垂直流人工湿地的设计及净化功能初探

阐述了垂直流人工湿地小试系统的设计,并测试其冬季污水净化效果,垂直流人工湿地由下地流和上行流方式的两池组成,对受污染地面水体中的CODCr,BOD5和TSS的去除率分别为53．6％,78．7％和80．2％,对细菌,总大肠菌,粪大肠菌和藻类的平均去除率分别达99．4％,85．9％,89．7％和97．7％,。对KN,HN4^ -N和TP的平均去除率分别为39．2％,16．5％和25．8％,各系统对污染物的去除作用无明显差异。系统出水NO3^-N浓度高于进水,而有植物系统中又高于无植物的对照,表明湿地植物的存在有利于硝化,表明下行流－上行流人工湿地在冬季仍能较好地改善水质,是一种有效的水处理技术,对水体水质改善和水生态系恢复具有重要意义。     

几种湿地植物净化生活污水COD、总氮效果比较

以无植被、基质为河砂的潜流型人工湿地为对照,研究了石菖蒲、灯心草和蝴蝶花3种类型植被、基质均为河砂的潜流型人工湿地净化生活污水COD、总氮的效果．结果表明,在污水COD浓度小于200mg·L^-1、总氮浓度小于30mg·L^-1的低浓度范围里,无植被的人工湿地和有植被的人工湿地对污水中COD、总氮均有很好的去除效果,两者差异不大,其COD去除率均达90％以上,总氮的去除率达80％以上．随着污水中COD和总氮浓度的增加,无植被人工湿地和有植被人工湿地去除COD和总氮的效果均有不同程度下降,两者差异明显,有植被的人工湿地能维持较高的COD、总氮的去除效果,无植被的人工湿地COD和总氮去除效果下降很快,植被在人工湿地系统去除污水COD和总氮过程中起着重要的作用．在整个试验阶段,石菖蒲植被人工湿地COD和总氮平均净化效率分别为80．46％和77．77％、灯心草人工湿地分别为75．53％和71．17％、蝴蝶花人工湿地分别为70．50％和66．38％,无植被人工湿地分别为61．39％和55．81％．同无植被人工湿地COD和总氮净化效果相比,石菖蒲植被人工湿地净化效果最好;其次为灯心草植被人工湿地,再次为蝴蝶花植被人工湿地．不同类型植被的人工湿地净化污水中COD和总氮的效果与其生物量关系密切,这与植被系统吸收同化有机物质和总氮数量、根际微生物分解有机物质和硝化-反硝化作用有关。     

刈割对人工湿地风车草生长及污水净化效果的影响

刈割对人工湿地植物的生长和净化作用的影响,国内外学者的意见存在分歧。实验于2010年7月至2011年1月在华南师范大学生物园进行。利用水池(2m×2m×0.6m)构建风车草人工湿地生活污水处理系统,研究了刈割对人工湿地风车草生长和污水净化效果的影响。结果表明,刈割组风车草在整个实验过程中均保持着良好的生长态势,而对照组在11月以后生长减缓。刈割组风车草2010年7月至2011年1月的累积地上生物量、累积地上氮磷含量以及新增分蘖数均大于对照组,表现为超补偿生长。刈割组风车草的叶绿素含量、净光合速率、蒸腾速率和气孔传导率均显著高于对照组。刈割组和对照组的TN、TP、NH4-N和NO3-N的平均去除率分别为77%、84%、64%、72%和65%、67%、55%、63%,前者显著大于后者。刈割组和对照组的CODcr和BOD5平均去除率分别为58%、79%和54%、76%,两者差异不显著。总之,刈割对人工湿地风车草的生长和污水净化效果有明显的促进作用,这可为风车草人工湿地的科学管理提供参考。     

风车草(Cyperus alternifolius)人工湿地系统氮去除及氮转化细菌研究

研究了风车草人工湿地污水处理系统TN去除率及氮转化细菌的数量。结果表明:风车草人工湿地对TN的去除率为73.8％,与无植物人工湿地系统相比较,去除率提高了17.4％。风车草人工湿地氨化细菌为7.98×10~5cfu·g~(-1)(细砂),硝化细菌为1.95×10~5MPN·g~(-1)(细砂),反硝化细菌为5.89×10~41.95×10~4MPN·g~(-1)(细砂)。与无植物系统氮转化细菌相比,氨化细菌无明显差异,硝化细菌及反硝化细菌均高出1个数量级。     

