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161.
Chao Song Xue-Fei Sun Su-Fang Xing Peng-Fei Xia Yi-Jing Shi Shu-Guang Wang 《Environmental science and pollution research international》2014,21(3):1786-1795
The antibiotics have attracted global attentions for their impact on aquatic ecosystem. The knowledge about the fate of antibiotics encountering extracellular polymeric substances (EPS) is, however, limited. In this study, we investigated the interacting mechanisms of tetracycline (TC) to EPS extracted from aerobic activated sludge. The contributions of the main components of EPS, extracellular proteins, and polysaccharides were evaluated using bovine serum albumin and alginate sodium, respectively. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance indicated that hydroxyl, carboxyl, and amino groups were the domain chemical groups involved in the interaction between TC and EPS, and the binding of TC onto EPS changed the structure of these chemical groups, thus causing shifts in their UV–visible absorption spectra. In addition, we found that extracellular proteins, rather than polysaccharides, were the major active contents involved in the interaction. Three-dimensional excitation–emission matrix fluorescence spectroscopy showed that the fluorophores in EPS were clearly quenched by TC and the static quenching process was observed, implying the complex formation of TC and EPS. Furthermore, thermodynamic analysis indicated that the binding of TC with EPS is spontaneous and dominated by electrostatic forces. 相似文献
162.
H. Christopher Frey Song Li 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1436-1447
Abstract Quantitative methods for characterizing variability and uncertainty were applied to case studies of oxides of nitrogen and total organic carbon emission factors for lean-burn natural gas-fueled internal combustion engines. Parametric probability distributions were fit to represent inter-engine variability in specific emission factors. Bootstrap simulation was used to quantify uncertainty in the fitted cumulative distribution function and in the mean emission factor. Some methodological challenges were encountered in analyzing the data. For example, in one instance, five data points were available, with each data point representing a different market share. Therefore, an approach was developed in which parametric distributions were fitted to population-weighted data. The uncertainty in mean emission factors ranges from as little as ~±10% to as much as -90 to 21+180%. The wide range of uncertainty in some emission factors emphasizes the importance of recognizing and accounting for uncertainty in emissions estimates. The skewness in some uncertainty estimates illustrates the importance of using numerical simulation approaches that do not impose restrictive symmetry assumptions on the confidence interval for the mean. In this paper, the quantitative method, the analysis results, and key findings are presented. 相似文献
163.
Assessment of fates of estrogens in wastewater and sludge from various types of wastewater treatment plants 总被引:1,自引:0,他引:1
We measured five estrogens in the wastewater samples from the municipal wastewater treatment plants (M-WWTPs), livestock wastewater treatment plants (L-WWTPs), hospital WWTPs (H-WWTPs) and pharmaceutical manufacture WWTPs (P-WWTPs) in Korea. The L-WWTPs showed the highest total concentration (0.195-10.4 μg L−1) of estrogens in the influents, followed by the M-WWTPs (0.028-1.15 μg L−1), H-WWTPs (0.068-0.130 μg L−1) and P-WWTPs (0.015-0.070 μg L−1). Like the influents, the L-WWTPs (0.003-0.729 μg L−1) and the M-WWTPs (0.001-0.299 μg L−1) also showed higher total concentration of estrogens in the effluents than the H-WWTPs (0.002-0.021 μg L−1) and P-WWTPs (0.011 μg L−1 in one sample). The L-WWTPs (37.5-543 μg kg−1, dry weight) showed higher total concentrations in sludge than the M-WWTPs (3.16-444 μg kg−1, dry weight) like the wastewater. The distribution of estrogens in the WWTPs may be affected by their metabolism in the human body, their transition through biological treatment processes, and their usage for livestock growth. Unlike the concentration results, the daily loads of estrogens from the M-WWTPs were the highest, which is related to the high capacities of WWTPs. 相似文献
164.
Based on the Environmental Kuznets Curve theory,the authors choose provincial panel data of China in 1990 2007 and adopt panel unit root and co-integration testing method to study whether there is Environmental Kuznets Curve for China’s carbon emissions.The research results show that:carbon emissions per capita of the eastern region and the central region of China fit into Environmental Kuznets Curve,but that of the western region does not.On this basis,the authors carry out scenario analysis on the occurrence time of the inflection point of carbon emissions per capita of different regions,and describe a specific time path. 相似文献
165.
Xu H Jiang Y Al-Rasheid KA Al-Farraj SA Song W 《Environmental science and pollution research international》2011,18(7):1213-1221
Introduction
Ciliated protozoa play important roles in aquatic ecosystems especially regarding their functions in micro-food web and have many advantages in environmental assessment compared with most other eukaryotic organisms. The aims of this study were focused on analyzing the application of an indicator based on taxonomic relatedness of ciliated protozoan assemblages for marine environmental assessment. 相似文献166.
采用溶胶凝胶法制备LixNi1-xO和ZnO粉体,利用球磨法制备ZnO/LixNi1-xO复合粉体,以紫外光为光源,通过降解甲基橙,研究了锂掺杂及n-p复合对氧化镍的光催化性能影响。结果表明:当投放量为0.1 g/L,x≤0.075(摩尔分数)的锂掺杂氧化镍均比未掺杂氧化镍的光催化活性高。当锂掺杂摩尔分数为0.025,投放量为0.4 g/L时锂掺杂氧化镍的光催化活性最佳,甲基橙最高降解率达到93.1%。当ZnO/Li0.025Ni0.975O在质量比为1∶1,投放量为0.2 g/L时光催化活性最佳,甲基橙最高降解率达到98.1%。 相似文献
167.
烧结脱硫灰制备蒸压加气混凝土砌块的研究 总被引:1,自引:0,他引:1
研究了烧结烟气半干法脱硫灰复掺粉煤灰、水渣/水泥,辅之外加剂,制备蒸压加气混凝土砌块的可行性.实验结果显示,当脱硫灰掺入量25%,粉煤灰掺入量45%,水渣和水泥掺入量均15%,铝粉掺入量0.04%,水料比0.6,稳泡剂掺入量0.0012%,烧碱掺入量1%,无需额外添加石膏,采用蒸压养护12.5 h(其中抽真空时间为0.... 相似文献
168.
169.
170.
固定化微生物法去除模拟渗滤液中氨氮的研究 总被引:1,自引:0,他引:1
采用固定化微生物曝气生物滤池(I-BAF)技术成功处理了模拟垃圾渗滤液,探讨了pH和溶解氧(DO)对系统脱氮性能的影响。结果表明,固定化微生物曝气生物滤池反应系统启动迅速,运行稳定,可以有效去除模拟垃圾渗滤液中的有机物和氨氮,其去除率分别达到97.1%和99.9%。在pH为7.5~8.5之间,DO 4.0 mg/L左右的条件下对模拟垃圾渗滤液中氮的去除最为有利,同步硝化反硝化效率以及总氮去除率均达到最高,分别为96.2%和94.3%。这主要是由于I-BAF系统中大孔载体提供了厌氧-兼氧-好氧的微环境,使硝化和反硝化反应在同一个反应器内发生,共同作用实现模拟垃圾渗滤液中总氮的去除。 相似文献