过氧化氢处理河流着生刚毛藻的效果研究

以深圳市某河流为研究对象,分析了投加H2O2对刚毛藻生物量的控制效果及其对水体p H、溶解氧、氨氮和总磷的影响。结果表明:H2O2≥1.25 mol/L时能有效抑制刚毛藻生长,使藻类光合活性在10 min内从5.8降低到0,叶绿素浓度在30 min内从5.8 mg/L降低至0.2 mg/L。现场试验投加H2O2处理河流水体中刚毛藻14 d内,藻类生物量、光合活性和叶绿素浓度降幅均高于90%。加药1 h后,河流p H值由原来的9.21~9.74迅速降低至8.23~8.80,14 d内保持在9以下。河流溶解氧、氨氮、总磷和H2O2残留浓度在除藻过程中存在变化,但是1 d后会迅速恢复至加药前水平。投加H2O2是一种有效、无污染的应急去除河流着生刚毛藻的方法。     

以刚毛藻为原料制备生物乙醇的技术研究

研究了以刚毛藻为原料制备生物乙醇的工艺.结果表明,刚毛藻预处理条件为:刚毛藻与2％(w/v)氢氧化钠混合,85℃反应80 min;酶解条件:藻粉质量浓度35g/L,纤维素酶用量80 U/g底物,加入5 g/L Tween-80,此时酶解率为61.74％;在30℃下培养40 h,发酵液中乙醇质量浓度为12.15 g/L,转化率42.63％,达到乙醇理论转化率的83.42％.     

Niche partitioning,shape of species response,and diversity in the phytobenthos across the rocky shoreline of a large peri-Alpine lake

By colonizing a particular depth zone across the transition from aquatic to terrestrial habitats, littoral species may exhibit specific physiological and ecological adaptations, as well as characteristic responses to the gradient of conditions across the ecotone. The objectives of the study were: (i) to identify the depth zone (location in relation to average water level) where the replacement of species occurs most rapidly; (ii) to test whether and to what extent the occurrence of species, their abundance and their response to the gradient evolves over time; and (iii) to assess the shape of the species' response to the gradient, calculating the niche overlap of the dominant species. Results showed that the diversity of species peaked at a depth between 18 and 48 cm, in a zone thought to be of intermediate disturbance (the transect depth was, on average, 103 cm). The main macroalgal species (the red alga, Bangia atropurpurea and the green algae, Jaoa bullata, and Cladophora glomerata), showed a variety of response shapes to the gradient: monotonic, symmetrical and skewed, depending on the stage of seasonal growth. The efficient regulation of growth of B. atropurpurea along the fluctuating gradient was interpreted as an adaptive trait giving it an advantage over more slowly reacting species. The spatial and temporal niches of B. atropurpurea and Jaoa bullata overlapped widely only in early spring, whereas later their optimal habitats were clearly differentiated. This suggested partial niche segregation between these two species, and a potential seasonal interaction.     

GC-MS detected difunctional carboxylic acids released by driedCladophora at the pH of lake ontario and the st. lawrence river

A study to identify the acidic components ofCladophora glomeata active againstAedes triseriatus larvae was extended to a mixture obtained by extracting the dried powdered alga in aqueous suspension at pH 8.5. The presence of 1,9-nonanedioic, 1,10-decanedioic, 1,11-undecanedioic and 4-ketononanoic acids was determined by GC-EIMS and GC-CIMS and confirmed by analytical coinjection GC. The presence of 5-pentyldihydro-2(3H)-furanone, a minor component, was also indicated. The group of major acidic constituents is different from those obtained by extracting driedCladophora with methanol. In contrast to the C₁₀–C₁₄ monocarboxylic acids, which hadLD ₅₀ values<20 ppm againstA. triseriatus, none of the dicarboxylic acids of the series G₄–C₁₄, C₁₆, and C₂₂ were active; nor were 4-ketononanoic acid and 5-pentyldihydro-2(3H)-furanone active.     

Desiccation and recolonization of phytobenthos in a regulated desert river: Colorado River at Lees Ferry,Arizona, USA

We tested the recolonization of the phytobenthic community in the tailwaters of Glen Canyon Dam following long- and short-term experimentally induced desiccation. The response of Cladophora glomerata, Oscillatoria spp., miscellaneous phytobenthos species and periphyton was studied over 18 weeks using three treatments: (1) undisturbed control cobbles from the submerged zone; (2) cobbles desiccated and replaced into the submerged zone; and (3) cobbles desiccated and replaced into the varial zone. Periphyton density and compositional response resulting from these treatments were also examined. Desiccation treatments were significantly different in biomass from controls throughout the study. The biomass of desiccated and replaced river cobbles averaged <30% of the controls for C. glomerata and periphyton during the 18-week recolonization period. In contrast, the biomass of the control Oscillatoria and miscellaneous phytobenthos species averaged only 3 and 50% of that in the desiccation treatments, respectively. Cladophora, the dominant alga, comprised 77% of the phytobenthic biomass. A significant positive relationship between discharge, Cladophora and periphyton biomass was present in all treatments, while there was a negative relationship with discharge for Oscillatoria and miscellaneous phytobenthos species. There was a significant inverse correlation, as well as a pattern of separate biomass dominance, between C. glomerata and Oscillatoria. Cladophora was the dominant phytobenthos species on cobbles below the baseflow and Oscillatoria was dominant on cobbles in the varial zone. In general, the Cladophora biomass decreased under intermittent drying conditions, while Oscillatoria declined under permanently wet conditions. Diatom composition was not significantly different between treatments; however, their density was lower on desiccated cobbles. Diatom density on desiccated cobbles in the submerged and varial zones averaged 69 and 42% of that of the controls, respectively. Recovery and maintenance of benthic resources are hindered by fluctuating flow regimes driven by electricity and irrigation requirements. Repeated desiccation of the phytobenthos has major effects on the bottom-up interactions in the Colorado River ecosystem. © 1998 John Wiley & Sons, Ltd.     