红树植物人工湿地对生活污水的净化效果

研究了潜流型海桑（Sonneratia caseolaris）人工湿地、桐花树（Aegiceras corniculatum）人工湿地和木榄（Bruguiera gymnorrhiza）人工湿地对生活污水的净化效果。一年来,3种红树植物人工湿地对BOD5、CODCr、TP、TN、NH4^＋-N和NO2^--N的平均去除率分别达到83%、71%、41%、55%、50%和84%以上。人工湿地各处理周期之间,BOD5和CODCr去除率波动较小,而TP、TN、NH4^＋-N和NO2^--N去除率波动较大。3种红树植物人工湿地对各种污染物的净化效果存在一定的差异。海桑人工湿地和桐花树人工湿地对BOD5、CODCr、TP、TN和NH4^＋-N去除率明显高于木榄人工湿地,而海桑人工湿地和桐花树人工湿地相比较,除TP外,BOD5、CODCr、TN和NH4^＋-N去除率没有显著差异。人工湿地单一处理周期内,去除率随水力停留时间（HRT）的延长而增加。BOD5、CODCr、TN和NH4^＋-N在HRT为1d和2d的去除率分别为HRT为3d去除率的54%-65%和73%-84%,NO2^--N在HRT为1d和2d的去除率分别达到了HRT为3d的70%-81%和85%-94%,而TP在HRT为1d和2d的去除率分别只有HRT为3d的39%-50%和65%-74%。另外,红树植物人工湿地与风车草（Cyperus alternifoliu）人工湿地相比,前者的BOD5、CODCr、TP、TN和NH4^＋-N去除率明显小于后者（P〈0.05）。总体上看,3种红树植物人工湿地对生活污水的净化效果呈现海桑人工湿地≈桐花树人工湿地〉木榄人工湿地。     

不同类型底栖动物对表面流人工湿地系统水质净化的影响

研究以表面流人工湿地为研究对象, 探讨不同类型底栖动物在夏季和冬季对人工湿地系统氮磷去除效果的影响, 并通过人工湿地系统运行前后不同介质氮磷含量变化及不同介质微生物丰度变化进行水质净化机理分析。结果表明, 夏季添加河蚌和添加田螺均能增强人工湿地系统NO₃-N和TN去除效果, 其中添加河蚌使得系统NO₃-N和TN平均去除率较对照组分别提升37.19%和24.32%, 添加田螺使得系统NO₃-N和TN平均去除率较对照组分别提升22.98%和12.46%。冬季添加摇蚊幼虫使得表面流人工湿地NO₃-N、TN和TP平均去除率分别在37.8%、54.0%和94.8%, 与对照组相比分别增加了29.51%、15.16%和37.62%, 添加河蚌和田螺受底栖动物半冬眠活动和代谢降低影响没有显著水质提升效果。这表明通过添加底栖动物可以增强表面流人工湿地运行效果, 选取适合的底栖动物种类组合可能在全年提升人工湿地水质净化效果。机理研究结果表明, 底栖动物通过增强底泥和基质中微生物硝化反硝化作用、植物氮吸收和基质氮吸附等促进人工湿地氮去除, 通过增强下层基质磷吸附沉淀和植物磷吸收提升水质磷去除。研究结果将为底栖动物在人工湿地的应用及表面流人工湿地运行效果提升提供理论依据和合理借鉴。     

两种生态型榕树的叶绿素含量、荧光特性和叶片气体交换日变化的比较研究

比较盆栽 生榕树和两栖型树的形态差异、叶片叶绿素含量、叶绿素荧光特性和气体交换的日变化。两栖型榕树具有较发达的气生根和水生不定根,叶片比陆生榕树宽,并有向中生性 倾向,陆生榕树的叶绿素含量比两栖榕树高,净光合速率略高于水培两栖型榕树,但明显高于土培两栖型榕树,蒸腾速率以水培两栖型树最高,陆生榕树次之,土培两栖型榕树最低,线性回归分析表明,三者的叶片气孔导度与净光合速率变化均呈正相关,气孔导度的变化     

