流动注射分光光度法测定水中痕量氟化物

研究并建立了测定水中痕量氟化物的氟试剂（ＡＬＣ）－流动注射分光光度法。将水样注入到水载流中,与ＡＬＣ－Ｌａ丙酮水溶液混合,在５０℃时反应生成蓝色三元络合物,在分光光度计上于波长６１８ｍｍ处进行检测。Ｆ＾－测定的线性范围为０．０４－３．０ｍｇ／Ｌ,检出限为０．０３６ｍｇ／Ｌ。     

京津冀地区城市三生空间碳代谢效率特征及演进模式

探究城市三生空间系统的碳代谢效率有助于实现区域要素整合和空间优化.基于城市代谢视角,采用物质流分析法构建了京津冀地区三生空间碳代谢效率评估框架,并运用超效率DEA模型和Malmquist指数分析了2000~2020年三生空间碳代谢效率的时空分布、动态变化及演进模式.结果表明：①2000~2020年,京津冀地区三生空间碳代谢效率呈波动增长趋势,各城市碳代谢效率空间分异明显,碳代谢效率水平整体偏低,呈中部高、南北低的分布格局.②京津冀地区碳代谢效率全要素生产率呈增加趋势,技术进步变化和纯技术效率贡献作用不显著.超过50%的城市全要素生产率呈改善趋势,仅有38.46%的城市在碳代谢效率改善过程中存在技术进步现象,超过1/2地区的纯技术效率呈下降趋势,大部分城市的技术效率和规模效率变化指数大于1.③各城市碳代谢效率呈现不同的类型特征,按照其发展路径划为稳定式、反复式、渐进式和突变式这4种演进模式.各城市应据此采取差异化措施,合理配置三生空间资源,提高技术水平和规模效率,以期提高城市碳代谢效率水平.     

The performance of RAMS in representing the convective boundary layer structure in a very steep valley

Data from a comprehensive field study in the Riviera Valley of Southern Switzerland are used to investigate convective boundary layer structure in a steep valley and to evaluate wind and temperature fields, convective boundary layer height, and surface sensible heat fluxes as predicted by the mesoscale model RAMS. Current parameterizations of surface and boundary layer processes in RAMS, as well as in other mesoscale models, are based on scaling laws strictly valid only for flat topography and uniform land cover. Model evaluation is required to investigate whether this limits the applicability of RAMS in steep, inhomogeneous terrain. One clear-sky day with light synoptic winds is selected from the field study. Observed temperature structure across and along the valley is nearly homogeneous while wind structure is complex with a wind speed maximum on one side of the valley. Upvalley flows are not purely thermally driven and mechanical effects near the valley entrance also affect the wind structure. RAMS captured many of the observed boundary layer characteristics within the steep valley. The wind field, temperature structure, and convective boundary layer height in the valley are qualitatively simulated by RAMS, but the horizontal temperature structure across and along the valley is less homogeneous in the model than in the observations. The model reproduced the observed net radiation, except around sunset and sunrise when RAMS does not take into account the shadows cast by the surrounding topography. The observed sensible heat fluxes fall within the range of simulated values at grid points surrounding the measurement sites. Some of the scatter between observed and simulated turbulent sensible heat fluxes are due to sub-grid scale effects related to local topography.     

Response of bioaerosol cells to photocatalytic inactivation with ZnO and TiO2 impregnated onto Perlite and Poraver carriers

