Anthropogenic pollutants in the Russian Arctic atmosphere: sources and sinks in spring and summer

The 5-day forward and backward trajectories of air mass transport to three Russian Arctic points for each day in April and July over a 10-year period from 1986 to 1995 have been analyzed. The important features and seasonal differences in air exchange processes in various areas of the Arctic have been investigated. Taking into account seasonal variations in aerosol scavenging mechanisms and velocities, the average contributions of large highly industrialized regions of the Russian Arctic air pollution were estimated for April and July. Reasonable correspondence between the calculated mean concentrations for six anthropogenic chemical elements (As, Ni, Pb, V, Zn, Cd) and experimentally determined values have been obtained. The atmospheric pollution transport from the Arctic was studied as yet another way of cleaning the Arctic atmosphere, in addition to the traditionally considered wet and dry depositions onto the surface. The average apportionment of conservative contaminants after passing the observation points was estimated for spring and summer. The air masses passing through the observation points in spring may take about 20–40% of pollutants out of the Arctic. In summer, however, more than 90% of pollutants transported into the Russian Arctic deposit within 5 days onto the surface inside the Arctic region. The monthly average fluxes of six anthropogenic elements onto the surface in the Russian Arctic were estimated for April and July.     

基于HYDRUS-1D模型的植物根系对人工基质水分特征曲线参数的影响

为了定量揭示绿色屋顶植物根系对人工基质水力特性的影响,选用两种景天属植物（垂盆草和佛甲草）及两种人工基质（珍珠岩和蛭石）进行水分及溶质运移实验,基于HYDRUS-1D模型反演人工基质水分特征曲线参数,以此分析植物根系所引起的人工基质水分特征曲线参数的变化.结果发现,植物根系使两种人工基质残余含水率θ_r降低、权重系数w增加.不同植物根系对两种人工基质饱和含水率θ_s的影响不同, 体现为垂盆草根系相较佛甲草根系对θ_s的影响范围更小.植物根系对人工基质吸力参数α₁、α₂的改变效应随人工基质种类发生变化,表现为珍珠岩基质α₁、α₂均因垂盆草根系得以提高、因佛甲草根系而降低,蛭石基质α₁、α₂则因植物根系分别降低和增加.研究结果可为绿色屋顶 植物-人工基质结构优化提供科学依据.     

定子叶片数对泵喷推进器空化性能的影响

目的 在改善泵喷推进器(泵喷)水动力性能的同时,兼顾其空化性能。方法 以某前置泵喷为原型,采用基于密度修正的RNG k-ε双方程湍流模型,结合Zwart空化方程,数值研究定子叶片数(Ns= 6~10)对空化性能的影响。结果 泵喷空化主要为叶梢涡空化和叶片表面的片状空化,而时–频空化曲线与叶片数目有关,其中单转子表面空化与定子数目相关,而总空化面积与转–定子影响有关。结论 增加定子叶片数虽然提高了泵喷推力和扭矩,但转子叶片及叶梢负荷增加,使空化范围大幅度增加。最终Ns从6增加到10时,总空化体积涨幅超过5倍。分析空化流动中的涡量输运方程发现,膨胀收缩项在空化演化占主导作用,并且随着定子叶数的增加而增大。     

可持续交通消费的接受和使用行为研究——基于上海市汽车共享的调查

汽车共享作为中国新兴的可持续交通方式,如何成功的使消费者接受和使用,是研究的关键挑战。本文基于UTAUT2模型,选择上海市居民作为调查对象,发现价格价值对行为意向影响最大,其次为享乐动机、努力期望、绩效期望和便利条件,社群影响对行为意向影响不显著;行为意向和便利条件对使用行为有显著正面影响,便利条件对使用行为影响更大。进而,使用个人特征为调节变量(是否有私家车、网约车经验和婚姻状况)验证对模型路径的影响,绩效期望对行为意向的影响受到是否有车、网约车经验和婚姻状况三个因素的调节,无车、无网约车经验与未婚的受访者调节效应更强;便利条件对行为意向和使用行为的影响同时受到是否有车单个因素的调节,无车者的调节作用更强;价值价格对行为意向的影响受到婚姻状况的调节,未婚者的调节效应更强;行为意向对使用行为的影响受到是否有网约车经验的调节,无网约车经验的调节效应更强。基于汽车共享服务发展初期的市场调查,本文建议汽车共享企业应提前布局服务网络,扩大会员数量,宣传它与私家车相比的成本优势和共享的价值观,获得细分市场。     

