Effect of Mirabilis jalapa (Linn.) Growth on Microbial Community in Bioremediation of Petroleum-contaminated Saline-alkali Soil

Microbial biomass and species in the rhizosphere soil of Mirabilis jalapa（Linn.）（the saline-alkali soil contaminated by total petroleum hydrocarbon（TPH））were studied with the technology of phospholipid fatty acids（PLFAs） analysis,to explore the effects of Mirabilis jalapa（Linn.） growth on the structure characteristics of microbial communities and degradation of TPH in the petroleum-contaminated salinealkali soil.The result showed that compared with the CK soil without Mirabilis jalapa（Linn.）,the kind change rates of PLFAs were 71.4%,69.2% and 33.3% in spring,summer and autumn,respectively,and the degradation of TPH increased by 47.6%,28.3%,and 18.9% in the rhizosphere soil in spring,summer and autumn,respectively.Correlation analysis was used to determine the correlation between the degradation of TPH and the soil microbial communities：77.8% of the microbial PLFAs showed positive correlation（the correlation coefficient r﹥0） with the degradation of TPH,and 55.6% of the PLFAs had high positive correlation with the degradation of TPH with a correlation coefficient r ≥0.8.In addition,the relative contents of SAT and MONO had high correlation with the degradation of TPH in the CK soil,and the correlation coefficients were 0.92 and 0.60,respectively;but in the rhizosphere soil,42.1% of the PLFAs had positive correlation with it,and only21.1% had high positive correlation with the degradation of TPH,the relative contents of TBSAT,MONO and CYCLO had moderate or low positive correlation with the degradation of TPH,and the correlation coefficients were 0.56,0.50 and 0.07 respectively.It was shown that the growth of mirabilis jalapa（Linn.） highly affected the microbial community structure and TPH degradation speed in the rhizosphere soil,providing a theoretical basis for the research on phytoremediation of petroleumcontaminated saline-alkali soil.

Microbial changes in rhizospheric soils contaminated with petroleum hydrocarbons after bioremediation

Effects of bioremediation on microbial communities in soils contaminated with petroleum hydrocarbons are a scientific problem to be solved. Changes in dominate microbial species and the total amount of microorganisms including bacteria and fungi in rhizospheric soils after bioremediation were thus evaluated using field bioremediation experiments. The results showed that there were changed dominant microorganisms including 11 bacterial strains which are mostly Gram positive bacteria and 6 fungal species which were identified. The total amount of microorganisms including bacteria and fungi increased after bioremediation of microbial agents combined with planting maize. On the contrary, fungi in rhizospheric soils were inhibited by adding microbial agents combined with planting soybean.

Petroleum Hydrocarbon Degradation Potential of Soil Bacteria Native to the Yellow River Delta

The bioremediation potential of bacteria indigenous to soils of the Yellow River Delta in China was evaluated as a treatment option for soil remediation. Petroleum hydrocarbon degraders were isolated from contaminated soil samples from the Yellow River Delta. Four microbial communities and eight isolates were obtained. The optimal temperature, salinity, pH, and the ratios of C, N, and P (C:N:P) for the maximum biodegradation of diesel oil, crude oil, n-alkanes, and polyaromatic hydrocarbons by indigenous bacteria were determined, and the kinetics changes in microbial communities were monitored. In general, the mixed microbial consortia demonstrated wider catabolic versatility and faster overall rate of hydrocarbon degradation than individual isolates. Our experimental results demonstrated the feasibility of biodegradation of petroleum hydrocarbon by indigenous bacteria for soil remediation in the Yellow River Delta.

Qualitative and Quantitative Assessment of Petroleum Contaminants in Soils under Tropical Weather Conditions

GC-FID methods for the analysis of Petroleum hydrocarbons were developed and optimised. Contamination of soil from the Niger Delta was investigated about 40 days after crude oil spillage from the Shell Petroleum marginal well head. Soil samples and controls were collected at depths of 0 - 15 cm, 15 - 30 cm and 30 - 60 cm. Samples were analysed using gas chromatography fitted with a flame ionisation detector. Penetration and migration of C10-C26 and C26-C34 hydrocarbons through the soil layers were assessed by cluster analysis to determine the spatial distribution, penetration and similarity of these compounds over the contaminated area. The results also indicated elevated levels of total hydrocarbon contents when compared with the reference sites. Recommendations are made to carefully monitor and remediate the environment.