Synergistic Effect of Abrasive and Sonication for Release of Carbohydrate and Protein from Algae

While algae have demonstrated significant potential as a raw material due to the high intracellular concentration of carbohydrates and proteins, a primary limitation as a biofuel feedstock is due to the fact that an economically feasible method of extraction has yet to be offered. Algae samples, acquired from a local waste treatment facility, were combined with abrasive materials and subjected to ultrasonication for specific time intervals. It was found that the synergistic effect of sonication in the presence of abrasive material, such as silicon beads or sand, could extract adequate protein and carbohydrate to be utilized in fermentation processes.     

Effects of atmospheric exposure on chlorophyll a,biomass and productivity of the epilithon of a tailwater river

Field experiments were conducted to determine the effects of atmospheric exposure on the chlorophyll a content, biomass and gross primary productivity (GPP) of littoral epilithon in the Colorado River below Glen Canyon Dam, Arizona. The chlorophyll a content of the epilithon was much more sensitive to exposure than the biomass. The epilithon was rapidly bleached during summer daytime exposures, but algal filaments remained attached for several weeks after reinundation. The percentage of initial chlorophyll a remaining after one day of exposure was not different from the percentage remaining after two days of exposure. However, significant reductions in chlorophyll a content were detected for daytime exposures as short as six hours. Overall, there were close inverse relationships (r² ≥ 0–73) between the time exposed or cumulative solar radiation (400–700 nm) and the percentage of initial chlorophyll a remaining after reinundation. The GPP of Cladophora glomerata-dommaled epilithon from the permanently inundated channel was 10 times higher than the GPP of epilithon from the zone of daily water level fluctuation. Experimental atmospheric exposure of the epilithon from each zone reduced the GPP, but not the assimilation ratio (GPP per unit of chlorophyll a) of the epilithon. The Glen Canyon epilithon has low resistance to exposure disturbances, and recolonization is slow under hydropower peaking flow regimes. Cladophora glomerata has an important structural role in Glen Canyon, the disruption of which is likely to precipitate effects at higher trophic levels.     

Evaluation of Surface and Bulk Characteristics of Cellulose I Powders in Relation to Compaction Behavior and Tablet Properties

Abstract

The particle properties and solid-state characteristics of two celluloses, Avicel PH101 and cellulose obtained from the alga Cladophora sp., were evaluated and related to the compaction behavior and the properties of the tablets made from them. The surface area of the celluloses was measured at different levels of penetration capacity, ranging from external surface area of particles to molecular texture with Blaine permeametry, Kr-gasadsorption, and solid-state NMR. The important cellulose fibril surface area was best reflected by solid-state NMR, although for the Cladophora cellulose, Kr-gas adsorption also resulted in a surface area of the order of what has been suggested earlier on the basis of the cellulose fibril dimensions. The difference in fibril dimension and, thereby, the fibril surface area of the two celluloses was shown to be the primary factor in determining their properties and behavior. Properties such as the crystallinity and the tablet disintegration could be related to the fibril dimensions. The Cladophora cellulose resulted in rather strong compacts that still disintegrated rapidly. The irregular surface morphology of the particles and the fragmenting behavior of Cladophora probably contributed to the strength of the tablets.     

Investigation of the Column Performance of Cadmium(II) Biosorption by Cladophora crispata Flocs in a Packed Bed

ABSTRACT

In this study the biosorption of cadmium(II) ions to dried floes of Cladophora crispata, a kind of green algae, was investigated in a packed bed column. The cadmium(II) removal performance of the column was investigated as a function of the cadmium(II)-bearing solution flow rate and the inlet cadmium(II) concentration. Re- moval and total removal percentages of cadmium(II) related to flow volume were determined by evaluating the breakthrough curves obtained at three different flow rates for two different constant inlet concentrations. At the lowest flow rate the effect of inlet cadmium(II) concentration on the column capacity was also investigated. Data confirmed that early saturation and lower cadmium(II) removals were observed at higher flow rates and at higher cadmium(H) concentrations. Column experiments also showed that maximum specific cadmium(II) uptake values of C. crispata floes were as higher as those of other biomass sorbents.     

青霉菌对刚毛藻纤维素降解的研究

研究了青霉菌对刚毛藻中纤维素的降解条件。首先通过单因素试验,研究了氮源种类、硫酸铵含量、料液比、pH、发酵温度、发酵时间对纤维素降解的影响。选择了pH值、料液比、硫酸铵含量进行L9（33）正交试验设计,考察各因素对蛋白、总糖含量、纤维素酶活的影响,得出最佳降解条件：藻粉3 g/L,料液比1∶15（g∶mL）,硫酸铵20 g/L,磷酸二氢钾1 g/L,硫酸镁0.5 g/L,缓冲液pH 6.0,发酵温度为30 ℃,发酵时间为7 d,在此条件下,蛋白含量为12.44 g/100 g,总糖含量0.58 mg/g,纤维素酶酶活4.84 U/g。