Direct methanol fuel cell bubble removal mechanism using magnetic actuation

This article develops a direct methanol fuel cell (DMFC) with a magnet-actuated bubble removal mechanism. A micro-DC motor is used to control the bubble removal mechanism. The lower magnetic device is operated to extrude a Polydimethylsiloxane (PDMS) runner to compress the liquid fuel in the anode flow channel, forcing the CO₂ bubbles in the runner to flow toward the outlet end. The bubble retention in the anode flow channel is thereby improved, enhancing the cell performance. The proposed mechanism stability and performance and Polymethylmethacrylate (PMMA) runner are also discussed.     

文思湖底泥COD释放规律模拟研究

采用室内模拟实验方法，研究环境因子（温度、pH、扰动强度、供气量）对底泥释放COD的影响。结果表明，水温升高能加速底泥中有机质的释放；上覆水在弱酸至中性条件下底泥释放有机质最低；扰动上覆水体会加快有机质的释放。     

保护臭氧层谈判中的美欧博弈

臭氧层损耗是重要的全球环境问题之一。最早认识到臭氧层危害的美国率先在国内立法控制相关物质,然而另一大经济体——欧共体,在这一方面却行动迟缓。在保护臭氧层的国际谈判中,美欧之间相互妥协,最终达成了对氟氯烃化合物(CFCs)进行限控的《蒙特利尔议定书》。美欧之间的分歧来自国内化工业巨头的影响,国际经济变动影响外交决策。国际环境问题背后隐藏的经济关系与大国的领导作用是影响国际环境合作的主要因素。     

Effect of factors on decolorization of azo dye methyl orange by oxone/natural sunlight in aqueous solution

Purpose  

The oxone process for azo dye decolorization has drawbacks such as difficulties with reuse, risks of secondary pollution, and high costs associated with UV irradiation. This study aims to explore the use of oxone for decolorization in the absence of catalyst and under natural sunlight conditions (i.e., oxone/natural sunlight system) and evaluate the impacts of operating parameters (reagent dosage, initial methyl orange (MO) concentration, and initial pH) and coexisting substances (humic acid, NO₃⁻, metal ions) on the system’s decolorization efficiency.     

有机物降解产气率模型研究

根据重庆市生活垃圾的组成特点,自配垃圾试样进行有机物降解实验,根据实验期间试样的质量变化,结合降解反应方程式,计算试样的产气量,并建立产气率模型.实验结果表明,试样质量随时间逐渐降低,呈指数型衰减规律.试样在实验初期产气率增加较快,达到产气高峰后逐渐降低.用建立的产气率模型进行计算,计算结果与实测数据比较接近,说明该产...     

湘江霞湾港段底泥的含镉量分布研究

为了研究湘江霞湾港段底泥中镉的含量分布和释放特性,对该河段底泥采样以测定含镉量,并采用Tessier连续提取法对镉形态进行分析测定.结果表明,湘江霞湾港段受到严重的镉污染,其底泥含镉量最高达359.8μg/g.湘江底泥和间隙水中含镉量的吸附-解吸平衡可采用Freundlich吸附等温式描述.对新霞湾和老霞湾排污口附近河流底泥的镉形态分析表明,镉污染物以有机质-硫化物结合态为主,分别占总量的73.3%(质量分数,下同)、65.3%,其次是残渣晶格结合态,分别占总量的26.5%、34.4%.     

碘掺杂Ti02可见光光催化性能研究

在低于100℃温度条件下，采用溶胶一凝胶法以钛酸正丁酯为钛源，碘酸钾为碘源，制备了I掺杂纳米TiO2催化剂（I-TiO2），运用x-射线衍射（XRD）、透射电镜（TEM）及x-射线光电子能谱（XPS）等对催化剂进行表征，结果表明，TiO2及I-TiO2催化剂均为锐钛矿，I吸附并包裹在TiO2表面或以间隙进入的形式存在，并未进入TiO2晶格。通过在可见光照射下（A〉420nm）以罗丹明B（RhodamineB，RhB）的光催化降解为探针反应研究了在不同条件下制备催化剂的催化性能，结果表明，掺杂比为n1：n^ti=0．05：l，焙烧温度为400℃，降解介质条件pH=7时，l-TiO2光催化活性明显优于未掺杂的TiO2。光催化降解过程通过红外光谱（IR），总有机碳（TOC）跟踪测定，比较了TiO2掺杂前后降解RhB和对氯苯酚（4-CP）的光催化特性差异；同时采用苯甲酸荧光光度法跟踪测定体系中的氧化物种，表明在可见光下，I-TiO2光催化体系中产生·OH高活性氧化物种从而氧化降解目标化合物。     

