铕离子掺杂和铕铝共掺高硅氧玻璃的光谱性能

Eu-doped and Eu/Al-codoped high silica glass to investigate the properties of europium ions in high silica glasses were obtained. The porous glasses were immersed into europium nitrate solution or mixed solution of europium nitrate and aluminum nitrate. After dried, the doped porous glasses were sintered at 1200°C to obtain Eu-doped and Eu/Al-codoped high silica glasses. The reduction of Eu³⁺&rarrEu²⁺ was observed in Eu/Al-codoped high silica glass. The ratio of trivalent and bivalent europium ions was adjusted by the addition of aluminum ions and then the luminescent color of the glasses was controlled. A detailed mechanism was given to explain this reduction process.

Planar waveguides formed in a new chemically stable Er3+/Yb3+ co-doped phosphate glass

A new Er(3+)/Yb(3+) co-doped phosphate glass has been prepared, which exhibits good chemical durability and spectralproperties. Planar graded index waveguides have been fabricated in the glass by (Ag+)-Na(+) ion exchange in a mixed melt of silver nitrate and potassium nitrate. Ion exchange is carried out by varying the process parameters such as temperature, diffusion time, and molten salt compositions. The diffusion parameters, diffusion coefficients, and activation energy are determined by the guidelines of fabricated waveguides, which are determined by the input prism coupling technique.

Direct synthesis and intense luminescence of Y2O3 : Eu nanophosphors by complexation combustion

In this paper, we report the synthesis of high-luminance Y2O3:Eu nanocrystal through a citrate-nitrate complexation combustion method at a low temperature of 200-280 degrees C. The as-combusted Y2O3:Eu phosphors are almost equiaxed crystallites with an average size of 30-40 run, and have an intense red luminescence. The present fuel-deficient method suggests that by control of the ratio of citric acid to nitrates, it is valuable for the fabrication of Y2O3 nanoparticles without heat treatment. This process should be applicable to a wide range of nanocrystal oxides.

Preparation and spectroscopic properties of Er3+-doped high silica glass fabricated by sintering nanoporous glass

A compact nonporous high silica (SiO2 % > 96%) glass containing 3400 ppm Er3+ ions, which was about ten times higher than that in Er-doped silica fiber amplifier (EDSFA), was synthesized by sintering porous glass immersed into erbium nitrate solution. The 1532 nm fluorescence has a FWHM (Full Width at Half Maximum) of 45 nm wider than that of EDSFA and possesses the glass with potential application in broadband fiber amplifiers. The Judd-Ofelt theoretical analysis reflects that Er3+ ions are located in a higher covalent environment which are comparable to those of aluminosilicate glass. (c) 2005 Elsevier B.V. All rights reserved.

