不同营养源对人工湿地基质生物膜培养液pH值的影响

采用恒温摇床培养方法,研究了不同营养源(处理1:尿素+乙酸钠;处理2:亚硝酸钠+乙酸钠;处理3:硝酸钾+乙酸钠;处理4:碳酸氢铵;处理5:硫酸铵+碳酸氢钠;处理6:磷酸二氢钾+碳酸氢钠)对复合垂直流人工湿地基质生物膜培养液pH值的影响,探讨了pH值变化过程中生物膜脱氢酶活性和多糖含量的变化规律。结果表明,处理1、4以及5中培养液pH值先下降然后再上升,但下降和上升的幅度不同。处理2、3以及6中培养液pH值添加碳源前在7.30~7.40之间缓慢变化,添加碳源后均上升至9.00左右。在培养液pH值变化的过程中

温度和pH值对嗜水气单胞菌毒力基因表达的影响

为了解培养温度和pH值对嗜水气单胞菌的毒力基因表达以及致病性的影响,利用反转录PCR(RT-PCR)对4种基因的表达进行了研究。研究结果显示嗜水气单胞菌毒力基因的表达受温度和pH值影响,其中溶血素(AHH)、气溶素(AerA)、外膜蛋白(OMP)和粘附素(Aha)毒力基因在15℃、25℃和37℃下均能高效表达,在4℃AHH和AerA两基因也能持续表达,但OMP和Aha两基因的表达停止。在中性或偏酸性的条件下(pH5.0和pH7.0)4种毒力基因都得以表达,在碱性条件下(pH9.0)4种基因中只有AHH得以

赤潮藻中肋骨条藻的光合作用对海水pH和N变化的响应

为探讨赤潮发生时中肋骨条藻 (Skeletonemacoatatum)的光合作用生理变化 ,研究了不同无机氮 (N)水平上 ,海水pH值升高对其胞外碳酸酐酶 (CA)和光合生理特性的影响。海水pH从 8.2升至 8.7时 ,中肋骨条藻胞外CA被诱导 ,细胞对无机碳的亲和力 (1/Km)提高 ;在pH8 7时 ,高N条件下的胞外CA活性是低N条件下的 3倍 ,1/Km 值也提高了 80 %。单位叶绿素a的最大净光合能力 (Pam)在不同pH和N水平上没有显著差异 ;但单位细胞的最大净光合能力 (Pcm)提高

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

Coagulation removal of melanoidins from biologically treated molasses wastewater using ferric chloride

The pigments (melanoidins) in molasses wastewater are refractory to conventional biological treatment. Ferric chloride was used as coagulant to remove color and chemical oxygen demand (COD) from molasses effluent. Using jar test procedure, main operating conditions such as pH and coagulant dosage were investigated. Under the optimum conditions, up to 86% and 96% of COD and color removal efficiencies were achieved. Residual turbidity in supernatant was less than 5 NTU and Fe3+ concentration was negligible because of effective destabilization and subsequent sedimentation. The results of high performance size exclusion chromatography (HPSEC) show that low molecular weight (MW) fraction of melanoidins is more reactive than high MW fraction and increase in the concentration of the lowest MW organic group is related to the capacity of charge neutralization. Aggregate size measurement reveals the size effect on the settleability of flocs formed, with larger flocs settling more rapidly. Charge neutralization and co-precipitation are proposed as predominant coagulation mechanism under the optimum conditions. (C) 2009 Elsevier B.V. All rights reserved.

Optimum temperature for the growth performance of juvenile orange-spotted grouper (Epinephelus coioides H.)

Effects of water temperature (17, 21, 25, 30 and 35 degrees C) and body size (14.75-281.41 g initial body weight) on food consumption, growth, feed conversion, and dry matter content in orange-spotted grouper fed to satiation were investigated. The combined effect of temperature (T, degrees C) and body weight (W, g) on maximum food consumption (C-max, g/day) was described as: InCmax= -7.411+0.828 lnW+0.317T-0.004 7T(2), and the optimum feeding temperature was 33.9 degrees C. The combined effect of temperature and body weight on growth (G) was described as: InG= -4.461-0.208lnW+0.394T-0.006 3T(2). The optimum growth temperature was 31.4 degrees C, whereas overall growth rates were high at 25, 30 and 35 degrees C. Feed conversion efficiencies (FCE, %), increasing first and then decreasing with increasing temperature, averaged from 1.8 to 2.1 in terms of dry weight of food fish. The optimum temperature for FCE tended to be lower than that for growth or feeding. Dry matter content increased with both increasing water temperature (17, 25, 30 and 35 degrees C) and body weight, and the combined effect of temperature and body weight on dry matter content (DM, %) was described as: lnDM =3.232+0.01 4 lnW-0.004 4T+0.001 2TlnW.