Distribution of Bacterial Communities in Petroleum-Contaminated Soils from the Dagang Oilfield, China

Diversity in bacterial communities was investigated along a petroleum hydrocarbon content gradient(0-0.4043 g/g)in surface(5-10 cm)and subsurface(35-40 cm)petroleum-contaminated soil samples from the Dagang Oilfield,China.Using 16S rRNA Illumina high-throughput sequencing technology and several statistical methods,the bacterial diversity of the soil was studied.Subsequently,the environmental parameters were measured to analyze its relationship with the community variation.Nonmetric multidimensional scaling and analysis of similarities indicated a significant difference in the structure of the bacterial community between the nonpetroleum-contaminated surface and subsurface soils,but no differences were observed in different depths of petroleum-contaminated soil.Meanwhile,many significant correlations were obtained between diversity in soil bacterial community and physicochemical properties.Total petroleum hydrocarbon,total organic carbon,and total nitrogen were the three important factors that had the greatest impacts on the bacterial community distribution in the long-term petroleum-contaminated soils.Our research has provided references for the bacterial community distribution along a petroleum gradient in both surface and subsurface petroleum-contaminated soils of oilfield areas.

Laboratory Design Criteria for Monitoring Biostimulated Bioremediation of a Crude Oil Contaminated Soil in Niger Delta Using Total Petroleum Hydrocarbon

The remediation of crude oil-impacted soil has always been a challenge in different soil environments and climatic conditions. Bioremediation technology has offered a breakthrough in restoring crude oil-impacted soil/sediment in muddy, dry soil and wetlands. Though, there have been varied environmental conditions that have hampered the success of the bioremediation process. This study has evaluated the effectiveness of a biostimulated bioremediation of crude oil-impacted soil using some design criteria—nutrient amendment (NPK fertilizer) and moisture content. Soil sample sets—A, B, C, D, E, F, and G were impacted with crude oil at a ratio of 10 g/kg and amended with varying amounts of nutrient 30, 60, and 80 g of N.P.K fertilizer. The medium for the inoculation of the nutrient was water and the volume of water applied varied from 30% to 80% saturation. The soil sample sets were harvested at an interval of 3 months for 180 days to determine the concentration of total petroleum hydrocarbon left in the soil. The analysis of the total petroleum hydrocarbon was achieved using a GC-FID with a capillary column and autosampler. Soil samples were extracted with mixed solvent dichloromethane and acetone at a 1:1 ratio. The total petroleum hydrocarbon results show that biostimulated bioremediation achieved better results in soil sample sets with low moisture content (30% water saturation) and moderate nutrient amendment. The biodegradation of the sample sets with high water saturation and a high nutrient amendment was slow with a higher amount of total hydrocarbon content at the end of the 180 days. The variability in the hydrocarbon degradation pattern of contaminated soil shows that biostimulated bioremediation achieved better results in soils with low moisture content than in soil environments with high water content (saturation). More so, nutrient overdosing of the substrate hampered the effectiveness of the remediation process.

In-situ remediation of deep petroleum-contaminated soil injection

A computational fluid dynamics(CFD)numerical simulation and field experiment were used to investigate optimal operating parameters of high-pressure jet grouting equipment and clarify the boundary law of the injection area in the remediation process.The response surface optimization design results show that the optimal injection pressure is 30 MPa,rotation speed is 23 r/min,commission speed is 30 cm/min,and the optimal injection diameter is 147.3 cm.Based on the CFD numerical simulation,the ratio of the injection core,turbulent zone,and seepage zone is approximately 1∶4∶2.The distribution law of jet core,turbulence zone and seepage zone at different cross-sections under 30 MPa operating conditions is as follows:The jet core radius is approximately 100 mm,the turbulence zone is mainly distributed at 100 to 500 mm,the seepage zone is mainly distributed at 500 to 700 mm,the seepage zone could be completed within 2 h,and the proportion of the three boundary zones in the injection zone is similar to that of the numerical simulation.This study provides theoretical parameters and practical reference for the remediation of deep pollution via in-situ chemical oxidation in the Loess Plateau soil environment.

