Changes of DOM and its correlation with internal nutrient release during cyanobacterial growth and decline in Lake Chaohu, China

The seasonal changes in dissolved organic matter (DOM), and its correlation with the release of internal nutrients during the annual cycle of cyanobacteria in the eutrophic Lake Chaohu, China, were investigated from four sampling periods between November 2020 and July 2021. The DOM fluorescence components were identified as protein-like C1, microbial humic-like C2, and terrestrial humic-like C3. The highest total fluorescence intensity (F_T) of DOM in sediments during the incubation stage is due to the decomposition and degradation of cyanobacteria remains. The lowest humification of DOM and the highest proportion of C1 in waters during the initial cyanobacterial growth indicate that fresh algae are the main source. The highest molecular weight of DOM and F_T of the C2 in sediments during cyanobacterial outbreaks indicate the concurrent deposition of undegraded cyanobacterial remains and microbial degradation. The components of DOM are affected mainly by the dissolved total phosphorus in waters, while the temperature drives the annual cycle of cyanobacteria. The decreasing C1 in sediments and increasing nutrients in waters from the cyanobacterial incubation to outbreak indicate that mineralization of algal organic matter contributes importantly to the release of internal nutrients, with the strongest release of phosphorus observed during the early growth of cyanobacteria. The humic-like C2 and C3 components could also affect the dynamics of internal phosphorus through the formation of organic colloids and organic–inorganic ligands. The results show that the degradation of DOM leads to nutrients release and thus supports the continuous growth of cyanobacteria in eutrophic Lake Chaohu.     

尘肺病危险环模型与尘肺病预防对策

介绍了尘肺危险环模型的结构、原理,并以尘肺危险环模型为基础,从呼吸性粉尘危害程度分级、呼吸性粉尘监测与治理及呼吸性粉尘管理等几个方面探讨了尘肺病的预防对策。     

A novel procedure for acid-catalysed K2FeO4 oxidation of benzyl alcohol in organic phase

Recent investigations have shown that ferrate(VI) salts oxidize organic compounds in aqueous phases with fast reaction from seconds to minutes and poor selectivity. Few studies have used ferrate(VI) in organic phases. The main issues are the poor solubility of K₂FeO₄ in common organic solvents and the low reaction rate. Therefore the interests to date are focused on finding a more effective catalyst in the organic oxidation. Up to now no work has been reported on acids as catalysis for the oxidative abilities of K₂FeO₄ in organic phases. Here we present a novel procedure for oxidizing benzyl alcohol to benzaldehyde without an overoxidation to benzoic acid by K₂FeO₄ in an organic phase. Using benzyl alcohol as a model, the catalytic activity of various acid solutions was measured. We found that the reactivity of K₂FeO₄ to the oxidation of benzyl alcohol can be highly enhanced by addition of a small amount of acid solution at room temperature. The catalytic ability of acid solutions follows the order acetic acid < oxalic acid < phosphomolybdic acid < phosphotungstic acid. On the basis of a theoretical analysis, a reaction mechanism is proposed. This method provides a new green way for oxidizing organic substances by K₂FeO₄ in nonaqueous media_.     

Modeling the influence of biogenic volatile organic compound emissions on ozone concentration during summer season in the Kinki region of Japan

Tropospheric ozone adversely affects human health and vegetation, and biogenic volatile organic compound (BVOC) emission has potential to influence ozone concentration in summer season. In this research, the standard emissions of isoprene and monoterpene from the vegetation of the Kinki region of Japan, estimated from growth chamber experiments, were converted into hourly emissions for July 2002 using the temperature and light intensity data obtained from results of MM5 meteorological model. To investigate the effect of BVOC emissions on ozone production, two ozone simulations for one-month period of July 2002 were carried out. In one simulation, hourly BVOC emissions were included (BIO), while in the other one, BVOC emissions were not considered (NOBIO). The quantitative analyses of the ozone results clearly indicate that the use of spatio-temporally varying BVOC emission improves the prediction of ozone concentration. The hourly differences of monthly-averaged ozone concentrations between BIO and NOBIO had the maximum value of 6 ppb at 1400 JST. The explicit difference appeared in urban area, though the place where the maximum difference occurred changed with time. Overall, BVOC emissions from the forest vegetation strongly affected the ozone generation in the urban area.     

