白腐真菌预处理对煤厌氧发酵产甲烷的影响

为研究白腐真菌预处理对煤厌氧发酵产甲烷的影响,以预处理长焰煤为实验组,未经预处理煤样为对照组,在适宜环境下进行厌氧发酵产气实验。利用重铬酸钾法、紫外分光光度法、扫描电镜等手段对产气过程中的COD（化学需氧量）质量浓度、辅酶F₄₂₀活性及煤形貌变化等进行阶段性分析。结果表明：实验组与对照组总产气量和碳转化率分别是2 322.0 mL与5.10%、1 330.2 mL与4.70%,且实验组初始产气时间明显提前;实验组降解更为彻底,两者COD值分别是32~176 mg/L与576~609 mg/L;实验组与对照组辅酶F₄₂₀活性最高值分别为0.011 72 μmol/L和0.007 97 μmol/L,且其活性受TOC（总有机碳）含量和产酸细菌的影响;预处理和产气结束后,实验组煤样表面更加粗糙,微生物吸附位点和吸附量也更多,且有菌簇的形成。实验证实,白腐真菌生物预处理在提高煤厌氧发酵产气量与碳转化率方面具有很强的优越性和可适用性,有利于煤层生物气资源的产业化利用。     

富硒土壤种植白芝麻试验研究

丰城市董家镇泉南村富硒白芝麻大田种植试验,是通过在富硒土壤中施用石灰、有机肥、草皮灰等方法,以改变土壤p H值和土壤中有效硒含量,以促进和提高白芝麻吸收土壤中的Se元素,进而探索出最简便、最经济和最适合普通农户操作的富硒农产品实用生产技术。种植试验共设置5个不同处理方法和1个对照区。通过对比不同处理方法对白芝麻中Se含量的影响,试验发现最经济有效的办法是:施石灰412.5 kg/hm2与土壤混合均匀后播种,这样既能提高白芝麻的Se含量又能提高产量,操作最简单且经济成本最低。     

Phytoremediation of soil contaminated by heavy oil with plants colonized by mycorrhizal fungi

The purpose of this study was to investigate the effect of phytoremediation on soils contaminated with heavy crude oil using plants infected by mycorrhizal fungi. Five plant species, Vetiveria zizanioides, Bidens pilosa, Chloris barbata, Eleusine indica, and Imperata cylindrica, infected with the species of mycorrhizal fungi Glomus mosseae, were selected for this study. The degradation of total petroleum hydrocarbons in soils and several physiological parameters of plants such as shoot length and biomass were analyzed. Out of the 5 plant species tested, only V. zizanioides, B. pilosa, and E. indica could take up the G. mosseae. Out of these three, V. zizanioides showed the greatest growth (biomass) in soils with 100,000 mg kg^?1 total petroleum hydrocarbons. In addition, B. pilosa infected with G. mosseae was found to be able to increase degradation by 9 % under an initial total petroleum hydrocarbons concentration of 30,000 mg kg^?1 in soils after 64 days. We conclude that plants infected with mycorrhizal fungi can enhance the phytoremediation efficiency of soils contaminated with high concentrations of heavy oil.     

Assessment of degradation of agricultural soils arising from brick burning in selected soil profiles

The study was conducted with the selected soil profile of burnt (soil around brick kilns) and unburnt (agricultural land) soils in the Dinajpur, Rangpur, Rajshahi, Khulna and Patuakhali districts at the western part of Bangladesh to evaluate the effects of brick kilns on soil degradation and environmental pollution. The pH values of the unburnt soils increased as a function of the soil depth for Rangpur, Khulna and Patuakhali, while decreased for the soil profiles in Dinajpur. Burning of soils significantly (p<0.05) decreased the average pH values of soils by 0.4 pH units (7 % increased over average content = IOAC), but strikingly increased the average EC values from 0.26 to 1.77 mS/cm (592 % IOAC) and the effect was pronounced with the depth function. The average sand content of the soil profiles increased by 330%, while the silt and clay contents decreased by 49 and 40 %, respectively. The average losses arising from the burning of agricultural soils were amounted to 63% for organic matter, 56 to 86 % and 23 to 88 % for available and total N, P, K and S, respectively. This huge loss through the burning of 1 m deep soil profile, i.e. almost 3/4^th of the deterioration of soil fertility is not only reducing the crop production but also polluting the associated environment and atmosphere. The burning of enormous C, N and S not only degrade the agricultural soils but also contributing to the changes in the global climate.     

