Pd/CZ/Al2O3催化剂的制备、表征与三效催化性能

以共浸渍法制得的氧化铝负载铈锆固溶体为载体,并浸渍贵金属Pd得到了Pd/CZ/Al₂O₃催化剂.实验结果表明,该催化剂在老化前后都表现出良好的三效催化活性,新鲜样品Pd/CZ/Al₂O₃活性与Pd/CZ相当,老化后样品前者优于后者.结合XRD,BET,TPR等表征手段,讨论了Pd/CZ/Al₂O₃的催化活性特别是高温老化后活性与其组成结构之间的内在关系,揭示了其老化后仍具有较高活性的主要原因在于保持了Pd与CZ/Al₂O₃复合载体之间的强相互作用(SMSI).     

潜流-垂直流改进型人工湿地处理河道水的研究

针对微污染河道水C/N比不足和磷浓度低的问题,将传统人工湿地改进后用于处理。改进后的人工湿地包含潜流段和垂直流段,潜流段填充沸石和腐木,其中腐木作为补充碳源,垂直流段填充水泥砖块,并种植美人蕉。试验结果表明:改进型人工湿地脱氮除磷效果良好,氮的去除主要发生在潜流段,氨氮和总氮的去除率达到90%以上,填充的补充碳源不会恶化水质;磷的去除主要发生在垂直流段,水泥砖块具有良好的去除低浓度磷的性能,但其寿命不长,需要及时的更换;美人蕉对湿地脱氮影响非常小。     

1990年以来我国大陆海岸线变迁及分形维数研究

选取1990年以来的9期的遥感影像共计371景,提取大陆海岸线数据,分析了海岸线长度历年变迁规律及分形维数的变化,得出以下结论:(1)近22 a来,我国大陆海岸线长度基本保持增长趋势;(2)自然岸线和河口岸线长度处于减少趋势,而人工岸线长度处于增加趋势,其增长速度大于自然岸线和河口岸线减少速度之和;(3)我国海岸线的分形维数呈直线增长趋势,其变化趋势与海岸线长度变化一致。     

Identification of Bacillus methylotrophicus and its application in preventing fly maggot production in the environment北大核心CSCD

This research aimed to screen Bacillus spp. to prevent the production of fly maggot on kitchen wastes from soil in the experimental bases of the South China Agricultural University. A nutrient-rich medium was used to isolate the Bacillus spp. with high temperature treatment. The seventeen Bacillus strains were obtained and assigned to three groups by using Insertion Sequence based PCR (IS-PCR) DNA fingerprinting patterns. The homology of the 16S rDNA gene was 100% between Group I and Bacillus methylotrophicus CBMB 205T, 99.61% between Group II and Bacillus aerophilus 28KT, and 99.87% between Group III and Bacillus cereus ATCC 14579T. The results of kitchen waste tests proved that the representative bacteria of Group I RF2 had the ability to prevent fly maggot production on kitchen wastes. Furthermore, the results of physiological and biochemical tests, carbon utilization tests, and antagonists against plant pathogen tests showed that the bacteria from Group I RF2 had the ability to decompose glucose into pyruvate and then decarboxylate pyruvate to diacetyl under alkaline conditions, convert ammonia to intracellular amino acids or other kinds of nitrogenous compounds, use many kinds of carbon source for self-growth, and be antagonistic against plant pathogenic rice sheath blight disease, banana fusarium wilt, and Fusarium oxysporum. Besides, the bacteria from RF2 could secret organic acids to dissolve insoluble phosphate [Ca3(PO4)2] for its own growth by decreasing the pH. Group I RF2 was a strong plant-promotion bacterium, and had good prospects of application for preventing fly maggot production on kitchen wastes. © 2018 Science Press. All rights reserved.     

End-of-life batteries management and material flow analysis in South Korea

Analysis of collection and recycling system of end-of-life batteries was examined. Relatively limited fractions of portable batteries were collected by EPR system. More effective and diverse collection pathways should be developed. Consumers increasingly have worn-out batteries as electrical and electronic equipment with new technical developments are introduced into the market and quickly replace older models. As a result, large amounts of end-of-life (EOL) or waste batteries are generated. Such batteries may contain a variety of materials that includes valuable resources as well as toxic elements. Thus, the proper recycling and management of batteries is very important from the perspective of resource conservation and environmental effect. The collection and recycling of EOL batteries is relatively low in South Korea compared to other countries, although an extended producer responsibility (EPR) policy was adopted for battery recycling in 2003. In this study, the management and material flow of EOL batteries is presented to determine potential problems and quantitative flow, based on literature review, site visits to battery recycling facilities, and interviews with experts in the Korea Battery Recycling Association (KBRA), manufacturers, and regulators in government. The results show that approximately 558 tons of manganese-alkaline batteries, the largest fraction among recycling target items, was disposed in landfills or incinerators in 2015, while approximately 2,000 tons of batteries were recovered at a recycling facility by simple sorting and crushing processes. By raising environmental awareness, more diverse and effective collection systems could be established for consumers to easily dispose of EOL batteries in many places. Producers, retailers and distributors in South Korea should also play an important role in the collection of EOL batteries from consumers. Lithium-ion batteries from many electronic devices must be included in the EPR system for resource recovery.     