森林生态系统中养分循环特征的比较研究

　通过研究都江堰地区三个不同林型下（般若寺亚热带常绿阔叶林、龙池杉木林、月亮湾楠木林）土壤氮素分布的异质性及其矿化动态、凋落物的分解，得出以下结论： 　　1. 在野外用顶盖埋管法培养土壤，测定土壤中的速效氮含量变化，我们发现，尽管铵态氮含量在三种林型下都大于硝态氮含量，但只有在龙池杉木纯林下净氨化速率和净硝化速率基本持平，其它两种林型下，净硝化速率都远远大于净氨化速率。净硝化速率的增强，暗示着土壤的退化程度的加剧。 　　2. 净氨化速率和净氮矿化速率在三种林型下均和土壤温度呈现一定程度的负相关，其中净氨化速率在龙池杉木纯林下和土壤温度达到了显著的负相关。而硝化速率在三种林型下均和土壤温度呈一定程度的正相关。这说明，虽然温度是影响净硝化速率、净氨化速率和净氮矿化速率的最重要的环境因子之一，但温度是通过影响土壤微生物的种群、数量和活力等来影响上述过程的，而由于生长环境的巨大差异性，温度的影响效果会出现很大的差异。另外，土壤含水量对三种林型下的净硝化速率、净氨化速率和净氮矿化速率也有很大的影响，但均没有达到显著的相关。 　　3. 不同的林型下具有不同物种多样性，而物种多样性会通过凋落物的质量和数量，土壤微生物类群的组成和性质以及植被盖度等角度对森林生态系统的土壤氮素循环产生深刻的影响。生物多样性的丧失会导致土壤无机氮（特别是硝态氮）流失的潜力增加，导致无机氮库的逐渐缩小。速效氮含量迅速降低。 　　4.铵态氮和硝态氮共同组成了土壤无机氮的绝大部分。但由于硝态氮易于淋溶, 从地表径流中流失，易被植物吸收，也可能通过反硝化损失掉，因此硝态氮的含量常常表现出较大的波动性，而且硝态氮的含量要远低于铵态氮的含量。但硝态氮占总速效氮的比例在不同的研究地点和时间上有很大的差别。 　　5 通过地统计学的变异函数和时间序列分析，我们发现，全氮和铵态氮在整个研究区域的异质性很大，并且异质性随着时间的推移发生了很大的变化，其中全氮和铵态氮的自相关尺度变化不大，但空间自相关度随着时间的推移变化明显，这说明，随着时间的推进，全氮和铵态氮的空间格局在大尺度上的变化很小，在小尺度的却发生了很大的变化。本研究还发现，对于全氮和铵态氮的空间异质性格局进行地统计学分析时，最小取样间隔应小于5米，并且铵态氮由于其自身的不稳定性，其在小尺度的空间异质性格局更明显，而其取样间隔应小于全氮的取样间隔。 　　6. 应用网袋法进行凋落物分解的实验，发现混合凋落物的分解速率在第一年就比按各组分混合比例计算的理论值更低。说明在本实验中几种凋落物——黄牛奶树、青冈栎、栲树和润楠的混合对分解没有促进作用。 　　7. 土壤湿度和凋落物干物质分解密切相关，而不同林地的温度差异对干物质分解影响不大。但对于具体元素（本文中的C和N）的分解而言，分解受更复杂的机制调节，其中可能包括不同林型土壤中的分解微生物群落以及土壤理化性质的差异，相比之下，土壤湿度影响就不重要了。 　　8. 初始凋落物中的C/N浓度的比值显著影响分解速率，和腐解率呈显著负相关。因此可以用它来预测分解。在N的分解中，初始凋落物中的N浓度也会影响分解，具体反映在初始N浓度和实验截止时的N浓度成正比。 　　9. 亚热带气候下，凋落物的分解比在暖温带分解要快，并且初始凋落物中N元素的含量普遍较高，因而在分解中没有出现大量富集。 　　10.凋落物质量本身分解较快的树种，有机质的分解并没有相应快，说明在凋落物干物质降解过程中占主要地位的不是有机质。

