate - R12 dichlorodifluoromethane - 1,1 DCE 1,1 dichloroethylenel - R114 dichlorotetrafluoroethane - 2,5 DCP 2,5 dichlorophenol - DEP diethyl phthalate - DiDP diisodecyl phthalate - DMP Dimethyl phthalate - DNP dinonyl phthalate - MSW dunicipal solid waste - PCE perchloroethylene - PA phthalic acid - PAE phthalic acid esters - R11 trichlorofluoromethane - 2,4,6 TCB 2,4,6 trichlorobenzoate - 2,4,6 TCP 2,4,6 trichlorophenol - VC vinylchloride     

电子垃圾拆解地区土壤和植物中邻苯二甲酸酯分布特征

近年来,电子垃圾不当拆解带来的环境问题引起国际社会的极大关注.本研究对浙江省台州市不同电子垃圾拆解地区土壤和植物样品中5种邻苯二甲酸酯类（PAEs）污染物进行了测定分析.结果表明：土壤（以干质量计）中PAEs类污染物的浓度为12.566~46.669 mg·kg^-1,其中邻苯二甲酸二异辛酯（DEHP）、邻苯二甲酸二丁酯（DBP）和邻苯二甲酸二乙酯（DEP）相对含量较高,约占PAEs总量的94%以上.拆解地区蚕豆（Vicia faba L.）中PAEs总量明显高于同地区其他植物,且土壤和所有植物体内PAEs浓度相关性均不显著(P>0.05).与美国国家环保局制定的土壤PAEs治理标准比较,台州电子垃圾拆解地区土壤PAEs污染较为严重.     

城市污泥和化肥对水稻土种植的通菜中邻苯二甲酸酯（PAEs）的影响

对水稻土施用城市污泥和化肥盆栽通菜,应用GC／MS联机检测技术对通菜中6种邻苯二甲酸酯化合物(PAEs)进行分析,探讨施肥对通菜中PAEs含量的影响,结果表明,各处理通菜中6种PAEs化合物的总含量(∑PAEs)在2．129～7.111mg·kg^-1之间,依次为广州污泥+化肥(7．111mg·kg^-1)>广州污泥(4．767mg·kg^-1)>佛山污泥(3;569mg·kg^-1)>佛山污泥+化肥(3．305mg·kg^-1)>化肥(2．638mg·kg^-1)>空白对照(2．129mg·kg^-1)。显示了施肥造成通菜中∑PAEs不同程度的提高,各处理通菜中的PAEs均以个别化合物为主,其中空白对照、化肥、佛山污泥和广州污泥处理的通菜中邻苯二甲酸丁基苄基酯(BBP)占∑PAEs的40％～81％。佛山污泥+化肥处理的通菜中邻苯二甲酸正二丁酯(DnBP)占∑PAEs的56％,而广州污泥+化肥处理的通菜中邻苯二甲酸丁基苄基酯(BBP)、邻苯二甲酸正二辛酯(DnOP)和邻苯二甲酸(2-乙基己基)酯(DEHP)各占∑PAEs的30％左右,通菜中∑PAEs和多数化合物的含量不同程度地大于其在根系中的含量。     

城市污泥与稻草堆肥中邻苯二甲酸酯（PAEs）的研究

将广州城市污泥与稻草进行翻堆、接菌-翻堆、连续通气和间歇通气4种方式的堆肥,应用GC／MS技术对堆肥中6种属于USEPA优控污染物的邻苯二甲酸醇化合物(PAEs)进行分析,探讨堆肥产物中PAEs的含量分布以及不同方式堆肥对PAEs的降解效果,结果表明,4种方式堆肥中PAEs总含量(∑PAEs)在9．815～17．832mg·kg^-1之间,依次为翻堆(17．832mg·kg^-1)>接菌-翻堆(13．927mg·kg^-1)>间隙通气(10．765mg·kg^-1)>连续通气(9．815mg·kg^-1),堆肥中PAEs以邻苯二甲酸正二辛酯(DhOP)为主,占∑PAEs的82．2％～89．696,不同方式堆肥中∑PAEs的降解率为连续通气(45．71％)>间隙通气(40．4696)>接菌-翻堆(22．97％)>翻堆(1．3796)(平均降解率为27．63％),其中邻苯二甲酸二乙醇(DEP)、邻苯二甲酸正二丁酯(DnBP)和邻苯二甲酸丁基苄基酯(BBP)的降解率分别为95．7696～98．6896、79．5696～99．46％和87．42％～98．42％;但邻苯二甲酸二甲酯(DMP)和邻苯二甲酸正二辛酯的含量反而增加,邻苯二甲酸(2-乙基己基)酯(DEHP)在所有堆肥中均未检出。     

