北江流域抗生素污染水平和来源初探

北江是发源于湖南(武水)和江西(浈水),汇于广东韶关,流经广东全境并入海的三大河流之一。为了解整个北江抗生素污染情况,共设置44个采样点,并采集了河水及部分沉积物样品,较全面地分析了各样品中12种典型抗生素含量并初步探究了其污染来源。研究发现,包括北江源头在内的全河段均有抗生素的检出,5类抗生素在表层水和沉积物中的平均浓度分别为77.8 ng·L~(-1)和3.6 ng·g~(-1)。其中,大环内酯类污染最为严重,其含量范围为11.7~114.6 ng·L~(-1)和0~435.3 ng·g~(-1),远高于其他类抗生素。表层水中磺胺类的磺胺甲恶唑和氯霉素类的检出率达100%,其中以磺胺甲恶唑(14.7 ng·L~(-1))和阿奇霉素(25.0 ng·L~(-1))为主,而沉积物中以阿奇霉素(35.9 ng·g~(-1))、氧氟沙星(5.4 ng·g~(-1))和四环素(3.3 ng·g~(-1))为主。由于流域污染源种类和数量不同,各抗生素在北江中的分布也存在差异。表层水中抗生素含量水平表现为下游高于上中游,在沉积物中则主要集中于中、下游之间河段。这反映了人类活动强度对北江抗生素污染的直接影响。     

Crowding in platform staircases of a subway station in China during rush hours

Crowding during the morning peak hours at a platform staircase in a subway station in China was studied in this paper. Passenger flow was surveyed with normal evacuation time recorded. The evacuation process was simulated with the software buildingEXODUS. Predicted results on the total evacuation time and maximum flow capacity of the selected staircase were compared with the field observations. Two parameters, the width of staircase utilized per person and the maximum upstairs walking speed used in the software were identified to be noticeably different from the field studies. Predictions agreed better with the observations after tuning these two parameters. It is concluded that the evacuation simulation software can be applied for safety design with appropriate tuning on the key parameters through field tests.     

石溪岷江特大桥薄壁高墩安全施工技术

1工程概述 石溪岷江特大桥是乐宜高速公路上的一座特大桥,位于乐山市犍为县境内,全桥长1226m,其跨径分布为：16×40m（简支T梁）＋103m＋180m＋103m（连续钢构）＋3×40m＋2×30m（简支T梁）（见图1）。     

Grafting increases cadmium accumulation in the post-grafting generations of the potential cadmium-hyperaccumulator Solanum photeinocarpum

ABSTRACT

To determine whether grafting increases cadmium (Cd) accumulation in the post-grafting generation of hyperaccumulator plants, the effects of grafting on Cd accumulation characteristics of post-grafting generations of a potential Cd-hyperaccumulator Solanum photeinocarpum were evaluated in pot and field experiments. The following four grafting combinations were examined: ungrafted (UG), self-rooted grafting involving one S. photeinocarpum seedling (SG), self-rooted grafting involving two S. photeinocarpum seedling developmental stages (DG), and grafting on wild potato rootstock (PG). Grafting did not induce genetic changes in S. photeinocarpum, and increased the shoot biomass and the amount of Cd extracted by the shoots of the first, second, and third generations of S. photeinocarpum (PG > DG > SG > UG). Additionally, enhanced superoxide dismutase, peroxidase, and catalase activities and increased soluble protein contents of the first post-grafting generation were observed for the DG and PG, whereas only enhanced superoxide dismutase and peroxidase activities were observed for the SG. Grafting increased the DNA methylation levels by inducing hypermethylation in the first post-grafting generation (PG > DG > SG > UG). Therefore, grafting can enhance the Cd accumulation (phytoremediation) ability of post-grafting generations of S. photeinocarpum by enhancing DNA methylation levels, especially when wild potato rootstock is used.     

有毒物质毒性效应数据库在化学灾害性事故中的作用

介绍了国内外主要的有毒物质毒性效应数据库,其中包括英国DESCNET系统,美国化学信息网(CSIN)和化学物质毒性效应登记(RTECS),联合国环境规划署的潜在有毒化学品国际登记中心(IRPTC),匈牙利生物活性天然产物数据库(BNPD),中国国家有毒化学品基础数据库(NRPTC),中国防化研究院的化学毒物数据库(CTDB),化工部化工毒物咨询中心(CTSIS),中国预防医学科学院有毒化学品资料数据检索和咨询系统,中科院生态环境研究中心三致效应数据库。评述了各数据库的数据源、数据覆盖范围、数据的运行环境和检索方式等。     

危险废物回转式流化冷渣多段焚烧系统焚烧特性研究

危险废物的处理和处置是摆在我国各级市政府面前的紧迫任务。然而我国已经运行的危险废物焚烧装置普遍存在回转窑挂壁结渣、热灼减率偏高和污染排放超标等问题,作者通过将回转窑和流化床特点相结合的方法提出了一种新型危险废物回转式流化冷渣多段焚烧处置装置。该装置采用回转窑(一燃室)、二燃室和流化床结合的热解-流化焚烧工艺,特别是采用控制窑头温度避免了回转窑挂壁结渣;采用流化冷渣装置延长未燃烬渣的焚烧时间,解决了热灼减率偏高问题;水冷式烟气急冷装置可以将烟气温度从1 100℃降到200℃,防止了二恶英的尾部低温再生成。该系统运行稳定可靠,可以处理医疗垃圾和大多数的固态和液态危险废物,实现了烟气污染物尤其是二恶英排放达到国家标准的目标。同时对该系统运行时窑头温度分布、二燃室炉膛出口氧量变化、回转窑和炉膛升温特性、燃烧室外壁温度分布等几方面运行数据都进行了详细的介绍,为危险废物焚烧炉的运行提供了宝贵的经验数据。     

基于多层次灰色评价理论的海洋输油管道安全评估方法

针对海上输油管道在多层次、多变量、多种非定量因素的影响下缺乏有效定量评估手段的情况,建立输油管道体系的多层次安全评估指标,结合层次分析法,确定各层指标对应的权重,提出采用多层次灰色理论,对输油管道体系进行安全评估,将风险影响程度进行定量化处理,给出了在役输油管道的可靠性量化结果。多层次灰色评估方法针对少数据、小样本、信息不完全和经验缺乏的不确定性问题有着计算简便、直接、科学和实用的特点,可为海上输油管道的在役安全评估提供一种有效手段。     

多水源用水网络优化模型研究

为了解决含有多类供水水源的用水网络优化设计问题,研究了过程工业用水特点,将各用水单元看成水阱,各单元的排水看成潜在水源,从而将供水问题转化为水阱和水源的匹配问题,建立用于多水源用水网络优化的配水模型,并详细阐述该模型应用步骤及其特点。     

已二酸生产副产物——混合二元酸的综合利用

采用一水合硫酸氢钠作为催化剂,催化己二酸生产副产物——混合二元酸与甲醇反应合成混合二元酸二甲酯。优化工艺条件为：混合二元酸加入量0．1mol,无水甲醇加入量0．5mol,一水合硫酸氢钠加入量4．0g,环己烷加入量20mL,反应时间1．5h。合成混合二元酸二甲酯的酯化反应收率大于97％。经气相色谱检测,产物中酯的质量分数为98．91％。一水合硫酸氢钠可重复使用3次。     

莆田县土地利用特征及合理开发利用对策

土地利用作为人地关系研究的核心内容,是人地关系最直接的反映。本文对莆田县土地利用特征进行了分析,针对其存在的问题,提出了相应的解决对策