Evolution of Petroleum Hydrocarbons in Soil Polluted with Crude Oil Treated with a Natural Product

Bioremediation of petroleum hydrocarbons contaminated/polluted soils has been recognized as an efficient, economic, versatile and environmentally good treatment. This method is limited by the microorganisms activity in degrading the spills hydrocarbons. Low solubility of the hydrocarbons involves low bioavailability to microorganisms. The main objective of this research is to increase biodegradation of petroleum hydrocarbons by treating the crude oil polluted soil with the natural biodegradable product and bacterial inoculum. Biodegradation was quantified by total petroleum hydrocarbons （TPH） analyses. The paper presents data obtained in biodegradation process of an artificial polluted soil with 5% and 10% crude oil, treated with a natural biodegradable product and bacterial inoculum during two years of experiment. Biodegradation process takes time to rehabilitate and reuse of the soil in agricultural scopes.

Assessment of organic compost and biochar in promoting phytoremediation of crude-oil contaminated soil using Calendula officinalis in the Loess Plateau, China

The Loess Plateau,located in Gansu Province,is an important energy base in China because most of the oil and gas resources are distributed in Gansu Province.In the last 40 a,ecological environment in this region has been extremely destroyed due to the over-exploitation of crude-oil resources.Remediation of crude-oil contaminated soil in this area remains to be a challenging task.In this study,in order to elucidate the effects of organic compost and biochar on phytoremediation of crude-oil contaminated soil(20 g/kg)by Calendula officinalis,we designed five treatments,i.e.,natural attenuation(CK),planted C.officinalis only(P),planted C.officinalis with biochar amendment(PB),planted C.officinalis with organic compost amendment(PC),and planted C.officinalis with co-amendment of biochar and organic compost(PBC).After 152 d of cultivation,total petroleum hydrocarbons(TPH)removal rates of CK,P,PB,PC and PBC were 6.36%,50.08%,39.58%,73.10%and 59.87%,respectively.Shoot and root dry weights of C.officinalis significantly increased by 172.31%and 80.96%under PC and 311.61%and 145.43%under PBC,respectively as compared with P(P<0.05).Total chlorophyll contents in leaves of C.officinalis under P,PC and PBC significantly increased by 77.36%,125.50%and 79.80%,respectively(P<0.05)as compared with PB.Physical-chemical characteristics and enzymatic activity of soil in different treatments were also assessed.The highest total N,total P,available N,available P and SOM(soil organic matter)occurred in PC,followed by PBC(P<0.05).C.officinalis rhizospheric soil dehydrogenase(DHA)and polyphenol oxidase(PPO)activities in PB were lower than those of other treatments(P<0.05).The values of ACE(abundance-based coverage estimators)and Chao 1 indices for rhizospheric bacteria were the highest under PC followed by PBC,P,PB and CK(P<0.05).However,the Shannon index for bacteria was the highest under PC and PBC,followed by P,PB and CK(P<0.05).In terms of soil microbial community composition,Proteiniphilum,Immundisolibacteraceae and Solimonadaceae were relatively more abundant under PC and PBC.Relative abundances of Pseudallescheria,Ochroconis,Fusarium,Sarocladium,Podospora,Apodus,Pyrenochaetopsis and Schizothecium under PC and PBC were higher,while relative abundances of Gliomastix,Aspergillus and Alternaria were lower under PC and PBC.As per the nonmetric multidimensional scaling(NMDS)analysis,application of organic compost significantly promoted soil N and P contents,shoot length,root vitality,chlorophyll ratio,total chlorophyll,abundance and diversity of rhizospheric soil microbial community in C.officinalis.A high p H value and lower soil N and P contents induced by biochar,altered C.officinalis rhizospheric soil microbial community composition,which might have restrained its phytoremediation efficiency.The results suggest that organic compost-assisted C.officinalis phytoremediation for crude-oil contaminated soil was highly effective in the Loess Plateau,China.

