一株耐盐柴油降解菌的分离鉴定及其降解性能

从某油田附近受石油污染土壤中分离出一株以柴油为惟一碳源的耐盐菌株LS1。通过对菌株的生理生化特性、菌体的形态观察及16S r DNA基因序列分析鉴定菌株LS1为假单胞菌属(pseudomonas)。该菌株可耐受的最高盐度(Na Cl)和柴油浓度分别为6%~8%和12 000 mg/L。菌株生长的适宜p H和温度条件分别为6.0~8.0和28~36℃。在盐度为6%、p H为7.0、温度为32℃、菌种投加量为10%的条件下,初始浓度为3 000 mg/L的柴油经6 d降解后,去除率可达78.3%,加入适量外加碳源葡萄糖和蔗糖,可使降解率分别提高至92%和90%左右。菌株LS1的耐盐机理可能是通过在细胞内积累甜菜碱以调节菌株细胞内外渗透压平衡。投加甜菜碱可提高耐盐菌LS1在高盐环境下对柴油的降解效率。     

浮游动物DNA宏条形码标志基因比较研究

DNA宏条形码技术作为一种新型生物监测方法,在未来生态环境监测中有巨大的应用潜力。目前,浮游动物DNA宏条形码监测仍在发展阶段,需要首先对其(采样方法、引物选择和数据分析等)进行标准化和调整,然后才能用于常规流域生态监测。其中,如何选择合适的PCR扩增引物是DNA宏条形码生物监测标准化的关键问题之一。本研究比较了COI、18SV9和16S通用引物在浮游动物DNA宏条形码监测中的差异,为初步建立规范化的浮游动物DNA宏条形码监测方法提供技术支撑。结果表明,16S引物对浮游动物具有更好的特异性,其产生的操作分类单元(operational taxonomic unit, OTU)有88.1%属于浮游动物。虽然18SV9引物具有更高的物种覆盖度,不仅能扩增出浮游动物,还能扩增出大量藻类和真菌,但其物种识别敏感性较差,不适合浮游动物物种水平多样性监测。COI引物的浮游动物物种特异性、物种覆盖度和物种识别敏感性都适中,检出的浮游动物物种数量高于18SV9引物和16S引物,更加适合浮游动物DNA宏条形码监测。     

基于谐波沉降的管道力学分析*

为避免地面沉降引发的油气管道事故，研究沉降管道的力学特性，提出基于谐波沉降的管道力学评估方法。以中国石化某沉降管道为研究对象，通过现场测量的方法获得沉降区管道高程，利用傅里叶级数展开对不均匀沉降数据进行处理分析，获得管道谐波沉降的拟合函数。建立ANSYS有限元模型，采用土弹簧模型模拟非沉降区管道与土体相互作用关系，将谐波沉降作为位移载荷施加到沉降区管道，对含内压管道的沉降进行数值模拟，分析其应力、应变分布规律。结果表明:沉降与非沉降交界处管道应变及应力最大，基于应变的评估准则，管道运行状态为安全，为应急响应提供支撑。     

Validation of Bacteroidales-based microbial source tracking markers for pig fecal pollution and their application in two rivers of North China

• Pig feces is the predominant excrement produced by animal husbandry in China. • The PF, Pig-1-Bac^TaqMan, and Pig-2-Bac^TaqMan MST assays showed better performance. • The pig-specific MST assays can contribute to managing the pig fecal pollution. In China, pig feces is the predominant source of excrement produced by animal husbandry. Improper use or direct discharge of pig feces can result in contamination of natural water systems. Microbial source tracking (MST) technology can identify the sources of fecal pollution in environmental water, and contribute to the management of pig fecal pollution by local environmental protection agencies. However, the accuracy of such assays can be context-dependent, and they have not been comprehensively evaluated under Chinese conditions. We aimed to compare the performance of five previously reported pig-specific MST assays (PF, Pig-Bac1^SYBR, Pig-Bac2^SYBR, Pig-1-Bac^TaqMan, and Pig-2-Bac^TaqMan, which are based on Bacteroidales 16S rRNA gene markers) and apply them in two rivers of North China. We collected a total of 173 fecal samples from pigs, cows, goats, chickens, humans, and horses across China. The PF assay optimized in this study showed outstanding qualitative performance and achieved 100% specificity and sensitivity. However, the two SYBR green qPCR assays (Pig-Bac1^SYBR and Pig-Bac2^SYBR) cross-reacted with most non-pig fecal samples. In contrast, both the Pig-1-Bac^TaqMan and Pig-2-Bac^TaqMan assays gave 100% specificity and sensitivity. Of these, the Pig-2-Bac^TaqMan assay showed higher reproducibility. Our results regarding the specificity of these pig-specific MST assays differ from those reported in Thailand, Japan, and America. Using the PF and Pig-2-Bac^TaqMan assays, a field test comparing the levels of pig fecal pollution in rivers near a pig farm before and after comprehensive environmental pollution governance indicated that pig fecal pollution was effectively controlled at this location.     