•ZnO/Perlite inactivated 72% of bioaerosols in continuous gas phase. •TiO₂ triggered the highest level of cytotoxicity with 95% dead cells onto Poraver. •Inactivation mechanism occurred by membrane damage, morphological changes and lysis. •ZnO/Poraver showed null inactivation of bioaerosols. •Catalysts losses at the outlet of the photoreactor for all systems were negligible. Bioaerosols are airborne microorganisms that cause infectious sickness, respiratory and chronic health issues. They have become a latent threat, particularly in indoor environment. Photocatalysis is a promising process to inactivate completely bioaerosols from air. However, in systems treating a continuous air flow, catalysts can be partially lost in the gaseous effluent. To avoid such phenomenon, supporting materials can be used to fix catalysts. In the present work, four photocatalytic systems using Perlite or Poraver glass beads impregnated with ZnO or TiO₂ were tested. The inactivation mechanism of bioaerosols and the cytotoxic effect of the catalysts to bioaerosols were studied. The plug flow photocatalytic reactor treated a bioaerosol flow of 460×1 0⁶ cells/m³_air with a residence time of 5.7 s. Flow Cytometry (FC) was used to quantify and characterize bioaerosols in terms of dead, injured and live cells. The most efficient system was ZnO/Perlite with 72% inactivation of bioaerosols, maintaining such inactivation during 7.5 h due to the higher water retention capacity of Perlite (2.8 mL/g_Perlite) in comparison with Poraver (1.5 mL/g_Perlite). However, a global balance showed that TiO₂/Poraver system triggered the highest level of cytotoxicity to bioaerosols retained on the support after 96 h with 95% of dead cells. SEM and FC analyses showed that the mechanism of inactivation with ZnO was based on membrane damage, morphological cell changes and cell lysis; whereas only membrane damage and cell lysis were involved with TiO₂. Overall, results highlighted that photocatalytic technologies can completely inactivate bioaerosols in indoor environments.     

Cu/Cr co-stabilization mechanisms in a simulated Al2O3-Fe2O3-Cr2O3-CuO waste system

• Cu and Cr can be mostly incorporated into CuFe_xAl_yCr_2−x−yO₄ with a spinel structure. • Spinel phase is the most crucial structure for Cu and Cr co-stabilization. • Compared to Al, Fe and Cr are easier to be incorporated into the spinel structure. • ‘Waste-to-resource’ by thermal process at attainable temperatures can be achieved. Chromium slag usually contains various heavy metals, making its safe treatment difficult. Glass-ceramic sintering has been applied to resolve this issue and emerged as an effective method for metal immobilization by incorporating heavy metals into stable crystal structures. Currently, there is limited knowledge about the reaction pathways adopted by multiple heavy metals and the co-stabilization functions of the crystal structure. To study the Cu/Cr co-stabilization mechanisms during thermal treatment, a simulated system was prepared using a mixture with a molar ratio of Al₂O₃:Fe₂O₃:Cr₂O₃:CuO= 1:1:1:3. The samples were sintered at temperatures 600–1300°C followed by intensive analysis of phase constitutions and microstructure development. A spinel phase (CuFe_xAl_yCr_2−x−yO₄) started to generate at 700°C and the incorporation of Cu/Cr into the spinel largely complete at 900°C, although the spinel peak intensity continued increasing slightly at temperatures above 900°C. Fe₂O₃/Cr₂O₃ was more easily incorporated into the spinel at lower temperatures, while more Al₂O₃ was gradually incorporated into the spinel at higher temperatures. Additionally, sintered sample microstructures became more condensed and smoother with increased sintering temperature. Cu / Cr leachability substantially decreased after Cu/Cr incorporation into the spinel phase at elevated temperatures. At 600°C, the leached ratios for Cu and Cr were 6.28% and 0.65%, respectively. When sintering temperature was increased to 1300°C, the leached ratios for all metal components in the system were below 0.2%. This study proposes a sustainable method for managing Cu/Cr co-exist slag at reasonable temperatures.     

用热分析法研究鼎湖山土壤的粘粒矿物

广东鼎湖山自然保护区的土壤主要为山地黄壤和赤红壤。本文用差热-热重-微商热重(DTA-TG-DTG)联合热分析法,对两种土壤的粘粒矿物进行了初步研究,确认两种土壤的粘粒矿物组成主要为伊利石、高岭石、三水铝石、蛭石、针铁矿等。伊利石、三水铝石、蛭石的含量山地黄壤多于赤红壤,而高岭石则相反。两种土壤的风化程度不高,土壤矿物风化主要处于幼年阶段,山地黄壤尤其明显。另外,对不同林型下的赤红壤也进行了对比研究,其粘粒矿物组成和数量差异不大。     

