双圆形衬砌隧洞对柱面SH波作用下附近场地动力响应的影响分析∗

在柱面SH波作用下,由于弹性半空间中存在水平和垂直平行双圆形衬砌隧道,附近场地的动力响应将会受到影响。因此,本文基于弹性波理论,采用波函数展开法分析了双隧洞周围的柱面SH波散射问题,给出了双圆形衬砌隧道附近场地的位移解析解,并验证了该解的收敛性。通过对衬砌隧洞的衬砌刚度、隧洞埋深、两隧洞的中心间距以及入射波频率等参数的分析,研究了双圆形衬砌隧洞附近场地土体的位移幅值沿水平方向和深度方向的变化规律。结果表明:衬砌刚度、隧洞埋深、中心间距以及入射频率对双圆形衬砌隧洞附近场地的动力响应有着显著的影响。     

Soil temperature and moisture sensitivities of soil CO2 e ux before and after tillage in a wheat field of Loess Plateau, China

As a conventional farming practice, tillage has lasted for thousands of years in Loess Plateau, China. Although recent studies show that tillage is a prominent culprit to soil carbon loss in croplands, few studies have investigated the influences of tillage on the responses of soil CO2 e ux (SCE) to soil temperature and moisture. Using a multi-channel automated CO2 e ux chamber system, we measured SCE in situ continuously before and after the conventional tillage in a rain fed wheat field of Loess Plateau, China. The changes in soil temperature and moisture sensitivities of SCE, denoted by the Q10 value and linear regression slope respectively, were compared in the same range of soil temperature and moisture before and after the tillage. The results showed that, after the tillage, SCE increased by 1.2–2.2 times; the soil temperature sensitivity increased by 36.1%–37.5%; and the soil moisture sensitivity increased by 140%–166%. Thus, the tillage-induced increase in SCE might partially be attributed to the increases in temperature and moisture sensitivity of SCE.     

化工园区重点液态环境风险源监控布点研究

对环境风险源进行科学监控是从源头规避重大环境污染事故发生的有效途径,迄今为止我国在环境风险源监控布点方面尚未形成系统的技术方法。以化工园区重点液态环境风险源为对象,借鉴流域水质目标管理的理念,按照分区、分类、分级监控的原则,初步建立了化工园区重点液态环境风险源的监控布点方法,在阐述不同级别重点液态环境风险源监控布点区域一般要求的同时,提出了不同区域重点液态环境风险源监控布点的方法和依据,并以某化工园区为例进行了监控布点示范。     

武汉东湖近代沉积物中总氮、总磷与生物硅沉积与营养演化的动态过程

选择富营养化程度较高的武汉东湖作为研究对象,于2011年对其中4个子湖湖心的沉积物进行了采集,并分析了沉积物中总氮、总磷与生物硅含量。结果表明:对照东湖沉积速率(约0.33 cm·a-1),在底层41～50 cm(1860—1890年)与31～40 cm(1890—1920年),东湖4处子湖氮、磷、硅基本为湖泊自然沉积;在中层21～30 cm(1920—1950年),人类活动有所增强,沉积有所变化;表层沉积物0～10 cm(1980—2010年)、11～20 cm(1950—1980年)中氮、磷、硅沉积普遍上升,这一时期对应着东湖人类干扰活动的普遍增加。对东湖4个子湖的沉积物氮、磷与硅的对比研究表明:人类活动增加了对东湖氮、磷的排放,促进了东湖硅藻的生长及硅的消耗,东湖不同子湖之间氮、磷、硅的沉积存在着明显差异,这可能与人类活动的影响差异有关。     

好氧反硝化菌种DF2的分离鉴定及生理生化特性分析

分离了新型的高效反硝化细菌并研究其生物脱氮效率。通过观察形态学、生理生化鉴定和16SrRNA基因同源分析来鉴定菌种,致力于研究微生物污水脱氮处理的实际效果和克服反硝化过程中有害中间产物的积累。利用BTB培养基从水平潜流人工湿地基质中初步筛选出了9株平板阳性菌,革兰阴阳性均有。经试验研究发现该9种菌株在好氧条件下均具有一定的脱氮能力,其中以DF2和DF3 2种菌株脱氮能力最为显著,在3 d时间内NOX--N去除率达到了95%以上,NO2--N仅有微量积累;而其它7种菌株对NO3--N的去除率可以达到98%以上,但是NO2--N积累比较严重,积累量达到了NO3--N去除的50%~70%左右。经测序分析鉴定DF2和DF3分别属于德克斯氏菌属(Derxia)和假单胞菌属(Pseudomonadaceae)。德克斯氏菌属作为除氮的反硝化菌属在以往的研究中鲜有报道,该菌在好氧条件下可以合成周质NAR的亚基基因(napA)。     

