In‐situ remediation of contaminated farmland by horizontal transfer of degradative plasmids among rhizosphere bacteria

Horizontal transfer of catabolic genes for pollutant degradation among rhizobacteria plays an important role in environmental bioremediation, but lacks support from field trial data. To address this problem, Pseudomonas fluorescens strain TP13 was inoculated into the soils of a phenol‐contaminated farmland on which tomato seedlings were growing in April 2009, 2010, 2011 and 2012. Results consistently showed that introduction of TP13 strain significantly reduced phenol content and increased plant biomass after 20 days, compared with controls. Strain TP13 was able to colonize the plant rhizosphere and the number of rhizosphere bacteria which were grown on phenol and contained the plasmids containing the gene encoding for catechol 2, 3‐dioxygenase (C23O) increased gradually in the later stages of the experiment. The increase in magnitude of the plasmid‐containing rhizosphere bacteria correlated well with plant biomass, while the number of plasmid‐containing rhizosphere bacteria and phenol content was strongly negatively correlated. Furthermore, six strains (T1‐T6) of rhizosphere bacteria were isolated and found to possess large plasmids containing identical C23O genes and similar HindIII restriction patterns. Sequence alignment showed that the C23O genes from strains T1‐T6 contained almost identical sequences and the sequence of the C23O of strain T1 was the same as that of strain TP13. These data indicated that the plasmids were transferred from strain TP13 to these rhizosphere bacteria and that horizontal gene transfer stimulated phenol degradation and plant growth in the contaminated farmland. This is an important finding for in situ remediation of contaminated farmland.     

竹束去青程度对竹束单板层积材物理力学性能的影响1）

采用通过帚化技术去青后的慈竹竹束单板,制备了28 mm厚的竹束单板层积材,探讨了竹束去青程度对竹束单板层积材的尺寸稳定性、静曲强度、弹性模量和水平剪切强度的影响。研究结果表明：随竹束去青程度的提高,竹束表面的明度L倡呈上升趋势,红绿轴色度指数a倡和黄蓝轴色度指数b 倡增加,色差ΔE倡增大;竹束去青程度越高,竹束表面的静态接触角越小,对应制得的竹束单板层积材的尺寸稳定性越好,干态静曲强度、弹性模量和水平剪切强度变化不大或稍有减小,但经过28 h处理后的强度均表现出更小的削减;不去青对竹束单板层积材强度降低的影响是最大的;针对水平剪切强度, A、B、C、D组板材均符合GBT／20241—2006《单板层积材》标准要求,A、B、C组达到《重组竹》（报批稿）规定的9V－12H级别。     

决不能把伪简当作“中华文明的根脉”

利用“纵横向”拉开档次评价法实证分析中国30个省级政府2002~2011年的环境基本公共服务绩效,结果表明省际差异显著。中西部大部分地区绩效整体逐年上升但总得分偏低,东部综合绩效水平明显高于中西部;环境安全性服务和环境信息性服务占综合绩效得分比重明显偏小。为此,应加大对中西部省份环境基本公共服务的财政投入,实施差异化区域性环境基本公共服务战略;同时增加对环境安全性服务和环境信息性服务的投入,提升环境基本公共服务整体水平。     

300W型绿光led集鱼灯的光学特性

蒙特卡罗模拟是一种有效的计算光场分布的数值模拟方法,通过将光束离散成大量光子,追踪光子路径计算目标区域的光照强度。为准确计算集鱼灯的海面光场分布情况,以金属卤化物集鱼灯为例对蒙特卡罗模拟求解过程中的光子数取值和光子辐射模型展开分析和优化。针对光子数取值问题,通过设定不同光子数进行数值模拟,探讨光子数差异对模拟结果稳定性的影响。针对光子辐射模型问题,根据灯具光度分布数据提出光子辐射优化模型,通过实测数据进行验证。结果显示：1) 模拟光子数取值越大,模拟结果的稳定性越好;以与灯具水平距离5 m的计算点为例,当取值设为10⁸时结果的差异系数为0.07%,光子数取值继续增加至10¹⁰,则差异系数为0.05%;2) 模型优化后,模拟计算结果与实测的相对误差均值从0.051 2减少至0.045 3。此外,应用优化模型计算了渔船在实际作业环境的光场照度情况,计算结果与实测值的平均误差约为0.052 3。     

京郊乡镇企业发展战略的初步探讨

中央指出:发展乡镇企业是振兴农村经济的必由之路。党的十一届三中全会以来,北京郊区的乡镇企业发展很快,已经成为京郊农村经济的重要支柱。如何推动乡镇企业进一步发展,从当前北京郊区的实际情况出发:一是要坚决执行中央提出的“四个轮子”一起转的方针,坚持所有制结构的多元化;二是要充分发挥北京郊区的地理优势,开展广泛的经济联合;三是要加强宏观指导,搞好行业结构的改革,提高经济效益。     