Hydrocarbon degradation potential of autochthonous bacteria from the Yellow River delta soil

Microbial remediation potential to crude oil-contaminated soils in the Yellow River delta was assessed. Hydrocarbons degradaters were isolated from the soil samples obtained from the Yellow River delta. A selected mixed microbial consortium （MYRD-1） and two individual isolates （YRD-3 and YRD-4） were further tested for optimal performance and degradation of different hydrocarbons. The results demonstrated that the optimal crude oil biodegradation conditions for the mixed microbial consortium were at temperature of 28 ℃, salt concentration of 15‰, and pH of 8, and the optimal C/N/P ratio was found to be 70 ： 3 ： 1. Isolate YRD-3 could only use n-alkanes （C8, C12 and C16） as the sole source of carbon and YRD-4 could transform only naphthalene and phenanthrene. The optimal performance conditions for both isolates were at salt concentration of 20‰, and pH of 7, and C/N/P ratio of 80 ： 5 ： 1, but the temperature for YRD-3 was 24 ℃ and 28 ℃ for YRD-4. Capacity to transform hydrocarbons for the mixed microbial consortium and both isolates could be improved in a liquid medium supplemented using a mixture of alkanes and/or aromatic hydrocarbons （naphthalene and phenanthrene）, but the transformation of different substrates by MYRD-1 was higher than both isolates, showing the importance of mixed bacteria （microbial community） in hydrocarbon degradation.     

The degradation characteristics of microbial biomass in soil

Soil microbial biomass is a primary source of soil organic carbon (SOC) and therefore plays a fundamental role in carbon and nitrogen cycling. However, little is known about the fate and transformations of microbial biomass in soil. Here we employ HR-MAS NMR spectroscopy to monitor ¹³C and ¹⁵N labeled soil microbial biomass and leachate degradation over time. As expected, there is a rapid loss of carbohydrate structures. However, diffusion edited HR-MAS NMR data reveals that macromolecular carbohydrates are more resistant to degradation and are found in the leachate. Aromatic components survive as dissolved species in the leachate while aliphatic components persist in both the biomass and leachate. Dissolved protein and peptidoglycan accumulate in the leachate and recalcitrant amide nitrogen and lipoprotein persists in both the degraded biomass and leachate. Cross-peaks that appear in ¹H-¹⁵N HR-MAS NMR spectra after degradation suggest that specific peptides are either selectively preserved or used for the synthesis of unknown structures. The overall degradation pathways reported here are similar to that of decomposing plant material degraded under similar conditions suggesting that the difference between recalcitrant carbon from different sources is negligible after decomposition.     

在小波域中恢复白噪背景下探地雷达信号

针对实际中所观测到的探地雷达信号时常会被噪声污染的问题,根据小波分析和分形理论在多尺度分析和自相似本质上的一致性,从研究分数布朗运动小波系数的统计特性,分析信号和噪声对小波系数统计特性的影响,在探地雷达信号处理中引入小波分析和随机分形理论,提出了在小波域中,使用平滑因子恢复加性白噪背景下探地雷达信号。仿真实验表明,该方法能有效地恢复白噪背景下探地雷达信号,显著地提高了信噪比(由0 db提高到13.9 db)。     