基于抗侧刚度比的防屈曲支撑组合框架优化研究

针对某26层设置了防屈曲支撑的钢管混凝土组合框架的benchmark模型,以振型分解反应谱法作为基础算法,编制了基于遗传算法的优化程序,通过改变结构各层的抗侧刚度比,对设置防屈曲支撑的钢管混凝土组合框架结构进行了防屈曲支撑截面面积的优化设计,对以变化抗侧刚度比设计的结构和以固定抗侧刚度比设计的结构进行了弹性阶段和弹塑性阶段的地震响应对比分析。结果表明:以变化抗侧刚度比设计的结构能在不减弱抗震性能的同时,减少48%的防屈曲支撑用量。在罕遇地震作用下,以变化抗侧刚度比设计的防屈曲支撑的耗能比例达54.98%,充分发挥防屈曲支撑的塑性变形能力消耗地震能量,起到保护框架梁、柱的作用。     

双层打包带加固村镇砖墙的抗震性能试验研究∗

为了提高村镇砖墙的抗震性能,对2片双层打包带加固墙体和2片未加固对比墙进行拟静力试验,研究0.35MPa和0.6 MPa竖向应力的作用下,墙体的破坏形态、水平承载力、滞回性能和耗能等抗震性能。试验结果表明原墙体均发生剪切破坏,加固后墙体在0.35 MPa竖向应力作用下,发生弯曲破坏,在0.6 MPa竖向应力作用下,发生剪切破坏,加固减轻墙体破坏程度,减小了裂缝宽度,破坏时加固层和墙体整体性较好;加固后墙体的开裂和极限荷载均得以提高,竖向应力大时的墙体提高幅度大;加固后墙体的滞回曲线更为饱满,试件延性和耗能能力都有提高,竖向应力较小时,加固墙体水平荷载-顶点位移骨架曲线的下降阶段更为平缓,试件延性提高了50%,耗能能力提高了447%。双层打包带加固法可明显减轻墙体的破坏,有效提高墙体抗震性能,尤其对承受较小的竖向应力时效果更好,研究成果为打包带加固方法的发展和村镇砖墙实地加固提供参考。     

京津冀一次污染过程的星地同步动态监测分析

京津冀地区大气污染监管逐渐走向区域联防联控模式,卫星遥感可实现大范围实时动态监测,地基监测能够获取精细的网点信息.结合卫星和地基数据,可对区域污染的生消过程进行三维立体的跟踪.本文通过综合分析卫星遥感数据、地面PM_(2.5)浓度数据、激光雷达垂直污染监测数据以及气象数据,分析了2018年3月8～10日京津冀区域污染的形成过程、传输路径、影响范围以及气象因子变化.结果发现,本次污染覆盖范围面积达20万km~2左右,区域内以四级中度污染为主,区域间的污染传输过程非常典型. 3月8～9日北京-保定偏南风频率为50%左右,冀南部分地区到达100%,在持续偏南风作用下,北京-保定一带空气质量由一级优迅速升至四级轻度污染,气溶胶光学厚度高值区由京津冀南部的邯郸-邢台西部山前推至北部燕山前. 3月10日该区域转以弱偏北风为主,湿度明显升高,京津冀南部形成污染辐合,污染重心南移至邯郸-邢台东部;午后,北京转偏东风,空气质量由东向西递次转好.从激光雷达垂直观测结果看,重污染期间北京地区污染层主要出现在1 000 m以下.近地面800 m以下,1 200～1 500 m多次出现双逆温层,且逆温强度高达4～7℃,非常不利于污染物垂直扩散.由此可见,在区域能源消耗和污染排放量依旧很大的背景下,一旦气象条件转差,很容易形成区域性重污染.     

碘代X射线造影剂的环境浓度、分析方法与毒性评估研究进展

碘代X射线造影剂(ICMs)是使用最广泛的血管内药物,近年来在水生环境中频繁检出.由于其高稳定性、高极性和持久性,ICMs会在水生环境中持续存在并且难以被降解.在水生环境中会与消毒剂、天然有机物结合生成具有毒性的消毒副产物(DBPs),由于其本身毒性以及转化产物DBPs的毒性增强了环境健康风险,进而引发了人们的密切关注.本文介绍了ICMs的环境浓度、分析方法以及毒性风险.重点描述了ICMs的前处理技术、检测方法及ICMs毒性评价现状,并展望了以后ICMs毒性的研究方向.     

污染场地风险管控环境经济政策体系：国外经验与本土实践

快速城市化和工业化给我国带来了大量的场地污染问题,污染场地修复和风险管控成为国土资源可持续利用的重要领域,创新土壤污染防治经济政策,充分发挥市场调节作用是土壤污染防治的内在要求,是破解土壤生态环境问题、推进土壤污染防治管理转型的重要支撑。本文从经济政策的体系、投融资模式与机制等方面展开,对美国、德国、荷兰等发达国家的污染场地风险管控环境经济政策进行了梳理分析,总结其可借鉴的成功经验;介绍了我国污染场地风险管控环境经济政策实施现状,最终从完善调控体系、明晰权责归属、拓宽资金来源、规范资金运营、丰富投融资模式、探索费用效益分析机制等方面提出我国污染场地风险管控环境经济政策体系的改进建议。