人工湿地-微生物燃料电池耦合系统缓解生物堵塞试验研究

微生物燃料电池(Microbial Fuel Cell,MFC)利用电极表面富集的电化学活性菌(Electrochemically Active Bacteria,EAB)对生物堵塞的胞外聚合物(Extracellular Polymeric Substances,EPS)进行降解,并通过产电过程中形成的微弱电场来抑制微生物胞外多糖大量分泌,可在一定程度上控制人工湿地(Constructed Wetland,CW)的生物堵塞。为此,研究将阴极和阳极电极分别嵌入垂直流人工湿地的不同深度位置处,构建了人工湿地-微生物燃料电池(CW-MFC)耦合系统。通过比较开路和闭路耦合系统的孔隙率、过水速率以及净化效果,评价CW-MFC系统的堵塞延缓能力。结果表明:相较开路系统,闭路系统的过滤速率增幅较大,孔隙率的降幅较小,在一定程度上缓解了堵塞。闭路系统对TN和NH4+-N的去除率显著高于开路系统。嵌入电极形成的CWMFC系统可原位缓解堵塞,有较好的应用潜力。     

柊叶和象草波式潜流人工湿地的对比研究

为探索柊叶和象草在人工湿地中的应用及其净化机理,该研究以柊叶和象草为人工湿地植物分别构建了波式潜流人工湿地系统,分析了柊叶和象草波式潜流人工湿地对生活污水中COD_(cr)、TN和TP的净化效果,观察了柊叶和象草两种植物在不同季节的生长状况。结果表明:经过15个月的连续运行,在表面水力负荷约0.3 m·d~(-1)的条件下,柊叶和象草波式潜流人工湿地平均去除率是COD_(cr)分别为66.1%和70.1%,TN分别为60.4%和63.7%,TP分别为74.1%和75.1%。两种植物生长良好,根系发达,象草的地上生物量是柊叶的2.1倍,地下生物量相当;冬季象草生长缓慢,柊叶部分叶片的四周干枯,但二者都不会枯亡。这说明两个人工湿地对COD_(cr)、TN和TP都具有较好的去除效果,但无显著性差异,柊叶和象草能明显提高潜流人工湿地的净化效果。     

复合人工湿地净化抚仙湖入湖河水的效果研究

通过构建复合人工湿地处理抚仙湖窑泥沟入湖河水,对其净化效果进行了一周年的研究。结果表明,窑泥沟复合人工湿地利用各类型湿地的特点进行有机组合,年清除漂浮垃圾869.7 t,年清淤600 m3,年净化入湖河水118.9万m3,对河水中SS、BOD5、COD、TN、TP的年平均去除率分别为88.5%、83.8%、82.1%、36.4%、45.6%。生物氧化塘没有进行及时清淤,形成了湿地系统最大的内源释放库,是影响复合人工湿地去除率进一步提高的主要原因。研究可为高原湖泊应用复合人工湿地处理入湖河水提供理论依据。     

湖榕和小叶榕花形态结构特征的研究

通过对湖榕（Ｆｉｃｕｓ　ｓｐ．）和小叶榕（Ｆｉｃｕｓ　ｍｉｃｒｏｃａｒｐａ　Ｌ．）花形态结构特征的比较研究表明：湖榕和小叶榕的花果形态结构有较显著的差别。湖榕雌花的萼片数多为４片,萼片顶部都有毛,花粉位为精园形,花粉壁较薄,其结实率较低,只有０．１％;小叶榕雌花的萼片数多为３片,萼片顶部光滑无毛,花粉粒为圆形而壁较厚,其结实率较高,为２９．１％。     

榕属与榕小蜂科的分类研究进展

简述了榕树与其传粉者的共生体系,讨论了榕属植物与榕小蜂科的分类历史和现状,指出了二者分 类研究中存在的分歧,并对榕属与榕小蜂科的分类不匹配问题进行了评述。结合我国榕属与榕小蜂科分类的 研究现状,展望今后研究的方向及前景。     

Initial Development of a Novel Amphibious Robot with Transformable Fin-Leg Composite Propulsion Mechanisms

Amphibious robots are very attractive for their broad applications in resource exploration, disaster rescue, and recon- naissance. However, it is very challenging to develop the robots for their complex, amphibious working environments. In the complex amphibious environment, amphibious robots should possess multi-capabilities to walk on rough ground, maneuver underwater, and pass through transitional zones such as sandy and muddy terrain. These capabilities require a high-performance propulsion mechanism for the robots. To tackle a complex task, a novel amphibious robot （AmphiHex-I） with,transformable fin-leg composite propulsion mechanisms is developed. With the fin-leg composite propulsions, AmphiHex-I can walk on rough and soft substrates and swim in water with many maneuvers. This paper presents the structural design of the transformable fin-leg propulsion mechanism and its driving module. A hybrid model is used to explore the dynamics between the trans- formable legs and transitional environment such as granular medium. The locomotion performances of legs with various ellip- tical shapes are analyzed, which is verified by the coincidence between the model predictions and the simulation results. Further, an orthogonal experiment is conducted to study the locomotion performance of a two-legged platform walking with an asyn- chronous gait in the sandy and muddy terrain. Finally, initial experiments of AmphiHex-I walking on various lands and swimming in water are implemented. These results verify that the transformable fin-leg mechanisms enable the amphibious robot to pass through a complex, amphibious working environment.     

