Photodegradation of the herbicide goal

Photodegradation products of the herbicide Goal active ingredient were obtained with a xenon lamp and analyzed using direct inlet mass spectrometry, MS/MS and GC/MS. A number of products were identified and their generation pathways were established to be mainly Ar—O bond cleavage, dechlorination and photocyclisation. The latter process gives chlorinated and unchlorinated dibenzofurans some of which may be toxic.     

Mass spectral studies of 6‐n‐propyl‐2‐thiouracil,its oxygen,selenium and fluorinated congeners∗

The electron ionization mass spectra of the clinically used antithyroid agent 6‐n‐propyl‐2‐thiouracil (la), its minor metabolite, 6‐n‐propyluracil (lb) and their synthetic selenium and fluorinated analogs (1c and d) have been examined. The fragmentation pattern of these thiouracil and selenouracil studied bear strong similarities with those previously derived from a study of uracil analogs. Thus, the first step in the fragmentation is a retro Diel‐Alder decomposition with the loss of HCNX (X=O, S or Se) and the production of an ion radical which undergoes further fragmentation pathways which are discussed. 6‐n‐Propyl‐2‐selenouracil (1c) did show more complicated spectra due to the six natural isotopic abundance exhibited by the selenium atom. While the fluorinated analogs (1d) did substantiate the fact that the fragmentation pattern of these derivatives proceed through fragmentation between C₂ and N₃ bond since this produces the more resonance stabilized ion.     

Dissipation of fluvalinate and characterisation of its degradation products on chickpea crop by mass spectroscopy

Fluvalinate was applied on chickpea crop at (i) 0.056, (ii) 0.112 and (iii) 0.56 kg a.i. ha^‐1 to evaluate its rate of dissipation. Two major degradation products of fluvalinate formed on the crop were identified and characterised as phenoxybenzoic acid and 2‐[2‐chloro‐4‐(trifluoromethyl)anilino]‐3‐methylbutanoic acid. They were estimated in day‐5 and day‐10 samples of chickpea crop as their methyl esters by gas liquid chromatography.     

考虑岩体各向异性强度的隧洞围岩稳定性分析

岩体中普遍存在着大量的节理裂隙等不连续面,这些不连续面对岩体的强度有着重要的影响。以具有较密集成组节理的岩体为研究对象,以Drucker-Prager准则和裂隙应力张开准则为基础,分别考虑岩块和节理面各自的物理力学性质,研究岩体在各向异性强度准则下的理论方法,并建立了岩体各向异性本构模型,用以描述节理岩体在强度方面的各向异性及其破坏特征。将该模型用于隧洞围岩稳定性分析工程中,研究表明,该模型可以较好地解释节理岩体围岩的破坏特征,与工程实践相符。研究成果对我国地下石油、核废料储存以及深埋地下工程的设计与施工具有重要的指导意义。     

加速溶剂萃取-固相萃取净化-超高效液相色谱串联质谱法测定土壤中11种全氟化合物

采用超高效液相色谱-串联质谱联用法（UPLC-ESI-MS/MS）,建立了分析土壤中11种全氟化合物（PFCs）的方法.以甲醇作为萃取剂,样品经加速溶剂萃取仪（ASE）萃取,固相萃取净化后,使用UPLC-ESI-MS/MS联用仪分析样品中11种PFCs.在6 min内就可快速稳定地将所选取的11种全氟化合物分离,且最低检测浓度为0.518—3.520 pg.g-1之间,这些化合物在土壤中的平均添加回收率在71.2%—119.2%之间.应用此方法测得宜兴市水稻土样品中所选取的PFCs含量为0.006—0.780 ng.g-1之间.     

基于液相色谱法分析水环境中大环内酯类抗生素污染的研究进展

大环内酯抗生素广泛使用,在水环境中的残留越来越引起世界关注.本文综述了国内外基于液相色谱技术分析水环境中大环内酯的方法,比较不同预处理法以及分析方法的灵敏度和检出限.固相萃取法可以同时富集和净化,消耗试剂少,方便,野外操作可行,是理想的预处理技术.液相色谱串联质谱技术选择性好、特异性高、灵敏度高,可以检测浓度低于ng.L-1的目标物,是一种可靠理想的分析方法.最后对大环内酯分析研究进行了展望.     

