AMPHIBIAN OCCUPANCY IN FLOOD‐CREATED AND EXISTING WETLANDS OF THE LOWER MISSOURI RIVER ALLUVIAL VALLEY

During the previous century, the wetland area in the lower Missouri River alluvial valley was reduced by 39% because of river channelization and bank stabilization projects. The Great Flood of 1993 reversed the trend of wetland loss by creating 466 new wetlands in the alluvial valley between Kansas City and St. Louis, Missouri. We estimated amphibian occupancy, detection probability and number of species exhibiting evidence of reproduction in eight flood‐created and 16 pre‐flood existing wetlands from 1996 through 1998. We also evaluated whether hydroperiod (the number of days any water was present in a wetland from 20 February through 31 August) and distance to river predicted those values. Detection probabilities for adult amphibian species were relatively constant across years and ranged from 0.013 [Great Plains toad (Anaxyrus cognatus)] to 0.280 [Woodhouse's toad (Anaxyrus woodhousii woodhousii)]. Occupancy of adult amphibians differed across years and was not correlated with habitat features. Estimated occupancy probabilities for amphibian species ranged from 0.126 [Plains spadefoot (Spea bombifrons)] to 0.896 [boreal chorus frog (Pseudacris maculata)]. Almost double the number of amphibian species showed evidence of reproduction in existing wetlands (wetlands created before the Great Flood of 1993) when compared with that in flood‐created wetlands. Similarly, temporary wetlands had nearly double the number of amphibian species showing evidence of reproduction when compared with permanent wetlands. Finally, the highest number of species showed evidence of reproduction in wetlands with spring–summer hydroperiods between 135 and 140 days. All these relationships suggest that the invasion and persistence of predators in wetlands negatively influence amphibian reproduction. If the Missouri River is allowed to reconnect with the alluvial valley, more predators may be introduced into wetlands, leading to reduced amphibian occupancy and reproduction. However, this connection will not likely occur over the entire alluvial valley and, therefore, should not adversely impact amphibians that find refuge in higher‐elevation, non‐connected regions of the alluvial valley. Copyright © 2011 John Wiley & Sons, Ltd.     

TOXICOKINETICS OF POLYCYCLIC AROMATIC HYDROCARBONS FROM CONTAMINATED SEDIMENT BY THE AMPHIBIAN LARVAE (PLEURODELES WALTL)

The molecular phototransformation mechanism of nitroarenes, genotoxic and ubiquitous pollutants in the atmosphere, is still under debate. With increasing exposure to radiation 1,6- and 1,8-dinitropyrene (DNP) in acetonitrile showed a decrease in their characteristic absorption bands (396 and 411 nm, respectively) in the presence of O ₂ , N ₂ and H ₂ O, and an increase in the 220–390 nm region and above 450 nm, indicating their photodegradation and transformation. The resulting photoproducts were highly fluorescent, presenting a broad emission band around 520–540 nm. Oxygen reactive species did not seem to be produced in the principal photodegradation pathways, since photodegradation rates were similar to those in anaerobic samples. In the presence of O ₂ or N ₂ 1,6-DNP photodegraded 4 times faster than 1,8-DNP, while in the presence of water is 1.5 times faster. Two chromatographic fractions were separated, and identified as pyrenediones using authentic samples and reported spectral data for hydroxy-nitropyrenes. Other chromatographic fractions are still to be identified. The properties of the identified products suggested that these were formed through a nitro-nitrite rearrangement.     

两栖车辆Al-Zn-In-Mg-Ti牺牲阳极的保护性能

两栖车辆工作在高温、干湿交替的环境中,腐蚀十分严重,常用牺牲阳极和防腐蚀涂层技术进行阴极保护。采用交流阻抗技术、失重法和扫描电镜（SEM）研究了自腐蚀、自放电条件下,两栖车辆Al-Zn-In-Mg-Ti牺牲阳极的溶解性能和对阴极材料的保护性能。结果表明：自放电下Al-Zn-In-Mg-Ti牺牲阳极一定程度上降低了阴极材...     

Ultrastructural aluminium detection in amphibian tissues by electron spectroscopic imaging and electron energy-loss spectroscopy

Aluminium causes a variety of toxic effects in living organisms but very little is known about its uptake, pathways and locations of deposition. We have applied electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS) to locate aluminium at the ultrastructural level in amphibian larvae from acidic ponds. It is found diffusely bound or precipitated in cell organelles. The spatial resolution of aluminium detection is high. The elemental composition of small areas can be demonstrated by EELS. Three different fixation procedures give similar results. The two- and three-window methods at the K- and L-edges are compared.     