A preliminary assessment of nitrate degradation in simulated soil environments

This study was directed toward a preliminary assessment of nitrate degradation in northeast Iowa soils. Soil experimental plots were created with variable combinations of fertilizers, ethanol, irrigation, and plant growth. The maximum average concentration of nitrate was much higher in the chemically fertilized plots (500 mg/km) than those fertilized organically (120 mg/kg). This was attributed to the excessive ammonia volatilization from the applied cow manure. Soil nitrate dropped from 155 to 50 mg/kg in a matter of 3 weeks in the deep samples of the intermittently irrigated plots. This is because higher soil moisture lowered the oxygen level, which favored denitrification. Although ethanol seemed to have restricted the release of nitrate in the manure-treated plots, the data are not conclusive. The highest degradation of soil-nitrate (lowest recovered 38 mg/kg) was observed in the plots that simultaneously grew corn, received cow manure, and were not irrigated. Soils in these plots were depleted of nitrogen by ammonia volatilization from manure, and through the uptake by corn plants. Nitrification of organic nitrogen to nitrate was restricted in plots that were left without irrigation. Rain events helped nitrification on the surface, but promoted denitrification at depth.     

考虑强度退化效应的堤坝抗震稳定性评价方法

考虑土的动强度随振动孔隙压力上升的衰减效应,将拟静力极限平衡分析和滑动体位移分析相结合,提出了堤坝抗震稳定性评价方法.首先,基于土工动力有限元分析,确定坝坡潜在滑动土体的平均加速度时程,进而,基于拟静力概念,采用极限平衡分析,确定坝坡的安全系数随时间的变化历程,其中当安全系数瞬时小于1时,表明坝坡在地震中处于瞬时超载状态,采用Newmark刚体滑块模型估算瞬时超载所产生的滑动位移,将各个超载阶段的滑动位移叠加,求得设计地震动作用下堤坝边坡的累积滑移量,根据这种方法所进行的数值计算与分析表明,考虑强度循环退化效应后所得到的坝坡滑移量更为合理.     

Enhancement of deltamethrin degradation by soil bioaugmentation with two different strains of Serratia marcescens

Deltamethrin is one of the most commonly used pyrethroid in agricultural practice in different geographic regions of the world. It is detected in many environments, especially in soil and water, and can exhibit toxic effect to human and other organisms. In this study, we describe two bacterial strains DeI-1 and DeI-2, isolated from soil, and both identified as Serratia marcescens based on profile of the fatty acid methyl esters, biochemical test, and 16S RNA gene analysis, which were shown to efficiently degrade deltamethrin. Degradation of deltamethrin in mineral salt medium (50 mg l^?1) proceeded by strains DeI-1 or DeI-2 reached the values of 88.3 or 82.8 % after 10 days, and DT50 was 2.8 or 4.0 days, respectively. Bioaugmentation of deltamethrin-contaminated non-sterile soils (100 mg kg^?1) with strains DeI-1 or DeI-2 (3 × 10⁶ cells g^?1 of soil) enhanced the disappearance rate of pyrethroid, and its DT50 was reduced by 44.9, 33.1, 44.4, and 58.2 days or 39.1, 25.8, 35.6, and 46.0 days in sandy, sandy loam, silty loam, and silty soils, respectively, in comparison with non-sterile soils with only indigenous microflora. The three-way ANOVA indicated that DT50 of deltamethrin was significantly (P < 0.01) affected by soil type, microflora presence, and inoculum, and the interaction between these factors. Generally, the lower content of clay and organic carbon in soil, the higher degradation rate of deltamethrin was observed. Obtained results show that both strains of S. marcescens may possess potential to be used in bioremediation of deltamethrin-contaminated soils.     