冬小麦对盐分与臭氧胁迫的生理生态响应机理研究

本研究选用抗盐冬小麦品种—德抗961（DK961）和盐敏感品种—济南17（JN17）为试验材料。一方面，研究了冬小麦对盐分及臭氧胁迫的生理生态响应机制；另一方面，探讨了外源硝酸钾对小麦盐伤害的缓解机理，提出了盐胁迫下小麦优质高产的栽培技术规程。主要结论如下： 1 冬小麦产量与品质对不同浓度盐胁迫的响应 同一小麦品种在不同盐浓度胁迫下产量和品质存在显著差异，不同小麦品种在同一盐分浓度胁迫下产量和品质也有显著差异，说明盐胁迫下小麦产量和品质与小麦品种特性和耐盐性关系密切。在对照栽培条件下，两小麦品种的产量次序为JN17＞DK961；在轻度（0.3%）盐胁迫下，耐盐品种仍获得了较高的产量（仅下降5.8%），而盐敏感品种下降幅度较大（为22.9%），此时的产量次序为DK961＞JN17；DK961在0.5%盐胁迫下，产量较对照处理下降9.7%，而JN17下降了54.3%；在0.7％盐浓度环境中，DK961和JN17产量均出现了大幅降低，但DK961的产量仍显著高于JN17。 盐胁迫下的小麦品质指标表现为：在0.3％和0.5%盐浓度下，随着盐浓度的升高，蛋白质含量升高，淀粉含量下降；当盐浓度达到0.7%时，两者都快速下降。 2 不同耐盐性冬小麦品种对盐胁迫的生理生态响应 2.1品种与盐浓度对小麦生长特性的影响 盐胁迫造成了小麦的后期衰老加快，光合速率降低，生育期缩短。但这种影响会因小麦的耐盐性不同而有很大的差异：DK961在轻、中度盐浓度（0.3％、0.5％）下，生育期与无盐处理时无显著差异，但当盐浓度达到0.7%时，生育期出现了明显的缩短；相反，JN17生育期在各个盐浓度下都出现了显著变化。对盐敏感品种，盐胁迫导致小麦出苗期、拔节期推迟3-5 d，抽穗期和开花期提前6-7 d，成熟期提前10-15 d。盐胁迫对小麦生育期的影响主要是缩短生殖生长期。 2.2品种与盐浓度对小麦生理代谢的影响 不同冬小麦品种对盐胁迫产生的生理反应程度不同，耐盐小麦品种在一定的盐浓度范围内，盐胁迫症状不明显，生理反应比较迟钝，光合速率、气孔导度、光饱和点等基本维持在无盐处理的水平，丙二醛和活性氧清除酶活性增加不显著；盐敏感品种在各种盐浓度胁迫下或耐盐品种在过重的盐分浓度胁迫下，盐胁迫症状极为显著，小麦植株生长矮小，光合速率、气孔导度、光饱和点等大幅下降，丙二醛和活性氧自由基含量大幅上升，严重的情况下，小麦植株不能正常生长，甚至出现“干死”现象。 3 盐胁迫下冬小麦生理生态特征对臭氧浓度升高的响应 3.1 臭氧污染对小麦生理代谢的影响 3.1.1对小麦叶片气体交换的影响 气孔是小麦叶片与外界气体交换的“大门”，是臭氧进入叶片的主要通道，控制着蒸腾、光合、呼吸等重要生理过程。通常，高浓度臭氧环境中，小麦表现出较低的气孔导度。气孔的这种反应是植物限制臭氧进入叶片中的一种避害机制。 臭氧的强氧化性导致高浓度臭氧环境中小麦的光合速率下降。臭氧通过气孔进入叶片后，对植物叶片光合作用的抑制主要是由Rubiso酶含量/活性的降低引起的。研究发现，臭氧低于某一临界值时，产生的氧化伤害可以被植物体的抗氧化系统清除而不会对光合作用产生抑制，而高于该临界值时由Rubsico限制引起的光合速率降低将与臭氧吸收量呈线性关系。高浓度臭氧环境下，植物光合作用降低的生理原因，主要是臭氧导致叶绿素和可溶性蛋白分解，叶片衰老加快、叶绿体结构发生改变、活性氧清除酶活性升高，而与碳素固定有关的酶活性降低、光合产物向外运输受阻而导致的反馈抑制。 3.1.2对小麦生长特性的影响 研究表明，环境中臭氧浓度升高可引起小麦生长特性发生巨大改变。臭氧污染首先加快老叶的衰老，而对新叶的影响很小。然而老叶衰老能够将其中的营养转移到新生长叶片中，有利于维持植株的生长。臭氧环境下，老叶迅速衰老的同时，同一植株中的新生组织具有较高的Rubisco合成速率和总量，同化速率加强。这一现象被认为是植株在臭氧环境下的一种补偿机制。臭氧显著降低植株同化物向根系的分配，而同化物向根系分配的改变将导致根系与整株植物功能关系的改变。在水分亏缺环境下，植物根系的生长受到抑制，导致根系对土壤营养吸收能力的降低，从而间接降低叶片的光合速率。 3.2 盐胁迫引起的生理响应提高了小麦抵御臭氧伤害的能力 试验结果表明，盐胁迫引起的小麦生理响应（如，气孔导度降低、抗氧化酶活性升高等），显著增强了小麦抵抗臭氧伤害的能力。但这种保护作用是相对的，因为盐胁迫本身已对小麦生长产生显著的抑制作用。 3.2.1 气孔导度下降减少了臭氧的进入 研究发现，臭氧是通过气孔进入植物体内的，而盐胁迫引起的小麦气孔导度下降，显著减少了臭氧进入小麦体内的量，大大减轻了臭氧对小麦的伤害。