石油烃对翅碱蓬生理特性的影响及植物-微生物联合降解

通过盆栽实验,测定在低浓度石油烃浓度下翅碱蓬的生长生理指标及沉积物和翅碱蓬中石油烃含量的变化,研究石油烃对翅碱蓬生理特性和抗氧化酶系统的影响及植物-微生物联合修复效果。结果表明,翅碱蓬抗氧化酶能够快速提高活性来抵御逆境,植株还可通过增加其叶绿素含量等来适应或补偿逆境造成的损失。同时还发现,当植物处于石油烃污染沉积物时,它体内污染物的分布会与自然情况下有所不同,自然情况下分布为茎>叶>根,受污染时分布为根>茎>叶,该结果可以作为判断沉积物是否受到污染的依据。实验的不同处理(加植物加菌组、只加菌未种植物组、种植物未加菌组)去除率分别为70.87%、63.66%和60.26%,翅碱蓬-降解菌处理的沉积物中石油烃残留浓度最低、去除量最高,表明植物-微生物联合作用更有利于石油烃污染沉积物的修复。     

不同处理条件对石油污染土壤植物修复的影响

针对石油烃植物修复过程中的主要影响因素,研究了不同植物种类、不同土壤调理剂和菌剂使用等不同条件对土壤中石油烃植物修复效果的影响.结果表明,不同种类的植物修复可使总石油烃的年降解率达到37.8％ ～ 73.98％,其中大豆和碱蓬具有较好的修复效果;3种不同土壤调理剂对石油烃污染土壤修复的效果为商业添加剂＞牛粪＞蛭石;先微生物修复后种植植物的处理要优于单独的微生物修复及微生物、植物修复同步进行的处理.     

土壤石油污染对植物种子萌发和幼苗生长的响应

研究了不同质量分数石油污染土壤对4种植物种子萌发和幼苗生长的影响,并对幼苗叶片的丙二醛(MDA)含量对污染胁迫的响应进行了研究,以期筛选适合石油污染土壤的潜在修复植物。设置了4组不同质量分数的石油污染土壤处理,对玉米(Zea mays L.)、高粱(Sorghum bicolor(L.)Moench)、披碱草(Elymus dahuricus Turcz.)和翅碱蓬(Suaeda hetroptera Kitag)4种供试植物进行了温室盆栽试验观测。结果表明,试验土属滨海盐渍土,在盐碱化和石油污染的双重胁迫下,不同的植物种子对石油污染表现出不同的耐受性;受试植物在10%(质量分数)石油污染处理下的发芽率均达80%以上,且石油的暴露水平越高,高粱、披碱草和翅碱蓬的种子发芽率越大;玉米和高粱的株高和根长均与土壤中石油浓度呈极显著正相关,而披碱草的根长则与之呈显著负相关;玉米的根冠比与土壤中石油浓度呈显著负相关,高粱和披碱草则与之相关性不明显;在石油污染土壤中生长的玉米和高粱,其叶片中MDA含量与空白对照组存在极显著差异,且随着污染土壤石油质量分数的升高呈现单峰响应特征;披碱草2个生长期(45、60d)叶片内的MDA含量均随土壤中石油浓度的升高而增加,土壤石油污染会对其造成毒害作用。总的来看,相比其他2种植物,高粱和披碱草具有较大的种子发芽率和石油污染耐受性,表明它们具有修复石油污染土壤的应用潜力。     

典型禾本科植物对石油污染土壤的修复作用

石油类污染物对土壤生态系统的结构与功能造成了较为严重的破坏,影响植物的生长,甚至直接影响到人类健康。选择典型禾本科植物-高粱和玉米,通过盆栽实验,种植于模拟石油污染的土壤中,植物成熟收割后,通过测定土壤中总石油烃的含量,植物体中多环芳烃和直链烷烃的含量,研究高粱和玉米对石油污染土壤的修复作用。结果显示:在种植高粱、玉米后,土壤中总石油烃含量明显降低,并且在收获的高粱、玉米植物体中直链烷烃和多环芳烃含量明显高于空白对照组(未检出)。说明高粱、玉米对石油烃具有一定的去除作用,且高粱对土壤中石油烃的去除作用高于玉米;高粱、玉米对土壤中的多环芳烃和直链烷烃具有一定的积累与富集作用。     

