《红楼梦》中的海啸

针对<红楼梦>第70回中记载的海啸,利用多种历史海啸资料进行了分析,结果表明,其提出的海啸系1751年3月15日(农历),在掖县、维县、平度、昌邑发生的海啸.     

蔬菜镉(Cd)富集因子变化特征及其影响因素

本研究以湖南省攸县为例,测定重金属镉(Cd)在585个灌溉水样品和625对土壤蔬菜样品中的含量水平,结合农业与气象调查数据,应用典型相关分析及路径分析模型研究各环境因子对于Cd在土壤-蔬菜系统累积水平的影响.结果表明研究区灌溉水、土壤、蔬菜中Cd含量差异较大.蔬菜Cd富集因子(PUF)服从自然对数分布,有10%的概率大于1.土壤pH和土壤有机质对PUF有着显著的直接效应,土壤阳离子交换量,灌溉水pH,降雨量和氮肥施肥量通过与pH及土壤有机质的相关关系间接影响PUF变化.研究区土壤pH和土壤有机质含量较低,对于Cd在土壤-蔬菜系统中的累积风险应给予一定关注.     

基于Matlab软件自动化求取参数的HEC-RAS模型构建

水质模型是水环境模拟的重要工具,近年来越来越多的应用于水环境预测与管理中,但平原河网水质模拟一直是个难点.本研究采用HEC-RAS模型开展湖州市长兴城区平原河网水动力和水质模拟.模型的水质模块率定采用Matlab软件自动化求取参数,代替常规试错法求参率定,减少了人工干预,提高了模型率定效率.HEC-RAS模型在平原河网地区水动力模拟结果较好,水质模拟结果基本符合要求,证明了HEC-RAS模型在平原河网应用的可行性,但模型的精度通常受水系概化、水文状况、污染源信息等因素影响,对于信息比较充分的短时段水质模拟其精度相对较好.     

Atmospheric deposition of PCDD/Fs measured via automated and traditional samplers in Northern Taiwan

Most polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the atmosphere are bound to particles which are suspended in the atmosphere, and eventually settle on soil, vegetation, water bodies or other receptors in the environment. Monitoring atmospheric deposition fluxes (dry/wet) is important in tracing the environmental fate and behavior of PCDD/Fs. PCDD/F depositions were collected via an automated PCDD/F ambient sampler and traditional cylindrical vessels, respectively, from April 2007 to February 2008. The automated PCDD/F ambient sampler used in this study can prevent both re-suspension and photo degradation of the PCDD/Fs collected and effectively separates the PCDD/F samples into dry and wet contributions. The results indicated that the ambient PCDD/F concentrations collected using the PS-1 sampler ranged from 0.02 pg I-TEQ/m³ to 0.16 pg I-TEQ/m³ in Northern Taiwan. The results also indicated that the PCDD/F deposition flux collected using the automated PCDD/F sampler (17.5 pg I-TEQ/m² d to 25.8 pg I-TEQ/m² d) was significantly higher than that sampled with the cylindrical vessels (2.0 pg I-TEQ/m² d to 9.9 pg I-TEQ/m² d). The difference was attributed to the fact that part of the PCDD/F depositions collected using the traditional cylindrical vessels had undergone photo degradation and evaporation. In addition, the wet deposition flux of PCDD/Fs (39.4 pg I-TEQ/m² rainy day to 228 pg I-TEQ/m² rainy day) observed in this study was significantly higher than the dry deposition flux (12.3 pg I-TEQ/m² sunny day to 16.7 pg I-TEQ/m² sunny day). These results demonstrated that wet deposition is the major PCDD/F removal mechanism in the atmosphere.     

Response of organic aerosol characteristics to emission reduction in Yangtze River Delta region

● The emission reduction causes significant change in organic aerosol composition. ● The atmospheric oxidizing capacity improved during emission reduction. ● The mixed oxygenated organic aerosol contributed higher during emission reduction. Organic aerosol (OA) is a major component of atmospheric particulate matter (PM) with complex composition and formation processes influenced by various factors. Emission reduction can alter both precursors and oxidants which further affects secondary OA formation. Here we provide an observational analysis of secondary OA (SOA) variation properties in Yangtze River Delta (YRD) of eastern China in response to large scale of emission reduction during Chinese New Year (CNY) holidays from 2015 to 2020, and the COVID-19 pandemic period from January to March, 2020. We found a 17% increase of SOA proportion during the COVID lockdown. The relative enrichment of SOA is also found during multi-year CNY holidays with dramatic reduction of anthropogenic emissions. Two types of oxygenated OA (OOA) influenced by mixed emissions and SOA formation were found to be the dominant components during the lockdown in YRD region. Our results highlight that these emission-reduction-induced changes in organic aerosol need to be considered in the future to optimize air pollution control measures.     