Reactive Oxygen Species and Relative Enzyme Activities in the Development of Aerial Roots of Chinese Banyan (Ficus microcarpa)

Although previous research has indicated that reactive oxygen species (ROS) regulate cell extension and tissue ontogenesis, the functions of ROS in aerial roots have not been previously studied. This research evaluated ROS production and dissipation in aerial roots of Chinese banyan (Ficus microcarpa). Aerial root segments (4 cm long) were cut from trees and divided into developmental zones 1, 2, and 3 (0–5, 5–15, and 15–25 mm from root tip, respectively). According to histochemical and biochemical determinations, production of the superoxide radical (O ₂ ^·– ), hydrogen peroxide (H₂O₂), and the hydroxyl radical (^·OH) decreased from zone 1 to zone 3. The detected ROS increased with the application of exogenous stimulators of ROS generation and decreased with the application of exogenous inhibitors of ROS generation. Based on protein content, superoxide dismutase (SOD) activity increased but peroxidase (POD) and catalase (CAT) activities decreased from zone 1 to zone 3, whereas based on root segment fresh weight, SOD and CAT activities did not differ among the zones but POD activity decreased from zone 1 to 3. We conclude that ROS are generated mainly in the rapidly developing zones of aerial roots and suggest that NADPH oxidase, POD, and SOD control ROS generation. POD activity and the hydroxyl cycle seem particularly important in ROS generation in aerial roots.     

Characterization of fungal antagonistic bacilli isolated from aerial roots of banyan (Ficus benghalensis) using intact‐cell MALDI‐TOF mass spectrometry (ICMS)

Aims

To characterize fungal antagonistic bacilli isolated from aerial roots of banyan tree and identify the metabolites responsible for their antifungal activity.

Methods and Results

Seven gram positive, endospore‐forming, rod‐shaped endophytic bacterial strains exhibiting a broad‐spectrum antifungal activity were isolated from the surface‐sterilized aerial roots of banyan tree. The isolates designated as K1, A2, A4 and A12 were identified as Bacillus subtilis, whereas isolates A11 and A13 were identified as Bacillus amyloliquefaciens using Biolog Microbial Identification System. The antifungal lipopeptides, surfactins, iturins and fengycins with masses varying in the range from m/z 900 to m/z 1550 could be detected using intact‐cell MALDI‐TOF mass spectrometry (ICMS). On the basis of mass spectral and carbon source utilization profile, all seven endophytes could be distinguished from each other. Furthermore, ICMS analysis revealed higher extent of heterogeneity among iturins and fengycins produced by B. subtilis K1, correlating well with its higher antifungal activity in comparison with other isolates.

Conclusion

Seven fungal antagonistic bacilli were isolated from aerial roots of banyan tree, exhibiting broad spectrum of antifungal activity, among which B. subtilis K1 isolate was found to be most potent. The ICMS analysis revealed that all these isolates produced cyclic lipopeptides belonging to surfactin, iturin and fengycin families and exhibited varying degree of heterogeneity.

Significance and Impact of the study

The endophytes are considered as a potential source of novel bioactive metabolites, and this study describes the potent fungal antagonistic bacilli from aerial roots of banyan tree. The isolates described in this study have a prospective application as biocontrol agents. Also ICMS analysis described in this study for characterization of antifungal metabolites produced by banyan endophytic bacilli may be used as a high throughput tool for screening of microbes producing novel cyclic lipopeptides.     

Microanatomy of the radius and lifestyle in amniotes (Vertebrata, Tetrapoda)

Radial cross-sections of 49 species of extant and two species of extinct amniotes of known lifestyle have been studied in order to assess the relationship between lifestyle (aquatic, amphibious or terrestrial) and bone microanatomy. Most compactness profile and body size parameters exhibit a phylogenetic signal; therefore, classical statistical tests should not be used. Permutational multiple linear regressions show an ecological signal in most compactness profile parameters and in the cross-section maximal diameter. A linear discriminant analysis is performed with these parameters to distinguish the various lifestyles. The discriminant function based on taxa of known lifestyle is used to infer the lifestyle of three extinct amniotes: the early nothosaur Pachypleurosaurus (amphibious), the therapsid Lystrosaurus (amphibious) and the synapsid Ophiacodon (aquatic). These predictions are congruent with classical palaeoecological interpretations. This model may be very useful when attempting to infer the ancestral lifestyle of amniotes and other early limbed vertebrates.     