洞庭湖湖面风速与湖区陆地风速的对比分析

对洞庭湖区水平方向与垂直方向的湖面风速与陆地风速进行对比分析。结果表明：在水平方向上,湖面平均风速比陆地平均风速大2．3m／s,湖面瞬时风速是陆地瞬时风速的2倍左右;在垂直方向上,湖面平均风速与陆地平均风速之间也存在一定差异。     

莱州湾大型砂壳纤毛虫丰度的水平分布

根据2011年5-11月及2012年3-4月在莱州湾进行的每月1次共9个航次的调查资料,通过解剖镜下镜检浮游生物网拖网样品,分析莱州湾3-11月大型砂壳纤毛虫丰度的水平分布。结果显示,砂壳纤毛虫总丰度的水平分布在不同时间呈现不同的特点:3–5月砂壳纤毛虫总丰度在湾底较高,向湾口递减;6-11月砂壳纤毛虫总丰度在湾中及湾口较高,湾底近岸海区较低。各月砂壳纤毛虫丰度较大的区域温度、盐度比较相似,表明砂壳纤毛虫可能有一定的适温性和适盐性。其中,6月砂壳纤毛虫丰度的分布与同期调查的鱼卵和仔稚鱼的分布较一致,表明砂壳纤毛虫可能是仔稚鱼的开口饵料,对鱼类仔稚鱼的成活和发育有帮助。3-11月砂壳纤毛虫种丰富度的变化范围是5-20种,有17个种在不同月份成为优势种。优势种种类数最多的是7、8月(10种),4月最少(2种)。各航次中不同优势种的最大丰度为489×103个/m3(运动类铃虫Codonellopsis mobilis,5月);较小的丰度仅为4×103个/m3(半旋拟铃虫Tintinnopsis hemispiralis,11月)。主要优势种(连续3个月或3个月以上为优势种的种类)有运动类铃虫(C.mobilis)、白领细壳虫(Stenosemella nivalis)、根状拟铃虫(Tintinnopsis radix)、妥肯丁拟铃虫(T.tocantinensis)和半旋拟铃虫(T.hemispiralis)。8月在黄河入海口附近的3个站位发现河口拟铃虫(Tintinnopsis estuariensis),这是在长江口海域发现的砂壳纤毛虫新种。     

Induction of toluene degradation and growth promotion in corn and wheat by horizontal gene transfer within endophytic bacteria

Some experiments involving important crop plants, corn and wheat, were carried out to characterize the agronomic and environmental application of Burkholderia cepacia strain FX2 able to degrade toluene and containing plasmids with the gene encoding for catechol 2, 3-dioxygenase (C23O), a key enzyme in the degradation pathway of monocyclic aromatic compounds. The inoculation of corn and wheat with FX2 led to the promotion of plant growth and reduction in evapotranspiration of toluene into the air. Endophytic bacteria able to grow on toluene as the only source of carbon and containing a C23O gene were found in the plants inoculated with FX2 but not in their non-inoculated controls. Compared to control plants, a greater number of toluene-degrading, phosphate-solubilizing and siderophore-producing endophytes were found in inoculated plants. Furthermore, a direct correlation occurred between plant biomass responses and the magnitude of C23O-containing endophytes. Phylogenetic tree comparison, plasmid analysis and filter mating assays showed that the C23O gene was transferred horizontally from FX2 to the natural endophytic bacteria of corn and wheat. Horizontal gene transfer among endophytic bacteria might contribute to pollutant degradation, growth promotion and potential for disease suppression in corn and wheat.     

Bedforms and sediment transport processes in the ephemeral streams of Kobo basin,Northern Ethiopia

Bedforms and channel deposits architecture were studied in the ephemeral streams of the structural basin of Kobo in northern Ethiopia.     

基于水平尺度扩展的土壤水分介电传感技术

设计了一种水平放置管式结构的介电水分传感器测量系统,通过水平往复移动扫描,测量一定深度下水平剖面的土壤水分。水分传感器的测量原理为频域(FD)外缘场阻抗法,该系统实现了土壤水平剖面含水率的线扫描测量,其最大扫描长度为380 cm。为了检验该测量系统的技术性能与可应用性,结合农田滴灌试验给出了2个点源激励下土壤入渗的应用测试案例。试验结果显示了不同质地土壤的入渗差异并记录了点源激励下土壤入渗过程的时间、空间三维数据。