潞安矿区煤层渗透率的各向异性特征实验研究

为了研究原位煤体渗透性的各向异性特征,以山西潞安常村矿3号煤层圆柱试样为对象,利用TCQT-Ⅲ型低渗煤层气相驱替增产试验装置,对煤样进行加载,并以氮气注入压力2.0 MPa的条件下,分析垂直层理和平行层理2个方向的煤体变形和渗透率变化特征。实验结果表明:煤样在加载过程中,平行和垂直层理煤样渗透率均随着有效应力的增大而减小,平行层理方向的渗透率始终大于垂直层理方向,应力加载初期渗透率急剧下降,最后逐渐趋于平缓;径向应变的增加量与渗透率呈正相关性,且平行层理相关性大于垂直层理;沿平行层理方向的裂隙度大于沿垂直层理方向,沿垂直层理方向的应变量大于沿平行层理方向;应变增加量均随有效应力的增加而逐渐减小。研究结果可为煤层井网布置及优化提供参考。     

基于不同强度等级混凝土的动力学特性研究

基于TAW-2000D电液伺服岩石三轴仪和直径75 mm的霍普金森压杆试验装置,得到了C25,C35和C45混凝土在静、动载荷作用下的应力-应变曲线,探讨了混凝土强度等级、动态峰值强度、峰值应变和应变率之间的变化规律。结果表明:混凝土准静态应力-应变曲线和动态应力-应变曲线在形态上存在明显差异,动态应力-应变曲线的峰值点随应变率的增大向右上方移动,线弹性阶段各曲线斜率变化不明显;动态峰值应力、动态弹性模量和峰值应变均存在不同程度的率相关性,并且混凝土材料的应变率敏感性随其强度等级的提高而增强;混凝土C45的各力学指标对应变率的敏感性最强,C35次之,C25的应变率敏感性最弱;推导了应变率与强度等级和冲击速率之间的经验公式,三者之间存在非线性变化规律。     

Ralstonia sp.strain U2菌株对萘的趋化作用

一株降解萘的细菌Ralstonia sp. strain U2对萘具有趋化现象,萘、水杨酸都可以作为其对萘产生趋化现象的诱导物.U2菌对水杨酸、龙胆酸同样都具有趋化性,但这种趋化性是组成型的,不需要诱导.图3参22     

Uncertainty, learning, and the optimal management of wildlife

Wildlife management is limited by uncontrolled and often unrecognized environmental variation, by limited capabilities to observe and control animal populations, and by a lack of understanding about the biological processes driving population dynamics. In this paper I describe a comprehensive framework for management that includes multiple models and likelihood values to account for structural uncertainty, along with stochastic factors to account for environmental variation, random sampling, and partial controllability. Adaptive optimization is developed in terms of the optimal control of incompletely understood populations, with the expected value of perfect information measuring the potential for improving control through learning. The framework for optimal adaptive control is generalized by including partial observability and non-adaptive, sample-based updating of model likelihoods. Passive adaptive management is derived as a special case of constrained adaptive optimization, representing a potentially efficient suboptimal alternative that nonetheless accounts for structural uncertainty.     

酵母融合菌对铬离子的吸附特性研究

酵母融合菌的完整细胞、细胞壁、细胞内含物富集水体中的铬,比较了各组分对铬离子的吸附能力差异,并进行了模型拟合.结果表明:细胞壁的去除率和吸附量都明显高于完整细胞;完整细胞及细胞壁对铬的吸附均符合Freundlich和Langmuir热力学方程,且细胞壁对Cr6 的最大吸附量和吸附亲和力都大于完整细胞,说明细胞壁是该吸附剂吸附重金属离子的主要部位.同时利用多种分析手段研究了各组分对铬的吸附行为:酵母细胞壁的特殊结构以及AFM图显示细胞壁可以为活性基团吸附、络合或螯合金属离子提供更为广阔的空间;X-射线衍射和FTIR分析检测表明吸附剂对铬的吸附并未破坏其本身的结构.     

给水生物预处理反应器的细菌种群多样性和群落结构

提取一生产性规模的给水生物预处理反应器中生物膜样品的总DNA,构建细菌16S rDNA克隆文库,并通过16S rDNA序列的系统发育分析,对生物膜中的细菌种群多样性和群落结构进行了研究.实验结果表明,给水生物膜反应器中的细菌种群多样性十分丰富;生物膜中的细菌分别属于10个主要类群,其中α-Proteobacteria是克隆文库中的最大细菌类群,占克隆子总数的32.28%,其次是β-Proteobacteria;与Rhodobacter系统关系密切的细菌是克隆文库中所占比例最大的一个菌属,占克隆子总数的12.6%;反应器中与硝化作用有关的是Nitrosomonas和Nitrospira属的细菌.研究结果表明,给水生物预处理反应器中的细菌群落结构和废水生物处理反应器中的细菌群落结构是有所差异的.图1表1参13