四种沉水植物的克藻效应

设计一系列试验研究了四种沉水植物(金鱼藻、微齿眼子菜、苦草、伊乐藻)对铜绿微囊藻的抑制作用．单独培养试验结果显示金鱼藻和微齿眼子菜具有较强的抑制藻类生长的作用,连续滴加种植水试验显示抑藻作用进一步加强．在植物的生长过程中其化感物质是连续释放的．并考察N、P等营养因素及微生物干扰对抑藻实验的影响．     

Effects of turbulence motion on the growth and physiology of aquatic plants

Growth, stem morphology and some biochemical parameters were studied of one completely submerged (Myriophyllum spicatum) and two floating leaved macrophytes (Nymphoides peltata and Trapa japonica) under different turbulence velocities. The root mean square velocities of the high, medium and low amount of turbulence that was generated for the experiment were 2.18 ± 0.66, 1.48 ± 0.26 and 0.70 ± 0.07 cm s⁻¹, respectively, in the microcosm. All three experimental plants survived exposed to all turbulence conditions provided, although a decrease in shoot elongation rate was associated with an increase in turbulence. Acceleration of tissue H₂O₂ generation and MDA content increased during the study period in all plant species. Oxidative enzymatic activities (POD, IAA and CKX) increased with time in plants under medium and high turbulence velocities. The shoot elongation rate, stem and leaf diameter, chlorophyll content and carbohydrate fractionations were found to be affected by this abiotic stress. It is evident from this study that high turbulence velocity inhibits normal metabolic activities of all three plants, while low to medium turbulence does not harm the floating leaved plants. Moreover, floating leaved plants were found to possess highly capable strategies to cope with this mechanical stress than completely submerged species.     

沉水植物生长对沉积物间隙水中的氮磷分布及界面释放的影响

采集未破坏沉积物结构的柱状沉积物样品,通过室内41 d的培养实验,研究了沉水植物生长过程对间隙水中NH_4~ -N和PO_4~(3-)-P的浓度的动态影响,分析了沉水植物生物量与沉积物中氮磷释放通量的对应关系．结果表明：随沉水植物生长和生物量增加,上部0-5 cm沉积物垂向各层间隙水中NH_4~ -N含量呈逐步降低,表现出沉积物-水界面氮的释放通量与沉水植物生物量存在负相关性;而间隙水PO_4~(3 )-P含量则随沉水植物生长呈单峰型变化,磷释放通量与生物量相关性不明显．初步反映沉水植物在沉积物的生长过程中对氮磷吸收的生物地球化学机制是不同的．     

Flow field downstream of individual aquatic plants—Experiments in a natural river with Potamogeton crispus L. and Myriophyllum spicatum L.

Flow disturbances generated by individual patches of submerged, flexible aquatic vegetation were investigated for two naturally growing macrophyte species, Potamogeton crispus L. and Myriophyllum spicatum L., in a sandy lowland river. Through acoustic Doppler velocimetry, 24 vertical profiles of the 3D velocity field were recorded downstream of each of the patches. The morphological features and biomechanical properties of the plants were also evaluated. The experiments showed the relationship between biomechanical characteristics and turbulence statistics. M. spicatum, which was stiffer and therefore less prone to dynamic reconfiguration, showed a greater effect on velocity damping, causing an increase in Reynold stresses, turbulence intensities, and turbulent kinetic energy downstream of the patch. These effects were present in regions both above and below plant height. In contrast for P. crispus, these effects were present only below plant height. The stiffer plant produced a mixing layer in its wake similar to that of dense plant canopies. The patch of less stiff and more streamlined P. crispus with longer leaves presented a much weaker effect on the flow. In contrast to previous studies conducted with rigid plant surrogates, we concluded that reconfiguration of the living flexible plants allows the plants to minimize drag forces, and therefore, their influence on the flow field was weaker than the effects reported for rigid surrogates.     

