Effects of initial decomposing leaf litter of Cinnamomum camphora on the growth and physiology of Impatiens balsamina北大核心CSCD

A pot experiment was conducted to study the allelopathic effects of initial decomposing leaf litter of Cinnamomum camphora on growth and physiology of Impatiens balsamina. Three leaf litter treatments included 20, 40 and 80 g of C. camphora leaf litter mixed with 8 kg of soil, namely T1, T2, and T3, respectively. In order to test the effect of leaf litter addition on the permeability and ventilation of soil simultaneously, a parallel trial with steamed leaf litter was conducted with the three treatments of the leaf litter. The leaf litter was steamed for 2 d to remove the secondary metabolites as much as possible, dried, and then mixed with 8 kg of soil, namely Z1, Z2, and Z3, respectively. No leaf litter was added in control (CK). The growth parameters of I. balsamina were determined at the 20 d, 60 d, 100 d and 120 d after sowing and the main physiology indicators were determined at the 60 d. The results indicated that: (1) The ground surface diameter and height of I. balsamina were inhibited significantly at 60 d (P < 0.05). Photosynthetic pigments and gas exchange parameters of I. balsamina were inhibited significantly at 60 d, and the inhibition effect was stronger with increased amount of leaf litter addition. The chlorophyll content, Pn and Ls decreased significantly with increased amount of leaf litter (P < 0.05). The activity of superoxide dismutase (SOD) and peroxidase (POD) in leaves of I. balsamina decreased with the increase of leaf litter addition. The content of MDA in treatments T1, T2 and T3 were all higher than that in CK, which indicated that I. balsamina suffered oxidative damage in a certain degree. The content of free proline (Pro) and soluble sugar (SS) in leaves of I. balsamina decreased significantly with the increase of the leaf litter (P < 0.05), while the content of soluble protein (SP) increased. (2) In the parallel trial, 60 d after sowing, no obvious difference was observed between CK and any steamed leaf litter treatment in terms of the morphological and physiological features stated above (P > 0.05). It indicated that the soil physical properties were not greatly influenced by leaf litter addition in the dose interval designed, or that the release of secondary metabolites from decomposing leaf litter was probably a better reason to explain the inhibition of leaf litter treatment to I. balsamina growth. (3)The compound effect (CE) of leaf litter decomposition on I. balsamina was enhanced with increase of the leaf litter, to 0.169, 0.354, and 0.497, respectively, in treatments of T1, T2 and T3. The study indicated that initial decomposition of C. camphora leaf litter in soil reduces the content of photosynthetic pigments, inhibits photosynthetic capacity and resistance physiology of I. balsamina, weakens its adaptability to the environment, and restrains growth of the plant. © 2015, Science Press. All rights reserved.     

基于esp基因和JCV标记的MST方法在五大流域典型水源地中的应用

非点源污染目前已经成为影响水体环境的重要污染。微生物源示踪技术(microbial source tracking,MST)是解决非点源污染的一项新技术,它可以确定污染的宿主来源。肠球菌esp基因和多瘤病毒JCV可以作为检测水体中人源粪便污染的分子标记,其灵敏度和特异性都很高。为分析五大流域水源地是否受到人源粪便的污染,对辽河、海河、淮河、长江和黄河五大流域典型水源地水样进行采集和检测,选取人源粪便特异病原微生物肠球菌的esp基因和多瘤病毒JCV建立了相应的MST分子检测方法。结果表明,五大流域的典型水源地采样点均有可能受到了人源粪便的污染,可为当地相关部门提供技术支持和数据参考。     

银川东换流站MRTB转换失败引起闭锁原因分析

针对银川东换流站金属回线转换开关(Metallic Return Transfer Breaker,MRTB)转换失败引起直流闭锁的问题,通过对 MRTB 动作顺序、避雷器击穿原因、银川东换流站和胶东换流站保护动作进行分析,提出了采用延时 90 s 开放逆变站金属回线接地保护使能信号的方法,解决在转化过程中由于 MRTB 重合造成保护误动的问题。应用结果表明:该方法可以有效避免直流闭锁,保证了直流系统可靠运行。     