Biological Soil Quality Indicators and Conditioners in a Plant-Assisted Remediation of Crude Oil Polluted Farmland

Owing to vital roles played by enzymes in the preservation of the make-up of soil ecosystem and functional diversity, the influence of organic manure on the resultant biological quality of a crude oil polluted agricultural soil from a 90 d phytoremediation pot experiment was investigated. A 4-factor phyto-assisted clean-up of crude oil polluted agricultural soil was designed with options of manure amendments, to boost micobial activities. Profiles of β-glucosidases, proteases, dehydrogenases, phosphomonoesterases and respiration were investigated. Analysis of variance of triplicate experiment was carried out. Application of soil conditioner gave no marked dehydrogenase activity, which increased with depletion of available phosphorus. Marked increases in CO2 release and alkaline phosphatase activity with soil conditioning may implicate beneficial relationship with the abundance of microbial populations. Flooding in some pots correlated with β-glucosidase and respiratory acitivities. A direct relationship between cellulose breakdown, measurable with β-glucosidase activity, organic matter and CO2 release, measurable with respiratory activity within all soils was found in the present study. Use of organic manure significantly improved CO2 release by soil biota in hydrocarbon-impacted soil and may be explored for phytoremediation technique.

Effects of 5-Aminolevulinic Acid (ALA) on Zinnia hybrida Growth and Phytoremediation Effects in Oil-Contaminated Soil

In this study, we compared plant height, weight, soil TPH concentration, and soil DHA level after 18 weeks of Zennia hybrida cultivation with four different concentrations of 5-Aminolevulinic acid (ALA)-based liquid fertilizer: 1500-fold, 5000-fold, and 8000-fold dilutions, along with a non-treatment control of diluted ALA. The plants of ALA-treated were significantly taller than the non-treatment control. The plants of ALA-treated plants were higher in shoot fresh weight, shoot dry weight, and root dry weight than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold dilution was significantly highest in shoot fresh weight, shoot dry weight, and root dry weight. ALA-treated plants were lower in the soil Total Petroleum Hydrocarbon (TPH) concentration than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold was significantly lowest in the TPH concentration. In addition, ALA-treated plants were higher in the soil dehydrogenase activity (DHA) than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold was significantly highest in the TPH concentration. This study indicated that ALA-applied zinnia-grown oil-contaminated soil is more effective than not. The remediation in oil-contaminated soil with ALA-based liquid fertilizer is more effective than the non-treatment control;furthermore, ALA application with 5000-fold dilution was most suitable in oil-contaminated soil among other plots.

Assessing Earthworm Influence on Remediating Potentials of Soil Micro-Organisms, and Bioavailable Hydrocarbon Pollutant in the Niger Delta, Nigeria

In the Niger Delta region of Nigeria, oil explorations and exploitations abound, causing environmental pollution with serious consequences on soil ecosystem and its biodiversity. In spite of the relationship between microbes and fauna in soil ecosystem, such that both organisms can metabolize certain range of petroleum hydrocarbon substrates with the fauna influencing the remediation potentials of bacteria, yet soil fauna is still not fully considered in bioremediation. The influence of earthworm;Lumbricus terrestris on the remediating potentials of soil bacteria in petroleum hydrocarbon contaminated soils was investigated. Eighteen pots were filled with 700 g of soil each, with nine treated with mixture of 3 levels crude oil and remediated with earthworm, while the other nine had no earthworm. The total petroleum hydrocarbon (TPH), soil physical, nutrient compositions, and TPH degrading bacteria biodiversity were determined before contamination or commencement of study and thirty days after. The results showed a decrease in TPH concentration of 55.58%, 62.57% and 67.07% in 1 ml, 2 ml and 3 ml crude oil contaminated soil, respectively. Species richness and abundance of bacteria organisms increased with high relative abundance in soils remediated with earthworms, hydrocarbon utilizing bacteria increased from less than 0.1 cfu/g to 0.4 cfu/g, and total heterotrophic bacteria 1.6 cfu/g at the end of the study. Earthworms increased rate of remediation potentials of bacteria, such that within 30 days post remediation treatment, 34.14% of reduced concentration was achieved over soil samples without earthworms at 3 ml, and 25.14% at 2 ml concentration. Reduction in pH levels in remediated soils was between 6.39 to 6.17 and 6.74 to 6.72 in unremediated soils, while moisture content was 6.73% to 6.77% unremediated and 5.85% to 6.62% in earthworm remediated soils. Total organic carbon, nitrates in soils inoculated with earthworms were lower in concentration than those without earthworms. Reverse was the case with potassium, phosphate and phosphorous concentrations which were above those without earthworms. Results indicate statistically, significant difference between reduction in TPH in earthworm remediated soils and unremediated soils, pointing out that earthworm is a good candidate for facilitation of bacteria remediation-petroleum hydrocarbon contamination.