城市化对北京夏季极端高温影响的数值研究

利用一个耦合了城市冠层模式（UCM）的区域数值模拟系统（WRF／NCAR）,引入由LandsatTM提取的京津冀区域30m分辨率下垫面GIS数据集代替美国USGS地表分类数据,对2009年6月24—25日出现在北京地区的一次超过40℃极端高温天气过程进行了高分辨率数值模拟,用以考察WRF／UCM系统对北京“城市热岛”及城市高温天气的模拟效果,并分析了城市化对北京地区城市高温和地表能量平衡的影响及其日变化特征。结果表明：采用精细化下垫面分类数据集后能更好地模拟出主要高温区的分布特征,并能较好再现夜间的“城市热岛”效应。城市化发展对近地层气温的影响主要表现在会促使城区及其下风向近郊区气温的升高,增幅可达0．5～2℃,这与城市热岛及其下游效应有关。城市下垫面的高粗糙度对近地层风速表现出明显的阻挡效应,表现在模拟的10m风场减弱明显。考虑了城市下垫面属性的敏感性试验更好地再现了城区温度的日变化,其模拟的日间最高温度与实际观测值更为接近,也较好地模拟出了城区具有较高最低温度的特征。通过城区与郊区能量平衡过程差异的分析表明,城市化可以显著改变能量平衡中各项所占的比重。地表对近地层大气热量输送过程的变化表明随着城市下垫面的日愈扩大,会显著增强白天地表对大气的向上感热输送,增大城区日间出现高温的可能。夜间,模式反映出地表能量收入来自土壤热通量的向上输送,同样由于城区的潜热通量小,收入的能量仍主要以感热形式加热大气,夜间城区具有较高的最低温度并表现出较强的热岛特征,主要与夜间感热加热的持续相关。     

Characterization of submicron aerosols in the urban outflow of the central Pearl River Delta region of China

Submicron aerosol particles (with aerodynamic diameters less than 1 μm, PM₁) were sampled and measured in Heshan, an urban outflow site of Guangzhou megacity in Pearl River Delta in South China, using an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) in November 2010 during 2010 Guangzhou Asian Games. The mean PM₁ mass concentration measured was 47.9±17.0 μg·m^-3 during the campaign, with organic aerosol (OA) and sulfate being the two dominant species, accounting for 36.3% and 20.9% of the total mass, respectively, followed by black carbon (17.1%, measured by an aethalometer), nitrate (12.9%), ammonium (9.6%) and chloride (3.1%). The average size distributions of the species (except black carbon) were dominated by an accumulation mode peaking at ~550 nm. Calculations based on high-resolution organic mass spectrum showed that, C, H, O and N on average contributed 58.1%, 7.3%, 30.7%, and 3.9% to the total organic mass, respectively. The average ratio of organic mass over organic carbon mass (OM/OC) was 1.73±0.08. Four components of OA were identified by the Positive Matrix Factorization (PMF) analysis, including a hydrocarbon-like (HOA), a biomass burning (BBOA) and two oxygenated (SV-OOA and LV-OOA) organic aerosol components, which on average accounted for 18.0%, 14.3%, 28.8% and 38.9% of the total organic mass, respectively.     

造纸废水短流程动态平衡水循环利用工艺

斜网脱水机、洗浆机及抄纸机产生的废水短流程逆向分段回用于水力碎浆机、配浆池和成浆池,同时在纸机抄造系统中加入与废水蒸发量相当的新鲜水,实现了废水动态平衡与短流程循环利用"零"排放的目标。河南滑县光明纸业责任有限公司采用该工艺以来,每年可节约水资源61万t,减排COD量为43 t,年减少污泥量510 t,故该工艺具有良好的应用前景。     

Relationship between EMR and dissipated energy of coal rock mass during cyclic loading process

Dynamic collapses of deeply mined coal rocks are severe threats to miners. In order to predict the collapses more accurately using electromagnetic radiation (EMR), this paper researched the energy conversion mechanism in the damage process of coal rock mass, analysed its EMR and dissipated energy, and a relationship between which was established using the voltage amplitude of EMR signal and hysteresis loop generated in the loading and unloading cycles as a bridge; then a series of cyclic loading experiments using coal samples of Junde and Xinlu coal mines from Heilongjiang province were carried out, and EMR signal released during these cycles were collected. Results show that during a whole damage process of a sample, the cumulative values of EMR energy and corresponding dissipated energy (hysteresis loop area) well subject to the form of y=aln(x)+b, whose correlation coefficients are above 0.90, and EMR signals received by different frequency antenna seldom impacted on this relationship; the total EMR energy released from the whole failure process of the samples obtained from adjacent sampling point in same mining area are different to some extent, so are the dissipated energy; compared with cyclic loading for coal rock mass orderly with the peak loads of 5 kN and 10 kN previously, the dissipated energy of direct using that of 15 kN increase 17.8%, and EMR signal is more abundant; EMR energy received in each cycle increase steadily with the improvement of load level, and in a single loading and unloading cycle, sometimes it is very rich in the unloading phase, even more than the loading one.