不同植物-微生物联合修复体系下石油烃的降解

石油烃作为环境中广泛存在的有机污染物之一,对人体健康造成严重的危害。以位于天津的大港油田原油污染土壤中筛选出的耐低温高效石油烃降解菌为供试菌株,以小麦、紫花苜蓿作为供试植物,比较不同类型植物以及不同的外源菌接种方式对石油降解的影响,并采用荧光素比色法分析荧光素二乙酸酯(FDA)酶活性随时间的变化规律。经过70 d的降解,原状土壤的总石油烃含量从30 720 mg·kg~(-1)下降为26 800 mg·kg~(-1),降解率为12.76%。相比于小麦,紫花苜蓿对石油烃的降解具有更好的促进效果,降解率为24.85%。接种菌悬液后再种植植物时,石油烃降解效果接近于单独接种菌悬液处理。小麦-固定化外源菌处理条件下,降解率为21.10%,实验后期石油烃的降解速率远远高于其他处理,表现出良好的修复潜力。FDA酶活性经历了先下降、后上升再下降直至平缓的过程,并且受到种植植物和投加外源菌的影响。     

石油降解菌的筛选及降解性能研究

从石油污染的土壤中分离驯化,得到特征明显的石油降解菌,研究了不同时间、石油浓度、接种量、pH值、基质及添加物等条件对降解菌降解石油的影响。结果表明：在实验条件下,降解菌接种量越多,降解效果越好;石油降解效率随着石油浓度的增加而降低;当初始pH值为7时,降解菌去除石油效果最佳;添加适量蔗糖或葡萄糖,对石油的降解有促进作用;吐温80对石油降解有一定的抑制作用。     

石油降解菌的筛选优化及其对油污土壤的修复特性

分别以牛肉膏蛋白胨-布氏哈斯培养基、蓝色凝胶培养基作为初筛和复筛培养基,从石油污染土壤中筛选出2株可产生微生物表面活性剂的石油烃降解菌。并将菌株投加到油污土壤中进行修复研究,考查了不同影响因素对修复效果的影响。研究结果表明,(1)2株菌对中度石油污染土壤有较好的修复效果,向油污土壤中直接投加菌株修复70 d时对石油烃的去除率为52%;(2)向油污土壤中投加降解菌并同时补充氮营养液,修复70 d时对土壤中总石油烃的去除率可达到75%;对土壤中正构烷烃的去除率为66%;(3)与土壤的含水率及土著菌的降解效果相比,向油污土壤中投加降解菌以及补充氮磷营养液是影响石油污染土壤修复效果的关键因素。     

西北黄土地区现场石油污染土壤生物修复研究

通过在陕北安塞油田某废弃油井建立中试试验基地,以实验室中筛选分离得到的高效降解石油的优势菌为添加的高效菌,研究土壤石油初始浓度、营养物质和高效菌对石油降解的影响.结果表明:(1)在各土壤石油初始浓度下,石油降解率总体均随降解时间的延长而升高.在土壤石油初始质量浓度为15.34 g/kg下,72 d时石油降解率为47.8...     

