Laboratory Measurement of Dry Deposition of Ozone onto Northern Chinese Soil Samples

We used laboratory experiments to investigate surface resistance (R _c) to dry deposition of ozone (O₃) on different types of soil samples collected from the arid deserts and the Loess Plateau of northern China. Furthermore, we measured the factors that affected R _c, which depends on the physical and chemical interaction between trace constituents and the deposition surface, and evaluated deposition velocity (V _d). There was little influence of geometric surface area, soil weight, or O₃ concentration on V _d of O₃. The effect of relative humidity (RH) (i.e. moisture content of the soil) on O₃ uptake was in agreement with results reported in the literature: a distinct RH dependence of V _d and little uptake under water-saturated conditions were observed. R _c values for all the soil samples examined were in the range 0.21–3.3 s mm⁻¹ and were exponentially related to the surface area of the particles and the organic carbon content of each soil sample at RH of both <10 and 60%.     

Contamination, Crop Trials, and Compatibility

This paper examines the ethical andsocial questions that underlie the present UKdiscussion whether GM crops and organicagriculture can co-exist within a given regionor are mutually exclusive. A EuropeanCommission report predicted practicaldifficulties in achieving sufficientseparation distances to guarantee lowerthreshold levels proposed for GM material inorganic produce. Evidence of gene flow betweensome crops and their wild relatives has beena key issue in the recent Government consultation toconsult on whether or not to authorizecommercial planting of GM crops, following theresults of the current UK farm scale trials.The admixture of imported Bt transgenes intolandrace varieties of Mexican maize alsopresents difficulties. An ethical evaluationis made of the claim that organic growersshould expect protection from adventitioustraces of GM constructs in their products. Towhat extent – on either side of the debate –can any particular group in society set upagricultural standards for itself that mayeffectively restrain others from an otherwisejust business? The assumptions behind notionslike ``purity'' and ``contamination'' areexamined, together with their underlying viewsof nature and human intervention. The 2001UK Agriculture and Environmental BiotechnologyCommission report is relevant to theseissues. While the Government wishes to promotethe UK biotechnology industry and is underpressure from US claims of trade restraint, astrong organic lobby demands purity from GMcontamination. Does this adversarial framingof the issues reflect broader public opinionin the UK public consultation? Inarriving at policy decisions, the role of thevirtue of tolerance is considered inpost-modern and Christian ethical contexts.     

Silver nanoparticles tolerant bacteria from sewage environment

Silver nanoparticle (SNP) is a threat to soil, water and human health. Protection of environment from silver nanoparticles is a major concern. A sewage isolate, Bacillus pumilus treated with SNPs showed similar growth kinetics to that without nanoparticles. A reduction in the amount of exopolysaccharides was observed after SNPs – B. pumilus culture supernatant interaction. The Fourier transform infrared spectroscopy (FT-IR) peaks for the exopolysaccharides extracted from the bacterial culture supernatant and the interacted SNPs were almost similar. The exopolysaccharide capping of the SNPs was confirmed by UV-Visible, FT-IR and X-ray di raction analysis. The study of bacterial exopolysaccharides capped SNPs with E. coli, S. aureus and M. luteus showed less toxicity compared to uncoated SNPs. Our studies suggested that the capping of nanoparticles by bacterially produced exopolysaccharides serve as the probable mechanism of tolerance.     

嗜盐菌相溶物质合成与转运调节机制

嗜盐菌是极端环境微生物的重要类群之一,作为新型微生物资源,为微生物生理、遗传分类及生命科学和相关学科许多领域的研究提供新的课题.文章综述了嗜盐菌的嗜盐渗透压分子调节机理中,相溶物质胞外吸收转运与胞内生物合成途径涉及的结构基因、主要酶类的相关研究进展,并对后续研究进行讨论与展望.     

单轴拉伸条件下先进增强结构力学性能研究

目的研究单轴拉伸条件下先进增强结构的力学性能。方法开展先进增强结构以0.02 mm/s匀速加载至20 000 N的静力拉伸实验,采用应变检测方法获取先进增强结构复合材料结构和金属基体结构的应力应变分布特点,研究先进增强结构对金属基体应力水平的降低程度。结果在确保先进增强结构完好的情况下,先进增强结构能大幅度降低金属基体结构的应力水平,降低程度约为85%。结论按照飞机高应力区结构特点和载荷分布特点,合理布置先进增强结构,能增加局部区域的传递路径,减小局部区域的应力水平,提高该区域的疲劳和损伤容限性能。     

Potential of Pteris vittata L. for phytoremediation of sites co-contaminated with cadmium and arsenic： The tolerance and accumulation

