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101.
Surface water methane (CH4) and nitrous oxide (N2O) concentrations and fluxes were investigated in two subtropical coastal embayments (Bramble Bay and Deception Bay, which are part of the greater Moreton Bay, Australia). Measurements were done at 23 stations in seven campaigns covering different seasons during 2010-2012. Water-air fluxes were estimated using the Thin Boundary Layer approach with a combination of wind and currents-based models for the estimation of the gas transfer velocities. The two bays were strong sources of both CH4 and N2O with no significant differences in the degree of saturation of both gases between them during all measurement campaigns. Both CH4 and N2O concentrations had strong temporal but minimal spatial variability in both bays. During the seven seasons, CH4 varied between 500% and 4000% saturation while N2O varied between 128 and 255% in the two bays. Average seasonal CH4 fluxes for the two bays varied between 0.5 ± 0.2 and 6.0 ± 1.5 mg CH4/(m2·day) while N2O varied between 0.4 ± 0.1 and 1.6 ± 0.6 mg N2O/(m2·day). Weighted emissions (t CO2-e) were 63%-90% N2O dominated implying that a reduction in N2O inputs and/or nitrogen availability in the bays may significantly reduce the bays' greenhouse gas (GHG) budget. Emissions data for tropical and subtropical systems is still scarce. This work found subtropical bays to be significant aquatic sources of both CH4 and N2O and puts the estimated fluxes into the global context with measurements done from other climatic regions. 相似文献
102.
Xi Yang Ping Xie Yunzhen Yu Hong Shen Xuwei Deng Zhimei Ma Peili Wang Min Tao Yuan Niu 《环境科学学报(英文版)》2015
We conducted an experiment to study the interaction effects of Microcystis aeruginosa and Pseudomonas pseudoalcaligenes on off-flavors in an algae/bacteria co-culture system at three temperatures (24, 28 and 32°C). Gas chromatography–mass spectrometry was applied to measure off-flavor compounds dimethyl sulfide (DMS), dimethyl trisulfide (DMTS), 2-methylisoborneol, geosmin (GEO) and β-cyclocitral. During the lag phase of co-cultured M. aeruginosa (first 15 days), P. pseudoalcaligenes significantly increased the production of DMS, DMTS and β-cyclocitral at all three temperatures. In the exponential phase of co-cultured M. aeruginosa (after 15 days), M. aeruginosa became the main factor on off-flavors in the co-culture system, and β-cyclocitral turned to the highest off-flavor compound. These results also indicated that DMS, DMTS and β-cyclocitral were the main off-flavor compounds in our M. aeruginosa/P. pseudoalcaligenes co-culture system. Univariate analysis was applied to investigate the effects of M. aeruginosa and P. pseudoalcaligenes on the production of off-flavors. The results demonstrated that both M. aeruginosa and P. pseudoalcaligenes could increase the production of DMS and DMTS, while β-cyclocitral was mainly determined by M. aeruginosa. Our results also provide some insights into understanding the relationship between cyanobacteria and heterotrophic bacteria. 相似文献
103.
Yu Zhang Zhimin Chen Wei An Shumin Xiao Hongying Yuan Dongqing Zhang Min Yang 《环境科学学报(英文版)》2015,27(4):252-258
Membrane bioreactors (MBR) are highly efficient at intercepting particles and microbes and have become an important technology for wastewater reclamation. However, many pathogens can accumulate in activated sludge due to the long residence time usually adopted in MBR, and thus may pose health risks when membrane integrity problems occur. This study presents data from a survey on the occurrence of water-borne Giardia pathogens in reclaimed water from a full-scale wastewater treatment plant with MBR experiencing membrane integrity failure, and assessed the associated risk for green space irrigation. Due to membrane integrity failure, the MBR effluent turbidity varied between 0.23 and 1.90 NTU over a period of eight months. Though this turbidity level still met reclaimed water quality standards (≤5 NTU), Giardia were detected at concentrations of 0.3 to 95 cysts/10 L, with a close correlation between effluent turbidity and Giardia concentration. All β-giardin gene sequences of Giardia in the WWTP influents were genotyped as Assemblages A and B, both of which are known to infect humans. An exponential dose-response model was applied to assess the risk of infection by Giardia. The risk in the MBR effluent with chlorination was 9.83 × 10-3, higher than the acceptable annual risk of 1.0 × 10-4. This study suggested that membrane integrity is very important for keeping a low pathogen level, and multiple barriers are needed to ensure the biological safety of MBR effluent. 相似文献
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105.
生物净化集成系统改善精养池塘水质的效果 总被引:1,自引:0,他引:1
2008年7月-9月,将3个精养池塘分隔为鱼类养殖区和水质净化区,除了对照池外,在另外两个试验池净化区构建了由水蕹菜、滤食性贝类和生物刷组成的集成生物净化系统来净化精养池塘的水质,并在8月初引进高分子纳米增氧管来改善池塘溶氧水平。2个阶段的试验结果表明,该集成生物净化系统在净化池塘养殖水中氮、磷营养盐和有机污染物方面具有明显的功能优势互补,对水中TSS、TN、TAN、NO2--N、NO3--N、PO43--P和TP都有较好地去除效果。而高分子纳米增氧管使得池塘溶氧始终保持在5 mg.L-1以上。3个池塘两阶段的内梅罗水质综合营养指数表明,2号池第二阶段生物净化材料密度配置稍高。 相似文献
106.
加氢裂化装置是石化炼油装置中爆炸和火灾危险性最高的装置,根据加氢裂化的工艺和装置特点,从物料和主要设备两个方面分析了加氢裂化装置的火灾危险特性,探讨了加氢裂化装置发生事故原因,从设置监测装置、防止反应失控和强化灭火预案等方面提出了加氢裂化装置安全管理对策. 相似文献
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109.
用哌嗪和二硫化碳反应合成氨基二硫代甲酸中间体,再与二卤代烃反应得到1,4-双(二硫代酯基)哌嗪聚合物,考察了中间体和螯合树脂对Ag^ ,Cu^2 ,Zn^2 ,Ni^2 ,CO^2 ,Pb^2 ,Pd^2 ,Cr^3 的静态吸附性能,结果表明,两者均可以吸附金属离子,缩聚后的螯合树脂具有更强的吸附能力。 相似文献
110.
Fe_2O_3/膨润土微波诱导氧化处理染料废水 总被引:2,自引:1,他引:2
以膨润土为载体,采用直接沉淀法制备了Fe2O3/膨润土负载型催化剂。制备催化剂的最佳工艺条件:硝酸铁质量浓度为8.08g/L,硝酸铁与膨润土质量比为1.0,焙烧温度为350℃,焙烧时间为3h。用Fe2O3/膨润土负载型催化剂微波诱导氧化处理50mL质量浓度为50mg/L的模拟活性嫩黄废水的最佳工艺条件:催化剂加入量为0.5g,微波功率为900W,微波作用时间为5min。在此条件下模拟活性嫩黄废水脱色率达96.40%。微波诱导氧化处理模拟活性嫩黄废水的反应符合一级反应动力学方程。 相似文献