闸阀填料密封件的改造与应用

针对闸阀阀杆填料密封泄漏的问题,介绍了密封填料的选择和闸阀填料压盖密封件结构的技术改进措施.实践证明,闸阀填料密封件的改造不仅能够解决密封渗漏,消除安全隐患,而且取得了较好的经济效益.     

19世纪美国芝加哥大火

19世纪70年代美国芝加哥有居民35．5万人。芝加哥河把该市分为3个区——西区、南区和北区。在经历了1871年夏天的大旱和酷暑之后,进入秋季的9月又是滴雨未下。极度干燥的各种物品处于见火就着的状态。仅10月份的第一个星期,这里就发生火警30次,10月7月晚该市西区发生一场火灾,造成75万美元的损失。10月8日晚8时     

静态清灰袋式除尘技术优势及产业化推广前景探讨

介绍了基于“静态气化清灰原理”的我国自主研制的静态清灰袋式除尘技术,分析了它的技术经济优势,并对其应用于600 M研燃煤机组锅炉烟气除尘进行了实例分析,最后结合袋式除尘行业发展态势、国家环保政策导向及静态清灰袋式除尘技术的优势,对静态清灰袋式除尘技术的产业化推广应用前景进行了分析和预测.     

基于“O”型冒落的Y型通风采空区气体分布特征

为了掌握Y型通风采空区气体的分布规律,进一步为采空区瓦斯及火灾防治工作提供理论依据,基于采空区“O”型冒落压实和遗煤耗氧的非均匀性,针对Y型通风系统建立非均质采空区内气体渗流数值模型,采用Fluent数值模拟软件对采空区漏风流场和各组分气体浓度场进行模拟分析。结果显示:瓦斯和氧气浓度场在Y型通风采空区内大致呈“L”形分布;风流集中由工作面上、下隅角进入采空区;沿空留巷侧的瓦斯浓度高于运输巷侧,而氧气浓度却恰恰相反;两进一回的Y型通风方式能有效解决瓦斯在工作面上隅角积聚的问题;在采空区深部靠沿空留巷侧存在一个扇形的高瓦斯浓度区域,而该区域氧气浓度较低;采空区自燃危险区域在运输巷侧分布更广,应适当采取防火措施。     

Factors influencing the preparation of supported iron oxide in fluidized-bed crystallization

Our previous work applied a novel supported iron oxyhydroxide (FeOOH) catalyst to effectively treat benzoic acid by hydrogen peroxide. The FeOOH catalyst was prepared via the oxidation of Fe2+ by H2O2 in the acidic condition using a fluidized-bed crystallization reactor. The major components coated on the surface were identified as amorphous FeOOH and gamma-FeOOH. In terms of the crystallization conditions of FeOOH, some parameters including the operational pH, superficial velocity, specific iron loading, and influent H2O2 concentration were investigated to quantify their effects on the crystallization efficiency. All these parameters were found to significantly influence the crystallization efficiency. Two types of FeOOH catalysts were synthesized: FeOOH I was prepared at pH 3.5, and FeOOH II was formed by aging FeOOH I at pH 13. The percentages of surface amorphous FeOOH reduced from 70% to 30% after aging. The FeOOH II catalyst presented a higher reactivity toward H2O2 but lower stoichiometric efficiency in oxidizing benzoic acid than FeOOH I, similar to the result of the commercial goethite. Therefore, it is concluded that the crystalline property significantly affects the performance of catalytic oxidation.     

危险化学品企业实施安全评价工作绩效分析

2006年安全生产工作取得了较好的成绩,呈现总体稳定趋向好转的发展态势,事故死亡人数总量也较大幅度下降。但是,在危险化学品行业非但没有得到扭转,事故死亡人数反而上升了16.2%。对此,我们有必要加强对危险化学品的安全管理。在安全评价方面,危险化学品企业实施安全评价后是否对企业的发展有实际的绩效,对此,我们对全国320家实施过安全评价的危险化学品企业进行了调研分析,尤其在安全设施、安全管理水平、事故发生频率等方面,并从中得出结论,进而了解评价过程中存在的不足,以及提出合理的对策措施。