菹草、伊乐藻对沉积物磷形态及其上覆水水质的影响

采集武昌南湖湖水、沉积物进行沉水植物的盆栽试验,试验设置沉积物未施磷处理和施100mg/kg磷处理,分别对应沉积物低内源磷和高内源磷状态,同时种植菹草、伊乐藻,以研究沉积物中磷形态及上覆水水质的变化特点.研究从2007年9月15日开始,历时160d.结果表明,高内源磷沉积物处理后,上覆水中水溶性总磷含量在沉水植物的作用下明显降低;种植沉水植物可使水体总磷、总氮、叶绿素a含量显著降低,且伊乐藻对总磷的净化效果优于菹草;沉水植物对高内源磷沉积物的上覆水中叶绿素a的控制比对低内源磷条件下的效果更好;无论沉积物是否输入磷,在盆栽条件下,上覆水中叶绿素a随时间的变化均能较好地用一级动力学模型来描述;上覆水TDP、TP与沉积物中Ca_(10)-P之间有极显著正相关;种植菹草或伊乐藻的沉积物中Ca_(10)-P与上覆水中TDP和TP的相关系数分别为0.990(P≤0.01)和0.977(P≤0.05).     

不同沉水植物叶片附着细菌群落多样性及网络结构差异

沉水植物叶表附着大量细菌,与沉水植物构成了复杂的共生体系.叶片附着细菌是水生态的重要组成部分,能影响沉水植物自身生长和水体物质循环过程.目前,对于沉水植物多样性对植物叶片附着细菌群落的影响知之甚少.本研究比较了不同沉水植物物种多样性对浮游细菌和叶片附着细菌群落的影响,同时探究不同植物——苦草(Vallisneria natans)、穗状狐尾藻(Myriophyllum spicatum)、微齿眼子菜(Potamogeton maackianus)和黑藻(Hydrilla verticillata)叶片附着细菌的群落结构和多样性特征.结果表明,浮游细菌和叶片附着细菌的群落α多样性和β多样性具有显著差异.与单一植物物种体系相比,高植物物种多样性体系中植物叶片附着细菌群落α多样性较高.在高植物物种多样性体系中,黑藻叶片附着细菌群落的α多样性显著较高而β多样性显著较低,苦草叶片附着细菌群落的α多样性较低.沉水植物叶片附着细菌群落优势菌群属于变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes).高植物物种多样性体系中苦草的物种共现网络最具模块性.嗜甲基菌(g_Methylophilus)、红杆菌(f_Rhodobacter)、黄杆菌(g_Flavobacterium)是物种共现网络的关键物种.本文研究植物物种多样性对淡水湖泊细菌群落结构的影响,并强调宿主植物对附着细菌群落的重要选择作用,加深对细菌群落在水生植物叶片定殖机制的理解.     

两种沉水植物对黄颡鱼(Pseudobagrus fulvidraco)夏花培育水体主要水质因子的影响

以黄颡鱼夏花培育水体为实验用养殖污水,伊乐藻、轮叶黑藻作为净化水质的沉水植物材料,建立封闭型(非换水)和交换型(定期换水)的两种鱼草共生的生态系统并与传统的商业性养殖系统模式作同步比较,分析了养鱼水体水质主要因子的变化及对鱼存活率的影响．实验结果如下：1．作为实验组的鱼草共生系统两种水体水质优良,鱼类生长良好,交换型水体中D0值≥8．0,NH4—N≤0．34,COD≤18mg/L,悬浮物≤12mg/L夏花成活率为93．3％;封闭型水体中D0值≥7．5,总NH4—N≤0.92,COD≤28mg/L,悬浮物毒20mg/L夏花成活率为60．0%．2．作为对照组有色无草的封闭系统中水质逐渐恶化,鱼类生长受到抑制甚至生存也不能保障,其中,D0值≥2．5,NH4-N≤3.22,COD≤88mg/L,悬浮物≤55mg/L,夏花成活率仅为6．7％;交换系统中D0值≥4．0,总NH4—N≤2．41,COD≤66mg/L,悬浮物≤51mg/L,即使定期换水夏花成活率也仅达66．7％;研究结果表明：鱼草共生系统中栽培伊乐藻、轮叶黑藻等沉水植物可有效地净化水质,不仅确保了夏花生产良性运行,还节约了水资源并达到无污染排放．     

