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971.
972.
973.
Soulwène Kouki Neila Saidi Fadhel M''hiri Houda Nasr Hanène Cherif Hadda Ouzari Abdennaceur Hassen 《环境科学学报(英文版)》2011,23(10):1699-1708
Autotrophic ammonia-oxidizing bacteria (AOB) have been widely studied in constructed wetlands systems, while mixotrophic AOB have been less thoroughly examined. Heterotrophic bacteria were isolated from wastewater and rhizospheres of macrophytes of constructed wetlands, and then cultivated in a mixotrophic medium containing ammonium and acetic acid. A molecular characterization was accomplished using ITS-PCR amplification, and phylogenetic analysis based on 16S rRNA gene sequences. Results showed the presence of 35 bacteria, among 400 initially heterotrophic isolates, that were able to remove ammonia. These 35 isolates were classified into 10 genetically different groups based on ITS pattern. Then, a collection of 10 isolates were selected because of their relatively high ammonia removal efficiencies (ARE ≥ 80%) and their phylogenetic diversity. In conditions of mixotrophy, these strains were shown to be able to grow (increase of optical density OD660 during incubation with assimilation of nitrogen into cellular biomass) and to oxidize ammonia (important ammonia oxidation efficiencies, AOE between 79% and 87%). Among these facultative mixotrophic AOB, four isolates were genetically related to Firmicutes (Bacillus and Exiguobacterium), three isolates were affiliated to Actinobacteria (Arthrobacter) and three other isolates were associated with Proteobacteria (Pseudomonas, Ochrobactrum and Bordetella). 相似文献
974.
XAD-8 resin isolation of organic matter in water was used to divide organic matter into the hydrophobic and hydrophilic fractions.
A pilot plant was used to investigate the change in both fractions during conventional and advanced treatment processes. The
treatment of hydrophobic organics (HPO), rather than hydrophilic organicas (HPI), should carry greater emphasis due to HPO’s higher
trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP). The removal of hydrophobic matter
and its transmission into hydrophilic matter reduced ultimate DBP yield during the disinfection process. The results showed that sand
filtration, ozonation, and biological activated carbon (BAC) filtration had distinct influences on the removal of both organic fractions.
Additionally, the combination of processes changed the organic fraction proportions present during treatment. The use of ozonation and
BAC maximized organic matter removal e ciency, especially for the hydrophobic fraction. In sum, the combination of pre-ozonation,
conventional treatment, and O3-BAC removed 48% of dissolved organic carbon (DOC), 60% of HPO, 30% of HPI, 63% of THMFP,
and 85% of HAAFP. The use of conventional treatment and O3-BAC without pre-ozonation had a comparable performance, removing
51% of DOC, 56% of HPO, 45% of HPI, 61% of THMFP, and 72% of HAAFP. The e ectiveness of this analysis method indicated that
resin isolation and fractionation should be standardized as an applicable test to help assess water treatment process e ciency. 相似文献
975.
经对鄂尔多斯市达拉特旗树林召镇的转基因试验林中的v系列转基因银中杨与非转基因对照组的生长性状的对比研究证明:该转基因系列具有较强的环境适应性,生长状况明显优于非转基因杨树。 相似文献
976.
通过现场测试对包钢中水水质类型及其用于高炉循环冷却系统的现状进行了调查研究。确定了在现有条件下4#高炉循环冷却水系统的水质类型为腐蚀为主,兼有结垢;包钢中水为微量结垢和腐蚀型水质,随着浓缩倍数的增加逐步转化为严重结垢型水质。 相似文献
977.
本文探讨了如何提高顶空气相色谱法测定三氯甲烷及四氯化碳的灵敏度、精密度与准确度。重点讨论了平衡条件的优化以及带顶空自动进器的气相色谱仪的各个关键参数的优化。 相似文献
978.
979.
高浓度氨氮废水排放量大、成分复杂、毒性强,因此对环境的危害极大。本文从总结高浓度氨氮废水的来源和特性入手,分析高浓度氨氮废水的危害性,提出高浓度氨氮废水的主要治理技术。 相似文献
980.
Xiaoming Xu Jie Tang Zhaoyang Li Chang Liu Weizheng Han 《Mitigation and Adaptation Strategies for Global Change》2011,16(6):721-731
In this study, paddy fields in Jilin province which are flooded parcel of arable lands used for growing rice (Oryza sativa Linn.) were selected as the object. Long-term exploitation of paddy fields led to variations of soil organic carbon (SOC) and green
house gases (GHGs) emissions which might contribute to global warming. In order to calculate the amount of global warming
potentials (GWPs) of emissions from ricepaddies and find the correlations among rice yield, SOC storage and GWP, DeNitrification-DeComposition
(DNDC) model was used to simulate SOC densities and fluxes of main GHGs emitted from paddy fields. After verification, simulation
results were used to calculate SOC storages and 100-year GWPs from 1949 to 2009. Results indicated that SOC densities in depths
of 0–10 cm, 10–20 cm and 20–30 cm all kept increasing. Average methane (CH4) and nitrous oxide (N2O) fluxes were 278.55 kg carbon (kgC) ha−1 a−1 and 2.22 kg nitrogen (kgN) ha−1 a−1. The SOC storage (0–30 cm) had increased from 3.96 × 109kgC in 1949 to 47.85 × 109kgC in 2009. In addition, GWP emission was increasing exponentially in the past 61 years, from 0.16 × 106 Mg carbon dioxide equivalents (CO2-equivalents) to 66.36 × 106 Mg CO2-equivalents. Both SOC storage and GWP presented obviously linear relation to rice yields. Overall, the research suggested
that long-term rice yields could be used to estimate the SOC storage and GWP variations. 相似文献