pH对萼花臂尾轮虫种群动态和休眠卵的影响

应用种群累积培养法,研究了pH3.5～11.5(间隔1.0)之间萼花臂尾轮虫(Brachionuscalyciflorus)的种群动态及休眠卵的形成。结果表明,该轮虫在pH5.5～10.5为正增长,pH7.5时种群增长趋势最好;pH4.5时为负增长;pH3.5和11.5分别是该轮虫存活下限和上限。pH对轮虫休眠卵的产量和形成效率、平均混交雌体百分率和受精率皆具极显著影响。7.5是该种轮虫休眠卵规模化生产的最佳pH值,此时休眠卵的产量和藻类食物的形成效率最大,分别为(132567±20264)/(20ml·

低pH值对大型溞（Daphnia magna Straus）存活、生长和生殖的影响

在静置换水条件下，研究了低ｐＨ值对大型存活、生长和生殖的影响。结果表明，在２５±１℃下，急性试验低ｐＨ值对大型的２４ｈ和４８ｈＬＬ５０值及其９５％可信限分别为ｐＨ值４．６６±０．１９和４．９４±０．２０。慢性试验进行了１４天，对存活和生长，ｐＨ值１．７５有影响，ｐＨ值５．０没有影响；对生殖，ｐＨ值５．０有影响，ｐＨ值５．５没有影响。显示出低ｐＨ值对大型的毒性阈限在ｐＨ值５．００－５．５０之间。

低pH对鱼类胚胎发育、鱼苗生长及鳃组织损伤影响的研究

本文研究了低pH水平对鱼类的胚胎,鱼苗和鱼种的影响以及鱼鳃的组织学观察。在硬水环境,pH≤4.5时,对泥鳅胚胎发育有严重影响。胚胎在低pH水平下,发育进程明显地迟缓。pH≤5.5时,泥鳅幼苗的生长受到抑制;在软水环境,pH≤4.5时,影响草鱼苗和幼鱼的存活率。低pH水平加上铝则对鱼类呈现出协同毒性。低pH使鱼鳃直接遭受严重的损害:出现大量的粘液、渗血、鳃上皮肿胀和脱落,组织增生和融合。

低pH和铝对几种淡水鱼类早期生活阶段的影响

在实验室条件下,把早期生活阶段的白链(Hyhophthalmichthys molitrix)、鳙鱼(Arist-ichthys nobilis)和草鱼(Ctenopharyngodon idellus)突然置于一系列低pH值水中,以测试产生毒性影响的pH水平.在受试的三种鱼中,未发现对低pH的敏感性有显著差异,但在发育过程中其敏感性逐渐降低.在pH5.0的水中,Al(0.1—16mg/L)对草鱼仔鱼毒性测试结果表明,96h的LC_(50)为0.26mg/L(0.21—0.31mg/L),致死阈浓度为0.

低pH对草鱼呼吸活动和耗氧代谢的影响

研究了低pH(6.0—3.6)对草鱼呼吸活动机能及耗氧代谢的影响.结果表明,在pH4.6—3.6条件下,草鱼呼吸和气体代谢活动受干扰的程度随酸度增大而急剧加重.其具体表现为:呼吸率加快,咳嗽反应增加,呼吸深度加大.耗氧率起始升高继而迅速下降,并在极端pH(3.6)下最终引起机体组织缺氧而致死.对于pH5.6,草鱼各类呼吸与代谢指标未受明显影响,基本属于正常.供试草鱼对低pH反应的灵敏程度依次为:咳嗽率>呼吸率>耗氧率>呼吸深度.

低pH对草鱼血液酸碱平衡的影响

研究了低pH(6.0—4.0)对草鱼血液酸碱平衡、p_(o2)及p_(co2)的影响,结果表明,低pH引起草鱼严重的酸血症.亚致死pH(6.0—5.0)时,血液酸碱平衡的影响主要表现为碱贮备[HCO_3]的丧失,血液pH的明显下降经机体缓冲调节可趋于稳定.致死低pH(4.0)时,血液pN和[HCO_3]下降均非常显著,并在96h内随酸化时间延长而日趋严重.仅在pH≤4.0的酸水中草鱼存在低氧症影响问题.草鱼是一种酸敏感性鱼类,为确保成鱼在天然水体的生存和繁育,水质pH至少应维持在6.0以上.

五种水蛭对不同pH值的生物效应

本文论述了使用常规试验方法研究5种水蛭:宽身舌蛭(Glossiphonia lata)、八目石蛭(Erpobdella octoculata)、光润金线蛭(Whitmania laevis)、尖细金线蛭(Whitmania acranulata)和日本医蛭(Hirudo nipponia)对12个pH值的24—96小时急性生物效应。结果表明:稻田3个种(尖细金线蛭,光润金线蛭和日本医蛭)均较湖泊近岸2个种(八目石蛭和宽身舌蛭)对pH值的变化要敏感,其中尖细金线蛭最敏感(pH6.0—7.2),八目石蛭的忍耐

Development of low-pH cements for immobilisation of intermediate level radioactive waste: Achievements and challenges

Although cementation is a widely recognized solidification/ stabilization process for immobilisation of Intermediate Level Radioactive Waste (ILRW), the low resistance to hyperalkaline pore waters compromises the effectiveness of the process when Portland Cement (PC) is employed. Moreover the manufacture of PC is responsible for significant CO2 emissions. In this context, low pH cements are environmentally more suitable and have emerged as a potential alternative for obtaining secure waste forms. This paper summarises the achievements on development of low-pH cements and the challenges of using these new materials for the ILRW immobilisation. The performance of waste forms is also discussed in terms of radionuclides release. Reactive magnesium oxide and magnesium phosphate cements are emphasised as they feature important advantages such as consumption of available constituents for controlling acid-base reactions, reduced permeability and higher density. Additionally, in order to identify new opportunities for study, the long-term modelling approach is also briefly discussed. Copyright © 2013 by ASME.