沿海城市多灾种耦合危险性评估的初步研究——以福建泉州为例

如何处理区域内多灾种之间的相互作用关系是当前多灾种综合风险评估研究的热点和难点之一。在梳理沿海城市多灾种之间相互作用关系的基础上,提出一种基于触发关系的多灾种耦合危险性评估方法。首先选取多指标建立单灾种分级方案,计算单灾种初始危险性指数;然后构建基于触发关系的多灾种耦合规则,结合GIS技术进行空间耦合,计算耦合后的危险性指数;最后对耦合后的多灾种危险性的综合进行了探讨。以福建省泉州市为例进行了案例研究,结果表明:该方法在多灾种耦合危险性评估中具有可行性,为后续多脆弱性和多灾种综合风险的研究提供支持,为决策者进行科学风险管理提供依据。     

煤矿突发事件应急救援的群决策方法

提出了基于直觉模糊集的煤矿突发事件应急救援TOPSIS群决策模型。其中决策者权重采用偏好值与群体平均偏好值的相似度计算,属性指标权重采用直觉模糊熵权法确定。通过直觉模糊加权集成运算将各决策矩阵进行合成得到综合决策矩阵,利用改进后的直觉模糊距离公式计算出全部备选救援方案到正负理想解的距离,根据TOPSIS运算结果可以确定最佳事故救援决策方案。最后通过黑龙江省鸡西某矿的实例分析,验证了该模型的有效性及合理性。     

赤潮灾害经济损失评估技术方法

为有效应对赤潮灾害防灾减灾、灾后救援及管理的需求,在综合分析前人提出的赤潮灾害损失评估技术方法的基础上,参考赤潮灾害对受灾体的危害特点,结合实际工作的需求及在实际中可获取的业务数据,提出了赤潮灾害经济损失评估指标体系;根据灾害经济学理论,借鉴其他自然灾害经济损失评估的先进思想,采用市场价格法,分别建立了包括海水养殖业经济损失、滨海旅游业经济损失、赤潮灾害业务与应急监测费用和赤潮灾害处置费用的赤潮灾害经济损失评估模型;最后,提出了赤潮灾害损失评估的技术流程。     

灾害条件下多层次应急疏散模型的构建方法研究

人们每天都要面对各种造成严重财产和人身安全损失的重大灾害,如何建立灾害条件下中国人口高密度大范围的应急疏散模型,具有重大的意义。该文基于我国灾害条件下高密度人口的集体疏散模式,按照灾害区域的具体情况和人口分布,以道路实时速度和路面损毁程度所决定的道路阻抗性作为评判道路疏散能力的依据,构建从危险区域的多集结点到安全区域的多安置点的多层次应急疏散模型,确定集体疏散人员的疏散路径、人数和车辆,实现在最短的时间内的受灾群众整体最优疏散,并以山东省德州发生地震作为实验区,采用Google Map API和C#搭建多层次应急疏散平台,验证了多层次应急疏散模型的可行性。     

Impact of dissolved organic matter on the photolysis of the ionizable antibiotic norfloxacin

Norfloxacin (NOR), an ionizable antibiotic frequently used in the aquaculture industry, has aroused public concern due to its persistence, bacterial resistance, and environmental ubiquity. Therefore, we investigated the photolysis of different species of NOR and the impact of a ubiquitous component of natural water — dissolved organic matter (DOM), which has a special photochemical activity and normally acts as a sensitizer or inhibiter in the photolysis of diverse organics; furthermore, scavenging experiments combined with electron paramagnetic resonance (EPR) were performed to evaluate the transformation of NOR in water. The results demonstated that NOR underwent direct photolysis and self-sensitized photolysis via hydroxyl radical (·OH) and singlet oxygen (¹O₂) based on the scavenging experiments. In addition, DOM was found to influence the photolysis of different NOR species, and its impact was related to the concentration of DOM and type of NOR species. Photolysis of cationic NOR was photosensitized by DOM at low concentration, while zwitterionic and anionic NOR were photoinhibited by DOM, where quenching of UOH predominated according to EPR experiments, accompanied by possible participation of excited triplet-state NOR and ¹O₂. Photo-intermediate identification of different NOR species in solutions with/without DOM indicated that NOR underwent different photodegradation pathways including dechlorination, cleavage of the piperazine side chain and photooxidation, and DOM had little impact on the distribution but influenced the concentration evolution of photolysis intermediates. The results implied that for accurate ecological risk assessment of emerging ionizable pollutants, the impact of DOM on the environmental photochemical behavior of all dissociated species should not be ignored.