两种氮浓度对轮叶黑藻(Hydrilla verticillata)腐解过程营养盐释放及附着生物膜内氮循环基因丰度的影响

氨氮是地表水常见污染物,尤其在农业区域,氮类化肥的不合理施用会导致周边水体氮浓度迅速升高并保持较高水平.然而,当前对高氮水平下沉水植物腐败和附着氮循环微生物的影响尚不清楚.以轮叶黑藻(Hydrilla verticillata)为研究用沉水植物,在实验室内模拟水体内8和16 mg/L氮浓度下轮叶黑藻腐解过程中营养盐释放及残体表面微生物氮循环功能基因丰度的变化.研究发现水体两种氮浓度下轮叶黑藻腐解过程中残体腐解及营养盐释放速率无显著差异;与对照相比,植物腐败初期水体内碳、磷浓度迅速增加,而溶解氧浓度及氧化还原电位迅速降低,随着时间的推移上述水质指标逐步恢复至初期状态(第146天);水体荧光溶解性有机质主要包括紫外类富里酸、可见类富里酸、色氨酸类蛋白质和酪氨酸类蛋白质等类型.在5个氮循环相关基因中,氮负荷增加对轮叶黑藻残体生物膜内amo A、napA和narG的丰度有显著影响.冗余分析表明氮循环基因丰度受水体总氮浓度的影响较小,与植物总有机碳含量和水体化学需氧量及溶解氧浓度存在相关性.研究结果表明虽然当前氮水平对植物腐败过程影响不大、对氮循环基因丰度有一定影响,但是对该水生植被(尤其是植物腐败初期)和农业退水排放的管理仍需加强,以降低其对水体的影响.     

不同生长型沉水植物配置对生物量积累和水质净化效果的影响

种植水生植物,尤其是沉水植物,是目前广泛应用于受损水体的最主要的生态修复方法之一.研究不同生长型沉水植物组合对水体理化因子的影响及营养物质的去除效率可为受损水生生态系统修复提供重要的科学依据.本研究以我国水体修复中常用的3种不同生长型沉水植物苦草(Vallisneria natans)、黑藻(Hydrilla vertiillata)和穗状狐尾藻(Myriophyllum spicatum)为研究对象,采用1种生长型种植和2种生长型及3种生长型混种模式,研究不同生长型沉水植物组合及其不同生长阶段对实验系统水质指标及氮、磷等营养物质去除率的影响.结果表明,所有植物组合处理均显著提高了系统中总氮、总磷和氨氮去除率;在实验前中期总氮、总磷和氨氮去除率最高.从本实验受试物种组合来看,1种和2种生长型组合比3种生长型组合具有更高的生物量累积量和总氮去除率.Pearson相关性分析显示,实验系统中的pH、DO浓度与植物总生物量呈显著正相关,总氮、总磷、氨氮浓度均与植物总生物量呈显著负相关.建议在受损浅水水生态系统修复过程中,根据生态修复不同阶段考虑不同生活型、生长型和功能群的水生植物组合;在生态修...     

滆湖底质特性对菹草(Potamogeton crispus)和伊乐藻(Elodeanattalii)生长的影响

通过模拟试验,研究滆湖3种沉积物(表层湖泥、硬底湖泥、表层覆岸泥)对菹草和伊乐藻生长的影响.结果表明,生长于表层湖泥、硬底湖泥、表层覆岸泥的菹草和伊乐藻生物量分别为4.07、1.98、3.69kg/m2和1.86、1.27、1.74kg/m2,表层湖泥较适合这两种沉水植物生长.3种沉积物对菹草和伊乐藻的干湿比影响显著,...     