Comparison on the removal of phthalic acid diesters in a bioreactor landfill and a conventional landfill

The removal of phthalic acid diesters (PAEs) in municipal solid waste (MSW) from two simulated landfill reactors was compared. The results showed that the original concentrations of dimethyl phthalate (DMP), dibutyl phthalate (DBP) and dioctyl phthalate (DOP) in the refuse were 3.3 μg g⁻¹, 18.5 μg g⁻¹ and 0.8 μg g⁻¹, respectively. The concentrations of DMP and DBP in both leachate and refuse decreased greatly during decomposition of the waste in both reactors. The major loss of PAEs from the landfill occurred during an active methanogenic environment with a low concentration of volatile fatty acids (VFA) in the later period. In addition, strong correlations were found between the residual DMP, DBP concentrations and the biologically degradable material (BDM) of the refuse. Finally, PAEs degraded more rapidly in the landfill that was operated in conjunction with the methanogenic reactor when compared to the landfill with direct leachate discharge.     

Kinetic analysis of the transformation of phthalate esters in a series of stoichiometric reactions in anaerobic wastes

Phthalates such as dimethyl phthalate, dimethyl terephthalate (DMT), diethyl phthalate (DEP), di(2-ethylhexyl) phthalate and mono(2-ethylhexyl) phthalate (MEHP) are degraded to varying degrees under anaerobic conditions in waste treatment systems. Here we kinetically analyse the enzymatic hydrolyses involved and the subsequent stoichiometric reactions. The resulting model indicates that the degradation of the alcohols released and the transformation of the phthalic acid (PA) result in biphasic kinetics for the methane formation during transformation of DMT, DEP and MEHP. The ester hydrolysis and the PA transformation to methane appear to be the two rate-limiting steps. The PA-fermenting bacteria, which have biomass-specific growth rates between 0.04 and 0.085 day⁻¹, grow more slowly than the other bacteria involved. Anaerobic microorganisms that remove intermediate products during phthalic acid ester conversion appear to be important for the efficiency of the ultimate phthalate degradation and to be inhibited by elevated hydrogen partial pressures. The model was based on (and the simulations corresponded well with) data obtained from experimental waste treatment systems.     

Phthalic Acid Esters in Soils from Vegetable Greenhouses in Shandong Peninsula,East China

Soils at depths of 0 cm to 10 cm, 10 cm to 20 cm, and 20 cm to 40 cm from 37 vegetable greenhouses in Shandong Peninsula, East China, were collected, and 16 phthalic acid esters (PAEs) were detected using gas chromatography-mass spectrometry (GC-MS). All 16 PAEs could be detected in soils from vegetable greenhouses. The total of 16 PAEs (Σ₁₆PAEs) ranged from 1.939 mg/kg to 35.442 mg/kg, with an average of 6.748 mg/kg. Among four areas, including Qingdao, Weihai, Weifang, and Yantai, the average and maximum concentrations of Σ₁₆PAEs in soils at depths of 0 cm to 10 cm appeared in Weifang, which has a long history of vegetable production and is famous for extensive greenhouse cultivation. Despite the different concentrations of Σ₁₆PAEs, the PAE compositions were comparable. Among the 16 PAEs, di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DnOP), di-n-butyl phthalate (DnBP), and diisobutyl phthalate (DiBP) were the most abundant. Compared with the results on agricultural soils in China, soils that are being used or were used for vegetable greenhouses had higher PAE concentrations. Among PAEs, dimethyl phthalate (DMP), diethyl phthalate (DEP) and DnBP exceeded soil allowable concentrations (in US) in more than 90% of the samples, and DnOP in more than 20%. Shandong Peninsula has the highest PAE contents, which suggests that this area is severely contaminated by PAEs.     

Direct LC-ES-MS/MS determination of phthalates in physiological saline solutions

A method for determining a group of phthalic esters (PAEs) in physiological saline solutions has been developed. The PAEs studied were dimethyl phthalate, diethyl phthalate, butyl benzyl phthalate and dibutyl phthalate. These groups of phthalates were determined by liquid chromatography–electrospray ionization-tandem mass spectrometry, working in positive ion mode. The compounds were separated by liquid chromatography working in gradient mode with acetonitrile–ultrapure water as a mobile phase. The separation was performed starting with 5% of acetonitrile and increasing to 75% in 5 min, followed by isocratic elution for 8 min. The method was precise (with relative standard deviation (RSD) from 1.0 to 6.8%) and sensitive, with LODs of 0.05, 0.38, 0.05 and 0.82 μg L^?1 for DMP, DEP, BBP and DBP, respectively. The proposed analytical method has been applied to determine these compounds in different physiological saline solutions commercialized in plastic bottles.     

