Diversity and vertical distributions of sediment bacteria in an urban river contaminated by nutrients and heavy metals

The aim of this study was to investigate the benthic bacterial communities in different depths of an urban river sediment accumulated with high concentrations of nutrients and metals. Vertical distributions of bacterial operational taxonomic units （OTUs） and chemical para- meters （nutrients： NH4＋, NO3, dissolved organic carbon, and acid volatile sulfur; metals： Fe, Zn, and Cu） were characterized in 30 cm sediment cores. The bacterial OTUs were measured using the terminal restriction fragment length polymorphism analysis. Biodiversity indexes and multivariate statistical analyses were used to characterize the spatial distributions of microbial diversity in response to the environmental parameters. Results showed that concentrations of the nutrients and metals in this river sediment were higher than those in similar studies. Furthermore, high microbial richness and diversity appeared in the sediment. The diversity did not vary obviously in the whole sediment profile. The change of the diversity indexes and the affiliations of the OTUs showed that the top layer had different bacterial community structure from deeper layers due to the hydrological disturbance and redox change in the surface sediment. The dominant bacterial OTUs ubiquitously existed in the deeper sediment layers （5-27 cm） corresponding to the distributions of the nutrients and metals. With much higher diversity than the dominant OTUs, the minor bacterial assemblages varied with depths, which might be affected by the sedimentation process and the environmental competition pressure.     

沉积物再悬浮对浮游细菌群落结构的影响

本研究通过小宇宙的模拟实验,设置3组处理,即无再悬浮的对照组(C)、强(SR)和弱(WR)2个不同再悬浮强度的处理组,采用末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)和变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)分析不同处理组中浮游细菌群落结构的变化.结果表明,再悬浮处理组浮游细菌的物种丰度高于对照组,并且弱再悬浮中浮游细菌物种丰度高于强再悬浮处理.弱再悬浮中细菌多样性也高于强再悬浮处理.浮游细菌与环境因子的典型对应分析(CCA)和冗余分析(RDA)结果表明,浮游动物枝角类(Cladocera)生物量和颗粒态磷(PP)浓度与浮游细菌群落结构动态变化均表现出显著的相关性(p0.05).由此可见,沉积物再悬浮对浅水湖泊浮游细菌的种类和多样性存在重要影响,其可能通过影响浮游动物群落结构以及水体中营养盐的形态和浓度对浮游细菌群落产生影响.     

“限塑令”对塑料袋回收利用影响的分析

针对我国塑料袋回收利用的现状及案例调研显示,“限塑令”对塑料袋的回收利用具有促进作用;但“限塑令”实施的预期效果目前尚不明显。“限塑令”有待进一步推广,相应的回收利用体系也亟待建设与健全。     

限制油料中的含硫量是确保烟气达标排放的有效途径

通过对燃油锅炉监测结果的统计而推导出二氧化硫与油品中含硫量的关系公式 ,再求出二氧化硫浓度达标排放的含硫量限制水平及可行性。     

长江流域空间经济系统的特征研究

从空间经济系统的角度来看,长江流域经济发展有三个具有内在联系的基本特征。道德是流域经济发展的空间差异性。这一特征集中体现在流域内各地区之间经济发展基础、经济发展速度、经济发展水平等同空间差异。其次是流域经济发展与自然条件和资源的空间耦合性。区域自然系统对区域经济发展有明显的作用和影响,突出地表现了上游经济发展属资源密集型、中游经济发展属劳动力密集型和资源密集型并存、下游为资金技术型。第三是流域经济     

生态环境约束下的黄河三角洲资源开发的思路与模式

黄河三角洲拥有十分丰富的土地资源、石油天然气资源、水沙资源与海洋资源。经过近20年来的大规模开发,出现了诸如土壤盐碱化加重、植被生态系统成逆向演化、海岸蚀退、生物多样性受到破坏等生态环境问题。根据实施可持续发展战略的要求,在对以往资源开发“外延式”模式进行反思的基础上,提出了协调好资源开发与生态环境保护的新思路,即:在保护生态环境的前提下,进行资源的适度开发,在资源开发过程中搞好生态环境保护;以建设生态经济区为目标,以资源高效利用为基础,以循环经济和链式经济为特色的区域经济发展新模式。并探讨了水土资源、能源等矿产资源和海洋生物资源可持续开发利用的途径与模式。     

Effect of short-term regional traffic restriction on urban submicron particulate pollution

During the 2013 and 2015 Lanzhou International Marathon Events(LIME1 and LIME2),the local government made a significant effort to improve traffic conditions and air quality by implementing traffic restriction measures. To fill the gap in information on the effect of short-period(several hours)traffic control on urban air quality,submicron particle size distributions and meteorological data were measured simultaneously during June 2013 and June 2015 in urban Lanzhou. The number and surface area concentrations of particles in the100–200 nm range declined by 67.2% and 65.0% for LIME1 due to traffic control,while they decreased by 39.2% and 37.1% for LIME2. The impact of traffic restriction on air pollution near the sampling site lagged behind the traffic control period for LIME2. In addition,the effect of traffic restriction on air pollution near the sampling site was dependent on the distance between the relative orientation of the sampling site and traffic-restricted zones,as well as meteorological conditions such as wind direction. The influence of traffic restrictions on the particle concentrations differed for different particle sizes. The size range most affected by traffic restriction was 60–200 and 60–300 nm for number and surface area concentrations in the urban environment,respectively,while for the particle volume concentration it was the 100–600 nm range. This study will provide a basis for implementation of future urban traffic-induced particulate pollution control measures.