人工湿地强化脱氮研究进展

脱氮效率不高一直是困扰人工湿地应用的问题之一,如何强化人工湿地脱氮已成为近年来的研究热点。人工湿地对于氮的去除作用主要有氮的挥发、水生植物的吸收、基质的吸附、沉淀以及微生物的硝化与反硝化作用,也发现了一些新的脱氮途径,如短程硝化反硝化、同步硝化反硝化等。从湿地结构改进、运行方式优化、建立湿地组合系统、基质优选、植物筛选、微生物调控等方面详细论述了人工湿地强化脱氮措施及净化效果,以期为人工湿地技术优化与工程应用提供参考。     

碳源补充促进人工湿地脱氮研究进展

介绍了人工湿地的脱氮机制和影响因素,以及常用的反硝化外加碳源。人工湿地的脱氮机制主要包括基质吸附、植物吸收和微生物硝化反硝化等。但进入人工湿地的污水往往碳氮比较低,限制了脱氮效率,往往需要添加外源碳来提高人工湿地的脱氮效果;结合微藻可同化吸收利用氮磷,并在死亡分解过程中会释放有机物的规律。认为可构建藻类-人工湿地耦合系统,利用藻类作为人工湿地反硝化过程的外加碳源,以提高人工湿地脱氮效率。     

湿地植物在人工湿地脱氮中的应用及研究进展

介绍了人工湿地系统中植物在污水脱氮方面发挥的重要作用,简述了目前研究中常用的3种湿地植物类型,包括挺水植物、浮水植物和沉水植物;介绍了植物脱氮的主要机理,植物通过吸收利用、根系微生物的硝化反硝化作用,来实现氮的去除,指出不同植物由于生理特性不同,对氮的去除效果不同。通过对比研究不同植物的脱氮效果,总结了人工湿地中植物的配置原则和影响植物脱氮的主要因素。对今后的相关研究方向进行了展望。     

潜流人工湿地对农村生活污水氮去除的研究

作者研究了潜流水平人工湿地处理农村生活污水中氮的去除效果,结果表明湿地进水TN负荷与出水TN负荷去除之间有较好的线性关系,随着水力停留时间的延长TN去除率也升高,停留时间为4d时,芦苇湿地和菖蒲湿地的脱氮效率可以达到60％以上。从脱氮效果看,芦苇湿地的略好于菖蒲湿地的,有植物系统明显好于无植物系统。在进水NO2^--N浓度小于0．062mg／L、NO3^--N浓度小于1．982mg／L的情况下,无论是连续运行还是间歇运行,大多数情况下,出水浓度都分别低于0．631mg／L和1．00mg／L,两者一般不会有较大的积累。试验分析了湿地脱氮的途径,微生物硝化／反硝化是人工湿地脱氮的主要途径,植物吸收、存储仅占湿地总氮去除量的10％左右,但是植物的存在间接地影响湿地脱氮的其它途径,对提高湿地氮去除率具有重要作用。     

植物和基质级配对水平流人工湿地处理污染河水的影响

为了研究植物和基质级配对水平潜流人工湿地处理污染河水营养物的影响,构建了有/无植物两组多粒径配比水平潜流人工湿地。结果表明,种有植物的水平流人工湿地的脱氮除磷效果均优于未种植植物湿地;通过基质不同粒径的配比与植物的联合作用可以使湿地内部空间的脱氮除磷效果更具有均匀性;植物对营养物的直接吸收在湿地脱氮、除磷总量中所占比例分别为11.3%和17.4%,且略大于植物对湿地其他组成的间接促进作用。     

西北地区潜流人工湿地冬季脱氮效果研究

对西安市皂河人工湿地示范工程中潜流人工湿地冬季脱氮效果、溶解氧和微生物的空间分布进行分析研究。结果表明,潜流湿地中总氮与氨氮的平均去除率分别为29.0%和35.1%,基质中氨化细菌、亚硝化菌和反硝化菌数量沿程都呈现递减的趋势,在深度上氨化和亚硝化菌数量都是随深度减少,而反硝化菌数量是随深度增加;溶解氧浓度与氨化细菌、亚硝化菌数量存在显著正相关性,而与反硝化菌存在显著负相关性,说明湿地中溶解氧的分布对脱氨效果有重要影响。     

国内期刊文摘

复合垂直流人工湿地污水处理系统硝化与反硝化作用；短程硝化生物脱氮工艺的稳定性；热水解预处理改善污泥的厌氧消化性能；高锰酸钾强化三氯化铁共沉降法去除亚砷酸盐的效能与机理；蠕虫污泥减量效果及其影响因素分析魏源送……     

强化反硝化脱氮湿地外加碳源研究进展

人工湿地作为一种新型污水处理技术已被广泛应用,碳源是影响其反硝化脱氮的主要因素之一,针对污水中C/N比较低的问题,需向系统中额外投加碳源。在大量相关文献研究基础上,对强化反硝化脱氮人工湿地的外加碳源进行了总结,并比较了外加碳源的种类和及其优缺点。并对人工湿地外加碳源的研究进行了讨论和展望,为今后强化脱氮人工湿地外加碳源的深入研究提供了建议。     

人工湿地除氮影响因素的研究

介绍了生活污水人工湿地的生物脱氮技术及去除污水中氮污染物的机理。通过人工湿地脱氮技术,详细阐述了人工湿地氨氮的机理、影响因素,重点研究了氮素去除的关键过程即微生物的反硝化过程及其影响因素。为人工湿地污水处理工艺的推广应用提供科学依据。     

景观植物潜流湿地对富营养化景观水的净化

研究了风车草、美人蕉两种植物人工湿地在不同月份对富营养化景观水的净化效果。分析了水力负荷、温度变化对污染物去除效果的影响,考察了两种植物人工湿地微生物的硝化/反硝化作用强度。结果表明:两种植物人工湿地对富营养化景观水中的污染物均有较好的净化效果,风车草湿地去除效果优于美人蕉湿地。污染物的去除效率随水力负荷的增加而降低;在最佳水力负荷为0.113m3/(m2.d)的条件下,出水TN、TP和CODCr的质量浓度分别在2、0.1和15mg/L以下;富营养化的控制因子磷的去除效率基本不受温度影响。风车草湿地硝化作用强度略高于美人蕉湿地,反硝化作用强度略低。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。