本实验中，无盐栽培条件下，臭氧引起的小麦光合速率降低，达到了显著水平；而盐胁迫下，由臭氧引起的小麦光合速率降低，未达到显著水平。这说明盐胁迫引起的气孔导度降低，起到了减轻臭氧对小麦生长抑制的作用。 3.2.2 渗透调节能力的增强弱化了臭氧的伤害 盐胁迫引起的可溶性糖、可溶性蛋白、脯氨酸等渗透调节物质含量的升高，大大增强了小麦抵御臭氧伤害的能力。如，臭氧往往造成植物蛋白质的分解，降低蛋白质含量；但盐胁迫下，可溶性蛋白含量是上升的，两方面协调，维持了植株蛋白质水平，促进了小麦生长。另一方面，渗透调节物质的积累，有利于小麦同化物的合成、转化和运输，加快了循环的节奏，这也是盐胁迫降低臭氧对小麦伤害的重要原因之一。 3.2.3 抗氧化能力增强降低了臭氧的氧化伤害 盐胁迫引起的小麦酶促保护系统抗氧化酶（SOD、POD等）活性升高，提高了小麦体内活性氧清除能力。臭氧污染可产生大量的活性氧自由基，对小麦产生强氧化伤害，抑制小麦生长。通常情况下，臭氧胁迫也可引起小麦抗氧化酶活性的提高，来适应这种污染环境。本实验表明，在盐和臭氧的交互作用下，小麦抗氧化酶活性的升高呈现了叠加效应，小麦的活性氧清除能力大大加强，减缓了小麦衰老进程，有利于小麦生长。 4 外源硝酸钾对冬小麦盐胁迫伤害的缓解机理及高产栽培技术规程 4.1 不同浓度硝酸钾处理对盐胁迫下小麦幼苗生理代谢的影响 植株体内K+/Na+比值是衡量小麦抗盐性的一项重要指标。盐胁迫下，小麦体内Na+含量快速上升，而K+含量相对下降，K+/Na+比值快速降低，打破了植株体内离子平衡，对小麦造成Na+“单盐毒害”，严重抑制小麦生长。可溶性糖、脯氨酸等低分子量渗透调节物质含量升高；膜质过氧化程度加重，电解质外渗量及丙二醛含量升高；活性氧自由基增多，抗氧化酶活性升高。 外源KNO3显著提高了小麦植株组织内K+/Na+比值，盐胁迫症状减轻，可溶性糖、脯氨酸等低分子量渗透调节物质含量比单独NaCl胁迫时降低；膜质过氧化程度减轻，电解质外渗量及丙二醛含量降低；活性氧自由基减少，抗氧化酶活性恢复到接近正常水平。但过量施用硝酸钾同样不利于小麦的生长。实验结果表明，小麦生长环境中最佳的K+/Na+ = 16:100。 4.2 抽穗期叶面喷施硝酸钾对盐胁迫下小麦花后生长及籽粒产量的影响 根据小麦生长环境中最佳的钾/钠 = 16:100的实验结果，设计了对100 mM NaCl生长环境中小麦抽穗期叶面喷施10 mM KNO3溶液试验（Hoagland 营养液中已含6 mM KNO3），得出外源硝酸钾有利于盐胁迫下小麦生长的恢复及籽粒产量的提高，DK961和JN17的穗粒数分别比单纯盐胁迫时提高了1.9%和7.1%；千粒重分别提高了2.3%和2.8 %；产量分别提高了4.5%和12.3%；叶面喷施钾肥后，盐胁迫对耐盐小麦产量指标影响变小，小麦各项指标恢复到接近于对照水平。盐敏感小麦品种受到盐胁迫的伤害较重，产量下降幅度较大，施钾肥后小麦盐胁迫症状虽有改善，但仍与对照相差较远。所以，盐胁迫下小麦高产优质栽培中，耐盐品种的选用是首要的。 4.3外源硝酸钾对盐胁迫下花后小麦旗叶气体交换的影响 盐胁迫下小麦叶面喷施钾肥，旗叶光合速率在灌浆期比不施钾处理显著升高，且维持高光合速率时间延长，小麦后期衰老速率减缓。由于施钾处理使旗叶光合速率提高，功能期延长，使籽粒可溶性总糖含量和蔗糖含量高于不施钾的处理，促进了淀粉合成底物的供应，由此促进了淀粉的合成。盐胁迫下小麦抽穗期施钾，可促进小麦旗叶、籽粒的碳、氮代谢，淀粉合成速率加快。同时游离氨基酸含量增加，籽粒中蛋白质合成底物的供应增加，蛋白质产量提高。适宜的钾肥处理能够显著促进小麦植株碳、氮代谢过程，加速碳水化合物和蛋白质的合成，使籽粒蛋白质、淀粉产量提高。 4.4外源硝酸钾对盐胁迫下小麦花后旗叶抗衰老酶活性的影响 盐胁迫可使小麦代谢过程中产生的活性氧自由基增多，刺激酶促防御系统的保护酶（如，SOD、POD、CAT等）活性提高，但当盐浓度超过其上限时，酶活性达到一定的极限，活性氧自由基不能及时的清除，代谢发生紊乱，植株加速衰老或不能正常生长，出现“早死”现象。外源硝酸钾可有效缓解这一抑制作用，提高小麦在盐胁迫下的代谢能力，减少活性氧自由基的产生，减轻活性氧清除系统的压力，能较长时间维持叶片细胞结构的完整性，提高小麦抵抗盐胁迫的能力。 4.5 盐胁迫下小麦优质高产栽培技术规程 研究结果表明：选用高产优质抗盐小麦新品种，并合理配合施用钾肥是获得小麦优质高产的一项有效措施： 1） 选用高产优质抗盐小麦新品种 在品种选用上，首先要考虑苗期耐盐力好、个体分蘖强、成穗率高三大因素，在此基础上选择多穗、粒大、粒多的性状。 2）配合施用钾肥 钾肥基施和抽穗期叶面喷施皆对盐胁迫下小麦生长有促进作用。钾肥的施用量应根据土壤盐浓度而定，小麦生长环境中最佳的K+/Na+比值为16:100。

