Fate of PM2.5-bound PAHs in Xiangyang, central China during 2018 Chinese spring festival: Influence of fireworks burning and air-mass transport

Variations of levels, possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM_2.5 during 2018 Chinese Spring Festival (CSF) in Xiangyang City, central China which is the North-South pollutant airmass transport channel of China. Totally 37 samples were collected. Mass concentrations of Σ₁₆PAHs for the Pre–CSF day (Pre–CSFD), during the CSF day (CSFD) and after the CSF day (Af–CSFD) are 33.78 ± 17.68 ng/m³, 22.98 ± 6.49 ng/m³, and 8.99 ± 4.44 ng/m³, respectively. High resolution samples showed that Σ₁₆PAHs are higher in the morning (06:00–11:00) or afternoon (11:30–16:30), than those in the evening (17:00–22:00) and at night (22:30–05:30), whereas the result is reversed during the CSFD. Fireworks burning can obviously increase the mass concentration of PAHs. Air mass trajectory indicated that Xiangyang is a sink area of pollutants for northwest and southeast, and the sources of the northeast and southwest. The air mass only can be transmitted out through northeast and southwest. It is effective for improvement of air quality in Wuhan and Hunan to control fireworks emission in Henan and local areas. Fireworks burning was an important source for PAHs during CSFD, biomass, coal combustion, and traffic emission were the main sources of PAHs for Pre–CSFD and Af–CSFD periods. The health risk on the CSFD was higher than the acceptable levels, especially during the intensive fireworks burning, the risk value far exceed 1.0 × 10^?4, controlling burning fireworks is required.     

护听器选择方法研究

简要介绍了护听器选择原则和一般要求，比较了评价护听器声衰减性能和选择护听器的常用方法，结合我国国情，给出了选择护听器的建议。     

基于流态化作用的吸附反应动力学和穿透特征

基于流态化作用的吸附反应动力学和穿透特征研究还鲜见报道.以苯酚为吸附质、活性炭为吸附剂,探讨了不同流态化紊流强度对基于流态化作用的吸附效率、吸附动力学特性、吸附反应穿透曲线和饱和吸附量的影响,并与相同条件的固定床吸附反应器进行了对比研究.结果表明,表观流速为8 mm·s-1和13 mm·s-1时,基于流态化和固定态的活性炭在5 min内的吸附效率均达到93%以上,吸附反应均符合经典二级动力学方程,且其相关系数大于0.999.穿透实验结果表明,表观流速为6 mm·s-1和8 mm·s-1时,基于流态化的活性炭对苯酚的吸附总量分别较固定态高8.77 mg·g-1和24.70 mg·g-1.可见,基于流态化吸附反应器与基于固定态吸附反应器相比,具有吸附反应效率高,吸附总量大的特征.     

微污染水源水处理技术探析

近年来,我国不少地区饮用水水源水质日益恶化,水质净化面临新的问题。通过对微污染水源水处理技术的分析,阐明了微污染水处理的基本理论,探讨了强化传统处理工艺、预处理技术、深化处理技术的作用效果与机理,展望了我国饮用水源水处理发展趋势。     

Effects of cathode potentials and nitrate concentrations on dissimilatory nitrate reductions by Pseudomonas alcaliphila in bioelectrochemical systems

The effects of cathode potentials and initial nitrate concentrations on nitrate reduction in bio- electrochemical systems （BESs） were reported. These factors could partition nitrate reduction between denitrification and dissimilatory nitrate reduction to ammonium （DNRA）. Pseudomonas alcaliphilastrain MBR utilized an electrode as the sole electron donor and nitrate as the sole electron acceptor. When the cathode potential was set from -0.3 to -I.1 V （vs. Ag/AgC1） at an initial nitrate concentration of 100 mg NO~-N/L, the DNRA electron recovery increased from （10.76 ± 1.6）% to （35.06 ± 0.99）%; the denitrification electron recovery decreased from （63.42 ± 1,32）% to （44.33 ± 1.92）%. When the initial nitrate concentration increased from （29.09 ± 0.24） to （490.97 ± 3.49） mg NO3-N/L at the same potential （-0.9 V）, denitrification electron recovery increased from （5.88 ± 1.08）% to （50.19 ±2.59）%; the DNRA electron recovery declined from （48.79 ±1.32）% to （16.02 ± 1.41）%. The prevalence of DNRA occurred at high ratios of electron donors to acceptors in the BESs and denitrification prevailed against DNRA under a lower ratio of electron donors to acceptors. These results had a potential application value of regulating the transformation of nitrate to N2 or ammonium in BESs for nitrate removal.     

