OPTIMUM USE OF PADDY FIELDS FOR FLOOD MITIGATION1

In Taiwan, the continuously increasing levels of rice imports are likely to result in surplus paddy fields. Hence, the surplus paddy fields may be developed into wetlands to increase ground water recharge, provide appropriate environments for wildlife, and most importantly, store flood water. This study developed a hydrological model incorporating the distributed rainfall‐runoff model based on the kinematics wave approach and the distributed tank model for simulation, respectively, in mountainous and flat areas. The hydrological model was found to simulate the rainfall‐runoff behavior well in the study area. Furthermore, a decision method based on the genetic algorithm concepts was proposed to give policy makers the optimal location and area size of paddy fields to construct wetlands for flood mitigation.     

Biodegradation of nonylphenol in river sediment

We investigated the biodegradation of nonylphenol monoethoxylate (NP1EO) and nonylphenol (NP) by aerobic microbes in sediment samples collected at four sites along the Erren River in southern Taiwan. Aerobic degradation rate constants (k1) and half-lives (t1/2) for NP (2 microg g(-1)) ranged from 0.007 to 0.051 day(-1) and 13.6 to 99.0 days, respectively; for NP1EO (2 microg g(-1)) the ranges were 0.006 to 0.010 day(-1) and 69.3 to 115.5 days. Aerobic degradation rates for NP and NP1EO were enhanced by shaking and increased temperature, and delayed by the addition of Pb, Cd, Cu, Zn, phthalic acid esters (PAEs), and NaCl, as well as by reduced levels of ammonium, phosphate, and sulfate. Of the microorganism strains isolated from the sediment samples, we found that strain JC1 (identified as Pseudomonas sp.) expressed the best biodegrading ability. Also noted was the presence of 4'-amino-acetophenone, an intermediate product resulting from the aerobic degradation of NP by Pseudomonas sp.     

Measurement of ultrafine particle size distributions from coal-, oil-, and gas-fired stationary combustion sources

Currently, we have limited knowledge of the physical and chemical properties of emitted primary combustion aerosols and the changes in those properties caused by nucleation, condensation growth of volatile species, and particle coagulations under dilution and cooling in the ambient air. A dilution chamber was deployed to sample exhaust from a pilot-scale furnace burning various fuels at a nominal heat input rate of 160 kW/h(-1) and 3% excess oxygen. The formation mechanisms of particles smaller than 420 nm in electrical mobility diameter were experimentally investigated by measurement with a Scanning Mobility Particle Sizer (SMPS) as a function of aging times, dilution air ratios, combustion exhaust temperatures, and fuel types. Particle formation in the dilution process is a complex mixture of nucleation, coagulation, and condensational growth, depending on the concentrations of available condensable species and solid or liquid particles (such as soot, ash) in combustion exhausts. The measured particle size distributions in number concentrations measured show peaks of particle number concentrations for medium sulfur bituminous coal, No. 6 fuel oil, and natural gas at 40-50 nm, 70-100 nm, and 15-25 nm, respectively. For No. 6 fuel oil and coal, the particle number concentration is constant in the range of a dilution air ratio of 50, but the number decreases as the dilution air ratio decreases to 10. However, for natural gas, the particle number concentration is higher at a dilution air ratio of 10 and decreases at dilution air ratios of 20-50. At a dilution air ratio of 10, severe particle coagulation occurs in a relatively short time. Samples taken at different combustion exhaust temperatures for these fuel types show higher particle number concentrations at 645 K than at 450 K. As the aging time of particles increases, the particles increase in size and the number concentrations decrease. The largest gradient of particle number distribution occurs within the first 10 sec after dilution but shows only minor differences between 10 and 80 sec. The lifetimes of the ultrafine particles are relatively short, with a scale on the order of a few seconds. Results from this study suggest that an aging time of 10 sec and a dilution air ratio of 20 are sufficient to obtain representative primary particle emission samples from stationary combustion sources.     

Relationship between electron donor and microorganism on the dechlorination of carbon tetrachloride by an anaerobic enrichment culture

An investigation involving the supplement of different concentrations of substrates and microorganisms was carried out under anaerobic condition to assess the feasibility of bioremediation of carbon tetrachloride (CCl₄) with the amendment of low concentrations of auxiliary substrate and microorganisms. The concentrations of substrate and microorganisms ranged from 10 to 100 mg/l and from 3.7 × 10⁴ to 3.7 × 10⁶ cell/ml, respectively. The biotransformation rate of CCl₄ increased progressively with the increase in the concentrations of the substrate and microorganisms. In the low biomass-amended system (3.7 × 10⁴cells/ml), 28–71% and 57–96% of CCl₄ removals were exhibited when 10–100 mg/l of acetate or glucose was supplemented, respectively, whereas nearly complete degradation of CCl₄ was observed in the heavily inoculated systems (3.7 × 10⁶ cells/ml). An addition of electron donor in the low microbial activity batches enhanced greater efficiency in dechlorination than in the high microbial activity batches. The second-order rate constants ranged from 0.0059 to 0.0092 l/mg/day in high biomass input system, while a two- to four-fold increase in rate constant was obtained in the low microbial activity system. This study indicates that biomass was the more important environmental parameter than substrate affecting the fate of CCl₄. The addition of auxiliary substrates was effective only in low biomass-amended batches (0.56 mg-VSS/l) and diminished inversely with the increase of microbial concentration.     

