Effects of cerium on growth and physiological characteristics of Anabaena flosaquae

In the present study, the effects of cerium (Ce) on the growth and physiological changes were investigated in the cyanobacterium Anabaena flosaquae (A. flosaquae) during a 17-day period. The results showed that the content of chlorophyll a (chl-a) and activity of anti-oxidase (e.g. superoxide dismutase, peroxidase, and catalase) increased with Ce3+ concentration in the range of 0.05 to 0.1 mg/L and the growth of A. flosaquae was stimulated. While at around 5 mg/L, the content of malondiadehyde (MDA) increased significantly but the activ-ity of antioxidase reduced, which resulted in the ruin of antioxidant defense system. Compared to the control (Ce3+-free), the population size of live cells declined significantly. Microcystin-LR (MC-LR), the most common and toxic cyanotoxins produced by A. flosaquae, was de-tected and the highest content of MC-LR was observed in 10 mg/L Ce3+ treatment. These results implied that the aqueous environment might suffer a more negative ecological impact when exposed to relatively low Ce3+ concentrations (<0.1 mg/L).)     

纳米银在饱和多孔介质含水层中迁移主控机理和影响特征

纳米银（AgNP）作为应用最广、生态毒性最强的工程纳米材料之一，一旦进入地下水环境，将引发环境问题。目前，环境因素对纳米银在地下水环境中运移的影响机理尚不清楚。通过室内柱实验，研究了流速（1、2 ml·min^-1）和介质粒径特征（0.605、0.115 mm以及混合粒径的玻璃珠）对纳米银在饱和多孔介质中迁移的影响。研究结果表明纳米银在粒径较大（0.605 mm）的介质中的迁移主要受吸附沉降控制；在小粒径介质中（0.115 mm以及混合粒径玻璃珠），迁移过程同时受吸附沉降和阻塞沉降两种机理的控制，且阻塞效应主要受小粒径部分介质控制。水流速度提高能降低大粒径介质中纳米银颗粒的沉降效率，从而提高其迁移能力。而对于小粒径介质和混合粒径介质，流速提高除了降低纳米银的沉降效率，还能降低阻塞效应和促进尺寸排除效应，不但能更显著地降低纳米银在介质中的衰减，还能提高纳米银在介质中的穿透速度。研究成果对于理解复杂的场地条件下纳米材料的迁移分布动态具有理论价值。     

Degradation of Dye Wastewater by Pulsed High-Voltage Discharge Combined with Spent Tea Leaves

Degradation of methylene blue （MB） was performed using the pulsed discharge process （PDP） combined with spent tea leaves （STLs）. The effects of STL dosage, concentration of initial solution, and pH were analyzed in the combined treatment. Results showed that the combined treatment was effective for dye wastewater degradation; when the dosage of STLs was 3.2 g/L, the degradation efficiency reached 90% after 15 rain treatment, and STLs showed a good repeatability. The degradation rate decreased with increasing initial MB concentration but not related to the solution pH in the combined treatment. Fourier-transform infrared spectra and N2 adsorption suggested that the number of acidic and basic groups in the STL surface increased after the treatment, but the surface area and pore volume remained unchanged.     

Effects of neodymium on growth and physiological characteristics of Microcystis aeruginosa

To investigate the effect of neodymium (Nd) on Microcystis aeruginosa, the growth and physiological changes were studied by lab cultured experiments. The results showed that the content of chlorophyll a (Chl-a), soluble protein and the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased compared with the control (Nd3+-free), and the growth of M. aeruginosa was stimulated in the treatments of initial Nd3+ concentration ≤1 mg/L; while the treatments of initial Nd3+ concentration was in the range of 5.00-10.00 mg/L, the content of malondiadehyde (MDA) increased immediately but the activity of CAT reduced, which resulted in weakened M. aeruginosa’s ability to eliminate the active oxygen and the ruin of antioxidant defense system, and stunting the growth of M. aeruginosa. With the initial Nd3+ concentration of 50 mg/L, the growth of M. aeruginosa was totally stunted. The ultrastructure showed that excess Nd3+ could lead to the decrease of thylakoid and the increase of fat particle in cells of M. aeruginosa, and the cell membrane became rough and even broken, causing an irreversible damage to algal cells.     

膜生物反应器脱氮除磷及细菌16S rDNA多样性研究

采用一体式膜生物反应器(MBR)处理富含氮磷、有机物、高悬浮物的畜禽养殖废水.在最佳的处理条件下,采用分子生物学手段,构建16S rDNA基因文库,并通过16SrDNA序列的系统发育分析,对膜生物反应器中的细菌种群多样性和群落结构进行了研究.实验结果表明,反应器中的细菌种群多样性十分丰富,系统中的优势菌群为γ-变形细菌(proteobacteria)和β-变形细菌(proteobacteria).