紫外光降解对生物过滤塔去除氯苯性能的影响机制研究

紫外-生物过滤联合工艺中的紫外单元促进了后续生物过滤单元的氯苯去除性能.为了进一步揭示紫外光降解对生物过滤塔运行性能的影响机制,本研究系统分析了紫外光降解对生物过滤塔填料层pH、生物膜特性和填料层结构特性等方面的影响.结果表明,氯苯紫外光降解产物导致了生物过滤单元填料层pH的下降(从pH 6～8降至pH 4～7);另外,紫外单元产生的臭氧降低了生物过滤单元生物膜厚度和生物膜的EPS含量,改善了生物膜的特性,提高了氯苯和营养物质在生物膜内的传质效率.同时,臭氧可以有效控制生物量过量积累,增加了填料层的比表面积(从784 m2.m-3增加至880 m2.m-3),优化了填料层的结构特性,提高了污染物的反应速率.上述各方面的综合作用最终促进了生物过滤单元的氯苯去除性能.     

紫外辐射对小球藻混凝效果作用途径探讨

针对藻类在常规水处理过程中难以被有效去除的现状,采用紫外辐射对藻类混凝过程进行强化处理.结果表明,随着紫外照射时间的增加,混凝后对藻细胞和浊度的去除均呈先上升后下降的趋势,并在照射50 min时达到最大值.PAC(聚合氯化铝)投加量为5 mg·L~(-1)时,照射样的除藻率和去浊率达到最大,分别比空白样高20.1%和18%左右.pH值在6~9范围内,紫外辐射强化混凝效果的变化较小.溶液pH=8、紫外照射50 min,混凝后的除藻率和去浊率分别达到了93.5%和90.6%.此时,藻细胞Zeta电位最大,同时释放出藻黏液,有利于混凝沉降.而当紫外照射超过60 min后,出现细胞膜破裂,胞内有机物渗出,使得溶液中的有机物浓度急剧上升,Zeta电位开始下降,不利于后续混凝的进行.     

染料探针技术对二级出水中优势污染物的定量检测

分别以刚果红和中性红为染料探针,建立了牛血清蛋白质(BSA)和海藻酸多糖(SA)含量与共振光散射(RLS)发射光谱强度间的线性关系;以甲苯胺蓝为染料探针,建立了腐殖酸(HA)含量与紫外吸光度间的线性关系;优化了3种标准物质的检测浓度范围及溶液p H值条件;考察了染料探针分析方法对标准物的二元和三元混合样品中的回收率.结果表明在适宜的浓度范围内,BSA、HA、SA浓度与染料探针光谱强度间的线性相关系数R0.98,3种标准物在混合样品中的回收率不小于95%,标准误差低于0.11%.以紫外光谱和3D-EEM光谱特征作为城市污水二级出水样品中蛋白质、多糖和腐殖酸的定性依据,确认了4种二级出水样品中的优势污染物.通过染料-探针技术与国标法测得的多糖和蛋白质质量浓度的相对偏差在1.2%~0.04%之间.     

Permanent exposure versus facultative concealment of sexual traits: an experimental study in the house sparrow