Dynamics of diesel fuel degradation in contaminated soil using organic wastes

Bioremediation is an effective measure in dealing with such contamination, particularly those from petroleum hydrocarbon sources. The effect of soil amendments on diesel fuel degradation in soil was studied. Diesel fuel was introduced into the soil at the concentration of 5 % (w/w) and mixed with three different organic wastes tea leaf, soy cake, and potato skin, for a period of 3 months. Within 84 days, 35 % oil loss was recorded in the unamended polluted soil while 88, 81 and 75 % oil loss were recorded in the soil amended with soy cake, potato skin and tea leaf, respectively. Diesel fuel utilizing bacteria counts were significantly high in all organic wastes amended treatments, ranging from 111 × 106 to 152 × 106 colony forming unit/gram of soil, as compared to the unamended control soil which gave 31 × 106 CFU/g. The diesel fuel utilizing bacteria isolated from the oil-contaminated soil belongs to Bacillus licheniformis, Ochrobactrum tritici and Staphylococcus sp. Oil-polluted soil amended with soy cake recorded the highest oil biodegradation with a net loss of 53 %, as compared to the other treatments. Dehydrogenase enzyme activity, which was assessed by 2,3,5-triphenyltetrazolium chloride technique, correlated significantly with the total petroleum hydrocarbons degradation and accumulation of CO₂. First-order kinetic model revealed that soy cake was the best of the three organic wastes used, with biodegradation rate constant of 0.148 day^?1 and half life of 4.68 days. The results showed there is potential for soy cake, potato skin and tea leaf to enhance biodegradation of diesel in oil-contaminated soil.     

Stabilisation of soil organic matter by interactions with minerals as revealed by mineral dissolution and oxidative degradation

Soil organic matter is known to contain a stable fraction with an old radiocarbon age. Size and stabilisation processes leading to the formation of this old soil carbon pool are still unclear. Our study aims to differentiate old organic matter from young and labile carbon compounds in two acid forest soils (dystric cambisol, haplic podzol). To identify such fractions soil samples were exposed to oxidation with Na₂S₂O₈ and to dissolution by hydrofluoric acid (HF). A negative correlation between ¹⁴C activity and carbon release after dissolution of the mineral matrix by HF indicates a strong association of stabilised carbon compounds with the mineral phase. A negative correlation between the ¹⁴C activity and the relative proportion of carbon resistant to oxidation by Na₂S₂O₈ shows that young carbon is removed preferentially by this treatment. The fraction remaining after oxidation represents a certain stabilised, long residence time carbon pool. This old fraction comprises between 1 and 30% of the total soil organic carbon in the surface horizons, but reaches up to 80% in the sub-surface horizons. Old OC is mainly stabilised by organo-mineral associations with clay minerals and/or iron oxides, whereas intercalation in clay minerals was not found to be important.     

重塑石灰土的力学特征与性能劣化机制分析

石灰土在公路等工程中应用很广泛,随着公路改扩建等工程的迅速增多,面临如何处理与利用废弃石灰土的难题。通过对比分析素土、石灰土、重塑石灰土的压缩、强度等力学指标,探讨重塑石灰土的力学特征。结果表明,重塑石灰土压缩系数与石灰土相比提高了2～3倍,无侧限抗压强度损失了30%～40%,内摩擦角增大了1.2倍,黏聚力降低了40%。提出用劣化系数评价重塑石灰土的力学特性劣化程度,并从石灰处治红黏土的团粒化、碳化、灰结机制等角度分析了重塑石灰土性能劣化的本质原因。与素土相比,石灰土的黏粒（d <0.002 mm）含量减少而粗粒（d >0.074 mm）含量增加,从而提高了石灰土的内摩擦角。但重塑过程则破化了石灰土中的胶结结构致使重塑石灰土的黏聚力降低,从而影响重塑石灰土的其他力学性能指标。     