两栖动物在梵净山环境变化监测中应用的探讨

两栖动物对环境变化的高敏感性已引起人们关注。梵净山国家自然保护区两栖动物资源丰富,文章主要通过分析两栖动物监测环境变化的优点和研究进展及其对环境污染的反应,来探讨两栖动物在梵净山环境变化监测中的应用,为监测和保护梵净山生态环境拓展新思路。     

Identifying pathways of exposure to highway pollutants in great crested newt (Triturus cristatus) road mitigation tunnels

Road mitigation tunnels are increasingly deployed for amphibians but very little is known about chemical pollution in such schemes. We assessed pollution pressures associated with road runoff at a major great crested newt mitigation scheme in England. Sediments and waters in the mitigation system were analysed for major physico‐chemical parameters, trace metals and total petroleum hydrocarbons and compared to a nearby reference site. Seven out of eight tested metals including copper, zinc, lead and iron were in significantly greater concentrations in the tunnels than at a reference site and at environmentally significant concentrations. Water samples also exhibited elevated concentrations of aluminium and chromium and occasionally extreme alkaline pH associated with leaching of portlandite in tunnel cements. High conductivity values in waters and sediments corresponding with seasonal de‐icing salt application were also apparent. The study highlights the potential pollutant pressures for amphibians associated with large‐scale urban development and road mitigation schemes.     

Ultrastructural characteristics of the lung of <i>Melanophryniscus stelzneri stelzneri</i> (Weyenberg, 1875) (Anura,Bufonidae)

The lung of the toad, Melanophryniscus stelzneri stelzneri was studied using scanning and transmission electron microscopy. In M.s.stelzneri the parenchyma forms a polygonal network arrangement, therefore the parenchyma is edicular. These spaces are delimited by the interconnection of third order septa which are covered by respiratory epithelium. Small patches of ciliated epithelium without goblet cells appear irregularly distributed on the septa. The respiratory epithelium consists of one type of pneumocyte, which shows characteristics of both type I and type II alveolar cells of higher vertebrates. The pneumocytes are irregular in shape and possess attenuated cytoplasmic processes, which spread around the capillaries to form the outer layer of the air-blood barrier. These cells contain different types of cytoplasmic bodies: electron dense bodies, multivesicular bodies and lamellar bodies. Dense bodies are probably the precursors of lamellar bodies and the multivesicular bodies are incorporated into the latter. Neuroepithelial bodies appear randomly distributed over the septa. These bodies are separated from the lumen of the lung by thin cytoplasmic processes of neighbouring pneumocytes. The air-blood barrier consists of three layers: epithelium, interstitial space and endothelium.
The relatively simple pulmonary structure of M.s.stelzneri is due to a lower degree of partitioning of the pulmonary lumen in comparison to the lung of other bufonid anurans, could be correlated with a well developed cutaneous and buccopharingeal respiration. The testing of this hypothesis awaits further studies.     

一种小型陆空两栖机器人的选型分析与结构设计

为了适应灾害救援、资源勘探、野外侦查等复杂作业、复杂场景、复杂地形产生的特殊需求,文章研究了一种小型陆空两栖机器人的总体构型及其结构设计。首先根据该机器人要能实现陆地低角度侦查和空中高角度侦查的使用需求,确定该机器人要兼具地面运动能力和空中运动能力,其功能是地面机器人和飞行机器人的有机结合,据此分别探讨了一体式和组合式两种设计方案,进行了机构的构型分析[1]。在一体式构型方案中,对两自由度结构腿和三自由度结构腿分别进行了阐述与分析。最后综合对比了一体式构型方案和组合式构型方案,通过对优缺点的综合对比,得出组合式构型方案在功能性、实用性和稳定性等方面具有明显优势,为该机器人物理样机的研制提供了可靠、可信的依据[2]。     

Cytotoxicity in the frog (Fejervarya limnocharis) after acute cadmium exposure in vivo

Chromosome aberrations (CA) in frogs (Fejervarya limnocharis) exposed to 5, 10 and 20 mg/L of cadmium chloride (CdCl₂) for 24, 48 and 72 h were invetegated. Treated frogs were compared to a control group. Cadmium (Cd) was not detected in the water or control frogs. The highest Cd concentrations in water and frog samples were found at 20 mg/L exposed for 72 h. The water samples indicated that exposure to 10 mg/L of Cd for 24 h was significantly different from the control (p < 0.05). Cd concentrations in frogs differed significantly between the control and experimental groups (p < 0.05). The cytotoxicity assessment revealed ten types of CA in the frogs, including single chromatid gap (SCG), isochromatid gap, single chromatid break, isochromatid break, iso-arm fragmentation, single chromatid decomposition, centric fragmentation, centromere gap, deletion and fragmentation. The most common CA in the study was SCG. The statistical analysis indicated significant differences in the percentage of cells with CA for exposures of 20 mg/L (24 h), 10 and 20 mg/L (48 h) and 5, 10 and 20 mg/L (72 h) compared to the control (p < 0.05). The results of this study show that high Cd concentrations and long duration exposure can cause CA in frogs.     

自动机两栖工作环境下的运动参数测试分析

两栖轻武器在水下工作时受到水介质的影响,会直接影响自动机运动,因此,研究两栖环境下的自动机运动规律具有重要意义.针对其自动机工作环境的特殊性,利用自制永磁式感应测速传感器组建了一套参数研究系统,利用Labview编写了数据采集和分析软件,对陆上和水下分别进行了自动机参数分析,获得了相应数据.根据自动机运动参数测试结果对其陆上和水下两种工作状态进行了分析,指出陆上复进阶段最大速度为水中的2倍左右,后坐和复进总时间与在水中的相差不大,单纯提高自动机后坐初始速度不能解决自动机后坐全行程的能量问题,对指导两栖武器设计具有参考价值.