In many bird species the cryptic winter plumage is due to the presence of light feather tips that conceal conspicuous colorations. The gradual abrasion of these tips that makes sexual traits visible has been interpreted as a strategy to improve mating success (here referred as the permanent exhibition hypothesis). However, under some circumstances, the maintenance of a full plumage that facultatively enables the bird to exhibit or cover aggression-inducing traits has proved to be advantageous (the coverable badge hypothesis). In a population of house sparrows where black throat patches (here called badges) are used in intrasexual competition, the degree of abrasion of dull feather tips that conceal bright colour early in the breeding season correlated neither with badge size nor with traits indicating morphology and body condition. These results are only in accordance with predictions of the coverable badge hypothesis. In 1992 experimental clipping of badge feather tips, which forced permanent exposure of badges, negatively affected birds with the largest badges in terms of nest acquisition, but an opposite trend was indicated for birds with the smallest badges. In 1993, when more novel birds in the study area were competing for nesting sites than in 1992, only badge size, but not the experimental manipulation, affected nesting success. These results suggest that the loss of the ability to conceal badges was disadvantageous, and more so if most competing individuals had already been resident in the colony in previous years and the larger their badges were. There is a striking contrast between the results reported for this study population, where badges mainly signal fighting ability, and those reported for another house sparrow population, where badges are mainly used in mate choice. In this last population, tip abrasion is advantageous for dominant individuals showing the largest badges. This suggests that the trade-off between conserving versus wearing off the feathers that conceal ornaments could have different optimal resolutions depending on the relative importance of inter and intrasexual selection on indicator traits. Received: 29 September 1995/Accepted after revision: 14 July 1996     

Role of Amino Acids on <Emphasis Type="Italic">In Situ</Emphasis> Photografting of Jute Yarn with 3-(Trimethoxysilyl) Propylmethacrylate

To improve the mechanical performance of natural lignocellulosic jute yarn, grafting with [3-(trimethoxysilyl) propylmethacrylate] (TMSPM) monomer has been performed on in situ UV radiation and optimized the monomer concentration (30%) and irradiation time (30 min). Effect of various amino acids (1%) as additives in TMSPM with photografted jute yarn at optimized system has been studied. The polymer loading (PL) and tensile properties like tensile strength (TS) and elongation at break (Eb) of treated samples were enhanced by incorporation of amino acids and the highest properties (TS = 300% and Eb = 386%) achieved by the sample treated with l-Arginine (Arg) with 32.5% PL value. Weak acid like 3% acetic acid and inorganic acid like 1% sulfuric acid were also incorporated in the optimized system of TMSPM grafting and compared their effect on the tensile properties with amino acid treated samples. Water absorption and weathering resistance of treated and untreated samples were also performed and treated sample showed lesser water uptake as well as less weight loss and mechanical properties as compared to untreated samples.     

紫外吸收剂在湖泊中的分布及其对底栖动物的毒性效应

紫外吸收剂大量用于工业材料和个人护理品中,近年来在水体中不断被检出,同时由于其高度亲脂性,易在底泥和水生生物体内富集,产生潜在的毒性效应,已成为一类新型污染物。本文综述了紫外吸收剂在湖泊环境中的分布和生物富集效应,重点分析了二苯甲酮类等典型紫外吸收剂对底栖动物的药物代谢系统、抗氧化系统及其生长发育的影响及其毒性作用机制,并对未来该领域的研究进行了展望。     

Using mRNA to investigate the effect of low-pressure ultraviolet disinfection on the viability of E. coli

UV can induce damages on mRNA consistently among different genes. SOS response was more active after UV treatment. Programmed cell death was not found to be more active after UV treatment. The efficacy of ultraviolet (UV) disinfection has been analyzed and validated by numerous studies using culture-based methods, yet the discovery of the viable but nonculturable state necessitates the investigation of UV disinfection based on viability parameters. Paired regulators of the SOS response system, recA-lexA, and the programmed cell death system, mazEF, in Escherichia coli were chosen as the target genes, and the effect of UV irradiation on the mRNAs of the four genes was studied. This research showed that, after UV irradiation, the responses of the mRNAs were highly consistent, with reduction percentages of approximately 60% at 20 mJ/cm², 70% at 40 mJ/cm², and 90% at 80 mJ/cm², and these reductions were believed to be the result of direct UV damage to nucleic acids. After 24 h of dark incubation, recA and lexA were both upregulated but to a lesser extent for repressor lexA; and mazE and mazF were both downregulated. This result implies that UV irradiation induces the dark repair system more actively, and the cells will proceed to death at a rate similar to that associated with natural decay.     

Bright plumage in the magpie: does it increase or reduce the risk of predation?