一氧化氮（NO）在硝酸盐调节玉米根伸长中的作用

植物根系大小和形态是决定植物吸氮能力的重要因素，而植物根系生长发育与土壤中营养元素的分布及其有效性密切相关，尤其是硝酸盐。然而目前关于硝酸盐调节植物根系生长的生理机制仍不清楚。一氧化氮（NO）是一种重要的气体信号分子，参与植物体内多种生理生化过程，包括调节根的生长发育。本研究以玉米自交系478为材料，采用营养液培养法，探讨了NO在硝酸盐调节玉米根系生长中的作用。主要结果和结论如下： 玉米幼苗在不同硝酸盐水平下生长7天后，主根伸长随着硝酸盐浓度的升高而下降;与0.01 mM硝酸盐处理下的玉米主根伸长相比，0.1 mM和1 mM硝酸盐处理对玉米主根伸长分别抑制了30%和36%。随着硝酸盐浓度的增加，玉米主根根尖过氧化氢（H2O2）含量表现出降低的趋势，而抗氧化酶，如超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）的活性则表现出增加的趋势。外源供应过氧化氢对低浓度硝酸盐（0.01 mM）和高浓度硝酸盐（10 mM）处理下的玉米根伸长都没有影响，这表明了根尖过氧化氢含量的下降不是高浓度硝酸盐抑制玉米主根伸长的原因。 NO供体硝普钠（SNP）能够缓解高浓度硝酸盐对玉米主根伸长的抑制，而对低浓度硝酸盐处理下的主根伸长没有影响，而且NO清除剂亚甲基兰（MB）和NO合成酶抑制剂Nω-硝基-L-精氨酸（L-NNA）显著抑制了低浓度硝酸盐处理下的玉米主根伸长，而对高浓度硝酸盐处理下的玉米主根伸长没有影响。用NO特异性荧光染料4,5-二氨基乙酰乙酸荧光素(DAF-2DA)检测结果表明：高浓度硝酸盐显著降低玉米根尖NO含量。而玉米根中的硝酸还原酶活性随硝酸盐浓度的增加而增加。以上结果说明，高浓度硝酸盐抑制玉米主根伸长可能是与根尖NO合成酶的下调所导致的内源NO含量的降低有关。 另外，外源生长素（IAA）能缓解高浓度硝酸盐对玉米主根伸长的抑制，同时，也增加了高浓度硝酸盐处理下玉米根中内源NO含量，而对低浓度硝酸盐处理下的玉米根中内源NO没有影响。因此推测，根尖生长素的下降导致内源NO含量的降低可能是高浓度硝酸盐抑制玉米主根伸长的原因。