Microbial biomass carbon and enzyme activities of urban soils in Beijing

Introduction  

To promote rational and sustainable use of soil resources and to maintain the urban soil quality, it is essential to assess urban ecosystem health. In this study, the microbiological properties of urban soils in Beijing and their spatial distribution patterns across the city were evaluated based on measurements of microbial biomass carbon and urease and invertase activities of the soils for the purpose of assessing the urban ecosystem health of Beijing.     

Pd/CeO2-Al2O3对烟气中多环芳烃的催化氧化性能研究

采用浸渍法制备了不同负载量及不同钯铈比(Pd:Ce)的Pd/CeO2-Al2O3催化剂,并结合XRD、BET、SEM、O2-TPD和H2-TPR等方法对催化剂的性质进行了表征,研究了所制备的催化剂对燃煤烟气中多环芳烃(PAHs)的催化转化效率.XRD和SEM结果表明,Ce和Pd在Al2O3表面呈高度分散状态,有利于PAHs的催化氧化.BET测试表明,Ce的引入改变了催化剂表面孔径结构,提高其比表面积.O2-TPD和H2-TPR测试表明,适当钯铈比条件下制备的催化剂有较强的储氧能力和活性.催化氧化实验结果表明,所制备的Pd/CeO2-Al2O3催化剂对PAHs具有较高的转化效率,其平均转化率均在80%以上,且PAHs的毒性当量显著降低,钯铈比对PAHs的催化氧化性能影响较大,当催化剂的钯铈比为1:1时,PAHs的转化率最高,可达90%以上.     

钢框架侧板加强型梁柱节点滞回性能研究

提出一种改进型侧板加强型梁柱节点,加强板由矩形柱侧板和直角梯形梁侧板组成,以现有的梁端翼缘侧板加强型节点试验为基础,运用有限元软件ABAQUS对11个不同细部尺寸的改进型侧板加强型节点进行循环加载作用下的模拟分析。研究结果表明,采用上下两块小矩形柱侧板加强的节点模型在循环加载作用下并未出现加强板末端梁截面的屈曲变形,但该截面的应力集中有所减小,塑性变形仍集中在节点域柱腹板上;将上下两块小矩形柱侧板更换为一整块柱侧板后,其承载能力大幅提高,且塑性变形集中在梁侧板加强末端的梁翼缘和腹板上,而节点域处于弹性工作状态,说明该种节点形式可以更好地满足"强节点弱构件"的抗震设计思想;建议柱侧板两端各伸出柱翼缘表面50mm,柱侧板的高度与钢梁截面高度相同,柱侧板厚度取6mm,梁侧板宽度边缘与柱翼缘边缘平齐,端部三角形部分长宽比可取为1∶2~1∶3,梁侧板矩形部分长度可与三角形部分长度相同,或稍大于三角形部分长度。     

Application of Tradable Emission Permits in Europe

The purpose of this study is merely to review the current situation in the designing and implementation of the emission trading programs in Europe. Historical data show that although there is a series of shortcomings in their current functioning, employing such instruments for GHG reduction policy making is strongly expected to be efficient and effective. The European Union Emission Trading Scheme （EU ETS）, Clean Development Mechanism （CDM） and Joint Implementation （JI） are just a few examples of the ambitious EU initiative that heavily relies on such instruments. We dwell on their operations and achievements by far and all the content in this article is expected to convince the Chinese government and regional public authorities to take positive actions and attitudes in promoting these instruments.     

Reduction of dioxin emission by a multi-layer reactor with bead-shaped activated carbon in simulated gas stream and real flue gas of a sinter plant

A laboratory-scale multi-layer system was developed for the adsorption of PCDD/Fs from gas streams at various operating conditions, including gas flow rate, operating temperature and water vapor content. Excellent PCDD/F removal efficiency (>99.99%) was achieved with the multi-layer design with bead-shaped activated carbons (BACs). The PCDD/F removal efficiency achieved with the first layer adsorption bed decreased as the gas flow rate was increased due to the decrease of the gas retention time. The PCDD/F concentrations measured at the outlet of the third layer adsorption bed were all lower than 0.1 ng I-TEQ Nm⁻³. The PCDD/Fs desorbed from BAC were mainly lowly chlorinated congeners and the PCDD/F outlet concentrations increased as the operating temperature was increased. In addition, the results of pilot-scale experiment (real flue gases of an iron ore sintering plant) indicated that as the gas flow rate was controlled at 15 slpm, the removal efficiencies of PCDD/F congeners achieved with the multi-layer reactor with BAC were better than that in higher gas flow rate condition (20 slpm). Overall, the lab-scale and pilot-scale experiments indicated that PCDD/F removal achieved by multi-layer reactor with BAC strongly depended on the flow rate of the gas stream to be treated.