厌氧菌群JAC1降解石油烃能力及其群落结构的解析

利用苯酚诱导获得厌氧菌群JAC1强化去除土壤中的石油烃，对其在厌氧条件下的石油烃降解条件进行了优化，得到最适降解条件为：pH 7.5～8.5,土壤总石油烃(TPH)质量浓度50 mg/kg, NaCl质量分数0.3%,JAC1接菌量0.15 mL/g。厌氧菌群JAC1对石油烃的降解符合一级动力学模型。通过气相色谱质谱联用仪分析，芳香烃较直链烷烃更难降解，推测部分长链烷烃在降解过程中会分解为短链烷烃后再进行降解。基于土壤宏基因组测序分析可知，土壤微生物群落多样性与TPH浓度呈负相关，投加JAC1后土壤中与石油烃降解有关的功能菌群相对丰度呈现出不同程度增高，说明JAC1有助于建立一个高效的微生物降解体系来强化石油烃降解。     

植物-微生物联合修复石油污染土壤的实验研究

筛选高效石油降解菌并考察菌株的石油降解能力,通过植物-微生物联合修复石油污染土壤室内实验,在修复过程中测定了土壤中细菌和固氮菌,碱解氮、速效磷和速效钾的含量变化,同时采用傅立叶变换离子回旋共振质谱(ESI FT-ICR MS)考察了植物-微生物联合修复效果。结果表明,菌株3#、4#的生长适应性较强,其混合菌的降解效果最好,将其混合菌液与植物进行植物-微生物联合修复不同浓度的石油污染土壤,经过150 d的温室降解,最高降解率达到73.47%。ESI FT-ICR MS分析结果表明,与空白组相比,植物组的O1、O2和N1类等化合物相对丰度都发生了显著变化,石油污染物得到一定程度的生物降解。     

Effect of biochar on the fate of volatile petroleum hydrocarbons in an aerobic sandy soil

Biochar addition to soil is currently being investigated as a novel technology to remediate polluted sites. A critical consideration is the impact of biochar on the intrinsic microbial pollutant degradation, in particular at sites polluted with a mixture of readily biodegradable and more persistent organic pollutants. We therefore studied the impact of biochar (2% on dry weight basis) on the fate of volatile petroleum hydrocarbons in an aerobic sandy soil with batch and column studies. The soil-water partitioning coefficient, K(d), was enhanced in the biochar-amended soil up to a factor 36, and petroleum hydrocarbon vapor migration was retarded accordingly. Despite increased sorption, in particular of monoaromatic hydrocarbons, the overall microbial respiration was comparable in the biochar-amended and unamended soil. This was due to more rapid biodegradation of linear, cyclic and branched alkanes in the biochar amended soil. We concluded that the total petroleum hydrocarbon degradation rate was controlled by a factor other than substrate availability and the reduced availability of monoaromatic hydrocarbons in the biochar amended soil led to greater biodegradation of the other petroleum compounds.     

Factors affecting the distribution of hydrocarbon contaminants and hydrogeochemical parameters in a shallow sand aquifer

The distributions of hydrocarbon contaminants and hydrogeochemical parameters were investigated in a shallow sand aquifer highly contaminated with petroleum hydrocarbons leaked from solvent storage tanks. For these purposes, a variety of field investigations and studies were performed, which included installation of over 100 groundwater monitoring wells and piezometers at various depths, soil logging and analyses during well and piezometer installation, chemical analysis of groundwater, pump tests, and slug tests. Continuous water level monitoring at three selected wells using automatic data-logger and manual measuring at other wells were also conducted. Based on analyses of the various investigations and tests, a number of factors were identified to explain the distribution of the hydrocarbon contaminants and hydrogeochemical parameters. These factors include indigenous biodegradation, hydrostratigraphy, preliminary pump-and-treat remedy, recharge by rainfall, and subsequent water level fluctuation. The permeable sandy layer, in which the mean water table elevation is maintained, provided a dominant pathway for contaminant transport. The preliminary pump-and-treat action accelerated the movement of the hydrocarbon contaminants and affected the redox evolution pattern. Seasonal recharge by rain, together with indigenous biodegradation, played an important role in the natural attenuation of the petroleum hydrocarbons via mixing/dilution and biodegradation. The water level fluctuations redistributed the hydrocarbon contaminants by partitioning them into the soil and groundwater. The identified factors are not independent but closely inter-correlated.     