锰钾矿光催化降解苯酚及其影响因素研究

利用回流法合成隧道结构的锰钾矿,并研究其光化学降解苯酚的效果及影响因素。分别采用X射线衍射、原子吸收光谱、扫描电镜、透射电镜和BET氮气吸附法对锰钾矿的晶体结构(包括晶型、晶胞参数和结晶度)、化学组成、微观形貌和比表面积进行了表征。研究表明,非光照时锰钾矿对苯酚的降解效果较差,光照能显著促进锰钾矿对苯酚的降解;光照条件下,p H值减小能显著促进锰钾矿对苯酚的降解;锰钾矿用量增加至1.00 g/L时能显著促进锰钾矿降解苯酚,但继续增加矿物用量却显著降低苯酚降解率;非光照条件下,p H值减小和矿物用量增加不能显著促进锰钾矿降解苯酚。     

水泥砾质土三轴试验研究

对某水泥砾质土进行了三轴固结排水剪切试验,研究在不同水泥掺入比下水泥砾质土应力-应变关系和强度特性。结果表明：随水泥掺入比的增加,水泥砾质土试样在不同围压下应力-应变关系曲线均表现出不同程度的软化和剪胀现象,尤其在低围压（200 kPa）和高水泥掺入比（8%）下,剪胀性比较明显;在相同水泥掺入比下,峰值强度 随围压的增加近似呈线性增长;与不掺水泥砾质土相比,水泥砾质土的内摩擦角 因掺入不同量的水泥而得到不同程度的提高,黏聚力 随水泥掺入比的增加呈增长趋势,且增幅显著;割线模量 和 均随围压和水泥掺入比的增加而增加。不同高度的心墙堆石坝三维有限元算例的计算结果表明：水泥砾质土作为心墙材料可以显著降低土石坝心墙沉降。     

Naphthalene and phenol degradation by Flavobacterium sp. DQ398100 and Pseudomonas putida, DQ399838 isolated from petroleum polluted soil

The solubilization and degradation of polycyclic aromatic hydrocarbons （PAHs） in soil was amending by many microorganisms. One of these microorganisms is Bacteria, which were isolated from different contaminated areas at Kafer El Zyat City, Gharbia governorate, Egypt. Wastes samples were collected and bacterial isolation was carried out using enriched media technique. More than 78 isolates were obtained and the degradation capability was examined for all of them. Fingerprinting was carried out for all the isolates using REP-PCR and the obtained results grouped them into 10 groups. Two bacterial strains from the isolated bacteria were showed high degradation talent and specificity for the type of the polyaromatic hydrocarbons （naphthalene or phenol）. Pseudomonas putida （DQ399838） and Flavobacterium sp. （DQ398100） were identified and their degradation capacity was examined using real time method. Strain P. putida showed degradation rate for naphthalene reached to 50% after 20 hours from inoculation. However, Flavobacterium sp. reached 50% rate of degradation after 17 hours from inoculation time. Whenever, the soil degradation rate can be enhanced by adding these adapted bacteria to the soil and amendment of these bacteria which will help in bioremediation technology.     

Influence of biotic-abiotic factors on the degradation of novaluron in tropical soil

In this study, the degradation of novaluron (benzoylphenyl urea insect growth regulator) was investigated under controlled laboratory conditions in clay loam alluvial and coastal saline soils of West Bengal, India. The application rates were field rate (FR); 2FR and 10FR. The incubation study was carried out at 30 °C and 60% of maximum water holding capacity of both the soils. Degradation of novaluron in both the soils followed first order reaction kinetics at all application rates under non-sterile and sterile conditions. The half-lives of novaluron in non-sterilized soils ranged from 17.0–17.8 days (alluvial soil) and 11.4–12.7 days (coastal saline soil), while the values in case of the sterilized soils were 53.7–59.0 days (alluvial soil) and 28.9–29.8 days (coastal saline soil) respectively. The novaluron degradation patterns were found to be highly influenced by soil types, application rates, and biotic abiotic factors. Abiotic factors strongly influenced novaluron degradation in both the soils. Biotic degradation was higher in alluvial soil compared to the coastal saline soil.