Extraction and characterization of bound extracellular polymeric substances from cultured pure cyanobacterium (Microcystis wesenbergii)

Preliminary characterization of bound extracellular polymeric substances（bEPS） of cyanobacteria is crucial to obtain a better understanding of the formation mechanism of cyanobacterial bloom. However,the characterization of bEPS can be affected by extraction methods. Five sets（including the control） of bEPS from Microcystis extracted by different methods were characterized using three-dimensional excitation and emission matrix（3DEEM） fluorescence spectroscopy combined chemical spectrophotometry; and the characterization results of bEPS samples were further compared. The agents used for extraction were NaOH,pure water and phosphate buffered saline（PBS） containing cationic exchange resins,and hot water. Extraction methods affected the fluorescence signals and intensities in the bEPS. Five fluorescence peaks were observed in the excitation and emission matrix fluorescence spectra of bEPS samples. Two peaks（peaks T1 and T2） present in all extractions were identified as protein-like fluorophores,two（peaks A and C） as humic-like fluorophores,and one（peak E） as a fulvic-like substance.Among these substances,the humic-like and fulvic-like fluorescences were only seen in the bEPS extracted with hot water. Also,NaOH solution extraction could result in strong fluorescence intensities compared to the other extraction methods. It was suggested that NaOH at pH 10.0 was the most appropriate method to extract bEPS from Microcystis. In addition,dialysis could affect the yields and characteristics of extracted bEPS during the determination process. These results will help us to explore the issues of cyanobacterial blooms.     

基于Theil指数KAYA分解的中国碳排放差异性分析

为了量化2005至2010年中国各省区市之间碳排放差异性及其变化趋势,本文运用Theil指数KAYA分解方法进行研究,结果表明:全国人均碳排放差异逐年减小,能源强度是差异的主要影响因素,人均GDP是人均碳排放差异缩小的主要原因;东中西部和东北地区区域划分方法的组内差异大于组间差异,且中西部地区内部差异是造成全国差异的主要原因;相对"十一五"能源强度目标分解,"十二五"碳强度目标分解已考虑省市区差异,但其基本上根据人均GDP差异进行分组,且很大程度沿用了东中西部和东北地区区域划分。因此,建议在对各省区市分配减排指标时,考虑各地经济发展水平差异的同时兼顾产业结构和资源禀赋,并根据中西部地区内部排放差异将目标分解方案精细化     

常村煤矿综掘面合理除尘方式选择及其应用

为了合理选择常村煤矿综掘面除尘的通风方式,本文根据煤矿中常用的通风方式和气固两相流的理论,利用fluent非稳态的数值模拟方法来模拟压入式和长压短抽两种不同通风方式下常村煤矿掘进面粉尘的运移规律以及司机处粉尘浓度分布,并进行了现场实测验证。结果表明:对于粉尘运移模型,采用非稳态的求解器要比稳态的求解器更加精确;在长压短抽通风方式下,涡流对粉尘运移影响较大,可以通过调整风速和除尘风机的负压来减小涡流的影响区域;采用长压短轴的通风方式比压入式通风方式在数值模拟情况下,前者比后者掘进机前部的粉尘浓度降低了22.2%,通过现场实测得到其降低了31.6%,巷道中部粉尘的平均浓度可由508mg/m3下降到185mg/m3,降幅为63.6%,表明长压短抽通风方式数值模拟和现场实测都要优于压入式通风方式;此外,需要在掘进机的前面和回风侧增加除尘措施,以确保司机处的粉尘浓度符合标准。     

高性能聚乙烯纤维手套防护性能研究

采用实验室测试和现场调查相结合的方法,测试了高性能聚乙烯纤维手套的防护性能,调查手套的适应性、防护时间和费用支出,探讨了其应用前景。     

烧结多孔管的制作及其沸腾传热研究

目的研究烧结多孔管表面多孔层的制造工艺,并对铜粉烧结多孔层表面的传热性能进行测定。方法利用烧结模具在铜管外面烧结铜粉层,并通过实验计算出多孔烧结管的热通量和强化换热系数。结果铜粉烧结后的铜管在酒精中的强化传热效果达到了光管的10倍左右。结论烧结铜粉粒径越小,烧结管的热通量越大,其传热性能越好。