Optimized combinations of abatement strategies for urban mobile sources

The maximum incremental reactivity (MIR) scale was chosen as a practical index for quantifying ozone-forming impacts. The integer linear and nonlinear programming techniques were employed as the optimization method to maximize MIR and volatile organic compound (VOC) reductions, and minimize ozone's marginal cost with varied control costs. Mobile vehicles were divided into nine categories according to the demands of decision makers and the distinctive features of local circumstance in metro-Taipei. The emission factor (EF) and vehicle kilometers traveled (VKT) of each kind of vehicle were estimated by MOBILE5B model via native parameters and questionnaires. Compressed natural gas (CNG) and inspection and maintenance (I/M) were the alternative control programs for buses and touring buses; liquefied petroleum gas (LPG), I/M, methanol, electrical vehicle (EV) were for taxis and low duty gasoline vehicles. EV, methanol, and I/M were the possible control methods for two-stroke and four-stroke engine motorcycles; I/M programs for low-duty diesel trucks, heavy-duty diesel trucks, and low-duty gasoline trucks. The results include the emission ratios of specific vehicle to all vehicles, the best combination of abated measures based on different objectives, and the marginal cost for ozone and VOC with varied control costs.     

倒置A^2／O工艺出水指标预测和评价方法的研究

研究了用一种简单的静态物理模型取代复杂的数学动态模型,实现对实际污水处理效果的实时预测及评价的方法。应用国际水协（IWA）GPS-X模拟软件中的ASM2d模型,建立了不同进水水质和不同运行参数条件下倒置A^2／O工艺出水TSS、COD、TN、NH4^＋-N、TP和溶解性磷酸盐浓度的数据库,结果表明,该数据库可以对倒置A^2／O工艺出水指标进行预测。以预测的出水指标和实际出水指标之间的差值为指标因素,采用专家打分法确定指标权重,通过对指标的分级界定建立因素指标的隶属函数,最后运用模糊综合评判的方法实现了对倒置A^2／O工艺处理效果的评价,建立了倒置A^2／O工艺处理效果的数学模型。     

低压旋转脉冲袋式除尘器的研究

中国的资源国情决定了中国能源结构以火电为主。随着烟尘排放标准的不断提高,袋式除尘器将在除尘领域发挥重大作用。综合比较三种类型的袋式除尘器,低压旋转脉冲袋式除尘器凭借其优点将在燃煤电厂的除尘领域中有十分广阔的应用前景。本文主要介绍了低压旋转脉冲袋式除尘器的滤料性能、本体结构特点和工艺系统等内容。     

两种常用兽药对作物发芽的生态毒性效应

采用室内生长箱培养的试验方法,研究了2种常用兽药磺胺嘧啶钠、环丙沙星对小麦、白菜和番茄种子发芽、根伸长、芽伸长的影响,分析了兽药和作物生长之间的剂量.效应关系,比较分析了小麦,白菜和番茄对2种兽药胁迫的敏感性.结果表明,根长抑制率和芽长抑制率与兽药浓度显著相关(p<0.05);种子发芽抑制率与2种兽药浓度不相关(p>0.05).2种兽药对根伸长和芽伸长的抑制明显强于对种子发芽的抑制.3种作物对磺胺嘧啶钠胁迫的敏感性依次为小麦＞白菜＞番茄;对环丙沙星胁迫的敏感性依次为白菜＞番茄＞小麦;磺胺嘧啶钠对3种作物的毒性效应明显强于环丙沙星.     

LabView平台下电源测控系统的实现

针对真空热试验设备中大规模电源测控的需求,在原有的外热流系统基础上,利用LabView平台重新设计了电源测控系统。该系统能够实现传统的大规模电源系统的灵活自动配置与控制,达到控制真空热试验设备中要求工况的目的,实现该电源测控系统软件的模块化更新,便捷地应对更换新型硬件电源所带来的软件更新需求。介绍了该电源测控系统的开发,包括其工作原理、硬件结构以及软件结构,重点介绍了LabView平台下的上位自动控制软件的设计。     

基于问卷调查的个人生态足迹测算及分析——以厦门大学在读学生为例

文章运用世界自然基金会提供的个人年生态足迹计算软件,通过问卷调查收集资料,测算厦门大学在读学生个人生态足迹,并分析探讨高校在读学生个人生态足迹的组成及影响因素。结果表明,厦门大学在读学生的个人生态足迹介于0.4 gh～1.6 gh之间,平均值为0.83 gh,远低于中国人均生态足迹;在各组成部分中,耕地、水域和碳足迹为主要用地类型,占人均足迹的90%以上;被访者的性别、学科和学历对其个人生态足迹的影响不明显,而个人月可支配收入及其出行方式与个人生态足迹的大小存在明显正相关性,即月可支配收入越高个人足迹越大,选择环保的出行方式则个人生态足迹较小。