国槐与其他树种绿化废弃物混合施用对石油污染土壤修复效果的影响

采用室内模拟试验,研究了国槐废弃物分别与侧柏、云杉、油松、元宝槭和刺柏等5种常见园林绿化植物废弃物等质量混合对其修复石油污染土壤效果的影响,以期为合理利用绿化废弃物资源修复石油污染土壤提供理论依据。结果表明:国槐分别与侧柏、云杉、元宝槭或刺柏废弃物混合的添加形式普遍能够显著(P<0.05)强化对石油(至少是其饱和烃组分)的降解效率,提高土壤脲酶、碱性磷酸酶和脱氢酶活性,但上述混合处理普遍不影响甚至会削弱绿化废弃物对土壤速效氮、磷养分含量的提高效果。国槐与油松废弃物的混合添加形式对所有方面的修复效果普遍产生拮抗削弱。混合绿化废弃物中较高的氮、磷、氨基酸和有机酸含量有利于其降解石油或其部分组分,前三者同时有利于提高土壤速效氮素(主要是铵态氮)含量,及脲酶和脱氢酶活性;较高的酚类物质含量有助于提高土壤转化酶、碱性磷酸酶、过氧化氢酶活性;而较高的内部化学分异和萜类物质含量则分别不利于其降解饱和烃组分以及提高土壤脲酶和过氧化氢酶活性。总体而言,以适当的组合形式添加绿化废弃物可以强化其对石油污染土壤的修复效果。

预氧化联合激活剂促进微生物长效降解土壤中烷烃的研究

微生物降解是一种修复石油污染土壤中烷烃的技术,但该技术易受环境条件影响,修复效率较低。为找到一种使土壤微生物能够长期有效降解烷烃的方法,进行了预氧化联合微生物激活剂降解土壤中烷烃的研究,其中利用芬顿反应进行预氧化,微生物激活剂由葡萄糖和乙酸共同组成。通过激活组(预氧化结合激活剂)、非激活组Ⅰ(仅添加激活剂,不进行预氧化)、非激活组Ⅱ(仅进行预氧化,不添加激活剂)和空白组4种不同处理方法,探究石油污染土壤微生物的数量、呼吸活性、种群变化对烷烃降解效果的影响。结果表明:激活组中烷烃半衰期只需64 d,比非激活组Ⅱ缩短了333 d,其烷烃降解率长期维持较高值,其中0~20 d、20~40 d和40~60 d的降解率分别为14.23%、17.93%和15.73%,且每20 d的烷烃降解量均维持在1500 mg/kg以上。然而其他3组的烷烃降解率随着时间推移而显著降低,40~60 d时烷烃降解率最高仅有5.50%。预氧化后土壤中类腐殖酸和类富里酸的荧光标准积分体积分别是土壤氧化前的2.80倍和3.82倍,预氧化促进了土壤微生物的快速增长。在添加乙酸和葡萄糖后土壤微生物被激活,激活剂的利用率分别达到88.06%和91.38%,其土壤微生物呼吸活性(以每kg土壤中微生物产生CO_(2)的物质的量计,下同)维持在5.00 mol/kg以上,而非激活组的土壤微生物呼吸活性在40~60 d时最高只达到2.12 mol/kg。此外,激活组的石油降解菌数量(以每g土壤中含有的石油降解菌数量计)在后期超过了9.00 lg(CFU/g),形成了芽孢杆菌属、不动杆菌属、微杆菌属、链霉菌属和水杆菌属5种优势菌属,而非激活组最多只形成了3种优势菌属。研究显示,微生物长效降解土壤中的烷烃主要由其呼吸活性、石油降解菌数量、优势菌属数和营养利用率驱动。研究结果为解决土壤石油污染问题提供了一种经济有效的方法。