User Perceptions and Attitudes on Sustainable Urban Transport among Young Adults: Findings from Copenhagen,Budapest and Karlsruhe

Abstract

This paper addresses the relevance of the demand side for the achievement of sustainable transport in urban areas. The underlying thesis is that a better understanding of user habits, perceptions and attitudes with its specific dynamics is essential for a successful design of targeted transport policies. In line with this, the paper at hand is based on research that aims at improving the knowledge of urban-transport-related habits and attitudes of young adults. The results of three interview meetings that were held in Karlsruhe, Budapest, and Copenhagen with participants aged between 20 and 30 are presented. Background of the interviews is a range of studies that indicate that young people in urban areas seem to be less interested in cars than the generation before. And indeed, the interview meetings reveal that participants had a rather pragmatic attitude towards transport modes. They wished a transport system that is flexible, convenient and cheap. Despite many differences, most participants showed rather positive attitudes towards policies supporting alternatives to car-based transport. However, it will be crucial for policy shaping to what extent the observed behaviour patterns and attitudes will persist over time.     

Enhancement of simultaneous nitrogen and phosphorus removal using intermittent aeration mechanism

Biological nutrient removal grows into complicated scenario due to the microbial consortium shift and kinetic competition between phosphorus (P)-accumulating and nitrogen (N)-removing microorganisms. In this study, three sequential batch reactors with constant operational conditions except aeration patterns at 6 h cycle periods were tested. Intermittent aeration was applied to develop a robust nutrient removal system aimed to achieve high energy saving and removal efficiency. The results showed higher correspondence of P-uptake, polymeric substance synthesis and glycogen degradation in intermittent-aeration with longer interval periods compared to continuous-aeration. Increasing the intermittent-aeration duration from 25 to 50 min, resulted in higher process performance where the system exhibited approximately 30% higher nutrient removal. This study indicated that nutrient removal strongly depends on reaction phase configuration representing the importance of aeration pattern. The microbial community examined the variation in abundance of bacterial groups in suspended sludge, where the 50 min intermittent aeration, favored the growth of P-accumulating organisms and nitrogen removal microbial groups, indicating the complications related to nutrient removal systems. Successful intermittently aerated process with high capability of simple implementation to conventional systems by elemental retrofitting, is applicable for upgrading wastewater treatment plants. With aeration as a major operational cost, this process is a promising approach to potentially remove nutrients in high competence, in distinction to optimizing cost-efficacy of the system.     

桐梓河流域输沙量变化及其对气候和人类活动的响应

基于桐梓河流域二郎坝水文站1975-2015年长时间序列降水、蒸散量及输沙量数据,通过累积距平法、Morlet小波分析和Hurst指数等数理统计方法;定量分析了流域40年以来输沙量的演变过程以及未来变化趋势,并应用累积量斜率变化率比较法定量评估了研究区降雨量变化和人类活动对流域输沙量变化的影响和贡献率。研究结果表明：（1）40年来流域降水量介于608.10~1132.70 mm之间,其平均值为829.00 mm,呈不显著减小趋势,年均减小量为-3.10 mm/a。（2）流域年输沙量介于0.44万~478.01万t,其平均值为64.68万t,呈极显著减少趋势,减少速率为-4.13万t/a。未来流域输沙量呈持续递减趋势,但10年后将呈现出增加趋势。（3）1989年为流域输沙量的突变年份,1989年以前呈现上升趋势,1989年之后呈显著下降趋势,且突变年份后输沙量较突变年份前减少了76.82%。（4）输沙量存在12年左右的年代际震荡周期,形成了两个高震荡周期和一个低震荡中心,高震荡周期位于1976-1979年以及1986-1992年,低震荡周期位于1979-1985年。（5）多年季节输沙量呈持续性减少趋势,夏季输沙量在8年之后可能呈现出增加趋势,而其他季节则不存在持续性周期。（6）以1975-1989为基准期,降水量和人类活动对流域输沙量的贡献在1990-2015年分别达到4.87%和95.14%;如果考虑蒸发量对流域输沙量的影响,则人类活动对桐梓河流域径流量变化的贡献率在2003-2015年会增加到98.65%。流域输沙量在1990-2015年的减少主要由人类活动控制,人类活动每年导致输沙量减少1.57万t。     