草莓有机与无机种植系统能流和经济流的比较研究

通过３年田间试验，比较分析了草莓有机与无机种植系统的能流、经济流及对土壤环境的影响。结果表明，有机系统草莓产量、经济效益均高于无机系统；有机系统能量产投比仅为无机系统的２５％，但投入的绝大部分为可再生能源；有机系统土壤有机质、微生物量高于无机系统，具有更好的土壤条件     

Thermal defluorination behaviors of PFOS,PFOA and PFBS during regeneration of activated carbon by molten salt

• New method of mineralizing PFCs was proposed. • Activated carbon was regenerated while mineralizing PFCs. • Molten NaOH has good mineralization effect on PFOS and PFBS. Current study proposes a green regeneration method of activated carbon (AC) laden with Perfluorochemicals (PFCs) from the perspective of environmental safety and resource regeneration. The defluorination efficiencies of AC adsorbed perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutanesulfonate (PFBS) using three molten sodium salts and one molten alkali were compared. Results showed that defluorination efficiencies of molten NaOH for the three PFCs were higher than the other three molten sodium salts at lower temperature. At 700°C, the defluorination efficiencies of PFOS and PFBS using molten NaOH reached to 84.2% and 79.2%, respectively, while the defluorination efficiency of PFOA was 35.3%. In addition, the temperature of molten salt, the holding time and the ratio of salt to carbon were directly proportional to the defluorination efficiency. The low defluorination efficiency of PFOA was due to the low thermal stability of PFOA, which made it difficult to be captured by molten salt.The weight loss range of PFOA was 75°C–125°C, which was much lower than PFOS and PFBS (400°C–500°C). From the perspective of gas production, fluorine-containing gases produced from molten NaOH-treated AC were significantly reduced, which means that environmental risks were significantly reduced. After molten NaOH treatment, the regenerated AC had higher adsorption capacity than that of pre-treated AC.     

Complex effects of habitat amount and fragmentation on functional connectivity and inbreeding in a giant panda population

The relationships between habitat amount and fragmentation level and functional connectivity and inbreeding remain unclear. Thus, we used genetic algorithms to optimize the transformation of habitat area and fragmentation variables into resistance surfaces to predict genetic structure and examined habitat area and fragmentation effects on inbreeding through a moving window and spatial autoregressive modeling approach. We applied these approaches to a wild giant panda population. The amount of habitat and its level of fragmentation had nonlinear effects on functional connectivity (gene flow) and inbreeding. Functional connectivity was highest when approximately 80% of the surrounding landscape was habitat. Although the relationship between habitat amount and inbreeding was also nonlinear, inbreeding increased as habitat increased until about 20% of the local landscape contained habitat, after which inbreeding decreased as habitat increased. Because habitat fragmentation also had nonlinear relationships with functional connectivity and inbreeding, we suggest these important responses cannot be effectively managed by minimizing or maximizing habitat or fragmentation. Our work offers insights for prioritization of protected areas.     

长江经济带城市对外服务能力时空演变分析

基于城市流强度模型测算2000年以来长江经济带126个地级以上城市在全国范围内的对外服务能力,进而采用改良锡尔系数、马尔可夫链和ESDA方法对城市对外服务能力的时空演变特征进行探讨。结果表明:研究时段内长江经济带各市城市流强度都有显著提升,但区域间的非均衡现象明显,城市对外服务能力呈现出由东部向西部的梯度递减;省内差异对城市对外服务能力的差异贡献率最高,是空间尺度差异的主要来源;对外服务能力存在明显的俱乐部趋同现象和空间自相关性,对外服务能力相似的区域聚集分布,东、中、西部分别形成长三角、武汉-长沙、成渝等对外服务区域中心;时空演变表现出阶段性特征,经历由极化向均衡的转变。最后指出多中心发展和寻找新增长点应成为长江经济带城市对外服务能力提升的方向。