一氧化氮在磷酸盐调节拟南芥根系形态变化中的作用

磷缺乏已成为制约世界农业生产的重要因子。植物根系的大小和形态是决定植物吸收土壤磷能力的重要因素，而且根系的生长发育与磷素的分布及其有效性密切相关。关于磷酸盐调节植物根系生长研究已有很多报道，但其生理和分子机制仍不清楚。一氧化氮 (NO) 是一种重要的气体信号分子，参与调控植物的生长发育和对多种逆境胁迫的应答反应。本文选用拟南芥为实验材料，研究探讨了NO与缺磷诱导的拟南芥根系形态变化之间的关系，主要结果如下： 用正常磷水平 (1 mM) 和低磷水平 (1 µM) 处理拟南芥幼苗，发现低磷抑制主根伸长，刺激侧根发生。外源NO供体销普纳 (SNP) 也抑制主根、刺激侧根生长，与低磷诱导根系形态变化相似。NO清除剂c-PTIO和一氧化氮合成酶 （NOS）抑制剂L-NNA均可部分减缓由低磷引起的对主根生长的抑制和对侧根的刺激作用。暗示低磷诱导的拟南芥根系形态的变化可能与NO含量的降低有关。 利用NO荧光标记物DAF-FM和激光共聚焦显微成像技术，本研究发现缺磷6 h和24 h后根细胞内源NO含量显著增加，而且NOS 抑制剂能减少低磷诱导的根细胞NO含量的增加。与正常供磷处理相比，低磷处理6 h和24 h，拟南芥根中编码与NO合成相关的基因（AtNOA1）的表达量增加，缺磷24 h后根中NOS酶活性升高。为了明确低磷诱导的NO 增加是否与硝酸还原酶（NR）介导的NO合成有关，本论文进一步研究了低磷对拟南芥硝酸还原酶活性和编码NR基因 （AtNR1和AtNR2）表达的影响。研究发现低磷处理6 h和24 h后和AtNR1和AtNR2基因的表达均没有变化，且蛭石中生长的拟南芥缺磷1个月后NR活性也没有发生变化;拟南芥的NR双突变体nia1，nia2在低磷处理24 h后，其根中的内源NO含量表现出与野生型相同的增加。因此这些研究结果表明，缺磷后拟南芥根细胞NO的含量增加主要由于NOS的活性升高，而与NR介导的NO合成无关。 已有资料表明低磷诱导植物根细胞内源过氧化氢（H2O2）分布和含量的变化。本论文研究了低磷处理对用H2O2标记物CM-H2DCFDA标记不同磷处理下的拟南芥根中的H2O2。研究发现，缺磷6 h根中H2O2的分布无明显变化，缺磷24 h后H2O2呈斑块状分布，且多集中在根尖伸长区。缺磷24 h后，叶片中的抗氧化保护酶—超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性没有明显变化。说明缺磷24 h 后产生的H2O2没有引起氧化胁迫，而是作为一种信号分子，与NO相互作用共同介导低磷胁迫的应答反应。关于NO与H2O2在低磷诱导的根形态变化中的信号转导过程还有待进一步研究。

增强UV-B辐射下一氧化氮对小球藻氮素代谢和类囊体的保护作用

由于到达地球表面的紫外线B辐射不断加强,生物生长受到了威胁。UV-B的增强改变了生物体赖以生存的环境,影响了藻类生物生长,抑制了其光合作用。以BG11为培养基,在室内培养的条件是光照强度为60μmol·m-2s-(1昼夜比为12h∶12h),温度为26℃,研究了一氧化氮(NO)在增强UV-B(强度为0.2J·m-2s-1)辐射下的对小球藻的作用。测定了小球藻的硝酸还原酶(NR,nitrate reductase)、亚硝酸还原酶(NiR,nitrite reductase)、谷胱甘肽还原酶(GS,gluta

复合藻-菌净化系统处理麦秆造纸废液初步研究

在室内模拟条件下,采用正交设计法建立了一种由蛋白核小球藻(Chlorella pyrenoidosa)、鱼腥藻7120(Anabaena sp.PCC7120)、硝化细菌(Nitrate bacteria)和荚膜红假单胞菌(Rhodopseudomonas capsulata)组成的复合藻-菌净化系统去除造纸废液中有机质和氨态氮的最优化模型,确定了藻类与细菌的最优化数量配比关系为蛋白核小球藻∶鱼腥藻7120∶硝化细菌∶荚膜红假单胞菌=1∶2.17∶2.83∶5.09.比较了复合藻-菌净化系统最优化模型与单

