滤纸法测定膨胀土总吸力试验及基质吸力预测研究

采用滤纸法测定膨胀土体吸力时,滤纸与土体表面距离不同所测得的滤纸含水率也不一样,获得的总吸力亦不相同。为此采用滤纸法开展了不同距离下的膨胀土总吸力测定试验,获得了不同距离条件下滤纸含水率的变化规律。干密度较小时,滤纸含水率随距离的增大呈现"减小-增大-减小"的规律;干密度较大时,滤纸含水率随距离的增大逐渐减小,最终趋于稳定。距离为3cm时所测得的吸力离散程度较小,可作为测定土体总吸力的标准距离。根据总吸力-距离关系式,通过引入伪基质吸力的概念,计算得到伪基质吸力,并与相应的真基质吸力进行比较。结果表明:不同干密度及含水率下的膨胀土真基质吸力与伪基质吸力之间存在良好的线性关系。此法可为测定现场土体基质吸力提供新的思路。     

Preparation and assay of C-glucosyltransferase from roots of Pueraria lobata

C-glucosyltransferase (EC 2.4.1.X) is one of the key enzymes for the biosynthesis of puerarin. This paper describes the methodology in purification and assay of the enzyme for the first time in Puerarin lobata (Wild.) Ohwi. C-glucosyltransferase from roots of P. lobata was extracted and partially purified by (NH4)2SO4 saturation. The effects of pH, temperature, and substrate concentration on the activity of the enzyme were investigated. The properties of the puerarin produced by C-glucosyltransferase were studied by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). The peak activity of C-glucosyltransferase was detected in fraction of by 80% saturation of (NH4)2SO4 and the optimal conditions for enzymatic reaction were 35.5 micromol l(-1) of isoliquiritigenin and 560 micromol l(-1) of UDP-G at pH 8.1, 28 degrees C for 1 h. Mn2+ at 1 mmol l(-1) and Al3+ at 1 mmol l(-1) increased the enzyme activity, while Mg2+ inhibited its activity. The enzyme activity in Nicotiana tabacum and P. lobata were detected under the above assay conditions. Higher activity was found in roots than in leaves and stems of P. lobata, while no enzyme activity was detected in leaves of N. tabacum. It was the first time that activity of C-glucosyltransferase, which transforms isoliquiritigenin to puerarin, was detected in P. lobata.     

活性炭辅助微波热解污泥反应条件的试验研究

针对微波不能直接实现原污水污泥高温热解的问题,采用活性炭作为微波能吸收物质辅助污泥热解。对影响污泥热解效能的3个主要因素：污泥样品量、活性炭掺杂量和微波辐射功率,各做了3个水平的考察,得到了试验条件下的最优方案：污泥样品量30g、活性炭掺杂量6g、微波辐射功率1200W。结果表明：在最优试验方案下,污泥能在7min内升至920℃的高温,实现污泥快速、高效热解。通过分析3个因素对污泥热解效能的影响,进一步对最优试验方案下的固体产物吸收微波的性能及用其作为掺杂物辅助微波热解污水污泥的可行性进行了研究,结果表明：固体残渣吸收微波性能良好,可以代替活性炭作为更经济、高效的污泥微波热解辅助材料。     

Biosorption of Cr(III) from aqueous solution by freeze-dried activated sludge: Equilibrium,kinetic and thermodynamic studies

Batch biosorption experiments were conducted to remove Cr(III) from aqueous solutions using activated sludge from a sewage treatment plant. An investigation was conducted on the effects of the initial pH, contact time, temperature, and initial Cr(III) concentration in the biosorption process. The results revealed that the activated sludge exhibited the highest Cr(III) uptake capacity (120 mg·g⁻¹) at 45°C, initial pH of 4, and initial Cr(III) concentration of 100 mg·L⁻¹. The biosorption results obtained at various temperatures showed that the biosorption pattern accurately followed the Langmuir model. The calculated thermodynamic parameters, ΔG^o (−0.8– −4.58 kJ·mol⁻¹), ΔH^o (15.6–44.4 kJ·mol⁻¹), and ΔS^o (0.06–0.15 kJ·mol⁻¹·K⁻¹) clearly indicated that the biosorption process was feasible, spontaneous, endothermic, and physical. The pseudo first-order and second-order kinetic models were adopted to describe the experimental data, which revealed that the Cr(III) biosorption process conformed to the second-order rate expression and the biosorption rate constants decreased with increasing Cr(III) concentration. The analysis of the values of biosorption activation energy (E_a = −7 kJ·mol⁻¹) and the intra-particle diffusion model demonstrated that Cr(III) biosorption was film-diffusion-controlled.     

基于地理探测器的区域植被覆盖度的定量影响——以京津风沙源区为例

植被覆盖度（FVC）是衡量生态环境优秀的重要指标.本文基于MODIS NDVI数据,运用像元二分法模型,估算了2000~2018年京津风沙源区FVC,分析了其时空变化特征.在此基础上,基于地理探测器模型,定量分析了自然因素和人类活动因素等12个因子对京津风沙源区FVC空间分布的影响.结果表明,近20a来京津风沙源区FVC整体上呈增加趋势,增加率为8.2%.空间上,研究区73.7%的区域FVC在增加,其中显著增加的区域主要集中在晋北山地丘陵亚区、燕山丘陵山地水源保护亚区、大兴安岭南部亚区和科尔沁沙地亚区的南部.2000~2018年,降水是影响京津风沙源区FVC空间分布的主要自然因子,解释力为63.3%;年末大牲畜头数是影响FVC空间分布的主要人为因子,解释力为34.8%.自然因素和人类活动之间的双因子交互作用以双协同作用和非线性协同作用为主,表明相对于单因子,自然因素和人类活动间的交互作用对FVC的解释力更强.其中,降水与其他11个因子的交互作用对研究区FVC起主导作用,解释力超过60%.     

软质防弹材料的发展

近年来,软质防弹材料发展非常迅猛,本文系统地分析了软质防弹材料的防弹机理及其影响因素,提出了防弹装备设计的关注点。     

高职GIS应用类课程项目化教学改革与实践——以《环境规划与评价GIS技术》为例

基于工作过程的项目化教学是高职院校课程改革的方向,以《环境规划与评价GIS技术》课程为例,探讨了高职GIS应用类课程项目化教学的改革与实践,主要内容包括课程设计思路、教学目标、课程内容选取、项目化教学实施与课程考核等。实践证明项目化教学改革取得了良好的教学效果。     

Geological emission of methane from the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China

A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS) together, the 13C/12C ratios of methane in the flux chambers were measured. The results demonstrated that methane gases were liable to migrate from deep oil/gas reservoir to the surface through microseepage and p...     

乌兰察布市饮用水水源地现状及管理对策研究

《国务院关于落实科学发展观加强环境保护的决定》要求"环保工作要以饮水安全为重点,切实加强水污染防治工作",经济的高速发展对饮用水水源地环境影响的日益严重也使我们对饮用水水源地的管理提出了更高的要求。本文在对乌兰察布市饮用水水源地环境现状进行调查、总结的基础上,分析了乌兰察布市饮用水水源地环境保护管理方面存在的问题,并提出了相应的对策。     

湖南省雷电特征及闪电数据分析

湖南是雷暴多发区,雷暴分布是南多北少,西多东少。近35年地面雷暴观测数据显示,全省年平均雷暴数呈下降趋势。湖南闪电以负地闪为主,占总地闪的94．59％,平均闪电强度随着海拔高度的增加而加大,长沙、韶山为闪电强度低值中心。一天中13～20时是闪电高发期,正地闪的平均能量要大于负地闪。