沉水植物苦草对上覆水各形态磷浓度的影响

沉水植物是影响湖泊磷营养状态的重要因素。在室内模拟了"水-苦草-沉积物"生态系统,在沉水植物苦草生长过程中分析上覆水中的总磷(TP)、溶解性总磷(TDP)、溶解性有机磷(DOP)、溶解性活性磷(SRP)、颗粒态总磷(PP)的变化,探讨了苦草对上覆水磷赋存形态的影响。结果表明,苦草在生长过程中减缓了沉积物磷的相对释放速率使上覆水中TP、SRP、DOP、PP均呈现不同程度的下降。上覆水TP、SRP、DOP、PP分别下降了37.5%、74.6%、42.0%、19.5%;苦草主要通过吸收上覆水和间隙水中的磷及对环境因子的影响,使得上覆水中各形态磷浓度保持在较低的水平,降低沉积物向水体释放磷的速率。     

Sphaerotilus natansFQ40合成聚β-羟基丁酸(PHB)条件的研究

从活性污泥中分离筛选到 1株产PHB的球衣菌FQ40。其最适发酵培养基配方为 (g/L) :蔗糖 1 0 ,牛肉膏 5 ,MgSO4 ·7H2 O 0 2 ,CaCl2 0 0 5 ,FeCl30 0 1 ,K2 HPO4 0 0 4,KH2 PO4 0 0 3 ,NaH2 PO4 ·2H2 O 0 0 5 ,H3BO30 0 0 5。最佳摇瓶发酵条件为 :2 5 0mL三角瓶装 80mL培养液 ,起始pH为 7 0 ,培养温度 3 0℃ ,接种量 1 0 % ,转速 1 5 0r/min ,周期 42h。在优化条件下 ,细胞干重达4 44g/L ,PHB含量为 48% ,PHB浓度为 2 1 3 g/L。     

不同密度铜锈环棱螺对沉水植物生长和水质的影响EI北大核心CSCD

通过试验研究不同密度铜锈环棱螺(Bellamya aeruginosa)对苦草(Vallisneria natans)和金鱼藻(Ceratophyllum demersum)生长及水质的影响。试验结果表明:铜锈环棱螺的存在显著促进了沉水植物的生长,高密度组苦草和金鱼藻的相对生长率分别是对照组的2.16和1.66倍,高密度组苦草和金鱼藻的相对伸长率分别是对照组的1.18和1.25倍;铜锈环棱螺的存在对水质有一定负面影响,水体电导率随着螺密度的增加而升高,溶解氧浓度随着螺密度的增加而降低,pH值、氧化还原电位和叶绿素浓度随着螺密度的增加没有一致的规律;水体氮的去除率随螺密度的增加呈下降趋势,高密度组苦草和金鱼藻对氮的去除率相对于对照组分别下降了70.0%和64.5%,磷的去除率组间没有显著差异;铜锈环棱螺密度对水体氮浓度变化起主要作用,方差占比为64%,沉水植物不同物种对水体磷浓度变化起主要作用,方差占比为72.54%。     

Impacts of different weed cutting practices on macrophyte species diversity and composition in a Danish stream

Various effects of stream management on biotic communities have been suggested on the basis of observations and investigations in regularly managed streams throughout Europe, but only very sparse information is available about if and how stream management can be combined with maintaining a natural and diverse stream flora. Our study was carried out to investigate how weed cutting practice and frequency can affect macrophyte communities to provide knowledge for future decisions regarding management in streams. We chose an experimental approach and applied four different weed cutting practices (cutting full width, central channel, diagonal channels and no cutting) and frequencies within one stream reach for four years. We found only very limited changes over the four years in overall macrophyte diversity parameters following different management practices and there were no changes in macrophyte diversity parameters either as a function of the weed cutting frequency or method applied. In contrast we found directional changes in macrophyte composition following frequent cuttings of either the whole stream channel or a less comprehensive cutting of only one central channel for four years. In both cases the macrophyte communities changed towards a more Ranunculus dominated community while Potamogeton natans became less important in the community. This change seemed to reflect a higher tolerance of Ranunculus towards disturbance. On the basis of these results, we recommend that the management frequency in streams is limited and, if several cuttings are needed to prevent bank over‐flow, cutting in several narrow channels is preferable to cutting in one central channel as directional changes in plant communities are avoided. Copyright © 2003 John Wiley & Sons, Ltd.     