Bioremediation assessment of diesel–biodiesel-contaminated soil using an alternative bioaugmentation strategy

This study investigated the effectiveness of successive bioaugmentation, conventional bioaugmentation, and biostimulation of biodegradation of B10 in soil. In addition, the structure of the soil microbial community was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis. The consortium was inoculated on the initial and the 11th day of incubation for successive bioaugmentation and only on the initial day for bioaugmentation and conventional bioaugmentation. The experiment was conducted for 32 days. The microbial consortium was identified based on sequencing of 16S rRNA gene and consisted as Pseudomonas aeruginosa, Achromobacter xylosoxidans, and Ochrobactrum intermedium. Nutrient introduction (biostimulation) promoted a positive effect on microbial populations. The results indicate that the edaphic community structure and dynamics were different according to the treatments employed. CO₂ evolution demonstrated no significant difference in soil microbial activity between biostimulation and bioaugmentation treatments. The total petroleum hydrocarbon (TPH) analysis indicated a biodegradation level of 35.7 and 32.2 % for the biostimulation and successive bioaugmentation treatments, respectively. Successive bioaugmentation displayed positive effects on biodegradation, with a substantial reduction in TPH levels.     

Monitoring of bioremediation by soil biological activities

An evaluation of soil biological activities as a monitoring instrument for the decontamination process of a mineral-oil-contaminated soil was made using measurements of microbial counts, soil respiration, soil biomass and several enzyme activities. The correlations between these parameters and with the levels of hydrocarbon residues were investigated; the effects of different N- and P-sources on hydrocarbon decontamination and soil biological activities were determined. Inorganic nutrients stimulated hydrocarbon biodegradation but not all biological activities to a significant extent. Biodegradation could be monitored well by soil biological parameters: the residual hydrocarbon content correlated positively with soil respiration, biomass-C (substrate-induced respiration), and with activities of soil dehydrogenase, urease and catalase. Soil lipase activity and the number of hydrocarbon utilizers correlated negatively (P < 0.0001) with the remaining hydrocarbon content.     

Ecorisk evaluation and treatability potential of soils contaminated with petroleum hydrocarbon-based fuels

We used a series of toxicity tests to monitor oil degradation in the Kuwaiti oil lakes. Three soils from different locations with a history of hydrocarbon contamination were treated in bench-scale microcosms with controlled nutrient amendments, moisture content, and temperature that had promoted mineralization of total hydrocarbon and oil and grease in a preliminary study. Two hundred days of bioremediation treatment lowered hydrocarbon concentration to below 2 and 5 mg g(-1) for soils A and B, respectively, while in soil C hydrocarbon concentration remained at 12 mg g(-1). Although 85% of the total petroleum hydrocarbons (TPHs) in soil A were reduced 50d after treatment, results of the seed germination and Microtox tests suggested an initial increase in toxicity, indicating that toxic intermediary metabolites may have formed during biodegradation. Also, the significant decrease of TPHs and corresponding high toxicity levels were noted in soil B 200d after bioremediation. Clearly, toxicity values, and not just hydrocarbon concentration, are a key factor in assessing the effectiveness of bioremediation techniques. Field chemistry data showed a significant reduction in hydrocarbon levels after the biological treatment. We concluded that the toxicity assessment of the contaminated soil with a battery of toxicity bioassays could provide meaningful information regarding a characterization procedure in ecological risk assessment.     

Multimedia fate of petroleum hydrocarbons in the soil: Oil matrix of constructed biopiles