Polishing Treatment of Molasses Wastewater with Iron Salts: the Role of Counter-ions

The effect of counter-ions on the coagulation of biologically treated molasses wastewater using iron-based coagulants was investigated. Parameters such as removals of chemical oxygen demand (COD) and color, and residual turbidity, were measured to evaluate coagulation performance. Experimental results showed that ferric chloride and ferric nitrate were more effective than ferric sulfate at optimal dosages, achieving 89 to 90% and 98 to 99% of COD and color removals, respectively, with residual turbidity of less than 5 NTU. High-performance size exclusion chromatography (HPSEC) results revealed differences in the removal of the molecular weight fraction of organic compounds using iron salts. Scanning electron microscopy (SEM) showed randomly formed coagulated flocs characterized with irregular, sheet-like shapes. Nitrate and chloride counter-ions had similar effects on coagulation performance compared to sulfate. Both FeCl3 and Fe(NO3)(3) yielded better results than Fe(SO4)(2) under underdosed and optimum dosage conditions. Coagulation efficiency was less adversely affected in the overdosed regions, however, if sulfate rather than chloride or nitrate was present. Water Environ. Res., 81, 2293 (2009).

In situ nutrient removal from aquaculture wastewater by aquatic vegetable Ipomoea aquatica on floating beds

Nutrient-rich effluents caused rising concern due to eutrophication of aquatic environment by utilization of a large amount of formula feed. Nutrient removal and water quality were investigated by planting aquatic vegetable on artificial beds in 36-m(2) concrete fishponds. After treatment of 120 days, 30.6% of total nitrogen (TN) and 18.2% of total phosphorus (TP) were removed from the total input nutrients by 6-m(2) aquatic vegetable Ipomoea aquatica. The concentrations of TN, TP, chemical oxygen demand (COD) and chlorophyll a in planted ponds were significantly lower than those in non-planted ponds (P<0.05). Transparency of water in planted ponds was much higher than that of control ponds. No significant differences in the concentration of total ammonia nitrogen (TAN), nitrate nitrogen (NO3-N) and nitrite nitrogen (NO2--N) were found between planted and non-planted ponds. These results suggested that planting aquatic vegetable with one-sixth covered area of the fishponds could efficiently remove nutrient and improve water quality.

EFFECTS OF IRON ON PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS OF Microcystis wesenbergii (Kom.) Kom. (Cyanobacterium)

Iron is an essential trace element for biological requirements of phytoplankton. Effects of iron on physiological and biochemical characteristics of Microcystis wesenbergii were conducted in this study. Results showed that 0.01 mu M [Fe3+] seriously inhibited growth and chlorophyll synthesis of M. wesenbergii, and induced temporary increase of ATPase activities, however, NR. ACP and ALP activities were restrained by iron limitation. Interestingly, iron addition on day 8 resulted in the gradual restoration of structures and functions of above enzymes and resisted a variety of stresses from iron limitation. M. wesenbergii in 10 mu M [Fe3+] treatment group grew normally. enzymes maintained normal levels, and residual phosphate contents in cultures first sharply decreased, then smoothly as M. wesenbergii has a characteristic of luxury consumption of phosphorus. Above parameters in 100 mu M [Fe3+] treatment group were almost same with those in 10 mu M [Fe3+] treatment group except for NR, ACP and ALP activities. In 100 mu M [Fe3+] treatment group, activities of ACP and ALP had temporary increase because phosphate and ferric iron could form insoluble compound - ferric phosphate (Fe3PO4) through adsorption effect. resulting in lack of bioavailable phosphate in culture media. The experiment suggested that too low or too high iron can affect obviously physiological and biochemical characteristics of M. wesenbergii.

