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51.
1国内外公共安全形势与城市公共安全的新挑战
进入21世纪,国际公共安全形势日趋严峻,城市面临的灾害形势从传统的自然灾害、火灾、瘟疫等为主扩大到传统灾害和生命线系统故障、信息安全、恐怖事件等非传统灾害共同影响的情况,呈现出以下特点:重大自然灾害的发生频率、量级加大,经济损失更严重;随着工业化、现代化和城市化的发展,事故灾难以及复合型事件的影响日益突出;生物和公共卫生危机严重威胁和影响公众健康;恐怖主义威胁呈现出新型化、大规模化和强灾难性的特点;经济危机连锁反应,各种社会危机交相激荡.…… 相似文献
52.
Min Qin Pinhua Xie Hang Su Jianwei Gu Fumin Peng Suwen Li Limin Zeng Jianguo Liu Wenqing Liu Yuanhang Zhang 《Atmospheric environment (Oxford, England : 1994)》2009,43(36):5731-5742
The temporal behavior of HONO and NO2 was investigated at an urban site in Guangzhou city, China, by means of a DOAS system during the Pearl River Delta 2006 intensive campaign from 10 to 24 July 2006. Within the whole measurement period, unexpected high HONO mixing ratios up to 2 ppb were observed even during the day. A nocturnal maximum concentration of about 8.43 ± 0.4 ppb was detected on the night of 24 July 2006. Combining the data simultaneously observed by different instruments, the coupling of HONO–NO2 and the possible formation sources of HONO are discussed. During the measurement period, concentration ratios of HONO to NO2 ranged from (0.03 ± 0.1) to (0.37 ± 0.09), which is significantly higher than previously reported values (0.01–0.1). Surprisingly, in most cases a strong daytime correlation between HONO and NO2 was found, contrary to previous observations in China. Aerosol was found to have a minor impact on HONO formation during the whole measurement period. Using a pseudo steady state approach for interpreting the nocturnal conversion of NO2 to HONO suggests a non-negligible role of the relative humidity for the heterogeneous HONO formation from NO2. 相似文献
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54.
Complexes of fulvic acid on the surface of hematite, goethite, and akaganeite: FTIR observation 总被引:3,自引:0,他引:3
The present work extended our knowledge on the binding and complexation of a fulvic acid (FA) derived from leonardite and the iron oxides (hematite, goethite and akaganeite) by Fourier transform infrared spectroscopy (FTIR). As a prerequisite, the iron oxides were firstly prepared and characterized by transmission electron micrograph (TEM). All iron phases were single and well-described crystalloid. The FTIR data obtained by two different sampling preparation methods gave the consisting evidences that under our experimental conditions the interaction mechanism was to the ligand-exchange involving carboxylic functional groups of the FA and the surfaces sites of both hematite and goethite, while no complexation can be evidenced in the case of akaganeite, only surface adsorption. In general, the binding affinities of the iron oxides with the FA was in the order of hematite>goethite>akaganeite. The present method, although associated with some uncertainties, provided an opportunity to increase the knowledge in the field of the humic chemistry. 相似文献
55.
某桥梁施工企业在对桥面施工时,塔式起重机空载起升发生冲顶事故,起升钢丝绳断裂,造成吊钩装置坠落砸死1人伤害事故.本文介绍了事故情况、事故勘查要点和模拟试验及相关计算方法,分析事故技术原因,提出预防事故的建议. 相似文献
56.
Cigarette smoke constituents are worthy of concern and characterized as carcinogens. Different experiment conditions may affect the environmental tobacco smoke (ETS) constituents. A study was undertaken in a 75.5-m3 spare office to evaluate ETS constituents in a real environment. Thirty-four volatile organic compounds (VOCs) including three ETS tracers: nicotine, 2,5-dimethylfuran and 3-ethenylpyridine (3-EP), 19 carbonyl compounds, 54 semi-volatile compounds (24 polycyclic aromatic hydrocarbons (PAHs) and 30 alkanes) as well as CO and total particulate matter (TPM) from 15 leading commercial brands were determined. ETS constituents did not increase with increasing cigarette tar. ETS tracers nicotine and 3-EP were affected greatly due to more sorption and surface reactions in real world compared to other studies conducted in chamber, which resulted in 2-5 times lower. Benzene, toluene, ethylbenzene, xylenes, acrolein, 2-butanone and the high molecular weight compounds exhibited little affect. Pearson correlation analyses show that gas-phase and particulate-phase ETS tracers did not show significant correlation, but within each homologue many of compounds correlated significantly. Indole and cholesta-3,5-diene were also detected in ETS. These results may be useful in efforts to better understand the health effect of ETS exposure and source apportionment. 相似文献
57.
58.
实验基于企业污水站的改造工程,研究了MBR对玉米深加工废水的处理效果并对工艺运行参数优化提出建议.结果表明,该工艺对COD的去除率可以达到90%以上,出水稳定在26 mg/L左右;出水NH4-N达到1 mg/L以下;TN去除率达到70%以上,出水TN达到10 mg/L以下,出水完全达到排放标准.通过4种工况的比较,说明在污泥浓度8 g/L左右,曝气池内DO在3 mg/L左右,MBR内DO>4 mg/L,好氧段停留时间13.5 h,并保证3h以上的缺氧段水力停留段时间的条件下,A/O+ MBR工艺可以有效去除玉米深加工废水中的污染物. 相似文献
59.
电吸附技术作为高效、环境友好型的除盐、除氨氮技术,可应用与水的深度处理领域内。为了使污水回用达到工业用水的水质标准,对电吸附去除水中盐类、氨氮、COD的效果进行分析,结果表明,电吸附设备处理不同氨氮浓度的废水,对中低浓度的氨氮去除效果稳定,当进水氨氮浓度低于20 mg/L时,处理后出水氨氮浓度低于5 mg/L,COD浓度小于25 mg/L,达到回用标准;随着进水盐浓度的增大电吸附处理效果逐渐变差,在电导率低于2 500 μS/cm时除盐率在75%左右,氨氮去除率达到70%左右,COD去除率达到60%左右。经电吸附处理后的低氨氮浓度废水,TDS、氨氮浓度均可达到工业回用水标准。 相似文献
60.
Xian-De Xie Xiao-Bo Min Li-Yuan Chai Chong-Jian Tang Yan-Jie Liang Mi Li Yong Ke Jie Chen Yan Wang 《Environmental science and pollution research international》2013,20(9):6050-6058
Floatation tailings (FT) are the main by-products of the hydrothermal sulfidation–flotation process. FT (FT1 and FT2) were obtained by treating two different neutralization sludges (NS) (NS1 and NS2). This paper quantitatively evaluated the environmental risks of heavy metals (Zn, Cd, Cu, Pb, and As) in FT versus NS. The total concentration and leaching rates (R 2) of heavy metals in FT were much lower than those in NS, demonstrating that the hydrothermal sulfidation–flotation process was able to effectively suppress the mobility and leachability of heavy metals. The BCR-three sequence leaching procedure of FT confirmed that all metals were transformed into more stable forms (residue and oxidizable forms) than were found that in NS. The potential ecological risk index indicated that the overall risks caused by heavy metals decreased significantly from 6627.59 and 7229.67 (very serious risk) in NS1 and NS2, respectively, to 80.26 and 76.27 (low risk) in FT1 and FT2, respectively. According to the risk assessment code, none of the heavy metals in FT posed significant risk to the natural environment except Zn (with low risk). In general, the risk of heavy metals in FT had been well controlled. 相似文献