A dynamic multimedia fugacity model was used to evaluate the partitioning and fate of petroleum hydrocarbon fractions and aromatic indicator compounds within the soil: oil matrix of three biopiles. Each biopile was characterised by four compartments: air, water, soil solids and non-aqueous phase liquid (NAPL). Equilibrium partitioning in biopile A and B suggested that most fractions resided in the NAPL, with the exception of the aromatic fraction with an equivalent carbon number from 5 to 7 (EC₅₋₇). In Biopile C, which had the highest soil organic carbon content (13%), the soil solids were the most important compartment for both light aliphatic fractions (EC₅₋₆ and EC₆₋₈) and aromatic fractions, excluding the EC₁₆₋₂₁ and EC₂₁₋₃₅. Our starting hypothesis was that hydrocarbons do not degrade within the NAPL. This was supported by the agreement between predicted and measured hydrocarbon concentrations in Biopile B when the degradation rate constant in NAPL was set to zero. In all scenarios, biodegradation in soil was predicted as the dominant removal process for all fractions, except for the aliphatic EC₅₋₆ which was predominantly lost via volatilization. The absence of an explicit NAPL phase in the model yielded a similar prediction of total petroleum hydrocarbon (TPH) behaviour; however the predicted concentrations in the air and water phases were significantly increased with consequent changes in potential mobility. Further comparisons between predictions and measured data, particularly concentrations in the soil mobile phases, are required to ascertain the true value of including an explicit NAPL in models of this kind.     

Assessment of five bioaccessibility assays for predicting the efficacy of petroleum hydrocarbon biodegradation in aged contaminated soils

In this study, the bioaccessibility of petroleum hydrocarbons in aged contaminated soils (1.6-67gkg(-1)) was assessed using four non-exhaustive extraction techniques (100% 1-butanol, 100% 1-propanol, 50% 1-propanol in water and hydroxypropyl-β-cyclodextrin) and the persulfate oxidation method. Using linear regression analysis, residual hydrocarbon concentrations following bioaccessibility assessment were compared to residual hydrocarbon concentrations following biodegradation in laboratory-scale microcosms in order to determine whether bioaccessibility assays can predict the endpoint of hydrocarbon biodegradation. The relationship between residual hydrocarbon concentrations following microcosm biodegradation and bioaccessibility assessment was linear (r(2)=0.71-0.97) indicating that bioaccessibility assays have the potential to predict the extent of hydrocarbon biodegradation. However, the slope of best fit varied depending on the hydrocarbon fractional range assessed. For the C(10)-C(14) hydrocarbon fraction, the slope of best fit ranged from 0.12 to 0.27 indicating that the non-exhaustive or persulfate oxidation methods removed 3.5-8 times more hydrocarbons than biodegradation. Conversely, for the higher molecular weight hydrocarbon fractions (C(29)-C(36) and C(37)-C(40)), biodegradation removed up to 3.3 times more hydrocarbons compared to bioaccessibility assays with the resulting slope of best fit ranging from 1.0-1.9 to 2.0-3.3 respectively. For mid-range hydrocarbons (C(15)-C(28)), a slope of approximately one was obtained indicating that C(15)-C(28) hydrocarbon removal by these bioaccessibility assays may approximate the extent of biodegradation. While this study demonstrates the potential of predicting biodegradation endpoints using bioaccessibility assays, limitations of the study include a small data set and that all soils were collected from a single site, presumably resulting from a single contamination source. Further evaluation and validation is required using soils from a range of hydrocarbon contamination sources in order to develop robust assays for predicting bioremediation endpoints in the field.     

Bioremediation of a soil contaminated by hydrocarbon mixtures: the residual concentration problem

The phenomenon of residual concentration was investigated in the aerobic biodegradation of three different petroleum commercial products (i.e., kerosene, diesel fuel and a lubricating mineral oil) in static microcosms. Two different soils exhibiting different physical-chemical characteristics were used (i.e., a biologically treated hydrocarbon-contaminated soil and a pristine soil). Residual concentrations were observed and a simple way to take this phenomenon into account was proposed.     

Use of selected autochthonous soil bacteria to enhanced degradation of hydrocarbons in soil

A mixed population of soil hydrocarbon degrading bacteria was used to accelerate the biodegradation of a petrochemical waste. An aromatic hydrocarbon storage tank bottom was mixed with soil (10% w/w). After a month 43% of the hydrocarbons were degraded in uninoculated and in fertilized soil, while 65% were degraded in inoculated soil. Nutrient supplemented vermiculite seems to be a good possibility to produce effective hydrocarbon degrading inoculants.