Microcystin-RR induces physiological stress and cell death in the cyanobacterium Aphanizomenon sp DC01 isolated from Lake Dianchi, China

The phytoplankton community in Lake Dianchi (Yunnan Province, Southwestern China) is dominated in April by a bloom of Aphanizomenon, that disappears Suddenly and is displaced by a Microcystis bloom in May. The reasons for the rapid bloom disappearance phenomenon and the temporal variability in the composition of phytoplankton assemblages are poorly understood. Cell growth, ultrastructure and physiological changes were examined in cultures of Aphanizomenon sp. DC01 isolated from Lake Dianchi exposed to different closes of rnicrocystin-RR (MC-RR) produced by the Microcystis bloom. MC-RR concentrations above 100 mu g L-1 markedly inhibited the pigment (chlorophyll-a, phycocyanin) synthesis and caused an increase of soluble carbohydrate and protein contents and nitrate reductase activity of toxin-treated blue-green algae. A drastic. reduction in photochemical efficiency of PSII (Fv/Fm) was also found. Morphological examinationn showed that the Aphanizomenon filaments disintegrated and file cells lysed gradually after 48 h Of toxin exposure. Transmission electron microscopy revealed that cellular inclusions of stressed cells almost leaked out completely and the cell membranes were grossly damaged. These findings demonstrate the allelopathic activity of Microcystis aeruginosa inducing physiological stress and cell death of Aphanizomenon sp. DC01 Although the active concentrations of microcystin were rather high, we propose that microcystin may function as allelopathic Substance due to inhomogeneous toxin concentrations close to Microcystis cells. Hence, it may play a role in species Succession of Aphanizomenon and Microcystis in Lake Dianchi.

How polluted is the Yangtze River? Water quality downstream from the Three Gorges Dam

The concentrations of major anions and cations, nitrogen and phosphorus, dissolved and particulate trace elements, and organic pollutants were determined for the middle and lower reaches of the Yangtze River (Changjiang) from below the Three Gorges Dam (TGD) to the mouth at Shanghai in November 2006. The concentration of dissolved inorganic phosphate (DIP) was constant at a low level of 6-8 mu gP/L, but the concentration of nitrate (NO3-) approximately doubled downstream and was closely correlated with K+. This translated to a daily load of well over 1000 It of dissolved inorganic nitrogen (DIN) at Datong. The average concentrations of dissolved Pb (0.078 +/- 0.023 mu g/L), Cd (0.024 +/- 0.009 mu g/L), Cr(0.57 +/- 0.09 mu g/L), Cu (1.9 +/- 0.7 mu g/L), and Ni (0.50 +/- 0.49 mu g/L) were comparable with those in other major world rivers, while As (3.3 +/- 1.3 mu g/L) and Zn (1.5 +/- 0.6 mu g/L) were higher by factors of 5.5 and 2.5, respectively. The trace element contents of suspended particles of As (31 +/- 28 mu g/g), Pb (83 +/- 34 mu g/g), and Ni (52 +/- 16 mu g/g) were close to maximum concentrations recommended for rivers by the European Community (EC). The average concentrations of Cd (2.6 +/- 1.6 mu g/g), Cr (185 +/- 102 mu g/g), Cu (115 +/- 106 mu g/g), and Zn (500 +/- 300 mu g/g) exceeded the EC standards by a factor of two, and Hg (4.4 +/- 4.7 mu g/g) by a factor of 4 to 5. Locally occurring peak concentrations exceed these values up to fourfold, among them the notorious elements As, Hg, and Tl. All dissolved and particulate trace element concentrations were higher than estimates made twenty years ago [Zhang, J., Geochemistry of trace metals from Chinese river/estuary systems: an overview. Estuar Coast Shelf Sci 1995; 41: 631-658.]. The enormous loads of anthropogenic pollutants disposed to the river were diluted by the large water discharge of the Yangtze even during the lowest flow resulting in the relatively low concentration levels of trace elements and organic pollutants observed. We estimated loads of e.g. As, Pb and Ni to the East China Sea to be about 4600 kg As d(-1), 3000 kg Pb d(-1), and 2000 kg Ni d(-1). About 6000 t d(-1) of dissolved organic carbon (DOC) was delivered into the sea at the time of our cruise. We tested for 236 organic pollutants, and only the most infamous were found to be barely above detection limits. We estimated that the load of chlorinated compounds, aromatic hydrocarbons, phenols, and PAHs were between 500 and 3500 kg d(-1). We also detected eight herbicides entering the estuary with loads of 5-350 kg d(-1). The pollutant load, even when at low concentrations, are considerable and pose an increasing threat to the health of the East China Sea ecosystem. (c) 2008 Elsevier B.V. All rights reserved.