Electrosensory basis for individual recognition in a weakly electric, mormyrid fish, Pollimyrus adspersus (Günther, 1866)

Pollimyrus adspersus discriminates the individually variable waveforms of Electric Organ Discharges (EODs) of conspecifics of only 150–250 s duration. We examined: (1) the discrimination threshold for artificially generated EODs of similar waveform, (2) the mechanism of signal analysis (spectral vs temporal) present, by determining the discrimination between different waveforms of identical amplitude spectra, and (3) the threshold field intensity and reach of discrimination. The triphasic P. adspersus EOD waveform was artificially generated by superimposing two Gaussians, one wide, the second narrow, inverted, and of threefold amplitude. The natural variability among individual EOD waveforms was simulated by phase-shifting one Gaussian relative to the other. The symmetrical waveform where the peaks of the two Gaussians coincided was used as a reference (phase shift=0, rewarded stimulus S+). Results were: (1) in food-rewarded conditioning experiments, trained fish (N=7) detected a phase-shift in artificial EOD stimuli as low as 2 s (N=2 fish), 6 s (N=1) and 10 s (N=1). (2) All fish tested (N=3) discriminated between artificial EODs of identical amplitude spectra but different waveforms (hence, different phase spectra), demonstrating a temporal mechanism of signal analysis. (3) The maximum reach of waveform discrimination was 130 cm at 4.9 V_p-p/cm and 100 S/cm water conductivity (test signal generated at natural amplitude), that is, similar to the reach of EOD detection. Therefore, among the three kinds of electroreceptor organ present in mormyrids, we consider Knollenorgane the relevant sensory organs for EOD waveform discrimination.Communicated by J. Krause     

Science and management in four U.S. coastal ecosystems dominated by land-ocean interactions

The influence of science in the recognition of the effects of landscape changes on coastal ecosystems and in the development of effective policy for managing and restoring these ecosystems is examined through four case studies: Chesapeake Bay, San Francisco Bay, the Mississippi Delta, and Florida Bay. These ecosystems have undergone major alterations as a result of changes in the delivery of water, sediments and nutrients from their watersheds. Both science and management have been challenged by the spatial, functional and temporal scale mismatches inherent in the watershed-coastal ecosystem relationship. Key factors affecting the influence of science on management include (1) sustained scientific investigation, responsive to but not totally defined by managers; (2) clear evidence of change, the scale of the change and the causes of the change; (3) consensus among the scientific communities associated with various interests; (4) the development of models to guide management actions; (5) identification of effective and feasible solutions to the problems.     

Stability and Mixing of a Vertical Axisymmetric Buoyant Jet in Shallow Water

The stability, mixing and effect of downstream control on axisymmetric turbulent buoyant jets discharging vertically into shallow stagnant water is studied using 3D Reynolds-averaged Navier–Stokes equations (RANS) combined with a buoyancy-extended k –ε model. The steady axisymmetric turbulent flow, temperature (or tracer concentration) and turbulence fields are computed using the finite volume method on a high resolution grid. The numerical predictions demonstrate two generic flow patterns for different turbulent heated jet discharges and environmental parameters (i) a stable buoyant discharge with the mixed fluid leaving the vertical jet region in a surface warm water layer; and (ii) an unstable buoyant discharge with flow recirculation and re-entrainment of heated water. A stratified counterflow region always appears in the far-field for both stable and unstable buoyant discharges. Provided that the domain radius L exceeds about 6H, the near field interaction and hence discharge stability is governed chiefly by the jet momentum length scale to depth ratio l_M/H, regardless of downstream control. The near field jet stability criterion is determined to be l_M/H = 3.5. A radial internal hydraulic jump always exists beyond the surface impingement region, with a 3- to 6-fold increase in dilution across the jump compared with vertical buoyant jet mixing. The predicted stability category, velocity and temperature/concentration fields are well-supported by experiments of all previous investigators.     