Amphibious fish: why do they leave water?

Summary Amphibious behaviour in fish has evolved separately many times since the first amphibious fishes, the rhipidistian crossopterygians, ventured onto land about 350 million years ago. This behaviour has resulted in the colonization and eventual domination by vertebrates of the terrestrial habitat. It is generally proposed that aquatic hypoxia, owing to metabolic oxygen consumption and organic decay, was the most important selective force in the evolution of air-breathing vertebrates (e.g. Randall et al., 1981). Modern amphibious fish species give an insight into the reasons for leaving and eventually abandoning the aquatic habitat. Amphibious fishes today leave the water for a variety of reasons associated with degradation of their aquatic habitat, or biotic factors within it.The possible causal factors which may elicit an emergence response are summarized in Fig. 1(a) and (b). Amphibious fish inhabiting closed systems, as typified by freshwater or intertidal pools, may leave water for any of the reasons detailed in Fig. 1(a). The relative importance of any one stimulus is likely to vary between different species. However, it is possible that in closed systems, adverse fluctuations in physico-chemical parameters will have a more important effect in eliciting amphibious behaviour than will biotic factors. In open systems, such as coastal waters or large freshwater bodies, effectively two routes of escape from adverse aquatic conditions are available to amphibious fish. They may move onto land, or alternatively they may move underwater to find better conditions. In such a system, where physico-chemical parameters remain relatively constant, abiotic factors are unlikely to have a significant influence on amphibious behaviour. The dominant stimulus in open systems is possibly the three-way interaction between predation, competition, and short-or long-term food availability (Fig. 1(b)).It is unlikely that any one of the factors discussed in this review will act alone in causing amphibious behaviour, and in this respect the available literature on fish leaving water is lacking. Much of it is fragmentary and partly anecdotal, and the limited amount of experimental work tends to concentrate on individual causal factors. There is evidently scope for detailed examination of emersion in a number of amphibious fishes, testing a matrix of environmental and biotic stimuli, in an attempt to determine in more detail the reasons for such behaviour.     

Evolution of bone microanatomy of the tetrapod tibia and its use in palaeobiological inference

Bone microanatomy appears to track changes in various physiological or ecological properties of the individual or the taxon. Analyses of sections of the tibia of 99 taxa show a highly significant (P 相似文献   

Insecticidal activities of two fig tree leaf extracts against the cotton pest Spodoptera litura (Fab.) and their impact on the non-target red worm Eisenia foetida (Savigny)

Extracts of botanical origin naturally contain a complex mixture of chemicals considered effective in managing lepidopteran pests. Chemical screening of the ethanolic leaf extracts of two fig tree species, Ficus lyrata and Ficus auriculata, delivered 12 and 15 phyto-compounds with relatively high peak area percentages in phytol and flavone, respectively. Larvicidal activity against Spodoptera litura yielded higher mortality rates at maximum-concentration treatment (600 ppm) with Ficus lyrata (91.3%) and Ficus auriculata (98.5%) extracts during the second instar. Sub-lethal dosages (300 ppm) of both Ficus lyrata and Ficus auriculata extracts impeded the development and reproduction of lepidopteran pests. The enzyme-inhibition activity of both fig extracts elicited a significant reduction in the major digestive enzymes alkaline phosphatase, acid phosphatase, and lactate dehydrogenase dose-responsively. Mid-gut histological screening of Ficus lyrata and Ficus auriculata extracts displayed gut lumen disruptions, shape alterations of columnar cells, and brush-border membrane damage. Further, the non-target toxicity of fig extracts against the red worm Eisenia foetida was minimal compared with that of the chemical temephos. Overall, the Ficus extracts proved to be eco-friendly strategies for managing the polyphagous pest Spodoptera litura and are potentially more sustainable and less harmful to non-target earthworms. Nonetheless, in silico predictions suggest that the active compounds in fig extracts are predominantly toxic against honeybees (16 compounds) and violate TICE rules (10 compounds). Therefore, the biological actions of fig extracts' individual novel chemistries need to be examined on target and non-target species to develop better pest management strategies.