A study of daily and seasonal variations of radon concentrations in underground buildings

A study of daily and seasonal variations of radon concentrations in underground buildings in major cities of China was carried out. According to the data from the Model 1027 continuous monitor, radon concentrations in the underground buildings changed through two cycles each day. The first cycle was from 12:00 to 0:00 and the highest or lowest value, depending on location, was at about 19:00. The second cycle had a little change. Based on the data from solid state nuclear detectors (SSNTDs), it was concluded that the radon concentrations in underground buildings in winter were lower than in summer, which was opposite to that above the ground level. Similar to that above the ground level, the radon concentrations in spring were close to the year-round average radon concentrations.     

某场地边坡稳定分析方法的比较研究*

为了对边坡稳定性分析方法进行研究,以某场地高填方边坡和直立边坡为研究对象,基于Geostudio、理正软件以及ANSYS软件,采用M-P法、Bishop法和强度折减法进行边坡稳定分析。结果表明:高填方边坡安全系数为1.3,为稳定边坡;AB,BC,CD段地块间边坡边坡安全系数依次为0.479,0.410,0.381,基坑边坡安全系数为0.436,均为不稳定边坡;其中,M-P法得到的安全系数偏保守,Bishop法得到的安全系数结果较可靠,强度折减法得到的结果最为理想。研究结果可为边坡稳定性研究与治理提供借鉴。     

水资源量与城市人口规模

城市发展与水资源息息相关。为保证城市规模的合理性,应综合考虑城市的水资源储量。通过城市水资源量估算城市人口规模的方法,以广西钦州水源工程为例,从钦州现有的几个水资源量分析钦州城市可能达到的人口规模,说明城市水资源是影响城市发展规模的主要因素之一。     

废水污染物总量监测中采样方法的研究

通过对21家有代表性的废水污染源进行现场采样、排放曲线分析、采样频率优化的研究,确定总量监测中采样频率优化结果,为污染源总量控制监测提供技术指导。     

城市土壤污染研究现状与趋势

城市土壤是城市生态环境系统的有机组成部分,对城市的可持续发展有着重要的意义.城市化和工业化进程的加快,造成城市土壤污染、侵蚀、酸化和硬化以及土壤生物和植被退化等一系列较为严重的城市环境问题,直接危及到城市居民的健康和安全;因此,城市土壤污染问题已经引起人们的高度重视.近10多年来,国内外有关城市土壤重金属污染,微有机物污染,生源要素污染和城市土壤污染的环境与健康风险评价等诸多研究取得了一系列的研究成果.本文主要就以上研究成果进行了较为系统地总结与阐述,并且在此基础上提出了今后有关城市土壤污染研究的发展重点与趋势,以期为改善城市生态环境质量提供重要的科学依据.     

Fe和Fe2+对混合细菌产氢发酵的影响

在研究Fe粉剂量和Fe²⁺浓度对混合细菌产氢发酵的影响基础上,确定Fe和Fe²⁺促进混合细菌产氢能力的最佳阈值,并对乙醇型发酵菌群在不同Fe粉和Fe²⁺浓度下的产氢量和最大比产氢速率进行考察和对比.结果表明,Fe粉和Fe²⁺对乙醇型发酵菌群的产氢能力均有明显的促进作用.以葡萄糖为底物,投加Fe²⁺试验中,Fe²⁺浓度200mg/L获得最大产氢量143.7mL/g,较对照组提高32%;Fe²⁺浓度50mg/L获得单位VSS最大比产氢速率21.2 mL/(h·g),较对照组提高33%.投加单质Fe试验中,Fe粉剂量1000mg/L获得最大产氢量156.1mL/g,较对照组提高44%;Fe粉剂量500mg/L获得单位VSS最大比产氢速率23.5mL/(h·g),较对照组分别提高47%.单质Fe浓度高于50mg/L时,对发酵菌群产氢的促进作用要优于同浓度下的Fe²⁺.同时对混合细菌中铁的全量和形态分布进行了考察.     

高铁酸盐对藻类肝毒素的降解

研究高铁酸盐对悦目颤藻(Oscillatoria amoena)肝毒素(Microcystin-LR)的降解效能及其与pH的关系. 结果表明,处理有机质含量很高的藻类肝毒素粗提液,当高铁投加量增到40mg/L,pH控制在6～10,肝毒素几乎被完全降解.同时高铁的还原产物Fe³⁺、Fe(OH)₃发挥其助凝、絮凝的作用,对水体中有机质吸附沉降去除,TOC去除率达到50%左右,铁几乎无残留.高效液相色谱分析发现,作用机制可能是高铁氧化或异构化Adda基团的共轭双键,使Adda基团的结构发生变化,从而降低其毒性.     

Propagation characteristics of subaerial landslide-generated impulse waves

Environmental Fluid Mechanics - Subaerial landslide-generated impulse waves were investigated in a rectangular prismatic channel based on the Froude similarity criterion. Landslides were modeled...     

Photochemical degradation kinetics and mechanisms of norfloxacin and oxytetracycline

Environmental Science and Pollution Research - The photochemical degradation of norfloxacin (NOR) and oxytetracycline (OTC) was investigated under ultraviolet (UV) irradiation. The results...