Conspicuous color patterns in birds may lead to increased risk of predation. Alternatively, bright birds may be aposematic or unprofitable prey, which leads to decreased predation. During four autumns, I examined whether the black-and-white plumage of (stuffed) magpies Pica pica increases or reduces the risk of attack by migrating goshawks Accipiter gentilis. Attack risk was higher for normal magpies than for cryptic, brown magpies whether the mounts were placed near one another or far apart. However, the brown magpie may have been avoided because of its novelty. For magpies and cryptic jays Garrulus glandarius exposed together, the attack risk was similar. In 2 years, magpie and jay mounts were also exposed far apart. In 1994, with an invasion of migrating jays, attack risk was much higher for jays than for magpies. In 1995, with a normal density of jays, hawks attacked the magpies more often. The results demonstrate frequency-dependent prey selection by goshawks, which would influence any predation cost of bright plumage. The attacks on normally colored magpie mounts suggest that magpies are not aposematic. Trials with photographs and human observers indicated that normal magpies were somewhat easier to detect than jays. The plumage of the magpie possibly increases the risk of predation, but may be favoured by sexual or social selection. Received: 18 January 1996 / Accepted after revision: 6 October 1996     

Parental effects on carotenoid-based plumage coloration in nestling great tits, Parus major

Carotenoid pigments have attracted much interest in behavioural and evolutionary ecology because of their dual function in immune physiology and as color signals. In vertebrates, carotenoids must ultimately be obtained from the diet, and the mechanisms and magnitude of this environmental dependence are central for understanding carotenoid signal functions and evolution. In the present cross-fostering experiment with great tits Parus major, we investigate pre- and postnatal parental effects (egg yolk carotenoids, parental coloration) on nestling size and carotenoid coloration, using HPLC analysis of egg yolk carotenoids, and a reflectance-based measure of ‘chroma’ that reflects the plumage pigment concentration. Both rearing environment and origin influenced offspring size and plumage chroma. Maternal allocation of carotenoids to eggs had a weak positive effect on nestling plumage chroma, whereas we found no prenatal maternal effects (egg size or yolk carotenoid concentration) on size. Nestling plumage chroma was also significantly predicted by the chroma of the rearing father, but not by the color of the rearing mother or either of the original (genetical) parents. Thus, both prenatal maternal effects and postnatal paternal effects influence the carotenoid-based plumage coloration of nestling great tits. Future studies will reveal if parental effects have long-term consequences for plumage development and associated fitness components.     

Environmental conditions influence egg color of reed warblers <Emphasis Type="Italic">Acrocephalus scirpaceus</Emphasis> and their parasite,the common cuckoo <Emphasis Type="Italic">Cuculus canorus</Emphasis>

The outer layer of the eggshell in birds is in many cases covered by pigments that are assumed to be genetically determined traits with a negligible environmental component. To test the hypothesis that spring environmental conditions (i.e., temperature and rainfall) may affect bird egg pigmentation, we measured by spectrophotometry and photography egg coloration and spottiness on reed warbler (Acrocephalus scirpaceus L.) clutches parasitized by the common cuckoo (Cuculus canorus L.) collected over a period of 24 years and preserved in the Zoological Museum, Copenhagen, Denmark. In addition, we investigated whether spring environmental conditions may influence the coevolutionary relationship between the cuckoo and its host via changes in cuckoo–host egg matching. Generalized mixed models revealed that reed warbler eggs were more brilliant in those springs with a higher rainfall and tended to be bluer and greener in springs with a lower relative temperature. On the other hand, cuckoo eggs were bluer and greener in springs with a higher rainfall. Cuckoo–host egg matching in blue-greenness and spottiness was better in springs with a higher rainfall. These results provide support for the existence of an environmental component on bird egg coloration and suggest that environmental factors may potentially affect the outcome of important features of the arms race between cuckoos and reed warblers.