地膜使用年限对遵义市烟田土壤和烟叶邻苯二甲酸酯累积的影响

研究地膜使用年限对土壤和烟叶邻苯二甲酸酯(PAEs)积累的影响,以明确地膜持续使用条件下PAEs的土壤污染分布特征及在烟叶中的富集状况.在遵义市连阡村和沙湾村采集了不同覆膜年限的烟田土壤及相应的烟叶,采用气相色谱仪质谱联用技术(GC-MS),对土壤-烟叶中6种优先控制PAEs含量进行了测定.结果表明: 所有土壤和烟叶样品中6种邻苯二甲酸酯化合物累计(∑PAEs)分别为(2.66±0.60)和(3.58±0.64) mg·kg^-1,其中,邻苯二甲酸二(2-乙基己)酯(DEHP)含量最高,邻苯二甲酸正二丁酯(DBP)次之,二者之和分别占土壤和烟叶∑PAEs的92.7%和88.9%.DEHP、DBP、邻苯二甲酸二乙酯(DEP)和邻苯二甲酸丁基苄基酯(BBP)检出率均为100.0%,邻苯二甲酸二甲酯(DMP)的检出率略低,邻苯二甲酸正二辛酯(DnOP)检出率最低.随着地膜使用年限的增加,土壤和烟叶中PAEs含量显著增加,且在地膜使用的前1~ 8年增加更为明显,后期趋于平缓.土壤和烟叶中的PAEs含量与覆膜年限呈显著正相关关系,覆膜年限的增加会显著促进土壤和烟叶中PAEs的积累.烟叶与土壤之间∑PAEs的累积量相关性不显著.     

Biodegradation of an endocrine-disrupting chemical, di-2-ethylhexyl phthalate, by Bacillus subtilis No. 66

A bacterial strain capable of rapidly degrading di-2-ethylhexyl phthalate (DEHP) was isolated from soil and identified as Bacillus subtilis. The organism also utilized di-butyl phthalate, di-ethyl phthalate, di-pentyl phthalate, di-propyl phthalate, and phthalic acid as sole carbon sources; and their biodegradation ratio was over 99%, when the incubation was performed for 5 days at 30°C. The microorganism degraded di-2-ethylhexyl phthalate and di-butyl phthalate through the intermediate formation of mono-2-ethylhexyl phthalate and mono-butyl phthalate, which were then metabolized to phthalic acid and further by a protocatechuate pathway, as evidenced by oxygen uptake studies and GC-MS analysis. The decontamination of soil polluted with di-2-ethylhexyl phthalate by B. subtilis was investigated. Experimental results showed that the strain could degrade about 80% of 5 mM DEHP simply by adding 8% culture medium to soil, indicating that the degradation can occur even when other organisms are present.     

Effects of three phthalate esters on the life-table demography of freshwater rotifer <Emphasis Type="Italic">Brachionus calyciflorus</Emphasis> Pallas

Phthalate esters (PAEs) are mainly used in the polymer industry as external plasticizers in PVC, and tend to migrate slowly out of the plastic, either into the air by volatilization or into water or other solvents by dissolution. Di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP) and di-2-ethylhexyl phthalate (DEHP) are three members of PAEs, identified as priority controlled hazardous substances by the United States Environmental Protection Agency, and have been shown to have potential for endocrine disrupting effects on vertebrates and humans. The effects of DBP, BBP and DEHP on survival and reproduction of the freshwater rotifer Brachionus calyciflorus were studied using life-table demographic methods. The results showed that all the life-table demographic parameters of B. calyciflorus were markedly affected by DBP and BBP, but not by DEHP. The net reproductive rate representing the output of reproduction was more affected than all the other parameters representing population growth, development or survival of the rotifers. Compared to the solvent control, DBP and BBP, both at 500 μg l⁻¹, significantly increased the net reproductive rate, and prolonged the generation time and the life expectancy at hatching of the rotifers. DBP at 50 μg l⁻¹ markedly decreased the intrinsic rate of population increase of the rotifers, but the reverse was true for BBP at 50 and 500 μg l⁻¹. Among all the parameters, the intrinsic rate of population increase was the most sensitive to DBP and BBP. The levels of PAEs in water from all the studied rivers and lakes in the world did not affect the population growth of rotifers.     