Preparation of pH-sensitive polymer by thermal initiation polymerization and its application in fluorescence immunoassay

A fluorescence immunoassay for human IgG (Ag) was developed using a pH-sensitive polymer prepared by thermal initiation or redox initiation polymerization as a carrier. In the competitive immunoassay, appropriate quantity of Ag was immobilized on the polymer and the standard Ag (or sample) solution, and a constant amount of fluorescein isothiocyanate labeled goat anti-human IgG antibody (Ab-FITC) was added. Immobilized Ag and the standard (or sample) Ag competed for binding to the Ab-FITC in 37 C in homogeneous format. After changing the pH to separate the polymer-immune complex precipitate, it was re-dissolved and determined by fluorescence method. The results showed that the immobilization efficiency, immunological reaction activities of immobilized Au and phase transition pH range were improved as Ag was immobilized by thermal initiation instead of redox initiation polymerization. Under optimum conditions, the calibration graphs for the Ag in both methods, thermal initiation and redox initiation, were linear over the concentration range of 0.0-1000 ng mL(-1), with detection limits 8 (thermal initiation) and 12 ng mL(1) (redox initiation), respectively. Moreover, some pH-sensitive polymer prepared only in organic solvent or under high temperature could also be used as an immunoreaction carrier by thermal initiation polymerization. Thermal initiation polymerization was a better immobilization mode. (C) 2004 Elsevier B.V. All rights reserved.

Fluorescence pH probe based on microstructured polymer optical fiber

A kind of optical pH sensor was demonstrated that is based on a pH-sensitive fluorescence dye-doped (eosin) cellulose acetate (CA) thin-film modified microstructured polymer optical fiber (MPOF). It was obtained by directly inhaling an eosin-CA-acetic acid mixed solution into array holes in a MPOF and then removing the solvent (acetic acid). The sensing film showed different fluorescence intensities to different pH solutions in a pH range of 2.5-4.5. Furthermore, the pH response range could be tailored through doping a surfactant, hexadecyl trimethyl ammonium bromide (CTAB), in the sensing film. (c) 2007 Optical Society of America.

不同pH值缓冲液处理下蚕豆叶片相对含水量、脯氨酸及丙二醛含量的变化

研究了外源pH缓冲液处理下,离体和整株蚕豆叶片相对含水量、脯氨酸含量和丙二醛含量的变化。结果表明,酸碱处理离体蚕豆叶片10 min和30 min后,叶片组织相对含水量在pH 6.5时最高;酸性处理下的叶片脯氨酸含量较高;pH 5.0时丙二醛含量较高。整株蚕豆叶片处理5 h的叶片组织相对含水量在pH 6.5时最高,处理12 h以pH 5.0时最高;pH 5.5处理5 h叶片脯氨酸含量最高,处理12 h脯氨酸含量的变化不大;处理5 h时丙二醛含量的变化随pH的降低略有下降,但处理12 h丙二醛含量的变化不大。

黄土高原小流域土壤pH、阳离子交换量和有机质分布特征

通过野外调查采样和室内分析,研究了黄土高原小流域土壤pH、阳离子交换量(cat-ion exchange capacity,CEC)和有机质的分布特征及其与土地利用方式、地形条件和土壤类型的关系.结果表明:黄土高原小流域土壤pH、CEC和有机质分别介于7.7~8.6、11.9~28.7cmol.kg-1和3.0~27.9 g.kg-1,分别服从正态分布、对数正态分布和负二项分布.3种土壤性质随地形、土地利用方式和土壤类型的不同差异很大.不同土地利用方式下,土壤有机质和CEC以林地、草地和农田较高,果园较低;pH则以林地较低,其他利用方式较高;不同地形条件下,3种土壤性质均呈塬面和坡地大于沟道和梯田的趋势;不同类型土壤中,有机质和CEC以黑垆土和红土较高,pH则以黄绵土较高.整体上,土壤有机质和CEC呈现出相似的变化趋势,而pH的分布特征则与之相反

不同pH缓冲液处理下蚕豆幼苗叶片SOD、POD和CAT活性的变化

利用不同pH值的酸碱溶液处理蚕豆或者离体蚕豆叶片,研究酸碱胁迫下蚕豆叶片保护酶活性的变化。结果表明,离体蚕豆叶片处理10 min和30 min的SOD活性相差不大,整株处理5 h的蚕豆叶片SOD活性远大于处理12 h的SOD活性;离体蚕豆叶片和整株蚕豆处理,较长时间处理下的CAT活性基本上高于短时间处理的CAT活性,短时间处理下(10 min、5 h)POD活性均显著低于对照值,较长时间处理(30 min、12h)下POD活性变化的规律性不强,且变化幅度较小。

黄土沟壑区小流域土壤pH值的空间分布及条件模拟

土壤pH值是影响土壤养分有效性和化学物质在土壤中行为的主要因素,研究土壤pH值的空间分布特征对于土壤养分管理和土壤污染预测具有重要意义。该文用地统计学方法研究了环境因素复杂的黄土高原小流域土壤pH值空间分布特征。结果表明,黄土沟壑区小流域土壤pH值具有球形—指数套合模型的空间结构特征,其空间异质性主要来源于流域内土地利用和土壤侵蚀等随机因素。与有机质协同的Kriging法能较好地对土壤pH值进行估值,其估值范围小于实测数据,估值误差来源于复杂的环境因素。序贯高斯条件模拟的土壤pH值范围与实测数据接近,模拟的平均值低于实测数据,模拟误差来源于模拟过程中独特的Kriging算法及高斯特性。