铜胁迫对菹草无菌苗多胺及活性氧代谢的影响

本文研究了不同浓度Cu2+(0、1、2、4、8、12μmol/L)对菹草无菌苗多胺(PAs)及活性氧代谢的影响.结果表明,随着Cu2+处理浓度的升高:(1)菹草无菌苗植株的超氧化物歧化酶(SOD)活性逐渐上升,过氧化物酶(POD)和过氧化氢酶(CAT)活性则表现为先升后降;(2)超氧阴离子(O2.-)产生速率逐渐增大,过氧化氢(H2O2)和丙二醛(MDA)有所积累,可溶性蛋白含量降低;(3)游离态多胺含量与多胺总含量的变化一致,均表现为腐胺(Put)含量先升后降,亚精胺(Spd)含量逐渐降低,精胺(Spm)含量逐渐上升;游离态多胺(Spd+Spm)/Put的比值在高浓度Cu2+胁迫时迅速上升;结合态Put和Spm的含量变化与游离态的变化一致,而结合态Spd的含量与对照相比均略有上升;束缚态Put和Spd含量先升后降,而Spm含量则逐渐降低;(4)精氨酸脱羧酶(ADC)、多胺氧化酶(PAO)和二胺氧化酶(DAO)活性均表现为先升后降,而鸟氨酸脱羧酶(ODC)活性变化不明显.可见,Cu2+对菹草无菌苗造成了明显的氧化胁迫,抗氧化酶活性的升高,Spm含量的升高,Put向Spd和Spm的转化以及不同状态多胺之间的转化,在菹草无菌苗抵抗Cu2+胁迫过程中发挥着重要的作用.     

鳑鲏对“蚌-草”关系的影响

重建沉水植物群落是修复浅水富营养化湖泊的关键.河蚌可改善水下光照条件、促进沉水植物生长,因此放养河蚌常被用于沉水植物群落恢复的并行手段.河蚌是鳑鲏产卵的重要基质,因此河蚌可能促进鳑鲏种群发展,而鳑鲏对水生态系统的影响还尚不清楚.本研究以密刺苦草、大鳍鱊和背角无齿蚌为研究对象,通过中宇宙试验研究河蚌和鳑鲏对附着藻的影响,以及鳑鲏对水质和沉水植物生长的影响及机理.结果发现：鳑鲏显著增加了水体总磷、总溶解性磷、总悬浮物和叶绿素a浓度,而对总氮和总溶解性氮浓度的影响不显著.河蚌对苦草的相对生长率、总株数、根冠比及苦草最大叶长均无显著影响,而显著增加了苦草的单株平均生物量,这可能与河蚌组较高的附着藻生物量有关.鳑鲏未显著影响河蚌与苦草间的关系,但鳑鲏的出现显著增加了附着藻类生物量;此外,鳑鲏还降低了苦草的根冠比,而增加了苦草的最大叶长,这可能与鳑鲏引起的营养盐和叶绿素a浓度升高,以及植物表面附着藻生物量显著升高有关.鳑鲏属于小型杂食性鱼类,在长江中下游地区分布广泛,与沉水植物关系密切,且易在修复后的湖泊中形成优势鱼类,因此在湖泊修复和管理中应加强此类小型杂食性鱼类的监测与管理.     

苦草(Vallisneria natans)和黑藻(Hydrilla verticillata)对沉积物各形态磷垂直分布的影响

采用沉水植物苦草(V.natans)和黑藻(H.verticillata)作为研究对象,在其旺盛生长期测定群落内外上覆水及沉积物各形态磷的含量,以探究不同根系特点的沉水植物对沉积物中各形态磷垂直分布的影响.结果表明:实验进行30 d后苦草和黑藻组沉积物总磷(TP)、无机磷(IP)和氢氧化钠提取磷(NaOH-P)含量在垂直方向均呈现不同程度的降低.苦草和黑藻组沉积物TP的含量在4.5 cm深度处降低幅度最大,较对照组分别下降了58.91和36.46 mg/kg;IP含量分别在沉积物6.0和3.0 cm深度处降低幅度最大,较对照组分别降低了85.41和57.41 mg/kg.总体来看,沉水植物苦草对沉积物各形态磷含量降低的影响大于黑藻.     