Field investigation and greenhouse experiments were conducted to study the tolerance of Pteris vittata L. （Chinese brake） to cadmium （Cd） and its feasibility for remediating sites co-contaminated with Cd and arsenic （As）. The results showed that P. vittata could survive in pot soils spiked with 80 mg/kg of Cd and tolerated as great as 301 mg/kg of total Cd and 26.8 mg/kg of diethyltriaminepenta acetic acid （DTPA）-extractable Cd under field conditions. The highest concentration of Cd in fronds was 186 mg/kg under a total soil concentration of 920 mg As/kg and 98.6 mg Cd/kg in the field, whereas just 2.6 mg/kg under greenhouse conditions. Ecotypes of P. vittata were differentiated in tolerance and accumulation of Cd, and some of them could not only tolerate high concentrations of soil Cd, but also accumulated high concentrations of Cd in their fronds. Arsenic uptake and transportation by P. vittata was not inhibited at lower levels （〈20 mg/kg） of Cd addition. Compared to the treatment without addition of Cd, the frond As concentration was increased by 103.8% at 20 mg Cd/kg, with the highest level of 6434 mg/kg. The results suggested that the Cd-tolerant ecotype of P. vittata extracted effectively As and Cd from the site co-contaminated with Cd and As, and might be used to remediate and revegetate this type of site.     

铜绿山矿冶废弃地优势植物重金属的积累与迁移

通过野外调查和取样分析,研究了大冶铜绿山矿冶废弃地鸭跖草等5种优势植物对重金属的吸收累积与迁移特性,以期为矿区退化生态系统的植被恢复、重金属污染土壤的治理等提供依据。结果表明,鸭跖草等5种植物对重金属Cu、Pb、Zn、Cd、Cr都有程度不等的高量积累,尤其是铜元素,其最高积累量出现在海洲香薷根部,达到844.65 mg/kg,是一般植物Cu含量（5~25 mg/kg）的33.8~1689倍;而在同样条件下,As在5种植物体内的含量为018~098 mg/kg,远远低于As在一般植物中的含量（＜10 mg/kg）,这说明这些植物对As可能具有某种规避机制。从植物对重金属的吸收、富集和转运能力综合考虑,鸭跖草等5种植物都不太可能是重金属Cu等6种重金属的超累积植物。但是,它们对重金属所表现出的耐性无疑对矿冶废弃地的植被恢复过程有重要意义。     

一株嗜酸硫氧化细菌的分离鉴定及生长特性

从北京清河污泥中分离出一株硫氧化细菌,命名为QH-1,并对该菌株进行了分离鉴定.同时,初步研究了该菌株对几种重金属离子的耐受能力.结果发现,该菌株为革兰氏阴性,短杆状,需氧型,可从氧化还原态的硫元素中获得能量.QH-1菌株具有很好的产酸和耐酸能力,培养24h后pH即可下降到2.0,1周内可达到1.0以下,对数生长期为15d,进入稳定期时pH降为0.6.QH-1菌株的16S rRNA基因测序与分析表明,该菌株与Acidithiobacillus thiooxidans strain AAU具有99%以上的16S rRNA基因序列相似性.通过构建该菌株在相关种属中的系统发育树,并结合形态与生理生化特征分析,将QH-1菌株鉴定为氧化硫嗜酸硫杆菌(Acidithiobacillus thiooxidans).QH-1菌株对Zn2+和Cu2+有一定的耐受性,对Mo2+的耐受性较差.     

臭氧氧化铜绿微囊藻及其对水质的影响

针对水华典型污染藻类-铜绿微囊藻(Microsystis aeruginosa),采用臭氧氧化处理,研究臭氧除藻及其对水质的影响。细胞氧化前后的光学显微摄影图片表明:氧化剂对细胞结构的完整性有明显的破坏作用,细胞最后被裂解成大小不等的碎片,同时胞内物质释放,导致溶解性有机碳(DOC)有所升高。藻细胞数量和叶绿素含量(以OD440、OD680和叶绿素a含量表示)均发生相应的降低。此外,藻液水质的pH值、浊度、UV254有一定的改善作用。     

Stress-related ecophysiology of members of the genus Rhodanobacter isolated from a mixed waste contaminated subsurface

• Rhodanobacter spp. are dominant in acidic, high nitrate and metal contaminated sites. • Dominance of Rhodanobacter is likely due to tolerance to low pH and heavy metals. • High organic content increases stress tolerance capacity. • Longer incubation time is critical for accurate assessment of MIC (various stresses). This work examines the physiologic basis of stress tolerance in bacterial strains of the genus Rhodanobacter that dominate in the acidic and highly metal contaminated near-source subsurface zone of the Oak Ridge Integrated Field Research Challenge (ORIFRC) site. Tolerance of R. denitrificans to levels of different stresses were studied in synthetic groundwater medium and R2A broth. Two strains of R. denitrificans, strains 2APBS1^T and 116-2, tolerate low to circumneutral pH (4–8), high Uranium (1 mmol/L), elevated levels of nitrate (400 mmol/L) and high NaCl (2.5%). A combination of physiologic traits, such as growth at low pH, increased growth in the presence of high organics concentration, and tolerance of high concentrations of nitrate, NaCl and heavy metals is likely responsible for dominance of Rhodanobacter at the ORIFRC site. Furthermore, extended incubation times and use of low carbon media, better approximating site groundwater conditions, are critical for accurate determination of stress responses. This study expands knowledge of the ecophysiology of bacteria from the genus Rhodanobacter and identifies methodological approaches necessary for acquiring accurate tolerance data.