Determination of PAEs in soil of municipal wards of Patna,India by microwave assisted extraction and LC-MS/MS

Phthalic Acid Esters (PAEs) have become ubiquitous in environment due to unrestrained manufacture and use of plasticizers. The occurrence of PAEs in food, beverages, environmental and biological samples has been reported worldwide. PAEs are widely used in plasticizers for imparting flexibility and are not covalently bonded with the polymers, enabling PAEs to leach out due to change in pH and temperature. This study attempts to identify and quantify the PAEs in soil of Patna, India. Soil samples were collected from 22 municipal wards of Patna, Bihar. Microwave-Assisted Extraction (MAE) technique was applied for the extraction of PAEs followed by LC-MS/MS with electrospray ionization for the identification of different PAEs. Mono(4-pentenyl)phthalate (M(4P)P), Bis(2-hydroxyethyl) phthalate (BHEP), 2-Methylbutyl benzyl Phthalate (MBBP), Octyl Decyl phthalate (ODP), Heptadecyl trimethylsilyl phthalate (HDTMP), Magnesium phthalate (MgP), Diethyl Phthalate (DEP) and Dibutyl phthalate (DBP) were identified by LC-MS/MS. Interestingly, it was observed that soil samples of nine municipal wards were contaminated with high levels of maximum number PAEs identified in the study. Conclusively, the assessment of PAEs in soils samples is imperative for the management of environmental pollution generated by human activity.     

Biodegradation of phthalic acid esters (PAEs) in soil bioaugmented with acclimated activated sludge

The degradation characteristics of four phthalic acid esters (PAEs), i.e. di-methyl phthalate (DMP), di-ethyl phthalate (DEP), di-n-butyl phthalate (DBP) and di-n-octyl phthalate (DOP) in the soil augmented with acclimated sludge was investigated in order to assess the efficacy of bioaugmentation as a strategy for remediating PAEs-contaminated soil and correlate the degradation rate of PAEs with their alkyl chain length. The results demonstrated that PAEs with shorter alkyl chain, that is, DMP and DEP could be degraded more quickly than DBP and DOP. The degradation of four PAEs in the soil conformed to a first-order reaction kinetic equation. The half-lives of PAEs degradation decreased significantly with increasing carbon number of the alcohol moiety. Half-lives decreased from 2.29 days for DMP to 28.4 days for DOP when the carbon number of alkyl chain increased from one for DMP to eight for DOP. The degradation rate of PAEs and the corresponding half-lives could correlate with the alkyl chain length and their octanol–water partition coefficients (K_ow) quite well for the four PAEs tested in this study.     

Genotoxicity studies of di(2-ethylhexyl)phthalate and its metabolites in CHO cells

The widely used plasticizer di(2-ethylhexyl)phthalate (DEHP), its hydrolysis products mono(2-ethylhexyl)phthalate (MEHP) and 2-ethylhexanol, and also phthalic acid have been tested for clastogenic activity in cultured Chinese hamster ovary (CHO) cells. Only MEHP was found to cause chromosome damage. MEHP was without effect in the SCE and HGPRT mutation test in CHO cells. The clastogenicity of MEHP suggests a role for this compound in the observed carcinogenicity of DEHP and its positive effect in the dominant lethal assay.     

广东省典型区域农业土壤中邻苯二甲酸酯含量的分布特征

采用气相色谱方法,对广东省典型区域农业表层土壤(0～20cm)样品中的6种邻苯二甲酸酯(PAEs)进行了测定.结果表明:6种PAEs化合物的总含量(∑PAEs)为nd(未检出)～25.99mg.kg-1,其中92.8%的样品分布在≤1mg.kg-1的范围;各种土地利用类型中∑PAEs的顺序依次为水田>香蕉地>菜地>甘蔗地>果园地;不同地区土壤中∑PAEs的顺序依次为东莞市>汕头市>佛山市顺德区>湛江市>中山市>珠海市>惠州市.邻苯二甲酸二(2-乙基已基)酯(DEHP)的检出率最高(85.1%),邻苯二甲酸二正丁酯(DnBP)含量最高(nd～17.51mg.kg-1).与美国土壤PAEs控制标准相比,除邻苯二甲酸二正辛酯(DnOP)外,其余5种PAEs化合物均有不同程度的超标,其中DnBP、邻苯二甲酸二甲酯(DMP)和邻苯二甲酸二乙酯(DEP)3种化合物超标率较高.广东省典型区域农业土壤受到不同程度的PAEs污染.     