The Effects of Environmental Conditions on Concentration and Emission of Ammonia in Chicken Farms during Summer Season

This paper presents a field study conducted in northwest Turkey and characterizes the NH₃ concentration and emission measured in summer season from three chicken farms. The influence of environmental conditions on NH₃ concentration and emission was also investigated in this study. Ammonia concentration, temperature, relative humidity and airflow rate were continuously recorded for four sequential days. The environmental conditions were measured using a multifunction temperature and humidity‐meter with a hot wire probe. Portable multiple gas detectors with electro‐chemical sensors were used to measure NH₃ concentration. The NH₃ emission rates for houses were calculated by multiplying simultaneously measured NH₃ concentrations and air flow rates. The average daily mean (ADM) house concentrations of house 1 (H1), house 2 (H2), and house 3 (H3) were measured as 4.43, 3.71, and 6.20 ppm, respectively. NH₃ concentration was inversely proportional to temperature (r = ?0.279), relative humidity (r = ?0.063) and airflow rate (r = ?0.554) for all monitored houses. The ADM house NH₃ emission was 135 g/(h house) for H1, 255 g/(h house) for H2, and 117 g/(h house) for H3. The combined average emission rate in this study (0.26 g/(d bird)) was lower than the emission rate measured in chicken farms in the USA. However, our results were comparable to rates calculated in European studies because house design, ventilation system and bird diet applied in Turkish chicken farms are very similar to those employed in European countries. The NH₃ emissions were significantly correlated to NH₃ concentrations (r = 0.45, p ≤ 0.001) and airflow rates (r = 0.97, p ≤ 0.001). A clear diurnal pattern was obtained for NH₃ concentrations rather than NH₃ emissions at the end of the study.     

不同密度团头鲂(Megalobrama amblycephala)对轮叶黑藻(Hydrilla verticillata)和密刺苦草(Vallisneria denseserrulata)群落结构的影响

冠层型水草轮叶黑藻在富营养情况下,生长迅速,覆盖水面,对于草甸型水草密刺苦草具有明显的竞争优势.为控制轮叶黑藻的竞争优势,于湖北省鄂州市团头鲂原种场的一个池塘进行了原位围隔（10 m×10 m）实验,研究不同密度（0、0.5和1尾/m²）团头鲂牧食作用对轮叶黑藻和密刺苦草群落结构的影响,并通过无人机数字图像处理获取水草覆盖度信息.实验过程中,沉水植物总覆盖度未发生变化.研究发现,团头鲂选择性牧食使得密刺苦草生物量和覆盖度显著增加.随着牧食强度的加大,团头鲂对轮叶黑藻的控制效果显著,放养密度为1尾/m²的围隔中轮叶黑藻比例降幅最明显.群落中轮叶黑藻与密刺苦草的生物量之比迅速下降,由6.14减少至0.002,覆盖度之比由4.88左右减少至约1.44.图像处理结果与实际采样情况相吻合,且通过误差矩阵得到图像分类平均精度达到90%以上,表明无人机数字图像处理在一定条件下可以作为获取沉水植物覆盖度的一种有效辅助手段.实验结束后,1尾/m²组的围隔中密刺苦草成为优势种,其植株密度、株高、株重和单株叶片数均显著增加,草甸更加密实.实验结果表明,放养1尾/m²密度的团头鲂可以有效控制轮叶黑藻并维持密刺苦草种群优势,结果为团头鲂对湖泊沉水植物群落的控制提供了参考.     

