Oscillatoria Sp. (Cyanophyta) mat metabolites implicated in habitat selection inBembidion obtusidens (Coleoptera: Carabidae)

In laboratory bioassaysBembidion obtusidens Fall adults were attracted to volatile metabolites (methyl esters of hexadecanoic and 9-octadecenoic acid) of mat-forming, filamentous blue-green algae (Oscilalatoria sp.; Cyanophyta) growing in the microhabitat of these beetles on the shores of saline lakes. Commercial preparations of these metabolites also were attractive, suggesting thatOscillatoria metabolites are token stimuli which serve as habitat cues forBembidion adults.Research supported by a National Science and Engineering Research Council of Canada grant (A1409).     

过氧化氢预氧化复合高岭土去除水中颤藻的研究

研究了H2O2预氧化复合高岭土混凝工艺对水中颤藻的去除效果。结果表明,H2O2具有显著氧化抑制藻活性的功能,高岭土则具有良好的助凝作用,经H2O2预氧化复合高岭土混凝后形成的絮体大而密实,沉降速度更快。试验得出最佳复配条件为:原水pH值为7,预氧化时间为20 min,H2O2、高岭土和PAC的投加量分别为3,34和3.5 mg/L。在该最佳试验条件下,浊度和叶绿素a去除率分别达到95.6%和97.8%,残留铝含量为0.13 mg/L。     

K2FeO4预氧化对颤藻和腐殖酸复合絮凝相互作用的研究

采用K2FeO4预氧化复合高岭土和聚合氯化铝（PAC）混凝处理含藻和腐殖酸的混合水.结果表明,当藻浓度不变时,在一定范围内,随着腐殖酸浓度的升高,浊度、腐殖酸及藻去除率均逐渐下降.当腐殖酸浓度固定时,随着藻液浓度的升高,腐殖酸和藻去除率逐渐上升,而浊度去除率基本不变.同时考察了矿物高岭土投加量及目数、K2FeO4预氧化时间、不同污染物浓度比例对K2FeO4预氧化处理混合水效果的影响,当高岭土投加量为8 mg/L、粒径为140目时,浊度和腐殖酸、藻类的去除率分别为91.0%,80.9%和88.2%,投加量过大或目数过大,沉降性能变差,起不到良好的助凝作用.     

颤藻聚金动态实验及其地质意义

对颤藻在含金培养液中生长情况的研究,发现10~(-6)的金对颤藻是安全浓度,当金浓度增至2×10~(-6)时,颤藻被明显致毒,生长繁殖受到抑制。颤藻在10×10~(-9)、100×10~(-9)的含金培养液中正常生长时,对金具有很强富集能力。在含金10×10~(-9)的培养液中,随着藻体的生长繁殖,富集系数逐渐增大,最高可达17614;在含金100×10~(-9)的培养液中,随着藻体的生长繁殖,前4天富集系数逐渐增大,以后则有所减少,藻粉中金的含量达91.2×10~(-6)。试验结果不仅为含金水体的生物净化和金的生物回收提供了可能,而且为藻类植物参与成矿作用提供了重要依据。     

A planktonic Oscillatoria species from Mississippi catfish ponds that produces the off-flavor compound 2-methylisoborneol

A planktonic, gas-vacuolate Oscillatoria species was isolated from catfish ponds in Mississippi during an episode of off-flavor and high 2-methylisoborneol (MIB) levels. Volatile compounds from unialgal cultures were isolated using closed-loop stripping, liquid-liquid extraction, and analyzed by gas chromatography and mass spectroscopy. The organism produced MIB at 75–87 μg 1⁻¹ after 2–3 wk of incubation at 25°C. The alga was found in moderate to high numbers in three pond water samples with high MIB levels, and low numbers in two other samples with low MIB levels. The organism was not present (less than one organism/10 ml) in nine other samples characterized by a “woody” or “swampy” odor and no detectable MIB. This Oscillatoria strain is believed to be the first blue-green alga that produces MIB ever isolated from Mississippi catfish ponds, and may be a cause of the off-flavor problem associated with MIB in those systems.