影响上海PM2.5污染不同源地和路径的数值模拟

对2014~2017年上海出现的PM_2.5中度及以上污染过程的地面形势进行分析,发现上海出现PM_2.5中度及以上污染的地面形势场主要可分为输送型、静稳型和叠加型3种类型,其中输送型是影响上海市PM_2.5中度及以上污染的主要天气形势,占比45.8%.通过选取典型个例,分析了3类污染天气型气象成因和维持机制.并利用WRF驱动FLEXPART模式,结合排放源清单,探讨不同污染天气型下影响上海的主要污染物来源：输送型污染有3条影响上海的主要污染传输通道,分别为东路（东海海面）、中路（江苏沿海）和西路（安徽-苏南）,主要时段在污染前1d;静稳型污染影响上海的潜在污染源区集中在上海及周边地区;叠加型污染既存在明显污染输送通道,也有明显的上海及周边潜在污染贡献区域.     

哈尔滨市一次大气污染过程及潜在源分析

本研究以2018年12月10~13日哈尔滨市一次严重的空气污染事件为研究对象,分析了此次污染过程的概况、成因以及污染的潜在源区.结果表明：此次空气污染过程以PM_2.5影响为主,污染类型由10日00：00~11日17：00的偏燃煤型发展为11日17：00~13日15：00的二次气溶胶复合污染,最终在13日15：00后稳定为偏燃煤型.从天气形势和风速风向分析可知此次10~13日的污染过程与不利气象扩散条件也是密不可分的.模拟的48h后向轨迹经过聚类分析主要分为4类,大部分来自内蒙古、吉林等方向,70.83%的轨迹PM_2.5超标,表明来自这些方向的污染气团对哈尔滨市的空气质量影响较大;而通过对模拟的48h后向轨迹进行PSCF、CWT分析,发现哈尔滨的WPSCF和WCWT分布特征类似,WPSCF和WCWT的高值主要集中在哈尔滨本地的双城、巴彦、阿城、吉林省的中部、西部地区等地区,以及大庆、绥化等地区,说明这些区域都是哈尔滨市PM_2.5的潜在源地.     

关中地区秋冬季颗粒物二次有机碳的估算

2017年9月4日~2018年1月19日期间分别在关中地区的5个主要城市西安（XA）,渭南（WN）,铜川（TCH）,宝鸡（BJ）,咸阳（XY）设置采样点进行PM_2.5,PM₁₀颗粒物手工采样观测,采用热光透射法（TOT）分析碳组分,最小值法估算二次有机碳（SOC）浓度,结果显示PM_2.5与PM₁₀中SOC平均浓度分别为（7.44±5.54）,（9.62±7.49）μg/m³,一次有机碳（POC）平均浓度分别为（7.04±2.59）,（9.33±4.33）μg/m³,不同粒径颗粒物中SOC各点位的浓度值分布表现基本相同为XY > XA > WN > BJ > TCH.PM_2.5中SOC含量为8.76%,OC占比为48.03%,PM₁₀含量为6.28%,OC占比为48.09%,季节分布均呈现为秋季低冬季高,关中地区SOC污染严重.后向轨迹聚类分析结果显示污染气团传输主要是关中地区局部污染和西北,东北方向传输,其中局部污染轨迹的数量占比较多,浓度较高.低空传输与近地面风向风速及污染物分布存在差异,结合关中地区盆地地形,静风频率高,边界层低等多种因素造成颗粒物中SOC浓度较高,其中BJ点位易受到东北气团的污染物传输累积.