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41.
本研究尝试用SF(OURmax/OURen)代替S(0)/X(0)来作为呼吸法确定COD组分最优实验条件的参数,从而简化测量过程且可实现自动化操作.另外由生长消耗COD与生物量的比值来判断测量结果的可靠性.结果表明,获得可靠的RBCOD组分分析结果的实验条件为:1对于易生物降解含量较高的水质(如由乙酸钠配制的污水),SF在2.8~5.3范围内,生长消耗COD与生物量比值在30%以内;2对于易生物降解和难生物降解物质适中的水质(如典型生活污水),SF应在5.8~6.4左右,生长消耗COD与生物量比值在30%以内;3而对于含有大量难生物降解物质的工业废水(垃圾渗滤液),SF在15以下,且生长消耗COD与生物量的比值在40%以内.由此可见,采用呼吸法确定COD组分,其最优条件SF范围随碳源的复杂程度的上升而上升. 相似文献
42.
超富集植物蜈蚣草能够累积土壤环境中的砷,为探明蜈蚣草植株中芘的赋存特征及其与砷的相互作用,采用双光子激光共聚焦扫描显微技术检测观察芘在该植物中赋存和分布规律.结果表明,添加芘导致蜈蚣草各部位砷含量显著降低,其中叶部和茎部砷含量下降幅度达35%左右,根部砷含量减少20.5%.芘的添加使得植物各部位三价砷比例下降,五价砷比例升高,蜈蚣草叶部三价砷和五价砷赋存浓度下降幅度最大,下降幅度分别为42.2%和32.49%.添加砷可促进蜈蚣草根部和茎部中芘的积累,每株分别增加了9.8μg和139 ng,但对叶部中芘的积累无显著影响.芘主要分布于蜈蚣草细胞膜与细胞内部的细胞器膜结构及细胞核核膜附近,但细胞质中芘的含量较少,茎部韧皮部与皮层以及叶部栅栏组织和海绵组织中几乎没有检测到芘. 相似文献
43.
以C57BL/6雄性小鼠为受试动物,研究慢性饮水型砷(As)暴露对肠道的损伤效应及作用机制.小鼠饮用含5 mg·L~(-1)或50 mg·L~(-1) As的亚砷酸钠(NaAsO_2)水溶液6个月后,检测空肠组织的氧化应激指标、病理学改变、免疫相关基因表达及黏膜杯状细胞数量.结果发现,As组小鼠空肠组织的超氧化物歧化酶活性和总抗氧化能力显著下降,脂质过氧化产物丙二醛含量显著升高;空肠黏膜受到侵蚀,上皮吸收细胞排列紊乱,部分肠绒毛脱落.氧化应激指标及病理学改变呈现剂量依赖性.5 mg·L~(-1) As组免疫相关基因TNF-α、IFN-γ、IL-4、IL-5和IL-13的mRNA水平显著升高,黏膜杯状细胞数量显著增加;50 mg·L~(-1)As组TNF-α、IFN-γ和IL-4显著下调表达,IL-5和IL-13的表达水平及黏膜杯状细胞数量无显著变化.结果表明,慢性饮水型As暴露诱导小鼠空肠氧化损伤及组织结构改变的同时可能诱发了肠道免疫紊乱.As暴露引起的黏膜损伤可能与As诱导空肠的氧化损伤相关. 相似文献
44.
为探究不同淋洗方式下螯合型表面活性剂LED3A(N-十二酰基乙二胺三乙酸钠盐)对重金属污染土壤的淋洗效果,采用室内土柱淋洗法研究了LED3A在不同流速条件下对Pb、Zn单一污染砂土的淋洗效果,并通过优化的BCR法分析了淋洗前、后土柱中不同深度处Pb、Zn的形态变化特征.结果表明:LED3A对Pb、Zn单一污染砂土的淋洗规律基本类似,淋出液中ρ(Pb)、ρ(Zn)随淋洗液累积孔隙体积数目的增加呈现急剧增大、达到峰值后逐渐降低的趋势;Pb、Zn的淋洗曲线中均存在不同程度的拖尾现象,且对称性较差;淋出液中ρ(Pb)、ρ(Zn)峰值和Pb、Zn最大累积去除率均随流速的增大而减小.随着淋洗深度和流速的增加,各形态Pb、Zn的去除率均呈现减小的趋势,LED3A对酸可提取态Pb、Zn的去除效果最为显著,去除率均大于50%;对氧化物结合态、有机结合态和残渣态Pb、Zn的去除率大小顺序与淋洗深度和流速有关;对比淋洗前、后土柱中重金属的形态分布可知,最易释放和被生物利用的酸可提取态的占比明显减少,不易或不能被生物利用的氧化物结合态、有机结合态和残渣态的占比明显增加.研究显示,LED3A低流速淋洗不仅能够去除一定量的土壤重金属,同时可有效降低残留重金属对环境的潜在风险. 相似文献
45.