粒径对土壤石油烃荧光特性影响及校正方法研究

采用紫外诱导荧光技术对土壤中石油烃污染物进行检测时,不同粒径土壤会对测量带来较大误差,为了消除土壤粒径(soil particle size,PS)对测量带来的影响,配制3种不同粒径的常见的土壤石油烃污染物(土壤原油、土壤柴油、土壤汽油)样本,搭建紫外诱导荧光检测系统,研究了不同粒径下各类土壤石油烃污染物的荧光特性,构建了土壤石油烃粒径校正方法。结果表明,对于土壤原油、土壤柴油和土壤汽油样本,当样本浓度为4、4和10 g·kg^(-1)时,各类型土壤油类样本的荧光信号与粒径具有良好的线性相关性,相关系数R^(2)分别达到了0.9989、0.9686和0.9045。通过土壤颗粒物吸附模型,对实验结果进行解释分析,建立土壤粒径校正方法,对各类型土壤石油烃样本在不同粒径下的荧光信号进行校正;粒径校正前后3种类型的土壤石油烃荧光强度与浓度的相关系数R^(2)分别由校正前的0.3265、0.0047、0.3298上升到校正后的0.9838、0.9832、0.9533,浓度反演的相对误差(RE)分别为11.02%、5.71%、10.19%。建立的土壤粒径校正方法可以有效地降低土壤粒径对土壤石油烃类污染物荧光强度的影响,为采用紫外诱导荧光技术快速、原位、准确的检测土壤石油烃类污染物提供了理论依据和技术支持。

吸附-包埋固定化微生物修复盐渍化石油污染土壤

为克服土壤中盐对微生物降解石油烃的不利影响,实验利用生物炭(BC)吸附石油烃降解菌后,再用海藻酸钠(SA)和聚乙烯醇(PVA)包埋,制备固定化微生物,用于修复盐渍化石油污染土壤。将制备的PVA-SA-BC固定化微生物(PSBB)用于石油无机盐液体培养基中及NaCl质量分数10 g/kg的石油污染土壤中,并考察其对石油烃降解率。研究结果表明:添加PVA能显著提高固定化载体的机械性能;吸附-包埋固定化能提高微生物耐盐能力,在无机盐液体培养基中,当NaCl质量浓度由20 g/L提升至40 g/L时,添加PSBB的石油烃降解率下降9.0%,降幅小于添加游离菌(下降13.5%)和添加BC固定化微生物(下降15.6%)的培养基。且添加PSBB的无机盐液体培养基中微生物浓度最高。经过120 d的土壤修复实验,PSBB组对石油烃的降解率达到61.5%,而游离菌(FB)组和BC固定化微生物(BCB)组的石油烃降解率分别为35.3%、45.9%,这表明添加PSBB对盐渍化石油污染土壤具有显著的修复效果。

锰负载炭化土壤对重金属的吸附性能及机理

采用高锰酸钾预处理和限氧热解相结合的方法处理石油污染土壤(PCS),并将其转化为负载锰氧化物的炭化土壤(Mn-CS).与单独热解处理获得的炭化土壤相比,Mn-CS粗糙多孔,具有更高的比表面积、微孔体积和更低的可溶有机物浸出风险.Langmuir等温线模型和拟二阶动力学模型可以很好地拟合Mn-CS对重金属的吸附特性.Mn-CS对Pb^(2+)、Cu^(2+)、Zn^(2+)和Cd^(2+)的最大理论吸附量分别为420.54,81.19,79.73,26.40mg/g.Mn-CS吸附的重金属主要与Fe/Mn氧化物结合,其次与碳酸盐和有机物结合.吸附过程以单层化学吸附为主,主要机理包括表面络合、共沉淀和矿物束缚/沉淀.高锰酸钾预处理增加了土壤表面的碳酸盐、锰氧化物和无定形碳含量,从而协同提升了Mn-CS对重金属的吸附性能.本研究提供了实现PCS增值转化的新方法,助推PCS治理从达标修复走向资源化利用.