Arsenic accumulation and speciation in the submerged macrophyte Ceratophyllum demersum L.

Introduction

Ceratophyllum demersum L. is a widespread submerged macrophyte in aquatic environments.

Methods

Simulation experiments were conducted in the laboratory to investigate arsenic (As) accumulation, speciation, and efflux of C. demersum exposed to arsenate and arsenite solutions.

Results

Plant shoots showed a significant accumulation of As with a maximum of 862 and 963???g?As?g^?1 dry weight after 4?days of exposure to 10???M arsenate and arsenite, respectively. Regardless of whether arsenate or arsenite was supplied to the plants, arsenite was the predominant species in plant shoots. Furthermore, a dramatically higher influx rate of arsenate compared with arsenite was observed in C. demersum exposed to As solutions without the addition of phosphate (P). Arsenate uptake was considerably inhibited by P in this study, suggesting that arsenate is taken up by C. demersum via the phosphate transporters. However, arsenite uptake was unaffected by P and markedly reduced in the presence of glycerol and antimonite (Sb), indicating arsenite shares the aquaporin transport pathway. In addition, C. demersum rapidly reduces arsenate to arsenite in the shoot of the plant and extrudes most of them (>60?%) to the external solutions. The efflux of arsenite was much higher than that of arsenate; the former is supposed to be both active and passive processes, and the latter through passive leakage.

Conclusion

C. demersum is a strong As accumulator and an interesting model plant to study As uptake and metabolism due to the lack of a root-to-shoot translocation barrier.     

中国水产养殖规划现状分析与对策

水产养殖规划可以降低水产养殖和水环境之间的不确定性、减少水产养殖活动的外部不经济性、提高水资源的利用效率,对中国水产养殖的可持续发展有重要作用.对已实施的水产养殖规划的现状分析结果表明,存在着水产养殖规划基础与水产养殖规划实施间的不协凋性、环境影响评价环节的缺失和水产养殖规划的实施效果蔗等主要现象.其根本原因是现有水产养殖相关制度的配置不完善.应从环境影响评价与水产养殖规划的集成关系入手,通过完善水产养殖容量的估算、水产养殖的技术与经济评估指标、制度和相关利益者分析与评估的方法和指标,建立水产养殖规划的技术体系.引入第三方评审制度以监督规划环境影响评价的质量.     

Tissue distribution of Dechlorane Plus and its dechlorinated analogs in contaminated fish: high affinity to the brain for anti-DP

Information on tissue distribution of Dechlorane Plus (DP) and its dechlorinated analogs in wildlife is scarce. DP isomers and two dechlorinated compounds, anti-Cl₁₁-DP and anti-Cl₁₀-DP, were examined in the muscle, liver, and brain tissues of two bottom fish species collected from an electronic waste recycling site, South China. The median levels of syn-, anti-, and anti-Cl₁₁-DP isomers in the tissues ranged 0.18-39.1, 0.22-52.9, and 0.01-5.63 ng/g wet wt, respectively. Anti-Cl₁₀-DP was only detected in one muscle sample of mud carp (0.01 ng/g wet wt), although it was consistently detected in the sediments (0.42-0.83 ng/g dry wt). Preferential distribution in liver relative to muscle was observed for syn-DP and anti-Cl₁₁-DP. However, a high persistent retention in the brain compared to the liver was observed for anti-DP, suggesting that this isomer can across the blood-brain barrier of fish, and may cause adverse effects to the nervous system in the exposed biota.