Determination of sexual hormones in liquid cosmetics by polymer monolith microextraction coupled with high performance liquid chromatography

A method was presented for the determination of testosterone, methyltestosterone and progesterone in liquid cosmetics by coupling polymer monolith microextraction (PMME) to high performance liquid chromatography with UV detection. A poly (methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column was selected as the extraction medium, which showed high extraction capacity towards these compounds. To achieve optimum extraction performance, several parameters relating to PMME were investigated, including extraction flow rate and pH value, inorganic salt and organic phase concentration of the sample matrix. By simple dilution with phosphate solution and filtering, the sample solution then could be directly injected into the device for extraction. The limits of detection of testosterone, methyltestosterone and progesterone were calculated to be 2, 3, 2, 8 and 4.6 mu g/L. Good linearity was achieved in the range of 10 to 1000 mu g/L with a linear coefficient. r value above 0. 996. Excellent method reproducibility was found by intra- and inter-day precisions, yielding the relative standard deviations of < 7. 7 % and < 7. 5 %, respectively. Recovery for them in the real samples was between 83% and 119%.

Analysis of estrogens in environmental waters using polymer monolith in-polyether ether ketone tube solid-phase microextraction combined with high-performance liquid chromatography

A simple, rapid and sensitive on-line method for simultaneous determination of four endocrine disruptors (17 beta-estradiol, estriol, bisphenol A and 17 alpha-ethinylestradiol) in environmental waters was developed by coupling in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography (HPLC) with fluorescence detection (FLD). A poly(acrylamide-vinylpyridine-NAP-methylene bisacrylamide) monolith, synthesized inside a polyether ether ketone (PEEK) tube, was selected as the extraction medium. To achieve optimum extraction performance, several parameters were investigated, including extraction flow-rate, extraction time, and pH value, inorganic salt and organic solvent content of the sample matrix. By simply filtered with nylon membrane filter and adjusting the pH of samples to 6.0 with phosphoric acid, the sample solution then could be directly injected into the device for extraction. Low detection limits (S/N = 3) and quantification limits (S/N = 10) of the proposed method were achieved in the range of 0.006-0.10 ng/mL and 0.02-0.35 ng/mL from spiked lake waters, respectively. The calibration curves of four endocrine disruptors showed good linearity ranging from quantification limits to 50 ng/mL with a linear coefficient R-2 value above 0.9913. Good method reproducibility was also found by intra- and inter-day precisions, yielding the RSDs less than 12 and 9.8%, respectively. Finally, the proposed method was successfully applied to the determination of these compounds in several environmental waters. (c) 2006 Elsevier B.V. All rights reserved.

Physico-chemical properties of alkaline phosphatases released by a planktonic crustacean, Daphnia magna (Cladocera)

Our studies investigated the physico-chemical properties of alkaline phosphatase excreted by D. magna. This cladoceran mainly released alkaline phosphatase, though it also released a small amount of acid phosphatase. The alkaline phosphatase showed a broad pH optimum (8.05-10.0), and had a broad optimum temperature (30-35 degrees C) with a temperature coefficient (Q(10)) of 2.45. The K-m of the enzyme is 0.15 +/- 0.02 mM when p-nitrophenyl phosphate is used as a substrate, and the V-max is 0.43 +/- 0.01 mu M pNP mg(-1) DW h(-1). Even though alkaline phosphatase had been incubated in chloroform saturated with WC medium for 13 days, its activity was 54% that of the original. The enzyme was strongly inactivated by EDTA, and appeared to be zinc dependent. The alkaline phosphatase activity remained constant when D. magna was fed different quantities of Chlorella sp. The sensitivity of D. magna phosphatase activity to phosphate was time-dependent. During the first 16 hrs, the enzyme was insensitive to phosphate addition, after 24 hrs incubation the enzyme became sensitive to phosphate addition.