震源机制和场地条件对近场强震地面运动特性的影响

将欧洲数百条地震动记录按震级、震中距、场地类别及震源机制等条件分类,通过对地震动记录加速度峰值比、加速度峰值衰减规律及反应谱比等内容的统计分析,研究了震源机制、场地类别等因素对竖向地震动的影响。结果表明,震源机制和场地类别这两种因素在近场区对竖向地震动特性有显著的影响。     

剪跨比和箍筋率对钢筋混凝土框架柱动态特性的影响效应

基于通用有限元软件ABAQUS,分别在准静态和动态加载条件下,对不同剪跨比和箍筋率的钢筋混凝土柱进行了数值模拟。对比现有试验结果发现,ABAQUS的模拟效果与试验结果吻合较好;加载速率的影响随着剪跨比和箍筋率的增大而降低;钢筋混凝土柱的峰值承载力随着加载速率增大而增大的趋势明显,刚度无明显变化,延性比趋于稳定。因此,在进行地震作用下钢筋混凝土结构的抗震分析时,对加载速率的影响效应要给予足够的考虑。     

钙离子添加对沉水植物菹草(Potamogeton crispus L.)和金鱼藻(Ceratophyllum demersum L.)富集水体磷的影响

沉水植物光合作用形成的微环境有利于水体中钙和磷形成CaCO_3-P共沉淀,从而将水体中的磷永久性去除,避免植物腐烂后的二次污染但不同的沉水植物种类形成CaCO_3-P共沉淀的能力不同本文以沉水植物菹草(Potamogeton crispus L)和金鱼藻(Ceratophyllum demersum L)为实验对象,研究水体中添加钙离子(0、100 mg/L)对水体磷(磷浓度:0、0.2、2 mg/L)的去除和植物富集磷的差异,并通过植物灰分磷的组分分析,聚焦植物钙磷的变化,为生态修复中沉水植物的选择提供理论依据结果表明:(1)菹草和金鱼藻体系中总磷(TP)和溶解性反应磷(SRP)浓度显著下降,添加钙离子使降幅升高,且菹草体系中水体TP和SRP降幅均高于金鱼藻TP和SRP降幅;(2)菹草的干重全磷在高磷低钙(2-0)水平最高,灰分总磷在高磷高钙(2-100)水平最高,而金鱼藻干重全磷在高磷高钙(2-100)水平最高,灰分总磷在中等磷低钙(0.2-0)水平最高;(3)在2 mg/L的磷浓度下,添加钙离子使菹草的钙磷(HCl-P)和水溶性磷(H_2O-P)含量升高,有机磷(NaOH-P)含量降低,结果使灰分总磷含量升高,而金鱼藻NaOH-P升高,HCl-P和H_2O-P含量均降低,结果使灰分总磷降低这表明菹草通过提高吸附性磷和钙磷含量增强磷的富集,而金鱼藻则只显著升高了灰分中有机磷的含量显然,水体富营养化背景下,相较于金鱼藻,菹草具有更强的形成CaCO_3-P共沉淀的能力,具备竞争优势.     

Effects of larval density and salinity on the development of perch larvae (Perca fluviatilis L.)

We performed two experiments, one to test whether survival and initial swim bladder inflation of perchPerca fluviatilis are affected by population density (4 or 16 larvae 1^–1) or salinity (0, 0.6 and 1.2), and the second to test the salinity tolerance of larvae. In experiment 1, survival was higher at low larval densities and at salinities of 0.6 and 1.2 rather than in fresh water. Initial swim bladder inflation was not affected by salinity or density. Average survival of fry 24 days after hatching varied from 29.6% to 86.3%, but only an average of 19.2% of the hatched larvae had grown into viable fish with an inflated swim bladder. In experiment 2, survival varied from 19% to 49%, but was not significantly affected by salinities of up to 4.8. At a salinity of 9.6, only 2 out of 344 larvae survived.