沉水植物苦草腐解对水体水质的影响

沉水植物可以有效控制湖泊富营养化,但不同水环境下其周期性衰亡对湖泊生态系统的影响不容忽视。以苦草为研究对象,采用分解网袋法进行为期66 d的室内模拟试验,研究高纯水和底泥悬浮液环境下不同生物量密度的苦草腐解过程及水体氮、磷等营养盐的浓度变化。结果表明:①不同生物量密度(0.1、0.2、0.4 g/L)的苦草腐解过程均可以分为快速淋溶和缓慢分解两个阶段,不同阶段内组间质量损失率存在差异,但总体趋势一致。②高纯水环境下,水体营养盐含量(COD、TP)与生物量呈正相关(相关系数r分别为0.478、0.697,P<0.05),0.4 g/L的苦草会明显提高水中各营养盐含量,破坏水体水质;苦草腐解时,磷的矿化速率比氮快。③底泥悬浮液环境下,苦草残体腐解对水体水质的影响有明显的时效性和阶段差异性,TN浓度与水体中DO浓度、pH值显著相关(r分别为0.839、0.806,P<0.05),苦草腐解释放的氮、磷等营养盐在底泥-水界面发生复杂的吸附和降解反应,适量的苦草残体腐解可促进各形态氮、磷的迁移转化。     

浮游球衣菌-纳米Fe_3O_4生物吸附剂处理电镀废水中Cd(Ⅱ)和Cr(Ⅵ)的研究

文章研究了浮游球衣菌-纳米Fe3O4生物吸附剂对重金属离子Cd(Ⅱ)和Cr(Ⅵ)的吸附性能,结果表明,此生物吸附剂对Cd(Ⅱ)和Cr(Ⅵ)有一定的吸附作用,当处理废水的pH为5.5、菌体投加量为0.3 g·L-1时,对20 mg·L-1含Cd(Ⅱ)和Cr(Ⅵ)废水的去除率分别为89%和68%。吸附-解吸试验结果显示,生物吸附剂可重复利用3次,在使用第3次时,Cd(Ⅱ)和Cr(Ⅵ)的去除率仍可达64%和42%。     

Study of the inhibition of certain trophic levels by the presence of metal cations in water

Bioassays and biological tools have been developed for the evaluation of the toxicity of water. A protocol of short-term tests allowed the examination of the influence of temperature, salinity, hardness and effect of complexation on the toxicity of Cd²⁺, Cu²⁺, Ni²⁺ and Zn²⁺ by means of a test daphnia (Daphnia magna). The development of an experimental installation functioning continuously, where the trophic level is represented by the daphnia, led to the development of a system of bio-indication. The survival of the daphnia is examined under conditions of disturbances produced by Cd²⁺, Cu²⁺, Ni²⁺ and Zn²⁺. The application of the chronic test (21 d) allowed the folow-up of the inhibition of the survival and the reproduction of D. magna by Cd²⁺, Cu²⁺ and Ni²⁺. A methodology with the help of the phototactic effect of D. magna was proposed. This one aims at developing a phototactic biosensor subjected to the toxicity of cadmium. Bioassays, using the purifying activity of the activated sludge, were considered and enabled understanding of the phenomena of inhibition and adaptation of these muds in the presence of trivalent chromium. In addition, two watery freshwater plants, Lemna minor and Salvinia natans, were exposed to Cd²⁺, Cu²⁺ and Zn²⁺ in order to test their sensitivity. We consequently carried out a histological study on leaves of S. natans contaminated by metal toxicity independently of the test.     

浮游球衣菌S9产铁氧化酶发酵条件优化及酶学特性研究

通过单因素及正交设计试验,研究了浮游球衣菌S9产铁氧化酶的发酵条件,并探讨了铁氧化酶的酶学性质。结果表明,菌株S9的最适产酶发酵培养基配方为柠檬酸铁铵1.0%,NH4Cl 0.1%,K2HPO4 0.05%,MgSO4·7H2O 0.05%,CaCl2·6H2O 0.01%;最佳发酵条件为：培养初始pH7.0,培养温度30 ℃,装液量50 mL/250 mL,转速150 r/min,培养时间84 h。在此优化发酵条件下,菌株S9的铁氧化率可达75.25%,与未优化前相比,提高了42.28%。所产铁氧化酶的最适温度为30 ℃,最适pH为7.5,Mg2+、K+、Na+对酶的活性具有增强作用,Pb2+、Ag+会抑制酶的部分活性,且Mn2+、Zn2+对酶具有很强的抑制作用。对该菌最适培养基和产酶条件及酶学性质,对铁氧化酶在给排水工程及其分离纯化和活性保护具有一定的参考价值和指导意义。