融雪剂对大叶黄杨生长和生理特性的影响

为了研究融雪剂对道路绿化植物的影响,以大叶黄杨(Euonymus japonicus Thunb)为研究材料,研究了其在3种融雪剂(JLR-01、LBR-4、芦笛一号)不同施用量影响下的生长量和生理特性。结果表明:随着融雪剂LBR-4和芦笛一号的施用量的增大,大叶黄杨叶片的相对生长量和株高相对生长量、光合速率(Pn)、水分利用效率(WUE)、蒸腾速率(Tr)和气孔导度(Gs)随之减小,而低施用量的融雪剂JLR-01对大叶黄杨生长量、Pn、WUE和Tr有促进作用。随着融雪剂作用时间的延长,3种融雪剂的Pn和WUE也随之减小,Tr则是先减小后有所增大。当融雪剂施用量较小和胁迫时间较短时,Pn下降是因为气孔关闭;而当施用量较大和胁迫时间较长时,Pn下降是因为叶肉同化能力下降;3种融雪剂对大叶黄杨的胁迫程度由大到小的次序为:芦笛一号>LBR-4>JLR-01;大叶黄杨对3种融雪剂施用量的忍耐阈值在80 g.m-2左右,大叶黄杨对施用LBR-4和芦笛一号的耐受时间阈值大约为3周,对施用JLR-01的耐受时间阈值为3周以上。     

地震专家谈日本地震

记得法国伟大的文学家雨果曾经说过：＂地球是一个善良的慈父,同时又是一个凶恶的屠夫。＂我们生活的家园——地球,一方面赐予人类宜居的环境和丰富的资源,使人类得以一代又一代繁衍生息;另一方面,地球上频发的自然灾害,严重威胁和伤害着人类,地震、火山喷发、海啸、飓风、洪水、干旱等等,几乎无时无刻不在发生。     

加强城市空气污染应急管理 切实落实《大气污染防治行动计划》——第10届中国城市空气质量管理研讨会纪实

2014年6月24日,由环境保护部环境保护对外合作中心、亚洲清洁空气中心和美国能源基金会合作举办的"第十届中国城市空气质量管理研讨会:空气污染应急管理"在北京召开。来自地方环保部门、国内知名高校、研究机构以及新加坡和美国环保部门等单位80多位代表参加会议。本次研讨会针对中国重污染天气应急管理的现状与挑战,分析总结了空气污染应急管理的国际经验,重点讨论了亚洲及中国区域空气应急管理的经验、挑战和未来设想,并进一步根据中国城市在预测、预警以及应急响应方面的现状、挑战与需求提出了相关的政策建议与解决方案。会议有利地推动了地方环保部门落实《大气污染防治行动计划》,并为《大气污染防治法》的修订和城市空气污染应急管理工作提供了政策参考。     

Eco-Compensation in Multi-District River Networks in North Jiangsu, China

Eco-compensation is a multi-disciplinary topic. There is no consensus on the issue of river eco-compensation across districts. Although policies regarding river eco-compensation have been issued in China since 2008, due to the high cost, eco-compensation has not been well implemented in the Taihu pilot region. Therefore, a simplified method based solely on water quality (both water quality and water volume included in the Taihu method) was proposed for North Jiangsu province (NJP). However, the formula was flawed and it led to payments being too low. Three problems need to be solved: (1) how to specify the eco-compensation areas; (2) how to test a reasonable eco-compensation model and (3) how to determine the compensation criterion. Solving these issues is already a priority. In this paper, three potential solutions surrounding eco-compensation are discussed: (1) three principles for selecting the representative eco-compensation areas are suggested; (2) the compensation calculation method based on contaminant flux above the ultra standard is revised and (3) a compensation criterion model based on the treatment costs of sewage is proposed. In the NJP case in 2009, the average eco-compensation criterion for chemical oxygen demand (COD) is 2,000 Chinese Yuan (CNY) per ton and ammonia nitrogen (NH₄–N) and total phosphorus (TP) are 8,000 CNY and 80,000 CNY per ton, respectively. Five districts needed to be compensated. The payments in the revised scheme were 4.15–586 million CNY, which were 16–48 times greater than that in the draft method. The new method can provide an important template for managers when drafting river eco-compensation schemes.     

Partial anammox achieved in full scale biofilm process for typical domestic wastewater treatment

• A full scale biofilm process was developed for typical domestic wastewater treatment. • The HRT was 8 h and secondary sedimentation tank was omitted. • Candidatus Brocadia were enriched in the HBR with an abundance of 2.89%. • Anammox enabled a stable ammonium removal of ~15% in the anoxic zone. The slow initiation of anammox for treating typical domestic wastewater and the relatively high footprint of wastewater treatment infrastructures are major concerns for practical wastewater treatment systems. Herein, a 300 m³/d hybrid biofilm reactor (HBR) process was developed and operated with a short hydraulic retention time (HRT) of 8 h. The analysis of the bacterial community demonstrated that anammox were enriched in the anoxic zone of the HBR process. The percentage abundance of Candidatus Brocadia in the total bacterial community of the anoxic zone increased from 0 at Day 1 to 0.33% at Day 130 and then to 2.89% at Day 213. Based upon the activity of anammox bacteria, the removal of ammonia nitrogen (NH₄⁺-N) in the anoxic zone was approximately 15%. This showed that the nitrogen transformation pathway was enhanced in the HBR system through partial anammox process in the anoxic zone. The final effluent contained 12 mg/L chemical oxygen demand (COD), 0.662 mg/L NH₄⁺-N, 7.2 mg/L total nitrogen (TN), and 6 mg/L SS, indicating the effectiveness of the HBR process for treating real domestic wastewater.