以剩余污泥和烟草废弃物为研究对象,探究了针铁矿对有机物厌氧消化产甲烷的影响.针铁矿投加能提高消化产气率至359.4mL/g,显著高于空白对照组.针铁矿有助于混合气体中甲烷含量的升高并减少CO2的体积分数.针铁矿利于剩余污泥和烟草废弃物共消化过程有机物溶出,纤维素减量,从而为产甲烷古菌提供充足的消化底物.针铁矿利于酸化代谢过程,在针铁矿投加组中挥发性脂肪酸的最大产量仅为56.2mg/g,显著低于空白组,此外针铁矿促进丙酸的合成.针铁矿促进乙酸降解,在消化第1d,针铁矿投加实验组中乙酸降解率高达65.5%,较高于空白组中的56.6%.酶活性分析表明针铁矿促进水解,酸化及产甲烷过程关键酶.Methanothrix和Methanobacterium是产甲烷阶段重要微生物,454高通量测序表明针铁矿提高Methanothrix和Methanobacterium的相对丰度至59.6%和23.5%,显著高于空白对照组. 相似文献
46.
E. G. Plotnikova D. O. Rybkina L. N. Anan’ina O. V. Yastrebova V. A. Demakov 《Russian Journal of Ecology》2006,37(4):233-240
Microorganisms capable of degrading monocyclic and polycyclic aromatic hydrocarbons and several chlorinated aromatic compounds were isolated from soils polluted with industrial waste from chemical plants. They were identified as representatives of the genera Pseudomonas, Flavobacterium, Alcaligenes, Rhodococcus, Microbacterium, Cellulomonas, Arthrobacter, and Brevibacterium. Among them, bacteria capable of utilizing xenobiotics in a wide range of ambient temperatures and pH and in the presence of high sodium chloride concentrations were revealed. 相似文献
47.
二氯异氰脲酸钠和三氯异氰脲酸对棕囊藻细胞去除的研究 总被引:2,自引:2,他引:0
研究了二氯异氰脲酸钠和三氯异氰脲酸对球形棕囊藻的灭杀和控制作用,及其投药时间对除藻效果的影响,并比较2种药剂的除藻效果,初步探讨了除藻机理.结果表明,这2种除藻剂可以缓释次氯酸,提高其稳定性,有较长的药效期.当有效氯浓度达到4.5mg/L时,2种药剂均能有效地控制和灭杀球形棕囊藻,具有高效、低毒的优点.有效氯浓度为5.0mg/L,藻细胞去除率在24h可达到90%以上.在等于和大于5.0mg/L有效氯浓度时,三氯异氰脲酸的除藻效果优于二氯异氰脲酸钠,通过对2种药剂除藻率的t检验进一步证实了这一结论. 相似文献
48.
49.
Runaway reactions present a potentially serious threat to the chemical process industry and the community; such reactions occur time and time again often with devastating consequences. The main objective of this research is to study the root causes associated with ammonium nitrate (AN) explosions during storage. The research focuses on AN fertilizers and studies the effects of different types of fertilizer compatible additives on AN thermal decomposition. Reactive Systems Screening Tool (RSST) has been used for reactivity evaluation and to better understand the mechanisms that result in explosion hazards. The results obtained from this tool have been reported in terms of parameters such as “onset” temperature, rate of temperature and pressure rise and maximum temperature. The runaway behavior of AN has been studied as a solid and solution in water. The effect of additives such as sodium sulfate (Na2SO4) and potassium chloride (KCl) has also been studied. Multiple tests have been conducted to determine the characteristics of AN decomposition accurately. The results show that the presence of sodium sulfate can increase the “onset” temperature of AN decomposition thus acting as AN thermal decomposition inhibitor, while potassium chloride tends to decrease the “onset” temperature thus acting as AN thermal decomposition promoter. 相似文献
50.
Effects of pond salinization on survival rate of amphibian hosts infected with the chytrid fungus
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Michelle Pirrie Stockwell Lachlan James Storrie Carla Jean Pollard John Clulow Michael Joseph Mahony 《Conservation biology》2015,29(2):391-399
The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of amphibian populations worldwide, but management options are limited. Recent studies show that sodium chloride (NaCl) has fungicidal properties that reduce the mortality rates of infected hosts in captivity. We investigated whether similar results can be obtained by adding salt to water bodies in the field. We increased the salinity of 8 water bodies to 2 or 4 ppt and left an additional 4 water bodies with close to 0 ppt and monitored salinity for 18 months. Captively bred tadpoles of green and golden bell frog (Litoria aurea) were released into each water body and their development, levels of B. dendrobatidis infection, and survival were monitored at 1, 4, and 12 months. The effect of salt on the abundance of nontarget organisms was also investigated in before and after style analyses. Salinities remained constant over time with little intervention. Hosts in water bodies with 4 ppt salt had a significantly lower prevalence of chytrid infection and higher survival, following metamorphosis, than hosts in 0 ppt salt. Tadpoles in the 4 ppt group were smaller in length after 1 month in the release site than those in the 0 and 2 ppt groups, but after metamorphosis body size in all water bodies was similar . In water bodies with 4 ppt salt, the abundance of dwarf tree frogs (Litoria fallax), dragonfly larvae, and damselfly larvae was lower than in water bodies with 0 and 2 ppt salt, which could have knock‐on effects for community structure. Based on our results, salt may be an effective field‐based B. dendrobatidis mitigation tool for lentic amphibians that could contribute to the conservation of numerous susceptible species. However, as in all conservation efforts, these benefits need to be weighed against negative effects on both target and nontarget organisms. 相似文献