Biodegradation of diethyl phthalate in soil by a novel pathway

Biodegradation of diethyl phthalate (DEP) has been shown to occur as a series of sequential steps common to the degradation of all phthalates. Primary degradation of DEP to phthalic acid (PA) has been reported to involve the hydrolysis of each of the two diethyl chains of the phthalate to produce the monoester monoethyl phthalate (MEP) and then PA. However, in soil co-contaminated with DEP and MeOH, biodegradation of the phthalate to PA resulted in the formation of three compounds, in addition to MEP. These were characterised by gas chromatography-electron ionisation mass spectrometry and nuclear magnetic resonance as ethyl methyl phthalate, dimethyl phthalate and monomethyl phthalate, and indicated the existence of an alternative pathway for the degradation of DEP in soil co-contaminated with MeOH. Transesterification or demethylation were proposed as the mechanisms for the formation of the three compounds, although the 7:1 ratio of H(2)O to MeOH means that transesterification is unlikely.     

Modelling MSW decomposition under landfill conditions considering hydrolytic and methanogenic inhibition

A landfill typically progresses through a series of microbial degradation phases, in which hydrolysis, production and consumption of fermentation products, such as fatty acids, and methane formation play important roles. For ultimate degradation of the waste, stable methanogenic conditions have to be attained, and maintained for sufficient time. Using experimental data from 100-L landfill simulation reactors containing municipal solid waste from a residential area, a distributed model, which accounts for vertical water flow, was developed. As a first step, the waste was divided into two fractions: readily degradable and recalcitrant waste. Secondly, the general hydrolysis of the recalcitrant waste was accounted for by including a specific, well-defined chemical substance in the model that generally occurs in Municipal Solid Waste (MSW) and is hydrolysed before its further degradation to methane. For this purpose we chose diethyl phthalate and its hydrolysis product monoethyl phthalate, for which leachate data are available from the reactors. The model indicated that inhibition of the hydrolytic and methanogenic processes occurred during␣the acidogenic phase and that it could be overcome either by improving the chemical environment or by the complete oxidation of the inhibiting, i.e. the easily degraded, fraction of the waste. The generality of the model was confirmed by the patterns of the phthalate di- and monoester transformations obtained. The validity of the model was further confirmed using experimental data from parallel reactors, which were subjected to either leachate exchange with an already methanogenic reactor or to initial aeration to force the reactor into stable methanogenic conditions.     

Use of surfactants and slurrying to enhance the biodegradation in soil of compounds initially dissolved in nonaqueous-phase liquids

A study was conducted to find means of enhancing the biodegradation of hydrophobic organic compounds in nonaqueous-phase liquids (NAPLs). The effects of surfactants, identity of the NAPL and agitation was investigated. When present in NAPLs, phenanthrene, di-(2-ethylhexyl) phthalate (DEHP) and biphenyl were mineralized slowly in soil. Addition of Triton X-100 or Alfonic 810-60 did not enhance the degradation of phenanthrene initially in hexadecane or dibutyl phthalate. Slurrying the soil increased the rate and extent of mineralization of phenanthrene initially in hexadecane but not in dibutyl phthalate. Addition of either of the two surfactants to the slurries did not promote the transformation. Triton X-100, Alfonic 810-60 and Tergitol 15-S-9 below their critical micelle concentrations increased the rate and sometimes the extent of mineralization in soil slurries of phenanthrene initially in 2,2,4,4,6,8,8-heptamethylnonane, but other surfactants were not stimulatory. Slurrying the soil promoted the initial mineralization of DEHP initially in dibutyl phthalate, and Alfonic 810-60 and Triton X-100 further stimulated the rate and extent of degradation in the slurries. Alfonic 810-60 increased the extent of mineralization in slurries of biphenyl in hexadecane but not in dibutyl phthalate, cyclohexane, kerosene or two oils. Little mineralization of biphenyl or DEHP initially in dibutyl phthalate occurred in soil slurries, but Tween 80, Tergitol 15-S-40 and Tergitol 15-S-9 increased the extent of mineralization. However, vigorous agitation of the slurries of soil acclimated to DEHP or the use of small volumes of the NAPL resulted in marked enhancement of the degradation. Thus, biodegradation of constituents of NAPLs in soil can be increased by the use of some surfactants, slurrying or intense agitation, but the effect will vary with the NAPL and the constituents.