辉光放电等离子体技术处理印染废水的研究

用辉光放电等离子体技术对茜素红降解进行了研究，藉助紫外光谱分析了其降解过程，结果表明，在pH=7时，茜素红于60min便可以被完全降解，且其排放液接近无色，降解过程中溶液pH值降低，说明反应过程中可能有羧酸类物质生成．两电极间的距离与催化剂对降解率有显著影响，COD先升高后降低，若在Fe^2 存在时，反应只需10min，且COD值不断减小．     

Science and management in four U.S. coastal ecossytems dominated by land-ocean interactions

The influence of science in the recognition of the effects of landscape changes on coastal ecosystems and in the development of effective policy for managing and restoring these ecosystems is examined through four case studies: Chesapeake Bay, San Francisco Bay, the Mississippi Delta, and Florida Bay. These ecosystems have undergone major alterations as a result of changes in the delivery of water, sediments and nutrients from their watersheds. Both science and management have been challenged by the spatial, functional and temporal scale mismatches inherent in the watershed-coastal ecosystem relationship. Key factors affecting the influence of science on management include (1) sustained scientific investigation, responsive to but not totally defined by managers; (2) clear evidence of change, the scale of the change and the causes of the change; (3) consensus among the scientific communities associated with various interests; (4) the development of models to guide management actions; (5) identification of effective and feasible solutions to the problems.     

飞灰和水在脉冲放电脱硫中作用的研究

为探讨脉冲放电脱硫和除尘结合的可行性 ,研究了飞灰和水对脉冲放电脱硫的影响。飞灰对脉冲放电脱硫影响不大 ;水对脉冲放电有明显抑制作用 ,但能显著提高脱硫效果 ,提高能量效率 ;飞灰和水协同作用对脱硫有利 ,不加氨时脱硫率达 1 6 2 % ,添加氨时电晕脱硫率达 30 5% ,总脱硫率 80 2 %。     

防洪保护及污水资源化工程对滇池环境保护的适用研究

滇池外海与草海分隔后，通过合理的调控，水资源是平衡的，且增加出口可从隧洞分洪达４０／Ｓ，满足２０年一遇分洪要求；工程运行将使滇池水质有所改善，对局部水域水质将会有较大改善；出水排入沙河使其失去饮用水功能，水生态环境变劣，而对螳螂川影响不明显；二期工程（三个水库的建设）使排水得到利用，产生一定的综合效益。     

辉光放电等离子体降解模拟染料废水的研究

用辉光放电等离子体技术对伊红B模拟染料废水降解进行了研究.借助紫外光谱和荧光光谱分析其降解过程,用酸度计测定了降解液pH的变化,用原子力显微镜观察了降解过程中伊红B的形貌并初步探讨了降解机理.结果表明,伊红B被降解为CO2、H2O和简单无机盐;在波长为513 nm时,降解110 min后,脱色率达到95%;反应后降解液pH降低,说明反应过程中有羧酸类物质生成.通过吸光度值计算得到了动力学常数k=0.0206 min-1,降解过程符合一级反应动力学特征.     

热排放对水生生态系统的影响及其缓解对策

综述了水域热排放对水生生态系统中的水体理化性质以及浮游生物、底栖动物和鱼类等生物因子影响的研究进展,并进一步探讨了水域热排放的缓解对策,为水体的水温控制标准和水环境评价提供科学依据。     

昆山市水环境问题及综合整治建议

水环境是城市形象的具体体现，是走生产发展、生活富裕、生态良好的新型工业化道路的重要保证。特别是我国在加速城市化、工业化、国际化的过程中，保护营造良好的水环境，对构筑以人为本的和谐社会具有非同一般的重要意义。以昆山市这个新兴工商城市为代表，从水环境的现状分析着手，阐述了当前水环境特征，提出一系列解决对策和工作目标，对于许多发展中的城市具有一定的借鉴意义。